Quantitative Precipitation Forecast
Issued by NWS

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000
FXUS04 KWBC 250700
QPFPFD

QUANTITATIVE PRECIPITATION FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
300 AM EDT TUE APR 25 2017


PRELIM DAY 1 QPF DISCUSSION
VALID APR 25/1200 UTC THRU APR 26/1200 UTC
REFERENCE AWIPS GRAPHICS UNDER...PRECIP ACCUM - 24HR


DAY 1

...MID ATLANTIC AND NORTHEAST...

THE CLOSED LOW ALONG THE CAROLINA COAST WILL MOVE NORTHEAST TODAY
OFF THE MID ATLANTIC AND SOUTHERN NEW ENGLAND COASTS. AN ANOMALOUS
PLUME OF MOISTURE AHEAD AND EAST OF THIS FEATURE...COMBINED WITH
STRONG ONSHORE FLOW AND SOME DIFFLUENCE ALOFT WILL RESULT IN A
STREAM OF SHOWERS MOVING NORTHWARD WITH TIME. THE EXPECTATION IS
THAT THE HEAVY RAINFALL CURRENTLY OVER PORTIONS OF NC/VA WILL
DECREASE IN INTENSITY THIS MORNING AS SOME DRY AIR IS ENTRAINED
INTO THE SYSTEM...AND THE CLOSED LOW BEGINS PICKING UP FORWARD
SPEED OFF TO THE NORTHEAST. HEAVIEST RAINFALL AMOUNTS DURING THE
DAY 1 PERIOD (12Z TUE-12Z WED) WILL LIKELY END UP FOCUSED FROM NJ
INTO SOUTHERN NEW ENGLAND...WHERE ONSHORE MOIST FLOW WILL PERSIST
THE LONGEST TO THE EAST OF THE CLOSED LOW. WHILE MOST OF THE
PRECIPITATION WILL BE SHOWERY WITH RAINFALL RATES NOT ALL THAT
IMPRESSIVE...THERE ARE SIGNS THAT SOME ELEVATED INSTABILITY WILL
TRY TO MOVE INLAND ACROSS PORTIONS OF NJ INTO SOUTHERN NEW
ENGLAND. THIS SHOULD ALLOW FOR SOME EMBEDDED CONVECTIVE ELEMENTS
LEADING TO LOCALLY HIGHER RAINFALL RATES. EXPECTING AREAL AVERAGED
RAINFALL AMOUNTS TO GENERALLY BE IN THE 1-2" RANGE FROM NJ INTO
SOUTHERN NEW ENGLAND...WITH LOCALIZED 2-3" AMOUNTS POSSIBLE. WPC
QPF ACROSS THIS REGION FOLLOWED A MULTI MODEL BLEND...ALTHOUGH WAS
WEIGHTED CLOSER TO THE LATEST HIGH RES MODEL MEAN. OVERALL TENDED
TO PREFER THE 3KM NAM AND NSSL WRF THE MOST OUT OF THE HIGH RES
RUNS FOR THIS REGION.

THE OTHER AREA TO WATCH THIS AFTERNOON IS ACROSS NORTHEAST NC INTO
SOUTHEAST VA UNDERNEATH THE 850MB LOW CENTER. CONVECTION BECAME
PRETTY ACTIVE TODAY UNDERNEATH THIS FEATURE OVER SC...WHICH
RESULTED IN SOME SLOW MOVING CONVECTION DROPPING SOME PRETTY HEFTY
TOTALS. SOME SIGNS WITHIN MOST OF THE HIGH RES GUIDANCE THAT THIS
COULD HAPPEN AGAIN THIS AFTERNOON AS WE DESTABILIZE UNDERNEATH THE
CLOSED LOW. THUS COULD END UP WITH SOME LOCALIZED 1-3" AMOUNTS
ACROSS PORTIONS OF NORTHEAST NC INTO SOUTHEAST VA ASSUMING WE CAN
DESTABILIZE ENOUGH THIS AFTERNOON.

...NORTHERN ROCKIES TO THE NORTHERN PLAINS AND UPPER MS VALLEY...

MULTIPLE PIECES OF SHORTWAVE ENERGY EMBEDDED WITHIN A DEVELOPING
LONGWAVE TROUGH WILL MOVE FROM THE NORTHERN ROCKIES INTO THE
NORTHERN PLAINS TODAY. THE COMBINATION OF FORCING FROM THESE
FEATURES...BROADLY DIFFLUENT FLOW ALOFT...AND ISENTROPIC LIFT OVER
THE BAROCLINIC ZONE IN PLACE...SHOULD RESULT IN A SWATH OF
PRECIPITATION FROM PORTIONS OF WY/MT INTO PORTIONS OF SD/NE AND
INTO THE UPPER MS VALLEY. EXPECT TO SEE ONE SWATH OF 0.5"+ AMOUNTS
ACROSS NORTHEAST WY INTO THE BLACK HILLS...WHERE A STRONG LOW
LEVEL CONVERGENCE AXIS IS SET UP. ALSO SHOULD SEE SOME 0.5" TO 1"
AMOUNTS FROM PORTIONS OF NORTHERN IA INTO MN/WI. SOME MODEL
DISAGREEMENTS WERE NOTED WITH REGARDS TO HOW FAR NORTHWEST THE
HIGHER QPF AXIS GETS ACROSS SD/MN. THE GFS/3KM NAM/NSSL WRF ARE
FURTHER NORTHWEST...WITH THE WRF ARW/NMMB AND 12Z ECMWF FURTHER
SOUTH. NO REAL STRONG SIGNAL TO PREFER ANY ONE SOLUTION...THUS WPC
QPF GENERALLY FOUND A MIDDLE GROUND SOLUTION FOR NOW.

...SOUTHERN PLAINS AND MID MS VALLEY...

CONVECTION IS EXPECTED TO BREAK OUT ACROSS PORTIONS OF EASTERN
OK/KS INTO WESTERN MO LATER THIS AFTERNOON INTO THIS EVENING. AT
THE SURFACE WILL HAVE A SLOW MOVING NORTHEAST TO SOUTHWEST
BOUNDARY STRETCHING ACROSS THE AREA. EXPECT THE AREA TO REMAIN
CAPPED OF MOST OF THE DAY...WITH THE APPROACH OF A SHORTWAVE AND
INCREASED DIFFLUENCE ALOFT HELPING BREAK THE CAP AFTER 0Z. 850 MB
MOISTURE TRANSPORT AND CONVERGENCE REALLY PICKS UP ACROSS THE AREA
AFTER 0Z AS WELL...WITH A SEVERAL HOUR PERIOD WHEN THIS 850MB
MOISTURE CONVERGENCE AXIS DOES NOT MOVE ALL THAT MUCH. THUS
SUGGESTS THAT THERE COULD BE A PERIOD OF BACKBUILDING AND/OR
REPEAT CONVECTION. STORM MOTIONS OFF TO THE NORTHEAST ARE ALSO
GENERALLY PARALLEL TO THE BOUNDARY...SUGGESTIVE OF SOME TRAINING
POTENTIAL. THE FRONT DOES EVENTUALLY PROGRESS OFF TO THE EAST...SO
THE WINDOW FOR TRAINING IS NOT ALL THAT LONG...WHICH SHOULD KEEP
RAINFALL AMOUNTS FROM GETTING TOO EXTREME. IN GENERAL WOULD EXPECT
1-2" AREAL AVERAGED AMOUNTS...WITH LOCALIZED 2-3" AMOUNTS POSSIBLE.

...NM/CO...

AS A STRONG SHORTWAVE FEATURE INTERACTS WITH A LOW LEVEL
CONVERGENCE AXIS...EXPECT TO SEE INCREASING PRECIPITATION COVERAGE
AND INTENSITY ACROSS PORTIONS OF NM/CO THIS AFTERNOON. SOME WEAK
INSTABILITY COULD EVEN DEVELOP UNDERNEATH THE SHORTWAVE...WHICH
COULD ALLOW FOR SOME EMBEDDED CONVECTIVE ELEMENTS AND LOCALLY
HIGHER RATES. SOME MODEL DIFFERENCES...BUT THE GENERAL CONSENSUS
IS FOR 1-2" OF PRECIPITATION ACROSS FAR SOUTHEAST CO...WITH
BROADER LIGHTER AMOUNTS EXTENDING SOUTH INTO NM AHEAD OF THE WAVE.

...PACIFIC NORTHWEST...

THE NEXT WAVE AND FRONT WILL MOVE INTO THE PACIFIC NORTHWEST
DURING THE DAY TODAY. IN GENERAL THE BETTER MOISTURE PLUME IS
DISPLACED FROM THE STRONGER FORCING. THUS NOT EXPECTING QPF
AMOUNTS TO BE ALL THAT HIGH. IN GENERAL GOOD MODEL AGREEMENT
ALLOWED FOR WPC QPF TO FOLLOW A MULTI MODEL BLEND WEIGHTED TOWARDS
THE HIGH RES MODEL MEAN.


CHENARD

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

24HR QP VT 26/12Z
 0.01 549811 549798 548783 543756 541743 537732 533728 531731
      527739 508780 505791 503788 501783 497778 500773 502762
      501750 498739 497725 495719 494712 489699 486686 486675
      485668 483663 478653 472645 468639 466637 463639 461638
      456639 452638 448642 441648 438652 434655 430653 424659
      419665 417668 413667 409666 408670 405672 400673 390674
      387678 383681 375685 369686 366687 363686 352688 346689
      343691 337694 333697 316709 309715 309724 310727 310732
      307738 304748 308755 315779 321785 323786 325784 344810
      351817 357818 363819 374818 380816 384814 389809 393803
      397800 399801 401804 405814 406821 407826 410831 414833
      430827 447829 450825 452820 455820 455823 454829 451840
      448848 445851 442856 439859 436863 433866 425867 419870
      414877 410882 407884 399891 392896 386900 380907 369921
      366924 362927 354931 345934 340937 336939 327944 317949
      312952 306956 303960 299962 297965 298969 301973 304972
      316970 325967 329967 335968 339969 342975 347977 349981
      351985 352990 346995 346999 344001 341004 338016 337019
      338024 335027 335034 336037 336042 335048 332050 327052
      325057 327060 331062 336069 334073 331076 337095 343103
      355105 365110 369111 372110 377108 384109 389107 392105
      399100 403098 402102 397107 390111 384114 380117 378122
      375126 374132 380134 383136 389142 392146 392153 391157
      389162 388169 389175 394172 401167 404162 407159 408154
      404151 401148 402143 403135 407131 411126 418129 418135
      418142 420152 422152 423149 425143 427137 429132 442124
      451127 453131 453136 451139 448138 444138 442143 443148
      439152 437158 443164 448174 446178 443182 439180 437175
      436172 432168
 0.01 432168 431166 427168 423171 420173 415182 409194 409199
      410202 411205 409209 407213 408218 408222 407224 403228
      399231 396235 394237 393244 390248 386252 384256 383262
      384265 383269 386273 394280 406284 412286 418286 430288
      439289 450292 455295 459299 464309 469315 475317 480318
      485316 501310 505301 507292 509287 511281 513273 516266
      517257 516251 514246 509236 503222 502215 499211 496207
      496200 494199 489200 481203 476205 470204 464203 462201
      462197 461191 465186 471183 476182 482186 485189 494192
      500194 502194 503190 503181 504174 507166 511163 515163
      518159 521152 525146 527139 529133 531126 531122 530121
      527117 524113 521109 517108 509102 508099 505096 501095
      496095 492093 489098 482097 480098 478095 475091 468085
      463084 460086 459087 458084 459075 460056 459042 457031
      455016 452002 452997 453991 458988 464984 468981 470975
      480954 484944 487936 490930 494920 504919 518908 521907
      524905 527905 535899 540894 542888 545874 546866 546857
      546839 548824 549811
 0.01 446077 444076 443077 444078 446079 446077
 0.01 402012 402009 401007 400005 400002 400000 400998 400995
      399993 398995 398998 397998 396000 396002 396004 396007
      395007 395009 395010 397010 399011 399012 401012 402012
 0.01 362188 360187 357187 355184 352183 350185 347187 347189
      346194 348195 350193 351190 354189 358190 360188 362188
 0.25 540791 539781 537776 534775 529780 525789 521800 518811
      512828 508834 503841 497858 490862 488863 486861 483859
      475855 471855 467857 457867 447881 443889 440899 439904
      438912 438918 435921 426933 423940 420950 416957 413966
      410978 410983 412987 415994 416999 415005 417010 420012
      426013 428016 430024 431030 433035 431052 432054 431058
      428067 426078 428079 430078 434075 440072 441072 446075
      449078 451080 453076 453061 453050 452039 449031 445023
      442014 436007 431999 429996 428990 430981 432978 436976
      442973 449968 462955 467948 471942 475935 478927 486911
      508885 513880 518874 528860 532853 536845 538840 539832
      540818 540804 540791
 0.25 505276 504268 502264 499261 496251 495245 492241 484238
      478232 471226 470221 473219 477219 481220 486221 491224
      495233 496239 497238 499234 499227 497224 493220 492217
      487213 484210 479210 473214 471216 469217 467215 462214
      458214 449216 442215 434217 426219 423221 425225 426230
      425233 422234 419232 415233 411236 409240 409245 410249
      412252 417259 424265 428268 433268 439271 443273 448274
      464279 470282 474284 480285 482284 485279 492274 500277
      503279 505276
 0.25 502124 503115 501108 499105 496102 492104 488109 484110
      482110 481112 482118 485123 485129 483135 481141 481148
      483154 485159 487161 490160 494157 497155 499152 499146
      498140 497133 502124
 0.25 473680 469668 466664 461663 456662 452661 447660 444662
      439667 423680 412680 398685 386689 377694 356707 348713
      339719 331728 325737 323741 322747 325751 328756 332759
      338760 345760 352759 362756 368754 373756 377785 376788
      378791 381790 387789 394787 399782 403780 414774 420768
      426765 429766 430769 432776 432784 433793 435793 436789
      439779 442774 443768 446763 448757 450750 453744 455732
      456726 460721 463716 465710 469696 473680
 0.25 473106 473105 473103 472101 472100 470098 469098 469097
      467096 465097 463099 461101 461102 462104 463106 464107
      466109 468110 469110 471110 473108 473107 473106
 0.25 459116 460114 460111 459110 457109 456110 455110 454111
      453112 452115 453117 453118 455118 457118 459116 459116
 0.25 434109 433108 432107 431106 430106 428106 427105 426106
      426107 427108 428109 430110 431110 433110 434109
 0.25 422919 421912 417911 411912 406910 401909 397911 391918
      377929 363943 358950 356954 354960 352972 356975 362974
      369970 372967 375966 379967 381968 385965 389962 392959
      401940 407935 414927 418923 422919
 0.25 410119 410118 409117 408114 406113 405114 403116 404118
      404119 406121 407122 409122 409121 410119
 0.25 410108 410105 409105 408105 407107 409109 410108
 0.25 394115 394114 392114 392115 394115 394115
 0.25 390050 390047 387046 386044 386039 388024 387021 385019
      380016 374003 369006 366011 361014 358018 355023 350026
      348030 349034 353033 355031 354040 364043 367048 367050
      365052 360054 355058 350059 345062 349067 355069 354075
      351080 350086 355090 359092 362092 363088 363080 366072
      373065 370061 371060 375062 376063 378061 381056 385053
      390050
 0.25 372772 370768 367766 362765 359765 355768 353772 354777
      355781 358784 363783 367781 370778 371773 372772
 0.25 367061 366059 364059 363060 362061 362062 364062 366061
      367061
 0.50 532808 532804 532798 528801 524814 520828 515840 510854
      507867 507870 509872 514870 517866 520859 523844 526829
      530816 532808
 0.50 495265 496262 495259 495257 494256 493254 493253 492252
      491253 490254 490255 489257 489258 490260 491261 492262
      494263 495265 495265
 0.50 479238 478235 477235 476234 474234 472236 472238 471239
      471241 473243 474244 476244 477243 478241 479239 479238
 0.50 481216 480215 478215 480216 481216
 0.50 472249 470247 468243 466240 463238 461235 457234 450233
      444235 437237 435238 434243 436247 439249 446250 454251
      461251 468252 470253 472251 472249
 0.50 463223 461218 456218 452220 448220 445218 442218 438221
      435223 435226 437227 442227 446227 449225 453224 458226
      462225 463223
 0.50 479912 475906 473899 472895 471890 472874 470866 466867
      458874 454879 452886 451893 451901 452905 452908 448916
      444926 436935 433939 430946 428952 424956 419968 417974
      418976 421974 438961 444960 448956 452952 455945 459933
      469927 475919 479912
 0.50 469103 468102 467102 466102 466103 468104 469103
 0.50 458694 457689 456682 453671 451668 447667 441674 430686
      426688 421687 412687 408687 403689 396693 386695 381697
      378700 370704 363708 355713 348719 338731 333737 331741
      330744 331748 336753 344755 349755 354754 363751 372749
      379752 384759 387762 392762 397758 400759 405758 413758
      416755 418750 419747 424746 427745 430749 434750 438747
      441744 444740 444730 444725 444718 448710 451706 455705
      458694
 0.50 430248 430243 428240 424239 423238 419237 417237 415239
      416241 416245 418247 421249 424250 427250 430248
 0.50 450073 449068 449063 450058 451054 450049 449046 446044
      444046 443049 441053 442057 442060 442062 442065 443069
      445071 447072 450073
 0.50 431733 431732 429733 429734 431733 431733
 0.50 403924 400917 398915 396916 391920 387925 383929 377932
      368941 363945 360952 357967 357970 361971 368968 377961
      388954 391949 394940 396934 400928 403924
 0.50 382051 383042 381035 380028 379026 375024 371021 368015
      365021 364026 365034 366041 369046 373050 375052 379053
      382051
 0.50 369775 369773 368770 367770 365769 364768 362769 361769
      360771 360772 359774 360776 361778 363779 365778 366778
      367777 368777 369775
 1.00 438704 436699 433699 429701 425701 418702 414703 411708
      409714 406720 404725 399729 392720 388717 383715 377714
      369714 358720 354723 350729 345738 343745 346747 348748
      355747 362746 369744 375744 386747 392748 397747 407748
      412746 416743 417740 416737 417734 420728 422722 424720
      427718 431716 434711 438704
 1.00 423243 423241 422241 421243 422244 423243
 1.00 418695 417694 416693 415693 414694 415696 417696 418695
 1.00 390945 389940 388941 387938 388934 385932 381934 377938
      371943 368945 367949 368952 367956 366959 366965 368965
      371963 376958 378956 382955 388950 390945
 1.00 375042 375039 375037 375036 374035 373033 371034 371035
      370037 369039 369041 371043 373044 374043 375042
 1.50 419714 418713 416713 414714 414715 415717 417718 418717
      418716 419714
 1.50 416724 414722 412726 411729 409731 408734 407738 406740
      408742 411743 412741 413737 413734 415730 415727 416724
 1.50 385726 381722 378721 374720 369721 365724 362727 362733
      364737 369739 373739 378737 379733 382730 385726
 1.50 388947 388945 388944 386944 385945 384947 383947 383949
      382950 382952 382953 384952 385952 386950 386949 388948
      388947
 1.50 374956 374954 373954 372955 370956 370957 369958 369961
      370962 371961 371960 373958 374956

$$




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