Quantitative Precipitation Forecast
Issued by NWS

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000
FXUS04 KWBC 141901
QPFPFD

QUANTITATIVE PRECIPITATION FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
201 PM EST TUE NOV 14 2017


PRELIM DAY 1 QPF DISCUSSION
VALID NOV 15/0000 UTC THRU NOV 16/0000 UTC
REFERENCE AWIPS GRAPHICS UNDER...PRECIP ACCUM - 24HR


DAY 1

...PACIFIC NORTHWEST...

A DEEP TROUGH JUST OFFSHORE OF THE PACIFIC NORTHWEST WILL AMPLIFY
FURTHER...AND A 250-MB JET STREAK OF AT LEAST 135 KNOTS IS
FORECAST TO BECOME BETTER DEFINED AND MOVE INLAND OVERNIGHT. THE
LARGE SCALE SYSTEM HAS THE DISADVANTAGE OF A FRONTAL ZONE HAVING
MOVED INLAND - LIMITING THE CONNECTION TO SUB-TROPICAL MOISTURE -
BUT STEEP LAPSE RATES WERE ALREADY IN PLACE AND PRECIPITABLE WATER
REMAINED SUFFICIENTLY RIPE TO FOSTER SOME HEAVY LOCAL RAIN
RATES...AIDED BOTH BY OROGRAPHIC ENHNACEMENT AND CONVECTIVE
ENHANCEMENT. AT 18Z DISCRETE CONVECTIVE CELLS WERE PROMPTING
DUAL-POL RADAR HYDRO CLASSIFICATIONS OF HEAVY RAINFALL AND
ESTIMATED HOURLY RATES BETWEEN 0.50-1.00 INCHES OVER COASTAL
WESTERN WASHINGTON. LAPSE RATES ARE LIKELY TO REMAIN STEEP...AND
CONVECTION SHOULD REMAIN ORGANIZED WELL THROUGH THE EVENING HOURS
AS WESTERN WASHINGTON REMAINS IN THE EXIT REGION OF THE DEVELOPING
JET STREAK. LOW LEVEL INFLOW IS FORECAST TO RATCHET UP TO 60 OR 65
KNOTS DURING THE PEAK OF THE SYNOPTIC DEEP LAYER DEVELOPMENT THIS
EVENING. A STRONGLY FORCED...NARROW LINE OF CONVECTION WITH SOME
THUNDER...MAY BE SLOW TO MOVE INITIALLY BEFORE PUSHING EASTWARD
ALONG WITH THE OVERALL WAVE/TROUGH. THUS...THERE IS SOME REAL
POTENTIAL FOR UNUSUALLY HEAVY SHORT TERM RAIN RATES ON A LOCAL
SCALE.

OVERALL...THE MODEL QPF CONSENSUS ON THE LARGER SCALE IS QUITE
STRONG...AND HEAVIEST AMOUNTS ARE EXPECTED ON THE OLYMPIC
PENINSULA AND POINTS SOUTH TOWARD ASTORIA. SOME OF THE HEAVIER
PRECIPITATION WILL SPILL OVER INTO THE NORTHERN CASCADES. FARTHER
SOUTH ALONG THE OREGON COAST THE JET STRUCTURE WILL BE LESS
FAVORABLE...BUT MOIST ONSHORE FLOW WILL ENSURE AREAL AVERAGE AT
LEAST 1 TO 2 INCHES THROUGH WEDNESDAY. FOR QPF...THE INHERITED WPC
FORECAST NEEDED VERY LITTLE CHANGE. WE LEANED SOMEWHAT TOWARD THE
EMC WRF-ARW2 FOR SOME OF THE DETAILS. SOME OF THE HEAVY
PRECIPITATION UP IN WESTERN WASHINGTON WILL FALL AS SNOW...AND
USERS MAY CONSULT THE WPC HEAVY SNOW DISCUSSION AND LOCAL FORECAST
PRODUCTS FOR DETAILS.


...NORTHERN CALIFORNIA...

AFTER THE 135 KNOT JET STREAK PUSHES INLAND ACROSS OREGON AND
WASHINGTON...MODELS DEPICT A SLOWING OF THE LARGE SCALE
PROGRESSION...AND ANOTHER PRONOUNCED SHORTWAVE TROUGH TO THE REAR
OF THE JET STREAK...THIS TIME AFFECTING NORTHERN CALIFORNIA. A
SHARPLY DEFINED LOW LEVEL JET ACCOMPANIES THIS FEATURE ON
WEDNESDAY...AND THE SYSTEM IS ALSO EXPECTED TO TAP SUB-TROPICAL
MOISTURE POSITIONED TODAY OUT AROUND 135 DEGREES WEST AND 30
DEGREES NORTH. PRECIPITABLE WATER VALUES SPIKE ABOVE 1.00 INCH AND
EVEN 1.25 INCHES OVER NORTH CALIFORNIA AS THE SHORTWAVE
ARRIVES...WITH STRONG SOUTH TO SOUTHWEST FLOW RESULTING IN
OROGRAPHIC ENHANCEMENT AND LIKELY SOME WEAK CONVECTIVE ENHANCEMENT
AS WELL. SIMILAR TO THE PACIFIC NORTHWEST...WPC QPF IN THIS REGION
LEANED TOWARD THE EMC WRF-ARW2 AND ALSO OUR IN-HOUSE ENSEMBLE.
GIVEN SIMILARITIES AMONG THE MODEL SOLUTIONS...THE ENSEMBLE AND
ITS BIAS CORRECTION SHOULD PERFORM WELL.


...CENTRAL U.S...

A FAIRLY STRAIGHT-FORWARD WAVE... MEDIUM WAVELENGTH AND WELL
MODELED...IS SET TO AMPLIFY OVER THE UPPER MIDWEST AND GREAT
LAKES. DEEP MOISTURE OF MODEST MAGNITUDE...PW VALUES 0.75 TO 1.25
INCHES WILL MOVE NORTHWARD ALONG THE 295-300 K ISENTROPIC
SURFACES. WHILE MOST PLACES WILL SEE A QUARTER INCH OF
PRECIPITATION OR LESS OWING TO THE QUICK MOVEMENT OF THE
SYSTEM...THERE SHOULD BE A SWATH OF HEAVIER RAIN...ESPECIALLY AS
THE WAVE MATURES AND DEEP LAYER ASCENT EXPANDS ITS INFLUENCE OVER
CENTRAL/EASTERN MICHIGAN. A SECONDARY MAXIMUM MAY OCCUR WHERE THE
TRAILING FORCING ALONG THE FRONTAL SYSTEM OVERLAPS WITH WEAK
INSTABILITY AROUND SOUTHERN MISSOURI AND SOUTHERN ILLINOIS. FOR
QPF...WPC STARTED WITH A 40/30/30 BLEND OF THE ECMWF/GFS/NSSL WRF.
OUR IN-HOUSE ENSEMBLE WAS TOO STRONGLY INFLUENCED BY THE
NAM...WHICH SEEMED TO HAVE ITS SECONDARY STRIPE TOO FAR NORTH AS
IS OFTEN ITS BIAS.


...FLORIDA...

SHALLOW EAST TO NORTHEASTERLY ONSHORE FLOW WILL MAINTAIN A SHOWERY
REGIME ALONG THE FLORIDA EAST COAST. UPPER LEVELS ARE SOMEWHAT
UNSUPPORTIVE...AND BECOME LESS SO...AS A TROUGH PASSES TO THE EAST
LATER TONIGHT.

BURKE

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

24HR QP VT 16/00Z
 0.01 382299 387295 393292 405287 417281 428274 439267 442266
      444267 451270 466268 471266 479267 485272 489280 492287
      499291 503292 505291 509283 513278 518277 523264 518238
      518230 516224 514221 513217 516210 521212 525214 530217
      533218 534214 536206 537199 537195 535187 532183 528173
      525168 521163 513154 508150 504149 503153 500155 495155
      490157 486160 481160 475163 474179 472195 468199 466201
      463200 460199 458201 452203 450204 448200 450193 455180
      456167 454159 452153 449148 444143 441141 436141 428148
      422150 418154 418170 416177 414182 407192 402195 400195
      396194 383189 374185 371185 370189 371195 376206 377209
      377215 374221 372225 370232 371243 372245 371250 368257
      365266 364271 365278 364289
 0.01 500926 501917 499909 497899 497887 496861 495847 496842
      496837 492825 489803 484783 480774 476767 476765 473763
      468761 461763 455766 442776 431784 419790 414793 409798
      398807 393812 388819 381829 375840 362869 359883 353896
      346910 340926 340934 341943 344949 348953 354957 358958
      359963 363969 366972 369974 382975 387979 391979 393977
      403968 409961 409954 407949 409947 414943 419947 425946
      438938 442935 446935 454935 460935 462937 466937 469937
      472940 475948 479957 481959 485960 489955 492947 497937
      500926
 0.01 387735 387730 385727 379723 378719 375717 371709 367703
      364701 360700 350693 344692 338698 335703 335708 338712
      342716 346723 348733 349738 351742 356744 366742 377735
      381739 385738 387735
 0.01 308799 308796 304794 299795 295794 288792 283792 278791
      271791 267789 262789 259788 256790 249794 243799 241807
      239810 239815 241821 243823 246823 248819 253813 255811
      260811 262813 266812 270811 275811 282813 287813 291812
      297811 300809 305804 308799
 0.25 529199 529192 527185 524179 520174 515169 511168 507168
      501170 494170 490171 485174 482180 481184 481191 480198
      475204 471208 465209 444213 433218 426219 421217 419215
      415212 409209 403206 398201 386195 381193 377194 378199
      384209 388215 388220 382223 380227 381231 381240 381250
      378257 375262 372269 370277 371284 373287 376288 383289
      389285 397280 406272 412269 418268 429264 439263 451261
      458261 464259 469258 477258 481259 486263 494272 497275
      501276 503273 505269 507265 509263 512261 513258 514241
      513233 511226 506210 505202 507199 511200 521205 527204
      529199
 0.25 482854 482845 481834 480824 477815 472800 469794 464789
      459788 452788 444790 439795 425817 417828 414834 412842
      410849 410855 412863 409870 409875 411878 416881 423878
      430875 435873 439871 442871 447876 450878 452882 451887
      455884 461879 465880 467883 468891 472887 474884 476880
      478872 482854
 0.25 404887 403859 400846 397844 394845 387847 385851 382855
      378860 375866 372877 372882 375889 375896 373901 368905
      364905 360907 358912 357919 353923 352928 351936 354941
      359940 362943 366945 372944 375940 376925 377923 380922
      384925 389925 392920 393913 396907 401899 404887
 0.25 386956 386955 385954 385952 384951 382949 382952 382954
      384956 384957 386957 386956
 0.25 363724 363722 362720 361718 361717 360716 359715 357715
      356717 356719 356720 356721 356723 357725 358727 359728
      361729 362727 362726 363724
 0.25 289799 288797 284796 279796 272795 266795 261797 255800
      258803 265804 270805 276807 283804 287802 289799
 0.50 525195 525190 522185 519181 516177 513174 509173 505177
      504181 503185 503189 507192 510195 514197 519198 524198
      525195
 0.50 512252 512240 510231 508225 507219 503212 498206 495205
      493201 491196 491191 492189 496184 496181 495178 491177
      488180 486184 487190 486195 482200 475208 471211 464212
      461212 458214 453215 444216 439219 435222 432227 426230
      420231 415229 412217 404210 393201 388198 384196 381196
      381200 383204 390214 393220 387224 385226 384230 385237
      386242 387249 380260 377266 374274 374279 375282 382284
      386283 390281 398272 401267 407265 413264 419264 438260
      444259 449257 462256 471254 476254 482255 488259 492265
      498271 501270 505256 509256 512252
 0.50 502254 501251 501250 500248 499247 498245 497244 495242
      494243 494246 495246 495249 496250 497252 498253 499253
      500254 502254
 0.50 475850 476845 475839 474828 472817 469808 465801 460795
      455793 451794 447796 443801 440808 432822 429828 426831
      426836 432836 440838 445841 451847 455851 457855 459859
      462860 466859 470858 473855 475850
 0.50 426864 426861 424859 422860 420863 418865 417868 415870
      416874 418875 421874 423872 424869 426867 426864
 0.50 399885 398877 395872 393871 390872 387877 384881 382888
      380895 378902 380906 382908 387904 390899 393895 397890
      399885
 0.50 285800 283799 281799 279800 278801 278803 280803 281802
      283801 285800
 0.50 270800 268799 266799 265800 264800 265801 266801 268800
      270800
 1.00 508246 508235 504223 502214 500211 495208 487205 480208
      474214 476217 481221 489226 493233 495238 499242 506246
      508246
 1.00 495257 492247 490241 489239 486238 483234 481228 480225
      477225 473227 470228 467229 464227 465224 464219 460218
      457219 454224 445228 428236 419236 416236 415238 417244
      418247 415254 417257 420258 425258 433256 443254 452252
      463251 471249 481249 484250 489254 492258 494259 495257
 1.00 466831 465821 463814 461809 457804 453804 449809 446814
      444819 444824 446826 448832 454833 459836 462836 465834
      466831
 1.00 411238 412235 412231 409227 405225 401226 397226 393228
      390230 391234 394236 397239 400243 405243 408241 411238
 1.00 404217 404214 403214 402212 401211 400210 399208 397206
      396205 394205 393205 392205 390206 391209 393211 393212
      394213 396214 396215 398216 399217 401218 403218 404217
 1.00 394261 395259 395257 395255 393254 392255 391256 390257
      389258 388259 387261 386261 385263 385265 384267 385269
      387269 387268 389267 389266 391265 391264 392263 394261
      394261
 1.50 503239 503231 502223 500215 496210 493211 489209 483209
      479213 480217 485220 488221 490220 492226 494233 497238
      500240 503239
 1.50 490247 489246 489244 488243 487241 485243 486246 488247
      489249 490247
 1.50 482244 483240 482236 481232 478228 466231 454232 448232
      442234 437236 431239 426240 423242 422248 421252 424254
      430253 435250 441249 446248 450249 455249 467247 471246
      479246 482244
 1.50 407234 407233 408232 406230 405229 403228 402228 401228
      399228 397229 395231 397233 398234 399234 400235 402236
      403237 405237 406236 407234 407234
 1.50 400213 398212 397212 398213 400213 400213
 2.00 501235 501230 501226 501222 500218 499215 496214 493215
      492219 493224 493227 494230 495233 498236 501235
 2.00 491216 491214 491213 489211 488210 486210 484210 482211
      480213 480214 481216 482217 483218 485219 486219 488219
      489219 490217 491216
 2.00 481241 481236 480231 478229 475230 468232 461233 455234
      449237 447240 448243 450245 455246 462246 467244 474244
      478244 481241
 2.00 444240 442239 440240 438241 435241 433242 431243 428245
      426247 426250 428250 431248 434247 436246 438244 440243
      442242 444240
 3.00 487215 486215 487216 487215
 3.00 479238 479236 479235 478233 478232 476231 475232 474233
      473234 472235 471236 470238 468237 467237 468238 470238
      472239 473240 475241 477241 478241 478240 479238
 3.00 467240 467237 465236 463235 460236 456239 458240 459240
      461240 463240 465240 466240 467240
 3.00 498232 499229 498227 498224 498221 497218 495219 494220
      494223 494225 494226 494228 495230 496231 497232 498232
 4.00 478235 477235 476234 475235 475237 476237 477237 478235

$$





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