Quantitative Precipitation Forecast
Issued by NWS

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000
FXUS04 KWBC 201900
QPFPFD

QUANTITATIVE PRECIPITATION FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
200 PM EST SAT JAN 20 2018


PRELIM DAY 1 QPF DISCUSSION
VALID JAN 21/0000 UTC THRU JAN 22/0000 UTC
REFERENCE AWIPS GRAPHICS UNDER...PRECIP ACCUM - 24HR


DAY 1


...PACIFIC NORTHWEST...

A CLOSED DEEP LAYER LOW WILL SLOWLY MOVE EAST OFF THE BRITISH
COLUMBIA COAST INTO SUNDAY. SHORTWAVE ENERGY AT THE BASE OF THIS
LOW WILL HELP PUSH A COLD FRONT INLAND INTO THE PACIFIC NORTHWEST
ON SUNDAY. THE APPROACH OF THE SHORTWAVE AND INCREASED DIFFLUENCE
ALOFT WILL PROVIDE GOOD SUPPORT FOR LOCALLY HEAVY SHOWERS MOVING
ASHORE...ALTHOUGH PWAT VALUES GENERALLY PEAKING NEAR 0.75" WILL
HELP LIMIT THE EXTENT OF HEAVY PRECIPITATION. ALSO...ANTICIPATE
THE FRONT AND HEAVIER SHOWERS TO OVERALL BE PROGRESSIVE IN NATURE.
ONE EXCEPTION IS ACROSS THE OLYMPICS...WHERE THE PLUME OF MOISTURE
AND ENHANCED ONSHORE UPSLOPE FLOW WILL LINGER FOR A GOOD PORTION
OF SUNDAY...ALLOWING FOR HEAVIER QPF AMOUNTS IN THE 2-4" RANGE
DURING THE DAY 1 PERIOD. ELSEWHERE LOOKING AT TOTALS OF UNDER 1.5"
ACROSS COASTAL WA/OR INTO NORTHWEST CA. MODELS WERE IN CLOSE
ENOUGH AGREEMENT TO GO WITH A MULTI MODEL BLEND FOR QPF.


...ROCKIES INTO THE PLAINS...

SHORTWAVE ENERGY OVER SOUTHERN CA/NV AS OF EARLY SATURDAY
AFTERNOON WILL PROGRESS TOWARDS THE FOUR CORNERS REGION BY 12Z
SUNDAY. BY THIS TIME IT WILL HAVE CLOSED OFF...WITH THE CLOSED LOW
EJECTING INTO THE WESTERN PLAINS BY 0Z MONDAY. THIS SYSTEM WILL
INTERACT WITH AN ENHANCED PLUME OF MOISTURE ALREADY OVER THE GREAT
BASIN REGION ASSOCIATED WITH AN OLDER PACIFIC FRONT. THE OVERLAP
OF THIS HIGHER MOISTURE AND INCREASED ASCENT WILL RESULT IN
WIDESPREAD SNOWFALL ACROSS PORTIONS OF CO...NORTH INTO WY...WITH
THE ACTIVITY SPREADING EAST INTO WESTERN NE/SD AS WELL.

THE 12Z SUITE OF GUIDANCE IS IN GOOD AGREEMENT THROUGH THE DAY 1
PERIOD. HAVE OVERALL NOTED A SLOWING TREND WITH THE SYSTEM IN THE
NCEP GUIDANCE...COMING INTO BETTER AGREEMENT WITH THE ECMWF. WPC
QPF FOLLOWED A BLEND OF THE 12Z GFS/UKMET/HREF MEAN AND THE 0Z
ECMWF. THIS IS A SHIFT NORTHWEST IN CONTINUITY...WITH AMOUNTS
INCREASING ACROSS PORTIONS OF UT/WY AND LOWER AMOUNTS ACROSS
PORTIONS OF NE. GIVEN THE INCREASED MODEL AGREEMENT AND CONSISTENT
TRENDS NOTED...HAVE HIGH CONFIDENCE IN THIS NORTHWEST ADJUSTMENT.


...EASTERN TX INTO THE LOWER MS VALLEY...

AS THE AFOREMENTIONED CLOSED LOW EJECTS INTO THE WESTERN
PLAINS...THE INCREASED SYNOPTIC SUPPORT WILL OVERRUN THE FRONTAL
BOUNDARY SITUATED OVER EASTERN TX/OK. WITH SOME MARGINAL
INSTABILITY FORECAST ALONG THIS BOUNDARY...ANTICIPATE WE WILL SEE
SHOWERS AND EMBEDDED THUNDERSTORMS FORM SUNDAY AFTERNOON. SOME
EAST/WEST DIFFERENCES WITH THIS QPF AXIS WERE NOTED WITHIN THE
GUIDANCE. WHILE THE CONVECTION MAY BECOME PROGRESSIVE OFF TO THE
EAST SUNDAY NIGHT AFTER IT DEVELOPS...THE 18Z-0Z PERIOD WILL BE
THE INITIATION STAGE. IN MOST CASES IT SEEMS LIKE FOLLOWING THE
FURTHER WEST GUIDANCE VERIFIES BEST WITH THE INITIATION OF
CONVECTION IN THE PLAINS. THUS LEANED OUR QPF TOWARDS THE
ECMWF/UKMET AND HRW ARW2. AREAL AVERAGED QPF AMOUNTS ARE EXPECTED
TO BE GENERALLY LIGHT THROUGH 0Z MONDAY.

CHENARD

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

24HR QP VT 22/00Z
 0.01 405307 412307 418305 429304 442302 445302 448301 450300
      452303 455309 460316 465316 470313 479305 484301 489299
      495299 500296 505294 510289 514285 518278 518277 533233
      534225 534218 536207 535198 533193 529183 525174 520172
      517169 496163 494162 492160 489157 484156 480153 472152
      466143 461143 458146 455149 454156 456162 459165 462168
      465167 475167 483173 474175 463173 447172 431180 428183
      424185 423188 425192 433200 434205 433208 432207 425200
      420199 416200 412211 407211 404210 401212 396212 394216
      394220 386224 382225 380231 378246 378258 377262 372261
      370267 369274 369281 372286 375291 377293 377297
 0.01 493145 492142 490137 486133 483130 480129 477132 476134
      474134 470137 470141 475142 479142 482143 485147 489148
      492148 493145 493145
 0.01 459706 457702 450703 441711 440714 441718 444718 440731
      440740 439743 439747 438750 440753 448761 450760 451756
      452748 451741 449736 447734 448731 450730 453728 454725
      455718 457712 459706
 0.01 454971 453961 450961 447964 439977 434979 430980 426978
      427965 428957 428932 428920 428910 427888 427885 428881
      432878 433871 435866 434861 434850 435845 435838 434827
      433815 431806 429800 426794 420787 415781 409784 404785
      398788 392790 389792 386795 382800 378806 375814 378820
      376828 373842 371850 367856 349899 342904 339904 335906
      331906 329910 329915 327918 322918 319917 315917 313915
      304909 301916 301921 300934 279957 279960 283962 286963
      288966 284972 281976 281980 284987 287992 288995 289997
      294000 299996 301991 313985 325977 334974 337976 343976
      346971 349968 352967 366961 369959 372960 378963 382963
      384966 386969 387974 387985 386992 385996 381004 377009
      368019 364025 362034 361045 360050 358051 349054 343054
      329051 323047 318045 315056 312057 313060 315067 318071
      324070 329068 333066 337067 337070 336073 333076 329075
      321076 318079 316083 313085 310083 302081 296079 291080
      290082 292085 297088 304090 304099 304105 307107 310109
      313109 317108 322109 328110 332112 334120 339125 347138
      352143 360144 366143 371139 373141 379140 384141 385138
      386133 389130 393126 396125 399127 402127 404126 407124
      409121 411119 417118 428111 435110 440104 444099 445096
      444092 441086 440082 442080 448076 446068 446057 447046
      447035 446022 447012 449003 452987 452977 454971
 0.01 392917 391911 389908 389902 387897 384893 382891 380893
      378897 378903 377909 375912 373916 369918 363925 363938
      367940 371942 375940 380940 384936 387934 387929 389924
      392917
 0.01 363114 363112 362110 360110 360109 359108 357107 355105
      354105 352106 351108 352110 353112 353113 354114 355115
      356116 358116 360116 362115 363114
 0.01 314768 312763 313758 311754 307754 305760 301763 292769
      285775 277782 276786 277790 283798 286803 292803 294805
      292807 290812 286820 282831 279841 281844 285844 289834
      294826 297820 298815 300804 305801 307797 310792 311786
      313776 314768
 0.01 266761 266754 264750 255748 245747 240747 234747 228748
      225750 219757 214764 211773 210778 211784 213788 214794
      214796 217797 221798 226807 229816 231820 235823 240824
      243822 247819 248814 253807 257797 258788 258782 262778
      266761
 0.25 521261 522253 522244 522238 521232 516220 511212 504202
      499193 496189 491187 486188 482191 477201 471209 466210
      461209 453215 448216 442214 438215 435218 429218 425220
      423227 418227 415226 413223 411222 403228 393230 390232
      387238 386242 386250 386262 384277 384283 389287 393289
      399291 402292 406292 409289 413284 418275 426269 434266
      444266 448266 451269 459278 459292 461296 467298 471297
      475295 479292 483291 491289 501287 505285 508283 516273
      519267 521261
 0.25 490232 490229 489228 487228 486228 485230 486231 488232
      490234 490232
 0.25 442038 441025 442014 444006 444999 443992 441990 435998
      430005 424012 422016 416016 409010 407006 404004 400007
      397011 393018 392041 391049 389053 388059 384058 381056
      382058 384063 382065 375062 371059 369057 370055 365052
      360054 357057 359060 360062 358067 359072 361076 367082
      374087 377089 379088 382088 383093 387093 391090 393095
      395099 397101 399100 399094 402089 405088 408084 410078
      412078 415081 418084 421084 428091 430090 431087 431079
      431075 433074 437073 438068 438062 439050 440044 442038
 0.25 416102 418099 417097 415095 413095 412094 410095 409096
      409098 409101 409103 409104 410105 411106 413105 414104
      414103 416102 416102
 0.25 394115 394114 392113 391114 390114 389115 388116 387117
      386118 385120 384121 384122 384124 384125 386127 387126
      389125 390124 390123 391121 391119 392117 392116 394115
      394115
 0.25 342100 342096 340093 338091 337089 337086 336084 332083
      332086 332088 335090 335093 335097 337100 339101 342100
 0.25 349954 350950 348948 346944 345939 342939 336945 330951
      323956 316960 315964 316969 324967 328966 332964 339960
      346955 349954
 0.25 299794 299792 299790 298788 298787 296787 294787 293788
      291788 291789 289790 289791 288792 287793 288795 288796
      289797 290798 292798 294798 296798 297797 298796 299795
      299794
 0.25 249772 248771 247772 245771 244772 243774 243775 242776
      241777 242779 242781 244781 246779 246778 247777 248776
      248774 249773 249772
 0.50 517265 519257 519250 517238 516232 513226 508218 502210
      494205 490201 487200 483201 480204 477207 475209 475213
      476217 476222 472225 470224 470221 471216 469213 467213
      461212 458215 455219 456223 456229 452231 445233 436236
      432237 427236 421234 417230 409227 406231 401232 397232
      393234 391239 390248 392258 393270 395274 398273 406269
      414267 431263 448257 456253 460254 464256 467261 468267
      468273 471279 474281 480282 488283 497283 504281 512273
      517265
 0.50 492235 492232 492231 491230 491227 491225 490224 489223
      488223 487223 486223 484224 483224 482227 482229 482232
      483234 484234 486234 488234 489236 491236 492235
 0.50 432059 433052 433046 432035 433028 434025 435021 433020
      432024 430028 427031 423039 416041 412050 403065 401069
      399071 395071 392070 389072 388075 390078 393080 395078
      400077 403075 405071 412068 416068 420069 423077 427071
      432059
 0.50 381081 381078 379075 378073 376070 375066 373065 371066
      370070 371073 372075 374080 374082 377084 380083 381081
 1.00 513258 514253 514248 513242 512236 509230 504220 500215
      497213 495215 493218 492224 493232 495239 497244 494243
      490239 487237 485238 482238 481234 479229 476228 472231
      469235 463235 453236 448236 446240 447243 454244 459242
      464242 468245 478253 480259 481265 485269 489270 496272
      500274 504274 508269 513258
 1.00 491219 492217 492214 491213 489211 487211 486212 485212
      484214 483216 483217 485219 486220 488220 490220 491219
 1.00 463223 463221 463218 461217 461218 459220 459222 460224
      462225 463223
 1.00 430250 431246 428242 423238 414235 413243 406242 405238
      402236 398237 397241 397244 399248 404252 408254 413255
      419254 426252 430250
 1.50 508256 511249 510243 507235 500219 498217 495218 494221
      494228 494233 498240 501249 501251 499252 496249 492243
      488239 486239 483240 481236 478229 475230 472234 471241
      473244 481248 490263 497268 500269 502267 502262 504260
      508256
 1.50 489218 490216 489214 487215 487217 487218 488219 489218
 2.00 506248 506242 504236 503232 502228 499223 496220 494223
      494228 495233 497237 500241 503245 506248 506248
 2.00 499263 499258 497254 494249 492245 489242 485240 484245
      486248 488254 490257 492261 495265 498265 499263
 2.00 481244 481242 480239 479236 479235 479233 478232 476230
      474232 473234 473236 473239 473240 475242 476242 476243
      478244 479244 481244
 3.00 496260 495257 495256 494254 494253 493251 492250 491248
      491247 489246 489247 489248 489250 490252 490253 491255
      491256 493258 493259 494260 496260 496260
 3.00 499234 499232 499229 499228 498226 497225 496225 496226
      496228 496231 496232 498234 499234
 3.00 478238 477235 476233 475235 475237 475238 477239 478238

$$




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