Weather Prediction Center

National Oceanic and Atmospheric Administration

Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
1238 PM EST Wed Feb 1 2017

Valid 00Z Thu Feb 2 2017 - 00Z Sat Feb 4 2017

...Rain and mountain snow returns to the western U.S. for the end
of the week...

After several days of a rather uneventful weather pattern across
most of the nation, things will begin changing for the West Coast
going into Thursday.  The western U.S. ridge will continue
breaking down and allow for a slow moving Pacific storm system to
work its way towards the Pacific Northwest coast and bring
moderate to heavy rain back to areas from central California to
western Washington.  Parts of the coastal ranges could get a
couple inches of rainfall by Friday night.  Heavy snow is expected
for the higher elevations of the Sierra and also for the northern
Rockies, where amounts in excess of a foot appear likely for the
higher elevations.

Elsewhere across the continental U.S., broad cyclonic flow aloft
will keep a cold and dry pattern in place for most areas.  Lake
effect snow is expected downwind of the Great Lakes, where
snowfall amounts in excess of six inches are possible.  Lake
effect snow warnings are in effect east of Lake Ontario, where the
greatest snowfall amounts are expected.  Another area of
precipitation in the form of rain is likely across portions of the
southern U.S. in association with a surface low developing along a
slow-moving cold front.  This should be a relatively minor event
with no widespread heavy rain or thunderstorms expected.

D.Hamrick


Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_wbg.php

EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1054 AM EST WED FEB 01 2017

VALID 12Z SAT FEB 04 2017 - 12Z WED FEB 08 2017

...OVERVIEW...

THE 00Z/06Z MODEL CYCLES HAVE CONTINUED THE TREND OF THE
LOW/TROUGH OVER THE NORTH PACIFIC TRACKING FARTHER SOUTH/SOUTHEAST
TOWARD THE ALASKAN AND BRITISH COLOMBIAN COASTLINE...WHICH WILL
RESULT IN ACTIVE WEATHER ACROSS THE NORTHERN STATES THIS
WEEKEND/BEGINNING OF THE WEEK. AN AMPLIFIED TROUGH WILL SET UP
OVER THE CENTRAL U.S. BY MIDWEEK...IN PART BY LOW OFF THE PACIFIC
NORTHWEST AND SHORTWAVE ENERGY CROSSING THE ROCKIES. GUIDANCE IS
SUGGESTING THAT A STRONG SURFACE LOW PRESSURE WILL LIFT THROUGH
THE MIDWEST/UPPER MIDWEST/GREAT LAKES AREA.


...GUIDANCE EVALUATION/PREFERENCES...

SOME ASPECTS OF THE CLOSED LOW NEAR VANCOUVER ISLAND ARE STILL
UNCERTAIN AS SOME OPERATIONAL RUNS SUGGEST THAT THE UPPER LOW
COULD BE COMPOSED OF A SERIES OF EJECTING AND RELOADING SHORTWAVES
RATHER THAN A SINGLE CIRCULATION.  THIS ALONG WITH THE NORTHERN
PACIFIC BEING AN AREA OF HIGH FORECAST UNCERTAINTY IN RECENT DAYS
SEEM TO MAINTAIN THE POTENTIAL FOR MEANINGFUL CHANGES IN FUTURE
RUNS. ADDITIONALLY... THE EVOLUTION OF THE INCOMING EASTERN
PACIFIC SHORTWAVE TO THE SOUTH AND ITS INTERACTION WITH THE UPPER
LOW ADDS TO THIS UNCERTAINTY.

MEANWHILE MODELS/MEANS CONTINUE TO SHOW A GENERAL AREA OF LOW
PRESSURE CROSSING THE EAST... MOST LIKELY BEST DEFINED ACROSS
NORTHERN AREAS... DURING THE WEEKEND IN ASSOCIATION WITH WEAK
SHORTWAVE ENERGY EMBEDDED IN LOW AMPLITUDE FLOW.  GUIDANCE
CONTINUES TO WAFFLE REGARDING THE POTENTIAL STRENGTH OF THIS
FEATURE.

THE MOST CURRENT RUNS OF THE UKMET/CANADIAN/GFS AND THE ENSEMBLE
MEANS ARE IN GENERAL AGREEMENT WITH A SLIGHTLY MORE
PROGRESSIVE/SOUTHERN LOW OVER NEAR COASTAL ALASKA/BRITISH COLUMBIA
AND AN AMPLIFIED TROUGH OVER THE CENTRAL CONUS FOR NEXT WEEK -
WITH INCREASING SPREAD Sunday AND BEYOND. WPC CHOSE A BLEND OF THE
00Z ECMWF AND ITS ENSEMBLE MEAN/06Z GFS AND ITS ENSEMBLE MEAN WITH
THE PREVIOUS FORECAST INITIALLY FOR SATURDAY AND SUNDAY. THE ECWMF
LAGS BEHIND OTHER GUIDANCE BY MONDAY INCREASING THE SPREAD
THEREAFTER. THE 06S GFS IS MORE PROGRESSIVE WITH THE PACIFIC
NORTHWEST LOW AND THE AMPLIFIED TROUGH OVER THE CENTRAL CONUS.
LESS EMPHASIS WAS PLACED ON THE DETERMINISTIC SOLUTIONS FOR MONDAY
- WEDNESDAY IN ORDER TO FIND A MIDDLE OF THE ROAD TRACK FOR THE
SURFACE LOW OVER THE PLAINS/MIDWEST/UPPER MIDWEST.


...WEATHER HIGHLIGHTS/THREATS...

SOME UNCERTAINTY REMAINS WITH THE EVOLUTION OF THE LOW/TROUGH OVER
THE NORTH PACIFIC AND THE BREAK DOWN OF THE WEST COAST RIDGE.
HOWEVER ONSHORE FLOW WILL LIKELY RESULT IN HEAVIEST COASTAL RAIN
AND INLAND/HIGHER ELEV SNOW TO FALL ACROSS FAVORED TERRAIN ACROSS
THE PACIFIC NORTHWEST...NORTHERN CALIFORNIA AND THE SIERRA NEVADA
RANGE- WITH SOME ENHANCED TOTALS ALSO OVER THE NORTHERN ROCKIES.
THE WIND ASSOCIATED WITH THIS LOW MAY ALSO BE STRONG AT TIMES AS
IT IS DIRECTED THROUGH THE MAINLAND. MUCH OF THE NORTHWEST AND
INTERIOR WEST WILL HAVE BELOW NORMAL TEMPERATURES DURING THIS
PERIOD...WHILE CENTRAL AND SOUTHERN REGIONS WILL BE SLIGHT BELOW
OR NEAR NORMAL.

EAST OF THE ROCKIES... AN AREA OF PRECIPITATION OF VARYING
INTENSITY WILL CROSS THE EASTERN HALF OF THE COUNTRY THIS WEEKEND
WITH SNOW TO THE NORTH AND RAIN ACROSS THE SOUTH... POSSIBLY
SEPARATED BY A NARROW BAND OF WINTRY MIX. A TRAILING FRONT
EXTENDING BACK INTO THE PLAINS MAY SUPPORT ANOTHER AREA OF
PRECIPITATION FOR EARLY NEXT WEEK AS IT LIFTS NORTHWARD AS A WARM
FRONT. THE SYSTEM THAT SPINS UP AND LIFTS THROUGH THE
MIDWEST/UPPER MIDWEST MAY POTENTIALLY HAVE VARYING PRECIPITATION
TYPES/INTENSITIES AS WELL AS STRONG ACCOMPANYING WIND GUSTS. HEAVY
RAINFALL MAY BE POSSIBLE AHEAD OF THE ADVANCING FRONT. MUCH OF THE
CENTRAL AND EASTERN STATES SHOULD SEE A PRONOUNCED WARMING TREND
BY NEXT WEEK AHEAD OF THE PLAINS-GREAT LAKES SYSTEM... WITH A
DECENT AREA OF PLUS 10-20F ANOMALIES FOR HIGHS AND PLUS 20-30F
ANOMALIES FOR MORNING LOWS. MEANWHILE COLDER AIR WILL SPREAD
ACROSS THE NORTHERN PLAINS MON ONWARD WITH SOME HIGHS AT LEAST
15-20F BELOW NORMAL.

RAUSCH/CAMPBELL

QUANTITATIVE PRECIPITATION FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
501 PM EST WED FEB 01 2017


FINAL DAY 1...DAY 2 AND DAY 3 QPF DISCUSSION
VALID FEB 02/0000 UTC THRU FEB 05/0000 UTC
REFERENCE AWIPS GRAPHICS UNDER...PRECIP ACCUM - 24HR


DAY 1

WPC QPF STRONGLY FOLLOWED WPC CONTINUITY AND A MULTI MODEL GLOBAL
AND HIGH RES BLEND OVERALL FOR ALL AREAS...WITH SOME EMPHASIS
STILL GIVEN TOWARDS THE HIGH RES ARW/NMMB AND NAM CONUS NEST TO
SHOW GREATER LOCAL FORCING FOCUS. PLEASE REFER TO PRODUCTS FROM
THE WPC WINTER WEATHER DESK FOR ADDITIONAL WINTERY PCPN RELATED
DETAILS.


...CALIFORNIA...

SATELLITE IMAGERY SHOWS A WELL DEVELOPED AND SLOW MOVING CLOSED
LOW OVER THE ERN PAC OFF CA. THIS DEEP LAYERED LOW WILL SLOWLY
SLIDE TOWARD THE COAST AS PER LATEST BLENDED TPW LOOPS. SHORTWAVE
ENERGY ON THE SRN PERIPHERY OF THIS FEATURE WILL APPROACH THE CA
COAST LATER TONIGHT...AND WILL BE ASSOCIATED WITH AN ANOMALOUS
PLUME OF MOISTURE AS WELL. WHILE THIS SETUP IS CERTAINLY
ANOMALOUS...WITH PRECIPITABLE WATER AND INTEGRATED MOISTURE FLUX
BETWEEN THE CLIMATOLOGICAL 90TH AND 98TH PERCENTILE...AND LOW
LEVEL SOUTH SOUTHWESTERLY FLOW ABOVE THE 90TH PERCENTILE ENHANCING
UPSLOPE PRECIPITATION AMOUNTS...NOTHING ABOUT THE SETUP REALLY
JUMPS OFF THE PAGE AS BEING REALLY EXTREME...WITH ANOMALIES
GENERALLY LESS THAN WHAT WE HAVE SEEN WITH SYSTEMS EARLIER THIS
WINTER. WITH THAT SAID...THE FAVORABLE DYNAMICS AND ABOVE NORMAL
MOISTURE WILL STILL SUPPORT STEADY TO LOCALLY HEAVY PRECIPITATION
MOVING INTO THE CA COAST LATER WEDNESDAY AND THURSDAY. THERE
SHOULD BE ENOUGH INSTABILITY FOR INCREASINGLY CONVECTIVE ELEMENTS
AND EMBEDDED HEAVIER RAIN RATES WITHIN THE RAIN SHIELD AS IT MOVES
ASHORE AND FOR HEAVY SNOWS LATER OVER INTERIOR HIGH TERRAIN
INCLUDING ESPECIALLY THE SIERRA. THROUGH 00Z FRIDAY EXPECT TO SEE
RAINFALL AMOUNTS GENERALLY BETWEEN 0.5" AND 2.5" SPREAD SLOWLY
FROM THE CENTRAL CA COAST...WITH RAINFALL AMOUNTS UPWARDS TO
0.5"/HR THAT COULD LEAD TO LOCAL RUNOFF ISSUES.


...NRN INTERMOUNTAIN WEST TO THE N-CENTRAL ROCKIES/HIGH PLAINS...

PERIODS/BURSTS OF SNOW WILL CONTINUE ACROSS PORTIONS OF THE NRN
GREAT BASIN INTO THE N-CENTRAL ROCKIES/HIGH PLAINS. LINGERING
MOISTURE REMAINS PLUMED OVER THE REGION AND PERSISTENT ISENTROPIC
LIFT OVER A NEARLY STATIONARY BAROCLINIC ZONE WILL COMBINE WITH
FAVORABLE JET DYNAMICS/PROGRESSIVE IMPULSE PASSAGES TO PROVIDE
ASCENT. AMOUNTS WILL BE LOCALLY ENHANCED BY UPSLOPE FLOW...WITH
THE GREATEST ACCUMULATIONS EXPECTED OVER FAVORED TERRAIN OF NW WY
AND VICINITY WHERE POSSIBLE LIQUID AMOUNTS IN EXCESS OF .5" COULD
RESULT IN SOME LOCALLY HEFTY SNOW TOTALS.


...GREAT LAKES/NORTHEAST...

COOLED CYCLONIC FLOW AND A SERIES OF PROGRESSIVE EMBEDDED IMPULSES
ALOFT SHOULD SUPPORT PERIODS OF MODEST LAKE ENHANCED SNOWS TO THE
LEE OF THE GREAT LAKES...WITH SOME ACTIVITY SPREADING INTO THE
N-CENTRAL APPALACHIANS/FAVORED NERN US TERRAIN.


...SOUTHERN US...

EXPECT MODEST GULF INFLOW AND LOWER ATMOSPHERIC CONVERGENCE
ASSOCIATED WITH A WAVY FRONT TO SUPPORT DEVELOPMENT OF SOME MAINLY
LIGHT RAIN/SHOWERS SPREADING FROM OVER THE LOWER MS/TN VALLEYS
NEWD TO THE SRN APPALACHIANS. ACTUALLY DOWNPLAYED THE NAM CONUS
NEST IN THIS AREA THAT SEEMS TOO FAR NORTH WITH PCPN AXIS GIVEN
FRONTAL POSITION/INFLOW.


DAYS 2 AND 3...

...WESTERN U.S...

CONDITIONS ACROSS MUCH OF THE WEST WILL REMAIN UNSETTLED THROUGH
THE DAY 2-3 TIME FRAME.  THE UPPER LOW CENTERED OFF THE
OR/NORTHERN CA COAST AT THE START OF DAY 2 (00Z FRI) WILL PUSH
STEADILY EASTWARD AND SHOULD MAKE IT INLAND OVER NORTHERN OR
BETWEEN 00-06Z SAT. SHORT WAVE ENERGY ROTATING AROUND THE BASE OF
THE LOW WILL REACH THE CA COAST DURING FRI...WITH ONSHORE FLOW
INCREASING AS AN ASSOCIATED SURFACE FRONT PUSHES INLAND. 
COMBINATION OF HEIGHT FALLS...A RELATIVELY MOIST PACIFIC FEED
(PRECIPITABLE WATER ANOMALIES ABOUT 1-2 STANDARD DEVIATIONS ABOVE
NORMAL)...AND FAVORABLE DIFFLUENCE ALOFT WILL SUPPORT MODERATE TO
LOCALLY HEAVY PRECIPITATION ACROSS NORTHERN CA/SOUTHERN OR BY THU
EVENING.  AS THE SHORT WAVE PUSHES INLAND AND GRADUALLY
WEAKENS...PRECIPITATION WILL ADVANCE SOUTHWARD DOWN THE COAST AND
EASTWARD ACROSS THE NORTHERN INTERMOUNTAIN REGION OVERNIGHT THU
THROUGH FRI. HEAVIEST PRECIPITATION THROUGH DAY 2 WILL TEND TO
FOCUS IN TWO AREAS...ALONG THE NORTHERN CA COAST WITH PERSISTENT
ONSHORE FLOW TO THE SOUTH OF THE UPPER LOW CENTER...AND ACROSS THE
NORTHERN/CENTRAL SIERRAS AND SHASTA RANGE WHERE OROGRAPHIC LIFT
WILL ENHANCE TOTALS.  WITH THE MODELS IN RELATIVELY GOOD
AGREEMENT...WENT WITH A MULTI-MODEL BLEND...THOUGH TRENDED TOWARD
HIGHER RESOLUTION GUIDANCE WHICH WILL HANDLE QPF BETTER IN THE
TERRAIN.  OVERALL...AM EXPECTING AMOUNTS IN THESE REGIONS TO RANGE
FROM ABOUT 2-3 INCHES...WITH LOCALLY HIGHER TOTALS LIKELY. 	
WHILE OVERALL AMOUNTS ARE NOT EXTREME...HIGHER PRECIPITATION RATES
WITH ANY CONVECTIVE ELEMENTS AS THE SHORT WAVE/FRONT MOVE INLAND
COULD RESULT IN LOCALIZED RUNOFF PROBLEMS...PARTICULARLY AROUND
BURN SCAR REGIONS...SO OPTED TO MAINTAIN THE MARGINAL RISK FOR
EXCESSIVE RAINFALL FOR SECTIONS OF NORTHERN/CENTRAL CA.

FARTHER EAST...WITH PACIFIC MOISTURE OVERRUNNING A RETREATING
ARCTIC BOUNDARY...EXPECT GENERALLY LIGHT TO MODERATE PRECIPITATION
FROM EASTERN OR EASTWARD INTO THE NORTH-CENTRAL HIGH PLAINS. 
FAVORED UPSLOPE FLOW WILL SUPPORT HEAVIER AMOUNTS OF UP TO .50-1
INCH IN THE HIGHER TERRAIN OF WEST-CENTRAL ID AND WESTERN WY.

THE UPPER LOW OVER NORTHERN OR AT THE END OF DAY 2 WILL QUICKLY
MOVE INLAND AND SHEAR OUT ACROSS THE NORTHERN INTERMOUNTAIN REGION
DURING THE FIRST HALF OF THE DAY 3 PERIOD. WHILE WEAKENING...THERE
SHOULD BE ENOUGH HEIGHT FALLS/JET DYNAMICS TO WORK ON AVAILABLE
PACIFIC MOISTURE TO SUPPORT WIDESPREAD PRECIPITATION THROUGH MUCH
OF ID/WESTERN MT EASTWARD ACROSS WESTERN WY/NORTHERN UT.  UPSLOPE
FLOW WILL AGAIN FAVOR THE HIGHER TERRAIN IN WESTERN ID AND WESTERN
WY...WITH A SECONDARY MAXIMUM POSSIBLE OVER NORTHERN ID WITH A
COMBINATION OF HEIGHT FALLS AND OVERRUNNING OF THE PERSISTENT
ARCTIC BOUNDARY.  MEANWHILE...UPSTREAM...A STRONG SHORT WAVE
DIVING OVER THE ALASKA UPPER RIDGE WILL CLOSE OFF ANOTHER CYCLONE
OFF THE COAST OF BRITISH COLUMBIA.  THIS WILL MAINTAIN A
CONSISTENT STREAM OF PACIFIC MOISTURE INTO THE WESTERN
U.S...THOUGH THE FOCUS OF QPF WILL BE FARTHER NORTH THAN ON DAY 2.
 AGAIN...MODEL MASS FIELDS ARE IN DECENT AGREEMENT...SO GENERALLY
OPTED TO BLEND THE LATEST ECMWF/GFS AND IN-HOUSE BIAS-CORRECTED
ENSEMBLE QPF FOR THE DAY 3 QPF.  HEAVIEST AMOUNTS...IN THE
.50-1.25 INCH RANGES...ARE EXPECTED ACROSS WESTERN WA/OR SOUTHWARD
INTO NORTHERN CA. 

...WESTERN GULF COAST STATES THROUGH THE SOUTHEAST AND SOUTHERN
MID-ATLANTIC...

A WEAK SURFACE FRONT WILL EXTEND ACROSS THIS REGION DURING DAY
2...THEN PUSH SOUTHWARD AND SLOWLY DISSIPATE DURING DAY 3 AS HIGH
PRESSURE BUILDS ACROSS THE OH VALLEY AND MID-ATLANTIC STATES. 
MOISTURE AND LOW-LEVEL CONVERGENCE IS FAIRLY LIMITED IN THE
VICINITY OF THIS BOUNDARY...BUT LIFT IN THE RIGHT ENTRANCE REGION
OF A JET MAX EXITING THE EAST COAST COULD PROVIDE ENOUGH LIFT TO
DEVELOP A WEAK FRONTAL LOW OVER THE SOUTHEAST EARLY ON DAY 2.
CONSEQUENTLY...COULD SEE SOME LIGHT OVERRUNNING PRECIPITATION
ACROSS THE CAROLINAS THURSDAY NIGHT-FRIDAY. ON DAY 3...RETURN FLOW
AROUND THE HIGH WILL LIFT GULF MOISTURE INTO TX AND THE WESTERN
GULF COAST...SUPPORTING SOME LIGHT OVERRUNNING PRECIPITATION. 
OVERALL...EXPECT AMOUNTS ACROSS THIS REGION TO REMAIN BELOW .25
INCH EACH DAY.

...NORTHERN PLAINS...UPPER MS VALLEY...

SHORT WAVE ENERGY ASSOCIATED WITH THE SYSTEM MOVING INTO THE WEST
DURING DAY 2 WILL PROMOTE DEVELOPMENT OF A WEAK SURFACE LOW ON
SATURDAY ALONG THE ARCTIC FRONT OVER THE HIGH PLAINS.  THIS LOW IS
EXPECTED TO ADVANCE EASTWARD INTO THE UPPER MS VALLEY BY THE END
OF DAY 3.  MOISTURE IS LIMITED...BUT THERE SHOULD BE ENOUGH LIFT
WITH THE SHORT WAVE AND OVERRUNNING TO SUPPORT LIGHT SNOWS ACROSS
NORTHERN/CENTRAL MN AND WESTERN/CENTRAL WI. 

...GREAT LAKES STATES AND NORTHEAST...

A SHORT WAVE ROTATING UNDERNEATH THE VORTEX IN EASTERN CANADA WILL
MAINTAIN PERSISTENT CYCLONIC FLOW ACROSS THE LAKES THROUGH DAY
2...WITH THE MAIN POTENTIAL FOR ORGANIZED BANDS DOWNWIND OF LAKES
SUPERIOR AND ONTARIO. EXPECT THE HEAVIEST AMOUNTS OVER THE TUG
HILL PLATEAU REGION AS UPSLOPE FLOW ENHANCES LIFT.  THE SHORT WAVE
WILL ALSO PROVIDE LIFT TO SUPPORT MOSTLY LIGHT SNOWS ACROSS THE
HIGHER TERRAIN IN NORTHERN VT/NH AND WESTERN ME. CONSULT THE
QPFHSD FOR MORE DETAILS ON THE WINTER WEATHER IMPACTS.


GRAPHICS AVAILABLE ON THE WEB AT
WWW.WPC.NCEP.NOAA.GOV/QPF/QPF2.SHTML

SCHICHTEL/KLEIN

24HR QP VT 03/00Z
 0.01 484672 483663 481656 475649 467645 459644 454643 451641
      447638 442640 439643 437648 435653 435659 440670 446676
      454681 460687 462690 462694 458698 451704 447708 444710
      439711 439716 436721 431725 424731 422733 428733 427737
      423741 418743 415746 413751 414758 415767 414773 413780
      408782 404780 401785 393791 389793 386797 383801 383805
      389804 392801 396799 399798 402800 404805 408808 412819
      413826 415827 419817 423813 426813 428815 434822 449819
      453824 456830 457837 456841 454842 450845 448849 445854
      439856 431852 427850 423846 420844 418844 415849 413854
      410861 410867 412872 416873 427869 438868 445863 450860
      452857 455853 458855 460856 461860 462866 464884 465893
      466898 470898 474894 479885 485861 486855 484849 479840
      474830 468821 457803 456791 453784 451783 450780 448778
      444781 444786 443790 440789 437785 439779 440773 441767
      446756 448746 451741 455738 459740 465738 468736 471731
      473727 474721 478709 480697 482683 484672
 0.01 465184 466181 464180 459177 457172 458164 462156 463148
      462142 460116 462104 462097 461092 460079 457066 456062
      454058 451054 448051 432013 428010 424008 420009 416008
      413005 413011 411014 408014 406012 404014 401018 397020
      397023 399030 400035 401040 403046 402051 399053 402053
      406054 408052 411052 416053 418056 414059 410059 406058
      403060 400063 399068 399074 403078 413081 419090 421100
      422105 419109 410104 407101 402101 398108 399115 402119
      406122 411123 414126 417132 415146 413151 409154 406156
      404162 400170 395181 393185 389186 384187 380185 370179
      359178 356180 357186 361195 362199 361202 353197 350193
      347189 342197 343200 343206 345216 343220 343227 347234
      353241 360247 374260 382267 386269 390272 399277 407275
      411268 417270 419271 424271 429268 433259 454237 451233
      449228 454224 458223 460218 457214 453212 453206 455195
      458190 462186 465184
 0.01 439731 438730 436731 435732 434733 433734 431735 429736
      428738 428739 427741 427743 429745 430744 431742 432741
      433739 435737 436736 437734 438733 439731
 0.01 390721 388716 385722 384729 383734 383738 382741 384745
      386749 387753 389753 390748 390744 391739 388730 389728
      389723 390721
 0.01 370815 370811 367810 363813 357821 355827 350831 346833
      343838 341843 338847 334859 331869 327881 325887 322893
      318903 312911 310916 306920 303924 298927 296922 296918
      297914 297901 297893 294889 289891 287895 286900 286908
      286914 288917 288921 288929 286935 282947 277958 274968
      275971 275974 279975 285974 290971 294973 298970 304961
      308958 316959 326962 334961 342956 348947 352935 354930
      354921 353906 353897 353892 354890 360863 366840 369827
      369819 370815
 0.01 271802 269798 267794 264790 261787 258789 254791 251795
      250798 250802 252808 256808 260806 263807 267806 270803
      271802
 0.25 474863 474858 474853 473850 472845 471843 468841 466839
      464841 464846 465851 465853 466858 467862 469865 470868
      472869 474865 474863
 0.25 455157 456150 454146 451142 448140 444141 439140 436143
      434147 434153 439156 441159 445162 450161 454159 455157
 0.25 444223 431216 429218 427221 428225 429229 427233 422231
      419228 416225 413218 407213 402205 396201 381191 374186
      366185 364188 366191 371199 377205 381211 379214 375212
      366212 360207 350205 348210 349221 350226 351230 354233
      358234 366237 373243 379248 385254 389260 393263 398262
      401261 404257 406253 410253 417258 421258 421255 420252
      424249 430247 436243 439241 437237 433231 435227 440225
      444223
 0.25 454105 455099 454095 449090 442088 436091 430094 432102
      431111 433114 436114 441117 446122 451117 454108 454105
 0.25 438760 438758 438755 437754 436753 435753 433753 433754
      432756 432759 432761 433763 434765 436765 437763 437762
      438760
 0.25 417191 417189 416188 414188 412190 411192 410195 409197
      410199 410201 412202 413200 413198 414196 415193 417191
 0.25 425791 424790 423791 421791 421792 419794 418797 419799
      420801 422800 422799 423797 424796 424794 425793 425791
 0.25 429037 428036 427037 427039 429037
 0.25 345882 345873 343876 338889 336895 335902 334908 332913
      326925 323930 322933 323936 326941 330944 334939 336934
      339920 342907 344893 345882
 0.25 307943 305943 304943 303944 302945 302947 303948 304947
      305947 306945 307944 307943
 0.50 449109 450104 450100 448098 445097 441097 439098 437100
      437104 437107 440110 442111 445112 447111 449109
 0.50 417242 418237 416236 413231 414224 412219 394203 376189
      371187 369187 368190 375198 384206 388210 390215 388217
      383218 379220 376219 374216 365214 361210 355208 353209
      351211 352216 357225 367230 374234 378238 387244 398248
      408248 413246 417243 417242
 1.00 411226 409222 406219 400211 394207 387201 381195 377194
      379197 386203 393209 397217 404222 406227 409227 411226
 1.00 401242 400237 397234 395231 392227 389223 384222 380224
      377226 379230 381234 384237 388240 394240 397241 401242
      401242
 1.00 364218 363216 363215 362214 360213 359212 358212 357212
      358214 359217 361218 363219 364218
 1.50 390234 390232 390230 389229 388228 387227 385226 383228
      382230 382231 383232 384234 385235 386235 387236 388236
      389236 390234
 2.00 388231 386230 385230 386232 388231 

24HR QP VT 04/00Z
 0.01 514202 512189 509176 506162 499152 493142 488137 483133
      473126 467120 468114 471111 470108 466104 463103 462099
      463090 465083 464075 463069 461062 461057 460054 458046
      455038 453033 451024 448018 444014 439007 434999 428988
      423977 418966 416959 413954 411951 407950 405952 405956
      403974 406993 408005 412018 416031 418037 417045 416050
      414052 412055 408056 404055 399055 395059 393061 392065
      394067 398067 399076 402079 406077 411076 413076 415072
      422072 428073 431074 432078 433085 426085 423086 423088
      423096 424099 423101 417104 413109 405107 403111 405117
      406119 410120 416121 419122 421124 422132 420140 415153
      408166 404170 400175 395179 392181 391184 392188 390190
      386187 375182 371179 364178 358179 354182 349184 345180
      343166 339168 337170 336174 334176 333180 329187 318196
      317201 313206 308215 305219 310223 320221 326220 330220
      335221 343224 347228 350229 355232 362243 370251 374254
      379257 401269 403271 407273 414275 420278 425282 435291
      449292 453291 457289 461286 465280 472273 477270 482271
      487269 491263 498255 503249 505247 505243 507231 509225
      510220 511209 514202
 0.01 477689 476681 473676 472672 469672 466674 464678 462683
      460689 457693 451698 445707 441712 439719 431733 435731
      441729 443734 441736 435740 429742 427743 426746 427757
      430764 432781 433785 435787 438784 440770 446756 447751
      451747 455735 457728 459722 467712 472701 477689
 0.01 486864 480848 478843 477836 476820 475807 475796 473785
      472778 470771 465764 466773 466780 466787 467801 465806
      462809 460809 459805 458802 456786 454772 450767 449770
      448776 444778 442783 440793 434810 434812 436817 439822
      442824 448829 454831 455835 454838 452841 446850 442856
      441860 442863 447863 450860 456852 456848 457846 459847
      460851 461858 462866 462873 462888 463898 466901 470900
      474890 479882 483874 486864
 0.01 429783 429779 427777 426772 424775 421775 418776 417783
      417787 416790 416800 419804 421804 423801 425796 428789
      429783
 0.01 384124 383122 381121 379121 377123 375125 373129 372131
      372136 373138 375141 377141 377139 378135 380131 382129
      382126 384124
 0.01 371738 371728 369718 368713 366710 364708 360707 356707
      350708 343712 332724 329728 327735 321749 318767 317774
      317781 316785 314800 311817 307833 302852 295882 293889
      289896 282912 282916 281919 277927 275933 272939 264954
      261962 258970 257972 257977 259982 264987 267994 271002
      277006 282006 284008 295008 303000 302993 299984 301979
      301974 305965 310959 316954 331933 337917 339908 342899
      344892 344882 347865 349856 351846 352836 357830 360824
      363816 365801 364788 365778 366773 366767 366757 371738
 0.01 364157 362157 361154 361156 360159 362159 364157 364157
 0.01 269800 269796 267793 264792 262792 258792 257794 254795
      252798 251800 251804 254806 256806 260805 261804 265803
      267802 269800
 0.25 482252 483248 484243 482237 479231 474228 470226 469221
      469218 466216 461212 453211 442210 437209 437205 438201
      443203 446196 451191 455185 457180 456174 452161 451153
      449150 445148 443146 441142 439140 436139 432143 430150
      431158 433164 436179 437189 436196 431198 426199 413200
      399198 392195 385191 376185 371182 364181 358183 356186
      357189 361195 366199 369203 369206 367208 357202 351199
      347194 342191 337196 338203 340208 349216 359225 371234
      379240 389248 393252 399255 406259 415262 428265 434267
      441269 448270 454268 465264 473259 479256 482252
 0.25 471848 471845 470843 469843 468843 467846 468848 470850
      471848
 0.25 456710 457707 455706 454706 452708 451709 449710 448712
      448713 447714 447717 448719 450719 451718 452718 453715
      455713 456710 456710
 0.25 447116 448112 447107 446101 445098 441096 434096 429093
      429096 431099 429103 425106 424109 425113 429118 433119
      438116 442115 444117 447116
 0.25 431214 430213 429211 427212 426213 426214 426215 428217
      429216 430215 431214
 0.25 439760 439757 440755 439753 438750 436750 435751 434751
      433754 433756 433759 433761 434763 434765 435765 436766
      438765 439762 439761 439760
 0.25 360727 359723 356720 351721 347723 339729 337732 337738
      339743 343745 346747 348752 348758 350763 352760 354755
      354748 355742 356738 360729 360727
 0.25 307939 308937 307936 305937 305938 304939 305939 307939
      307939
 0.50 480244 480243 480241 479238 478235 477235 476233 474233
      473234 472236 473239 473240 475242 476243 478244 480244
      480244
 0.50 447253 449249 449244 449239 447236 442231 441221 435220
      429222 422224 419214 416209 411205 403202 395198 384192
      377188 370184 362183 360184 360189 364194 370199 378209
      380212 380216 371215 366214 359211 355212 357215 359219
      362221 383239 394247 400251 409255 423258 431259 439260
      444257 447253
 0.50 453174 450169 448163 447155 446152 443151 440146 437145
      435148 435152 436157 438162 442166 446172 449175 452176
      453174
 0.50 446111 446109 445108 444106 442104 441103 439103 437103
      435105 434107 433107 432109 433111 434111 435112 437111
      438111 440111 442111 443112 445112 446111
 1.00 434247 429240 420234 417231 415227 417222 417218 416215
      410214 403206 385196 378191 374188 369188 367190 368193
      370197 378204 391218 388221 384222 380225 380229 385236
      393242 403247 412249 422251 427252 431250 434247
 1.50 419240 418237 414235 412231 414225 415221 415217 410216
      407213 404209 401207 393202 379194 372190 370192 372195
      384207 389211 395218 402221 401226 398227 389226 385226
      384230 386234 390236 397241 401243 406243 413242 419240
 2.00 413224 413222 413219 412217 410218 409218 408219 407220
      406222 406224 405226 406228 408228 410228 412226 412225
      413224
 2.00 404240 404238 403236 402235 401235 400235 398234 397234
      395235 396237 397238 398239 399240 401240 403241 404240
 2.00 405217 404212 401209 397206 394204 389202 385200 381199
      383203 386206 390209 393213 396216 399218 403218 405217
 3.00 401213 400212 399211 398210 397209 395209 395210 395211
      395212 396213 398215 399215 401213 

24HR QP VT 05/00Z
 0.01 530240 526238 526233 530230 537206 539193 539178 539171
      538167 535155 533144 530134 522112 515093 510086 503080
      503077 504075 506072 509066 510052 508041 507034 506029
      503025 503018 503001 501990 500977 499973 500970 502965
      504954 503940 503931 502926 500913 497899 493889 472869
      475856 476850 475843 475837 472831 468823 467818 464813
      461815 462824 462833 462842 462856 463864 461866 458865
      450864 447863 444864 440866 436868 433869 428874 418888
      413894 408901 406906 403910 400920 398924 398931 398940
      389947 386949 383953 373970 371972 371979 376979 378977
      384972 389970 402959 407952 409949 409943 408941 409938
      412936 416933 418931 421931 438935 446941 451947 457954
      463963 469984 472994 475999 485015 489023 492025 493030
      490033 489038 488056 491066 489069 487069 485069 482067
      467061 464070 463084 464091 464094 461094 453094 451092
      446091 439089 434088 431086 424081 419073 417070 415065
      414061 410057 407054 402053 387062 376075 375079 379081
      384080 388082 394083 398083 402081 406081 413080 419083
      417087 416095 416101 414103 412102 406095 400101 396108
      388112 385114 381117 379121 375125 372132 371143 374148
      378152 381156 386157 397159 401160 404165 407173 407182
      406188 403191 398191 393190 382187 375183 369181 364180
      359181 355184 354189 357192 363197 377210 378213 374213
      370213 367212 365207 361204 356202 351198 347191 345185
      344180 341177 340175 336176 335182 335187 337196 338201
      340204 348211 354216 360223 363227 367230 374234 382242
      386246 388250 390260 392270 393272 398274 404276 407275
 0.01 407275 417273 420272 424273 426272 427274 430277 430280
      434284 438282 444280 446278 449279 452282 458280 461281
      464279 465287 464289 463294 461303 462309 466315 469317
      476318 482321 489322 492321 494318 496320 499322
 0.01 463710 461706 458703 455701 450703 446705 444709 442713
      440715 437714 437717 438724 440728 443731 445737 446744
      447748 450748 453743 454738 455727 459719 463710
 0.01 459830 454808 453798 449789 446787 444786 443783 441778
      440774 439768 440764 441752 442749 440745 433739 428742
      423749 425760 427764 428772 429775 431781 433792 434805
      433814 439820 446823 451828 453831 459830 459830
 0.01 418142 417136 415132 410128 403125 401122 399123 391124
      388125 384125 378130 378136 381138 385140 389141 397143
      403148 407149 410147 416144 418142
 0.01 367746 366736 364726 361718 357714 346707 343706 340706
      332710 329714 325720 321727 319733 313746 311752 309756
      309760 308767 302771 297772 293771 287770 283773 282777
      283782 284790 284798 293806 298809 303809 305812 312812
      317817 321817 323815 328811 338802 346792 351787 355781
      359774 362767 365757 367746
 0.01 372945 372938 370932 366929 364927 361927 354927 350930
      346934 343941 341943 339949 336956 335962 334966 332964
      326965 323966 319964 316962 310962 306962 303960 307948
      309941 309933 307926 303924 299925 296924 296920 295904
      293891 291888 289889 285893 282898 280902 277914 272928
      271934 268939 261960 255970 253975 253984 257994 262003
      269014 271017 276020 282020 285020 287018 298015 305016
      310018 318019 323022 325025 330027 334028 336026 339022
      343018 344012 344002 342997 340992 339988 340984 341969
      350963 355960 361956 364956 368952 371948 372945
 0.01 243803 242795 241790 238787 235787 230788 226793 223799
      223805 225815 227823 232826 235821 240816 243809 243803
 0.25 502270 505247 504236 502227 503215 503207 502202 500193
      504186 505181 506176 503168 500160 496153 494149 494143
      491137 485131 481129 476128 471130 467135 462136 459137
      454141 450142 446141 440138 436137 432140 430144 429149
      442176 444186 448190 456188 462183 466179 469177 471178
      478180 486184 489187 491190 489194 487196 481201 474204
      469206 466208 462207 459207 455208 452210 447208 441212
      433213 426215 424216 423212 427208 425203 423202 411210
      398201 383193 378190 371187 367187 368192 372197 381208
      383212 385217 382225 389237 395244 401249 408251 417252
      431252 444251 452251 459251 468254 473255 478257 490266
      496271 500272 502270
 0.25 449112 449105 447102 440096 436095 431093 428091 426096
      427101 424103 421106 419112 413116 412118 415119 420121
      423122 427121 434118 445118 449112
 0.25 409110 407109 406109 405110 404111 405113 407113 408112
      409110 409110
 0.25 412071 412070 411068 410067 408066 407066 405067 406069
      407070 408072 408073 408072 410071 412071 412071
 0.25 406116 404116 404114 403112 401113 400113 401114 403115
      404116 406116 406116
 0.25 234808 234806 234805 232806 234808 234808
 0.50 498229 499223 498217 496212 494209 488207 484206 476207
      469210 461211 445216 430219 426222 424227 421229 415228
      415223 416217 414215 411216 408217 406219 406216 405212
      403207 398203 391199 384198 376192 374194 376198 381204
      387212 391215 396217 399219 403219 406220 405225 403228
      399229 396233 396238 399242 404244 413246 422247 432246
      439245 447244 456245 466245 475249 484251 490253 491252
      492249 490243 488239 481232 483229 490231 495232 498229
 0.50 487164 485158 480154 476151 470148 464145 461146 460148
      460156 463162 467165 474168 481169 486166 487164
 0.50 454176 454169 454161 453157 451154 448150 443147 439143
      435143 434145 433150 434155 437159 442163 445167 449173
      452177 454176
 0.50 445111 444106 442104 441103 437102 436103 432104 430105
      428107 428110 428113 431114 433113 436112 438112 442112
      445111
 1.00 491219 491215 489213 484211 480211 475213 471216 466217
      462216 457217 447219 443220 439222 438225 439227 442229
      445228 453226 459227 464226 471220 475218 481220 487221
      491219
 1.00 478238 477236 476235 475235 474237 475239 477240 478238
 1.00 472158 473156 472154 471153 470153 469151 467150 466151
      465152 465154 465155 466157 467157 468158 470158 472158
      472158
 1.00 461238 460236 459235 459234 457233 456234 455234 453234
      452235 451235 449236 449237 449239 451239 452240 454240
      456240 458240 459240 460239 461238
 1.00 447157 447155 446154 445154 443153 441152 439153 440156
      441157 442157 444158 446158 447157
 1.00 426242 426238 425236 421235 418234 415233 413233 410235
      410238 412240 415243 418243 422244 424244 426242
 1.00 401213 400211 399209 399208 397206 396205 394204 392203
      391202 389202 387203 387205 388208 390209 391211 393212
      394213 396214 398215 400215 401213
 1.50 395210 395208 395207 394206 392205 390206 392208 393209
      393210 395210 395210 

EXCESSIVE RAINFALL DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
916 AM EST WED FEB 01 2017

...VALID 15Z WED FEB 01 2017 - 12Z THU FEB 02 2017...
...REFERENCE AWIPS GRAPHIC UNDER...DAY 1 EXCESSIVE RAINFALL...


MARGINAL RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
45 SW UKI 30 SW UKI 20 WSW UKI 20 SW UKI 15 SSW UKI 10 SE UKI
25 NNW STS 20 N STS 25 NNE STS 25 WNW VCB 20 WNW VCB 25 ENE STS
25 WSW VCB 20 WSW VCB 20 N APC 15 N APC 20 N APC 20 NNW APC
10 WNW APC 15 WNW APC 15 SE STS STS 15 S STS 25 W APC 15 WSW APC
15 WNW OAK SQL 10 SW NUQ SJC RHV 15 SE RHV 10 E WVI WVI
10 NNW MRY 10 WNW MRY 10 WSW MRY 10 S MRY 15 S SNS 20 SSE SNS
30 SSE SNS 35 N 87Q 30 N 87Q 20 N 87Q 20 NNW 87Q 25 NW 87Q
35 S MRY 35 WSW MRY.


15 UTC UPDATE...

OPTED TO MAINTAIN A MARGINAL RISK AREA...BUT SHRUNK THE PREVIOUSLY
ISSUED AREA TO FOCUS ON MOST FAVORED TERRAIN AND BURN SCAR AREAS.

SCHICHTEL 


...CENTRAL CALIFORNIA COAST...

A DEEP LAYER LOW OFF THE WEST COAST WILL SLOWLY PUSH EASTWARD
TODAY. SHORTWAVE ENERGY ON THE SOUTHERN PERIPHERY OF THIS FEATURE
WILL APPROACH THE CA COAST LATER TONIGHT...AND WILL BE ASSOCIATED
WITH AN ANOMALOUS PLUME OF MOISTURE AS WELL. WHILE THIS SETUP IS
CERTAINLY ANOMALOUS...WITH PRECIPITABLE WATER AND INTEGRATED
MOISTURE FLUX BETWEEN THE CLIMATOLOGICAL 90TH AND 98TH
PERCENTILE...AND LOW LEVEL SOUTH SOUTHWESTERLY FLOW ABOVE THE 90TH
PERCENTILE ENHANCING UPSLOPE PRECIPITATION AMOUNTS...NOTHING ABOUT
THE SETUP JUMPS OFF THE PAGE AS BEING REALLY EXTREME...WITH
ANOMALIES GENERALLY LESS THAN WHAT WE HAVE SEEN WITH SYSTEMS
EARLIER THIS WINTER. WITH THAT SAID...THE FAVORABLE DYNAMICS AND
ABOVE NORMAL MOISTURE WILL STILL SUPPORT STEADY TO LOCALLY HEAVY
PRECIPITATION MOVING INTO THE CA COAST LATER WEDNESDAY. OVERALL
NOT LOOKING LIKE ENOUGH INSTABILITY FOR INTENSE CONVECTION...BUT
SHOULD BE JUST ENOUGH WEAK INSTABILITY TO RESULT IN SOME
CONVECTIVE ELEMENTS AND EMBEDDED HEAVIER RAIN RATES WITHIN THE
RAIN SHIELD AS IT MOVES ASHORE. THROUGH 12Z THURSDAY EXPECT TO SEE
RAINFALL AMOUNTS GENERALLY BETWEEN 0.5" AND 1.5" ALONG THE CENTRAL
CA COAST...WITH RAINFALL AMOUNTS APPROACHING 0.5" IN AN HOUR FOR A
SHORT PERIOD OF TIME SOMEWHERE BETWEEN 06Z AND 12Z. OVERALL THE
FLOOD THREAT APPEARS LOW THROUGH 12Z THURSDAY...ALTHOUGH SOME
ISSUES COULD ARISE IN LOCATIONS MORE SUSCEPTIBLE TO
FLOODING...SUCH AS URBAN AREAS AND BURN SCARS...AND THUS WILL
CONTINUE THE MARGINAL RISK FOR PORTIONS OF THE CENTRAL CALIFORNIA
COAST.

CHENARD

PROBABILISTIC HEAVY SNOW AND ICING DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
250 PM EST WED FEB 01 2017

VALID 00Z THU FEB 02 2017 - 00Z SUN FEB 05 2017

DAYS 1 THROUGH 3...

...PACIFIC NORTHWEST AND CALIFORNIA TO THE NORTHERN/CENTRAL
ROCKIES AND GREAT PLAINS...

SNOWFALL WILL BECOME INCREASINGLY WIDESPREAD FROM PORTIONS OF THE
PACIFIC NORTHWEST AND THE HIGHER ELEVATIONS OF CALIFORNIA INTO THE
NORTHERN/CENTRAL ROCKIES DURING THE LATER HALF OF THE WEEK AND
EARLY THIS WEEKEND AS A DEEP UPPER TROUGH INITIALLY OFF THE WEST
COAST MOVES EAST AND GRADUALLY OPENS UP INTO A PROGRESSIVE TROUGH
AXIS ALONG WITH MULTIPLE LOW-AMPLITUDE VORT IMPULSES THAT WILL
PRECEDE IT.

THE INITIAL FOCUS FOR SNOW WILL AGAIN BE IN VICINITY OF AN ARCTIC
FRONT DRAPED ACROSS WYOMING AND INTO CENTRAL IDAHO AND
OREGON...WHERE INCREASING MOISTURE AND LIFT AHEAD OF SHORTWAVE
ENERGY DROPPING OUT OF BRITISH COLUMBIA WILL COMBINE WITH STRONG
LOW LEVEL CONVERGENCE ALONG THE FRONT TO GENERATE PERIODS OF
MODERATE TO HEAVY SNOW THROUGH THURSDAY. MEANWHILE...FARTHER EAST
WITH THE INITIAL SURGE OF ENERGY...A SWATH OF ACCUMULATING SNOW
COULD ALSO EXTEND EASTWARD INTO PORTIONS OF SOUTHWEST SOUTH DAKOTA
AND NORTHERN NEBRASKA IN RESPONSE TO AN UPPER LEVEL JET STREAK
ADVANCING EAST ACROSS THE CENTRAL ROCKIES AND INTO THE HIGH PLAINS
WHICH WILL HELP INDUCE A FRONTOGENETICAL BAND OF FORCING FOR AT
LEAST SOME LIGHT ACCUMULATING SNOWFALL THURSDAY THROUGH EARLY
FRIDAY. A FEW INCHES OF SNOW WILL BE EXPECTED HERE LOCALLY.

THE HEAVY SNOWFALL THREAT WILL BECOME A BIT FURTHER ENHANCED
FRIDAY INTO AT LEAST PART OF SATURDAY OVER THE HIGHER TERRAIN OF
NORTHERN GREAT BASIN AND NORTHERN ROCKIES AS MORE SIGNIFICANT
AMOUNTS OF UPSTREAM PACIFIC MOISTURE TRANSPORT AND WARM ADVECTION
ARRIVES AHEAD OF THE MAIN UPPER TROUGH. THE HEAVIEST SNOWFALL
THROUGH THE MULTI-DAY PERIOD WILL BE ACROSS THE UPSLOPE AREAS OF
THE SAWTOOTH RANGE OF IDAHO AND ESPECIALLY THE GRAND TETONS OF
NORTHWEST WYOMING. SNOWFALL TOTALS OF AS MUCH AS 2 TO 3 FEET ARE
EXPECTED AT THIS TIME...WITH ISOLATED HEAVIER AMOUNTS GIVEN THE
PERSISTENT MOIST UPSLOPE FLOW PATTERN.

ACROSS THE HIGHER TERRAIN OF THE CENTRAL AND ESPECIALLY THE
NORTHERN SIERRA-NEVADA...A MULTI-DAY HEAVY PRECIPITATION EVENT
WITH SEVERAL FEET OF NEW SNOW IS EXPECTED THROUGH SATURDAY...AS
THE UPPER TROUGH APPROACHES AND CROSSES THE REGION. THE STRONGEST
ONSHORE FLOW/MOISTURE TRANSPORT WILL ALLOW THE HEAVIEST SNOWFALL
TO OCCUR FROM THURSDAY NIGHT THROUGH FRIDAY NIGHT FOR THESE AREAS.
ON SATURDAY...THE REMNANTS OF THE ORIGINAL TROUGH AXIS WILL
ADVANCE INLAND ACROSS THE GREAT BASIN AND WEAKEN...AND THIS WILL
ALLOW THE SNOWFALL TO TAPER DOWN SOMEWHAT FOR THE SIERRA-NEVADA.
NEW SNOWFALL TOTALS HERE THROUGH SATURDAY OF AS MUCH AS 3 TO 5
FEET WITH ISOLATED HEAVIER AMOUNTS ARE EXPECTED.

FARTHER NORTH OVER THE PACIFIC NORTHWEST...THE INFLUX OF PACIFIC
MOISTURE AND WARMER PACIFIC AIR OVERRUNNING THE AFOREMENTIONED
ARCTIC FRONT DRAPED OVER THE GREAT BASIN WILL ALSO ALLOW FOR SOME
ACCUMULATING SNOW AND ALSO A LIKELIHOOD OF AREAS OF SLEET AND
FREEZING RAIN FARTHER NORTH ACROSS WASHINGTON AND OREGON. THE
HEAVIEST SNOWFALL POTENTIAL WILL BE RESIDING OVER THE
CASCADES...BUT SOME ACCUMULATING SNOW FOR CENTRAL/EASTERN OREGON
AND CENTRAL/EASTERN WASHINGTON WHERE LOCALLY SEVERAL INCHES CAN BE
EXPECTED. A NOSE OF WARMER PACIFIC AIR WILL ARRIVE WITH TIME...AND
SOME OF THE DEEPER INTERIOR VALLEYS WHERE SHALLOW ARCTIC AIR WILL
BE IN PLACE ARE LIKELY TO SEE AN INCREASED THREAT FOR SLEET AND
ESPECIALLY FREEZING RAIN. THIS WILL BE ESPECIALLY THE CASE FOR
AREAS OF SOUTHERN/SOUTHWEST WASHINGTON AND NORTHERN OREGON
INCLUDING THE WILLAMETTE VALLEY AND THE COLUMBIA RIVER GORGE WHERE
SOME SIGNIFICANT ICE ACCUMULATIONS WILL BE POSSIBLE. THE WORST
ICING CONDITIONS SHOULD BE ACROSS PARTS OF THE COLUMBIA RIVER
GORGE WHERE SOME MULTI-DAY ICE ACCUMULATIONS MAY APPROACH OR
POTENTIALLY EXCEED A 0.50 INCH. WILL NEED TO CONTINUE TO MONITOR
THIS SET-UP.


...GREAT LAKES/CENTRAL APPALACHIANS/NORTHEAST...

A DEPARTING CLIPPER-TYPE SHORTWAVE MAY BRING SOME ADDITIONAL LIGHT
SNOW TO PARTS OF EASTERN MAINE EARLY THIS EVENING...BUT THIS
SYSTEM WILL QUICKLY EXIT OUT OVER THE ATLANTIC OCEAN TONIGHT. IN
THE WAKE OF THIS SYSTEM...DEEP COLD CYCLONIC FLOW WILL FOSTER
ADDITIONAL SNOW SHOWERS AND A FEW SQUALLS DOWNWIND OF THE GREAT
LAKES AND OVER THE FAVORED UPSLOPE REGIONS OF THE CENTRAL
APPALACHIANS THROUGH THURSDAY. SURFACE HIGH PRESSURE BUILDING
EASTWARD OVER THE OHIO VALLEY AND MID-ATLANTIC STATES BY LATE
THURSDAY SHOULD THEN BEGIN TO DIMINISH SNOW SHOWER ACTIVITY ACROSS
THE CENTRAL APPALACHIANS AND DOWNWIND OF LAKE ERIE BY EARLY
FRIDAY...WITH THE ACTIVITY LINGERING AT LEAST THROUGH THE END OF
THE WEEK IN THE LEE OF THE UPPER GREAT LAKES AND LAKE ONTARIO
THROUGH THE END OF THE WEEK. GRADUALLY VEERING LOW LEVEL FLOW AND
WARM ADVECTION ARRIVING ON SATURDAY WILL ALLOW ALL OF THE LAKE
EFFECT SNOW TO BEGIN TO TAPER OFF.


...UPPER MIDWEST...

LOW PRESSURE EJECTING OUT ACROSS THE NORTHERN PLAINS ON SATURDAY
IN CONJUNCTION WITH AN UPPER LEVEL SHORTWAVE WILL HELP DRIVE A
SWATH OF LIGHT WARM ADVECTION SNOWFALL ACROSS AREAS OF
CENTRAL/NORTHERN MINNESOTA...CENTRAL/NORTHERN WISCONSIN AND THE
U.P. OF MICHIGAN. MOISTURE TRANSPORT AHEAD OF THIS SYSTEM WILL BE
LIMITED...AND SO ACCUMULATIONS SHOULD BE LIGHT WITH UPWARDS OF A
COUPLE INCHES OF NEW SNOW.

ORRISON

EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1054 AM EST WED FEB 01 2017

VALID 12Z SAT FEB 04 2017 - 12Z WED FEB 08 2017

...OVERVIEW...

THE 00Z/06Z MODEL CYCLES HAVE CONTINUED THE TREND OF THE
LOW/TROUGH OVER THE NORTH PACIFIC TRACKING FARTHER SOUTH/SOUTHEAST
TOWARD THE ALASKAN AND BRITISH COLOMBIAN COASTLINE...WHICH WILL
RESULT IN ACTIVE WEATHER ACROSS THE NORTHERN STATES THIS
WEEKEND/BEGINNING OF THE WEEK. AN AMPLIFIED TROUGH WILL SET UP
OVER THE CENTRAL U.S. BY MIDWEEK...IN PART BY LOW OFF THE PACIFIC
NORTHWEST AND SHORTWAVE ENERGY CROSSING THE ROCKIES. GUIDANCE IS
SUGGESTING THAT A STRONG SURFACE LOW PRESSURE WILL LIFT THROUGH
THE MIDWEST/UPPER MIDWEST/GREAT LAKES AREA.


...GUIDANCE EVALUATION/PREFERENCES...

SOME ASPECTS OF THE CLOSED LOW NEAR VANCOUVER ISLAND ARE STILL
UNCERTAIN AS SOME OPERATIONAL RUNS SUGGEST THAT THE UPPER LOW
COULD BE COMPOSED OF A SERIES OF EJECTING AND RELOADING SHORTWAVES
RATHER THAN A SINGLE CIRCULATION.  THIS ALONG WITH THE NORTHERN
PACIFIC BEING AN AREA OF HIGH FORECAST UNCERTAINTY IN RECENT DAYS
SEEM TO MAINTAIN THE POTENTIAL FOR MEANINGFUL CHANGES IN FUTURE
RUNS. ADDITIONALLY... THE EVOLUTION OF THE INCOMING EASTERN
PACIFIC SHORTWAVE TO THE SOUTH AND ITS INTERACTION WITH THE UPPER
LOW ADDS TO THIS UNCERTAINTY.

MEANWHILE MODELS/MEANS CONTINUE TO SHOW A GENERAL AREA OF LOW
PRESSURE CROSSING THE EAST... MOST LIKELY BEST DEFINED ACROSS
NORTHERN AREAS... DURING THE WEEKEND IN ASSOCIATION WITH WEAK
SHORTWAVE ENERGY EMBEDDED IN LOW AMPLITUDE FLOW.  GUIDANCE
CONTINUES TO WAFFLE REGARDING THE POTENTIAL STRENGTH OF THIS
FEATURE.

THE MOST CURRENT RUNS OF THE UKMET/CANADIAN/GFS AND THE ENSEMBLE
MEANS ARE IN GENERAL AGREEMENT WITH A SLIGHTLY MORE
PROGRESSIVE/SOUTHERN LOW OVER NEAR COASTAL ALASKA/BRITISH COLUMBIA
AND AN AMPLIFIED TROUGH OVER THE CENTRAL CONUS FOR NEXT WEEK -
WITH INCREASING SPREAD Sunday AND BEYOND. WPC CHOSE A BLEND OF THE
00Z ECMWF AND ITS ENSEMBLE MEAN/06Z GFS AND ITS ENSEMBLE MEAN WITH
THE PREVIOUS FORECAST INITIALLY FOR SATURDAY AND SUNDAY. THE ECWMF
LAGS BEHIND OTHER GUIDANCE BY MONDAY INCREASING THE SPREAD
THEREAFTER. THE 06S GFS IS MORE PROGRESSIVE WITH THE PACIFIC
NORTHWEST LOW AND THE AMPLIFIED TROUGH OVER THE CENTRAL CONUS.
LESS EMPHASIS WAS PLACED ON THE DETERMINISTIC SOLUTIONS FOR MONDAY
- WEDNESDAY IN ORDER TO FIND A MIDDLE OF THE ROAD TRACK FOR THE
SURFACE LOW OVER THE PLAINS/MIDWEST/UPPER MIDWEST.


...WEATHER HIGHLIGHTS/THREATS...

SOME UNCERTAINTY REMAINS WITH THE EVOLUTION OF THE LOW/TROUGH OVER
THE NORTH PACIFIC AND THE BREAK DOWN OF THE WEST COAST RIDGE.
HOWEVER ONSHORE FLOW WILL LIKELY RESULT IN HEAVIEST COASTAL RAIN
AND INLAND/HIGHER ELEV SNOW TO FALL ACROSS FAVORED TERRAIN ACROSS
THE PACIFIC NORTHWEST...NORTHERN CALIFORNIA AND THE SIERRA NEVADA
RANGE- WITH SOME ENHANCED TOTALS ALSO OVER THE NORTHERN ROCKIES.
THE WIND ASSOCIATED WITH THIS LOW MAY ALSO BE STRONG AT TIMES AS
IT IS DIRECTED THROUGH THE MAINLAND. MUCH OF THE NORTHWEST AND
INTERIOR WEST WILL HAVE BELOW NORMAL TEMPERATURES DURING THIS
PERIOD...WHILE CENTRAL AND SOUTHERN REGIONS WILL BE SLIGHT BELOW
OR NEAR NORMAL.

EAST OF THE ROCKIES... AN AREA OF PRECIPITATION OF VARYING
INTENSITY WILL CROSS THE EASTERN HALF OF THE COUNTRY THIS WEEKEND
WITH SNOW TO THE NORTH AND RAIN ACROSS THE SOUTH... POSSIBLY
SEPARATED BY A NARROW BAND OF WINTRY MIX. A TRAILING FRONT
EXTENDING BACK INTO THE PLAINS MAY SUPPORT ANOTHER AREA OF
PRECIPITATION FOR EARLY NEXT WEEK AS IT LIFTS NORTHWARD AS A WARM
FRONT. THE SYSTEM THAT SPINS UP AND LIFTS THROUGH THE
MIDWEST/UPPER MIDWEST MAY POTENTIALLY HAVE VARYING PRECIPITATION
TYPES/INTENSITIES AS WELL AS STRONG ACCOMPANYING WIND GUSTS. HEAVY
RAINFALL MAY BE POSSIBLE AHEAD OF THE ADVANCING FRONT. MUCH OF THE
CENTRAL AND EASTERN STATES SHOULD SEE A PRONOUNCED WARMING TREND
BY NEXT WEEK AHEAD OF THE PLAINS-GREAT LAKES SYSTEM... WITH A
DECENT AREA OF PLUS 10-20F ANOMALIES FOR HIGHS AND PLUS 20-30F
ANOMALIES FOR MORNING LOWS. MEANWHILE COLDER AIR WILL SPREAD
ACROSS THE NORTHERN PLAINS MON ONWARD WITH SOME HIGHS AT LEAST
15-20F BELOW NORMAL.

RAUSCH/CAMPBELL