Quantitative Precipitation Forecast
Issued by NWS

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000
FXUS04 KWBC 211818
QPFPFD

QUANTITATIVE PRECIPITATION FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
217 PM EDT SAT OCT 21 2017


PRELIM DAY 1 QPF DISCUSSION
VALID OCT 22/0000 UTC THRU OCT 23/0000 UTC
REFERENCE AWIPS GRAPHICS UNDER...PRECIP ACCUM - 24HR


DAY 1

...NORTHWEST INTO THE NORTHERN ROCKIES...

THE ONGOING ATMOSPHERIC RIVER DRIVEN HEAVY RAIN EVENT ACROSS THE
PAC NW IS EXPECTED TO PEAK SAT NIGHT WITH THE APPROACH OF UPSTREAM
SW/V AND ASSOC POWERFUL JET STREAK WHICH ARE EXPECTED TO MOVE
ONSHORE ACRS WA STATE BY SUN MORNING. ONCE ONSHORE...S/WV RIDGING
BEHIND THE SYSTEM WILL FORCE THE ERN PAC END OF THE IMPRESSIVE
MSTR PLUME SWD TOWARD THE OREGON/CA COAST BY SUN EVENING WITH A
SHARP REDUCTION IN PRECIP DURING THE AFTERNOON FROM NORTH TO SOUTH
ALONG THE NW PAC COAST INTO THE NRN INTERMOUNTAIN REGION.
OTHERWISE...LATEST GUIDANCE MAINTAINS RATHER GOOD CONTINUITY AND
AGREEMENT WITH PREVIOUS RUNS WITH ONLY A VERY SLIGHT SWD SHIFT OF
QPF AXIS FROM CONTINUITY NOTED.

AS NOTED IN PREVIOUS DISCUSSION...THE ANOMALIES ASSOCIATED WITH
THIS EVENT ARE QUITE IMPRESSIVE AS LOW LEVEL WESTERLY
FLOW...INTEGRATED MOISTURE TRANSPORT...AND PWAT VALUES...WILL ALL
BE NEAR THEIR CLIMATOLOGICAL MAXIMUM VALUES FOR AT LEAST A PORTION
OF THIS EVENT.  THERE THE EXTREME RAINFALL AMOUNTS OF 3 TO 6+"
DEPICTED BY MODEL CONSENSUS ACROSS THE WA/OR COASTAL RANGES WITH
STORM TOTAL AMOUNTS OVER 8" APPEAR REASONABLE.  WHILE THE CASCADES
AND COASTAL RANGES WILL TEND TO SQUEEZE OUT THE MORE EXTREME PCPN
AMOUNTS...PATRN REMAINS FAVORABLE GIVEN STG WLY DEEP LAYERED FLOW
TO SPREAD HEAVY PCPN AMOUNTS EWD INTO THE NRN INTERMOUNTAIN
REGION..WITH SNOW LEVELS THERE RISING RAPIDLY THROUGH THE PD.

WITH THE EXCEPTION OF A MINOR SPEED ADJUSTMENT SWD LATE IN THE PD
WITH QPF AXIS ALONG THE PAC NW COAST...PRELIM DAY 1 MAINTAINED
CONTINUITY TO A LARGE DEGREE TOGETHER WITH THE HREF MEAN.  GIVEN
THE VOLUME OF RAIN FORECAST..EXPECT POTNL FOR BOTH RIVER AND URBAN
FLOODING OVER PORTIONS OF WRN WA/OR.


...SOUTHERN PLAINS/LOWER MS VALLEY NWD INTO THE UPPER MS VALLEY...

12Z MODEL TRENDS OF THE GFS/NAM GENLY SUPPORTED FASTER TIMING WITH
THE HIGH AMPLITUDE UPPER TROF PUSHING EWD FROM THE ROCKIES INTO
THE CNTL U.S.  WHILE SOME DIFFERENCES STILL EXIST...THE GENL TREND
OF SHOWING A SPLITTING OF THE UPPER TROF WITH SRN PORTION OF THE
TROF TRENDING TOWARD CLOSING OFF OVER SRN PORTIONS OF THE MID MS
VALLEY BY SUN EVENING...WHILE NRN PORTION LIFTS NEWD INTO SCNTL
CANADA ARE GENLY AGREED TO BY LATEST GUIDANCE.   WHILE THE NAM MAY
BE SLIGHTLY ON DEEPER SIDE WITH THE SRN PORTION OF THE 5H
TROF...THE 12Z UKMET ALIGNS WELL WITH THE GFS...WHICH AT LEAST
MASS FIELD WISE LOOKS REASONABLE.  WITH REGARD TO QPF...EXPECT
CONVECTION TO BE FAIRLY ACTIVE ALONG THE ASSOCD COLD FRONT AT THE
BEGINNING OF THE PD ESPECIALLY FROM PORTIONS OF THE MO VALLEY SWWD
INTO OK/NRN TX WHERE BETTER INSTABILITY..MSTR..AND DIFFLUENT UPPER
JET STRUCTURE WILL BE IN PLACE.  THE STG HEIGHT FALLS AND
PROGRESSIVE NATURE OF THE TROF WILL SUPPORT A GRADUAL ACCELERATION
OF THE ACTIVITY TO THE E/SE SAT NIGHT..BUT THE SLOWER INITIAL
DEVELOPMENT SAT EVENING WILL LIKELY GENERATE A NEAR SOLID LINEAR
CONVECTIVE BAND THROUGH PARTS OF THE MID MS VALLEY INTO THE SRN
PLAINS WHICH GIVEN THE NEAR UNIDIRECTIONAL FLOW ALOFT WITH THE
FRONT COULD LEAD TO SOME BRIEF TRAINING EARLY SAT NIGHT.   AREAL
AVG AMOUNTS OF 1-2+" APPEARS REASONABLE ACRS PORTIONS OF WRN MO
SWWD INTO OK/NE TX..WITH ISOLATED AMOUNTS UP TO 4 INCHES PSBL.
THESE AMOUNTS COULD LEAD TO SOME FLASH FLOODING CONCERNS FROM
PARTS OF ERN KS/OK INTO WRN MO/AR ESPECIALLY WHERE HIGHER AMOUNTS
OCCUR OVER EXISTING LOWER FF GUIDANCE VALUES.

WITH THE SPLITTING OF THE UPPER TROF..SHOULD SEE GENLY LIGHTER
AMOUNTS WITH THE NRN PORTION OF THE FRONT BY SUNDAY OVER THE UPPER
MS VALLEY...WHILE A RENEWED FOCUS FOR HEAVIER RAINS IS EXPECTED
OVER PORTIONS OF THE LOWER MS VALLEY AS FRONT OR PREFRONTAL
OUTFLOW ENCOUNTERS A STRENGTHENING SEPARATE INFLOW AXIS OVER THE
CNTL NRN GULF WHERE PWS OF BETWEEN 1.75-2" ARE EXPECTED TO NOSE
NWD INTO THE LOWER MS VALLEY.

MAIN CHANGE FROM CONTINUITY ACROSS THIS REGION  WAS TO LEAN MORE
TOWARD FASTER TIMING OF LATEST GUIDANCE..WHILE ALSO INCREASING
AMOUNTS OVER PORTIONS OF LA INTO MS GIVEN TRENDS OF LATEST HI RES
GUIDANCE.


...FLORIDA/SE U.S...

AS HIGH PRESSURE SLOWLY MOVES OFF THE NE COAST THIS PD..VEERING
LOW LEVEL SELY FLOW ALONG THE SE COAST/FL WILL ALLOW MSTR TO
STEADILY INCREASE THIS PD..WITH SHWERS EXPECTED TO SPREAD NWD THRU
THE FL PENINSULA ESPECIALLY ON SUN INTO SRN PORTIONS OF THE SERN
STATES.  AT THIS TIME..IT APPEARS ACTIVITY WILL LACK ANY ORGANIZED
FOCUS..AND IN THE CASE OF THE NAM..IT LOOKS SOMEWHAT SUSPECT WITH
ITS MUCH HIER PW PLUME INTO THE SE GA COAST BY SUN EVENING.  THUS
OVERALL..CONFIDENCE IN DETAILS IS RATHER LOW BUT GENL TREND TOWARD
INCREASING RAINS TOWARD NORTHERN PORTIONS OF THE STATE WAS
FOLLOWED.

SULLIVAN


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

24HR QP VT 23/00Z
 0.01 541206 539195 537185 533178 529168 516154 510148 503141
      498137 495135 493130 487124 479119 472119 463120 461122
      459121 457117 457112 462113 465115 467113 472108 470103
      467102 462099 457099 454094 450092 442094 438096 434095
      428091 427094 429097 429102 426104 420117 423122 423127
      423129 426128 431126 434121 438121 441122 445124 447123
      450121 453121 454123 452130 448129 444130 442133 438136
      435141 427145 424142 423138 420140 418143 415150 415154
      420156 423159 423163 419161 414160 414164 417168 422170
      426173 430175 430181 427184 427187 434190 438197 439202
      438206 435210 434213 432212 430208 425206 422202 421204
      425210 421229 416228 412228 405233 401234 399239 400246
      403248 411251 419255 421259 421264 420271 418276 417282
      418288 421296 437294 443293 447294 451293 466287 472282
      480281 485283 488287 493295 498299 504300 509297 513291
      524262 524259 525258 525257 526255 526252 527250 527247
      528245 528242 529240 530237 531235 532232 532230 533228
      534228 534225 535223 536221 536220 536218 537215 538213
      539212
 0.01 551876 551866 550857 547851 542845 538842 531840 527840
      525836 525823 521814 516808 501811 485815 478818 471820
      467822 461824 450832 441840 429849 416856 410860 402862
      399863 394864 384865 366866 359867 352868 347869 339868
      331868 324867 318864 313860 309858 309854 310845 312835
      313831 318830 323830 326831 333835 344840 348839 349836
      349832 348827 345825 340823 335806 334800 336795 337789
      340780 334778 317780 307782 298780 293777 284777 281779
      276778 273778 271781 267786 252789 247792 240790 234791
      231793 225797 228805 230814 231824 231830 233832 234837
      230842 230847 235849 239852 242854 243859 249893 250897
      251902 251912 251924 252930 250935 246939 242945 241948
      241953 241957 242960 250966 251969 250972 244977 241982
      239990 239995 240001 242002 247008 252009 257009 261007
      265007 269001 270999 273997 276996 279998 280006 285011
      290014 293012 294010 296012 296017 298017 305014 309010
      314006 324006 332009 338013 349007 354001 359994 362988
      367983 370979 374975 378971 384968 395961 402957 409954
      438943 445941 454940 460939 466940 490945 498945 506944
      510940 514934 513911 514901 514895 516895 531899 537897
      543893 548887 551876
 0.01 520046 519039 515034 512029 512024 513019 515002 515991
      512983 509968 505964 502965 500967 498969 494969 492975
      490985 490995 488002 488012 488017 489020 489033 490040
      490050 489061 489066 490071 492076 496080 496084 493083
      486085 483087 479092 479097 481098 485098 487101 491106
      493107 495105 499103 501099 503096 501081 504075 504069
      506063 520046
 0.01 272824 271820 271816 269814 267812 264812 260812 259814
      258817 259819 262821 265823 267824 269824 272824
 0.25 538205 538200 537197 533190 529183 526175 522167 517161
      508157 504150 495140 490134 484128 482126 478125 470122
      467124 465129 457131 452134 451138 448141 446144 444145
      439145 436148 433152 432156 436163 443168 447175 448178
      447182 446185 448188 453191 458185 463184 467185 475183
      478186 478190 475197 471201 466204 462203 458204 453210
      446213 439214 436217 432219 426223 430228 431231 430234
      424236 415235 413240 415242 420248 423251 428254 430257
      431261 434269 437275 438278 441277 447272 453269 458263
      464256 470251 474249 478250 480252 485258 488267 492276
      496283 500286 504286 509283 514280 519273 522264 523257
      521252 517244 514236 510226 506219 503212 500204 499195
      501192 506194 513199 517205 523213 528218 531217 534212
      538205
 0.25 546874 546868 545866 542864 539865 537867 535868 533871
      533875 535877 537878 540879 543879 545876 546874
 0.25 498247 496244 494239 492235 490231 487227 484225 480225
      481229 483233 488235 491238 493243 496247 498247
 0.25 500870 498865 498857 496852 491848 488844 483842 473840
      469839 464839 457842 446848 438855 431862 417875 412879
      407880 393882 386883 380881 367880 353878 341877 318876
      300865 277861 269853 265847 263839 260831 254821 252816
      252808 248803 246801 243802 238806 235813 235819 236825
      239831 243835 250840 250851 252855 256859 263865 270875
      273880 275886 262888 261891 262894 264900 264913 266917
      270920 275921 280920 285921 289925 293928 293933 293937
      289942 284946 279950 276956 285972 287977 288981 289988
      292993 294998 297998 299996 303993 306992 313995 315997
      317996 325995 333997 338997 344995 351990 357984 365977
      380962 387956 398951 403947 408944 421939 429935 438930
      446924 457918 460914 462912 463907 460904 457903 452902
      450900 446901 441902 435901 432900 432897 434887 434883
      437878 446873 452871 459870 464874 469873 474869 480867
      488872 495882 498878 499873 500870
 0.25 453103 452098 448096 446100 441101 438103 435105 434112
      437112 440114 443117 447116 449109 451105 453103
 0.25 313813 312809 311807 307803 302800 297798 294798 290799
      285802 284804 285808 289811 293816 297819 301822 307819
      312816 313813
 0.25 267804 267802 266801 266800 265798 264796 262796 262797
      261799 261800 261801 262803 263803 265804 267804 267804
 0.50 529210 531205 530201 527192 526183 523173 519167 516166
      514168 511169 509167 501162 494159 492156 492153 499151
      494143 491137 486131 481127 477126 472124 469125 468131
      468137 468140 465140 461139 459135 457137 453143 450150
      447151 443150 438150 436153 437160 442165 448170 452178
      454184 460183 465179 473178 478175 479177 484177 491180
      498176 517199 520202 523207 526211 529210
 0.50 520269 521264 521258 518251 515245 511234 509228 504221
      502214 497205 493200 487196 483195 481198 475202 472203
      470205 464206 460205 457208 455211 451213 439217 434221
      431224 433229 434232 432236 430239 426238 421237 418238
      420244 425248 430249 431253 436258 439261 442261 448259
      453255 459252 465247 470244 476245 483248 488255 491263
      494269 498276 504281 513278 517274 520269
 0.50 502254 501248 497242 494237 492231 489226 483223 477223
      478228 482234 487237 492242 494247 498253 500255 502254
 0.50 465172 465169 463166 461163 461160 459160 457163 455166
      453167 453169 455172 458173 460171 463172 465172
 0.50 469863 467863 467864 469863 469863
 0.50 445111 445108 444107 442106 442105 442106 440106 439108
      438110 440111 442112 443113 445111
 0.50 449913 445909 437909 421911 417911 416908 416901 418899
      423892 422884 418881 412884 406887 399889 392891 385894
      383896 387896 396896 400898 401899 397901 389901 382898
      375898 366896 358896 353895 351892 353886 348883 342880
      335880 318878 311877 303874 299872 293873 292878 295886
      294890 291892 287891 282892 277899 275904 274908 275911
      281913 293918 305928 307933 303940 294947 288951 284955
      285959 286960 294963 295968 294974 294985 346991 355983
      365974 374965 386955 390952 396949 407942 412939 419936
      432928 441921 445918 449913
 0.50 302815 302812 301810 300810 299809 298808 297809 297811
      298813 299814 300815 301815 302815
 0.50 250808 249806 249805 247804 246805 245805 244807 244809
      244811 245812 247812 249810 250808
 0.50 247825 247821 247817 245815 244811 242810 239811 238814
      238818 238822 238826 239827 243829 247827 247825
 1.00 518268 520262 517258 512250 510241 504231 499224 499213
      496209 493206 489202 484200 471207 464209 460207 457212
      451214 443216 440217 438222 438227 439229 438233 433238
      433242 436246 438250 442249 451247 459245 465241 483241
      485245 488248 490252 491258 493263 496267 499268 500266
      501261 499257 496254 493251 491246 489241 487239 484239
      478231 475229 473226 475222 478220 489222 492225 494230
      497239 503246 505250 507255 508267 510272 513274 518268
 1.00 491170 491165 488160 485154 482153 478149 471148 465143
      460142 457145 457152 459155 465162 470170 476169 480168
      483168 487170 491170
 1.00 488144 490141 489137 486134 483132 478130 474129 470128
      471133 471136 472139 474140 477139 480139 484141 488144
      488144
 1.00 463178 463176 463175 461174 459175 458176 457177 456179
      457181 459181 460181 461181 462179 463178
 1.00 453174 453173 451171 450173 451174 453174 453174
 1.00 453161 454159 453157 451156 450156 450155 448155 447155
      446156 444157 444159 443162 444162 445163 447164 449163
      450163 452162 453161
 1.00 428242 427242 426242 424240 422240 421240 421243 422244
      424244 426242 427243 428242
 1.00 431923 429918 424916 419917 413919 407922 400924 393924
      387926 379930 373933 368934 361926 359925 356923 351919
      348916 346910 338902 335898 330894 330889 327887 322885
      309884 306885 305888 307892 309897 307899 299900 291900
      286902 283906 288909 297915 306922 312919 321918 325920
      327921 326926 326930 332929 337926 339924 341926 339934
      337939 334942 329945 319952 315953 311957 309971 312974
      319975 322975 325975 325979 327986 332986 346987 353982
      362974 370966 379958 386951 396945 417933 424929 431923
 1.00 365909 364909 362908 360908 358909 357910 355912 357913
      359913 360913 362912 364910 365909
 1.00 303954 303952 303951 302952 301953 299952 298954 297954
      297956 299956 301956 303954 303954
 1.50 515269 515267 515266 515264 514263 512262 511263 511265
      511268 513270 515269 515269
 1.50 503239 503236 502235 501236 500238 501239 502240 503239
 1.50 498263 498261 498258 496256 495255 493255 493256 493258
      493259 494261 494262 495263 497264 498263
 1.50 496215 494211 490208 487204 481203 473207 469210 464210
      460211 456214 447217 442217 440223 442229 445230 452228
      453231 451232 446233 441234 438237 438241 440243 443245
      453243 461240 465239 469234 477241 480240 480235 476232
      471232 466230 466228 469228 471223 475219 480219 485220
      490220 494218 496215
 1.50 485161 485160 484158 482155 480154 479155 479157 480158
      481160 481161 483163 485162 485161
 1.50 478160 477154 473153 471150 467147 463145 459148 460153
      463157 466160 469164 473163 476162 478160
 1.50 476136 476134 474132 474131 473130 472131 472133 473136
      474138 475137 476136
 1.50 462178 461176 459176 458177 459180 461180 462178
 1.50 424924 422921 419921 416921 414923 412926 410928 409931
      412931 414930 416931 417929 419928 421928 422926 424924
 1.50 399940 398938 396936 389937 379942 368945 363946 358949
      355949 356943 354937 350934 346935 343939 334947 319960
      317965 319970 325969 331967 334967 335971 338975 343979
      345982 350982 359974 366967 373961 389947 399940
 1.50 321909 321907 320907 320909 321909 321909
 1.50 311907 310906 308907 310907 311907
 1.50 298910 297908 297907 295906 295905 293906 292908 293909
      294910 295910 297910 298910
 2.00 488218 490216 489213 487208 484205 480206 476207 473210
      469211 464211 458215 454215 451217 443219 441222 442225
      444227 447228 454225 459227 462231 449234 441236 440239
      442242 445240 450241 459240 461238 465237 464226 478218
      483218 488218
 2.00 480239 480236 479235 478234 476233 474233 473234 473236
      474238 475239 477240 478240 480239
 2.00 483161 483160 482158 483161 483161
 2.00 472161 472158 472157 471155 471153 470153 469151 467152
      465152 464150 462149 461151 462153 462154 463155 465156
      465157 467157 468158 469160 470160 471161 472161
 2.00 461178 461177 459177 459178 461178 461178
 2.00 379952 378948 373949 366951 361956 357960 354969 350976
      352978 355976 359972 364966 370961 375956 379952
 2.00 351965 350964 348964 346964 346965 345965 343967 342969
      343971 344971 346970 348969 350967 351965
 2.00 349947 348941 344943 341946 337948 334952 334956 335960
      337960 340960 343958 346954 348949 349947
 3.00 485212 483209 479210 475212 470215 467212 464214 459216
      455216 452220 458224 462226 464224 467224 471219 475216
      480215 485212
 3.00 459237 458235 458234 457234 456234 455234 453235 451236
      450235 448236 447236 448237 448239 449239 450239 451239
      453238 455237 456238 458238 459237
 3.00 450224 451222 450221 448220 447220 445221 445222 444223
      446226 448225 450224 450224
 4.00 470218 470217 468215 467215 467214 466214 466215 466217
      468219 469218 470218
 4.00 462223 463221 462220 461219 459219 457219 456221 457222
      458223 460224 462224 462223

$$




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