Quantitative Precipitation Forecast
Issued by NWS

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000
FXUS04 KWBC 231859
QPFPFD

QUANTITATIVE PRECIPITATION FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
258 PM EDT SAT SEP 23 2017


PRELIM DAY 1 QPF DISCUSSION
VALID SEP 24/0000 UTC THRU SEP 25/0000 UTC
REFERENCE AWIPS GRAPHICS UNDER...PRECIP ACCUM - 24HR


DAY 1

SOUTHERN TO CENTRAL HIGH PLAINS---CENTRAL TO EASTERN PORTIONS OF
THE NORTHERN PLAINS INTO THE FAR NORTHERN PORTIONS OF THE UPPER MS
VALLEY

THE BEGINNING OF THE WELL ADVERTISED MULTI DAY HEAVY PRECIP EVENT
STRETCHING ACROSS LARGE PORTIONS OF THE PLAINS INTO THE UPPER MS
VALLEY IS ALREADY UNDERWAY AND WILL CONTINUE TO ENHANCE DURING THE
UPCOMING DAY 1 TIME PERIOD AHEAD OF THE SLOW EASTWARD MOVING
LONGWAVE TROF STRETCHING INITIALLY FROM THE NORTHERN ROCKIES INTO
THE GREAT BASIN AND SOUTHWEST.  GOOD AGREEMENT IN THE LATEST MODEL
GUIDANCE WITH THE EVOLUTION OF THIS TROF AND THE DEPICTION OF AN
AXIS OF MUCH ABOVE AVERAGE PW VALUES---WELL DEFINED UPPER
DIFFLUENCE AND STRONG FRONTAL CONVERGENCE AHEAD OF THIS TROF AND
IN THE VICINITY OF THE ASSOCIATED SURFACE FRONTAL BOUNDARY.  WHILE
THERE ARE THE USUAL AMOUNT OF QPF DETAIL DIFFERENCES AMONG THE
GUIDANCE AT THE SHORTER TIME SCALES---THERE IS A STRONG SIGNAL FOR
THE ABOVE MENTIONED POTENTIAL FOR WIDESPREAD HEAVY TO LOCALLY
EXCESSIVE RAINFALL AMOUNTS ACROSS THESE AREAS.   DEEP LAYERED
SOUTHERLY TO SOUTH SOUTHWESTERLY FLOW AHEAD OF THE SLOW MOVING
CLOSED LOW WILL SUPPORT POTENTIAL FOR TRAINING OF AREAS OF
PRECIPITATION IN A GENERAL SOUTH SOUTHWEST TO NORTH NORTHEASTERLY
DIRECTION.  HOW QUICKLY THESE AREAS OF ENHANCED PRECIPITATION MOVE
EASTWARD IS CREATING THE MOST SIGNIFICANT DIFFERENCES AMONG THE
MODELS.  CONFIDENCE ON WHICH SOLUTION IS BEST IS LOW GIVEN POOR
RUN TO RUN CONTINUITY AND THE LARGE SPREAD AMONG THE MODELS IN
DETAILS.  THE IN HOUSE HI RES QPF MEANS WERE USED PRIMARILY FOR
THESE DETAILS DAY 1---DEPICTING WIDESPREAD AREA AVERAGE 1-2"+
TOTALS FROM THE SOUTHERN TO CENTRAL HIGH PLAINS INTO THE CENTRAL
TO EASTERN PORTIONS OF THE NORTHERN PLAINS AND FAR NORTHERN
PORTIONS OF THE UPPER MS VALLEY.  ISOLATED TOTALS IN EXCESS OF 5"
POSSIBLE WHERE TRAINING OR VERY SLOW MOVEMENT OF CELLS  OCCURS.
NO CHANGES MADE TO THE PREVIOUS BROAD MARGINAL AND SLIGHT RISK
AREAS DEPICTED ON THE DAY 1 EXCESSIVE RAINFALL POTENTIAL OUTLOOK.

GREAT BASIN INTO THE CENTRAL-NORTHERN ROCKIES

CLOSER TO AND TO THE NORTHEAST OF THE CLOSED LOW CENTER ASSOCIATED
WITH THE LONGWAVE WESTERN TROF---A DEVELOPING COMMA
HEAD/DEFORMATION PRECIPITATION AREA WILL SUPPORT MOSTLY MODERATE
TO ISOLATED HEAVY PRECIP TOTALS FROM EASTERN PORTIONS OF THE GREAT
BASIN IN THE VICINITY OF THE WASATCH/UINTA---NORTHEASTWARD INTO
THE CENTRAL-NORTHERN ROCKIES OF WY.  OVERALL---MODELS ARE FAIRLY
SIMILAR WITH PRECIP TOTALS ACROSS THESE AREAS.

CENTRAL GULF COAST INTO FLORIDA

AN UPPER LEVEL LOW ALONG THE GULF COAST WILL SUPPORT BROADLY
DIFFLUENT PATTERN FROM THE CENTRAL GULF COAST INTO FLORIDA DAY 1.
THIS DIFFLUENT UPPER PATTERN COMBINED WITH MOIST LOW LEVEL
EASTERLY FLOW WILL SUPPORT A SHOWERY PATTERN ACROSS THESE AREAS
WITH LOCALLY HEAVY PRECIP TOTALS POSSIBLE.  THIS IS ESPECIALLY SO
ALONG PORTIONS OF THE EAST-CENTRAL TO SOUTHEAST COAST OF FLORIDA
WHERE MANY OF THE HI RES GUIDANCE SHOW LOCALLY VERY HEAVY TOTALS.
THE LOCATION OF THESE MAXIMA DIFFER AMONG THE MODELS---LEADING TO
LOW CONFIDENCE IN PLACEMENT.

ORAVEC

GRAPHICS AVAILABLE ON THE WEB AT WWW.WPC.NCEP.NOAA.GOV

24HR QP VT 25/00Z
 0.01 314697 319708 322715 323721 324730 325736 324743 321749
      313757 308760 301762 295764 290762 286760 278760 267759
      261757 256754 248748 245742 244734
 0.01 223070 229074 232076 238076 259076 270070 277066 280064
      286064 294064 305066 309067 315067 318066 324066 340064
      355070 368075 375081 378083 383084 390082 396079 400077
      404078 404084 402087 391098 387104 382110 376119 372128
      372134 373137 377144 383141 389136 401137 405138 409137
      423134 428130 432127 434121 437113 438106 440103 446100
      450100 453098 455096 457091 460081 467075 472068 477061
      482054 484049 488045 494041 504032 509027 513017 517008
      521998 525989 528978 531971 534960 537951 541944 545936
      547924 550895 551872 553848 553842 551838 547830 545826
      544822 546821 549817 548808 544799 540790 534793 533790
      535785 535779 534775 530764 528759 526753 527746 526740
      525734 524726 523720 521715 524695 522681 520672 513651
      508642 504636 497632 490626 484624 481624 476625 474635
      474641 473644 470644 465646 462650 463656 465662 468670
      472676 474683 475691 475695 476704 476717 477731 478743
      479749 481754 482764 485773 488783 493793 501810 502815
      501820 501832 494837 491839 489844 487867 485877 480882
      475887 469895 465903 460912 453929 451933 448937 442942
      431951 417960 406968 393975 386980 377984 360989 345994
      337997 329001 303015 286017 276017 267013 263011 260008
      255004 245003 240003 238007 229019
 0.01 353744 353741 351742 348743 339749 328761 323767 318774
      312781 309788 304795 301804 298809 297813 297817 301817
      306812 311805 320791 330776 335769 341762 350747 353744
 0.01 333898 333890 331886 324879 316873 309869 308858 306854
      305847 301838 294832 277824 274822 272816 272812 274811
      279812 283813 290812 291802 290797 286792 280788 269787
      259790 248793 244795 240798 238802 236808 236812 237817
      239823 241826 247835 248842 250845 254855 258866 259870
      260876 262881 263888 264902 268925 269930 270935 274939
      277938 288923 293925 299925 305918 310916 315915 324911
      326908 328903 331898 333898
 0.25 540885 540875 540864 539854 537846 533835 529832 522832
      517835 514840 509852 507859 505864 500875 498880 496888
      493894 488897 481904 478908 474913 462935 455944 449951
      440957 430963 421968 413974 405980 396986 387991 377997
      367001 355004 335011 325016 314020 295027 285031 281036
      279042 281047 286049 297054 307056 314058 320057 330053
      342048 352045 358044 364042 372038 383035 394033 398034
      398036 394041 390044 389046 390050 398056 401062 405066
      412068 415071 419075 421080 419088 418091 415092 410093
      406096 404101 401106 390111 386115 383119 383127 395126
      401127 407127 417125 422124 425123 426120 428113 429103
      432089 434082 436076 443066 451058 458052 468046 475041
      483033 490026 496014 503004 505998 508991 518969 522959
      525953 527946 531931 534917 538900 540885
 0.25 502695 501687 498683 495681 492686 491691 491698 491703
      490708 492713 495713 497709 499704 501700 502695
 0.25 248733 248738 251745 253749 258752 269755 282756 291759
      298760 302759 309756 313753 317748 320744 321739 320730
      319722 317714 314708 311704 308701
 0.25 302888 303882 302877 302871 301865 294851 291842 285837
      273830 267829 263831 261834 262839 265847 266858 268869
      270878 274896 278903 282909 288909 291908 297902 302888
 0.25 261062 260053 259049 257047 251043 245040 238036 234036
      232039 228045 227050 228054 233059 238062 246064 254065
      260062 261062
 0.50 534885 534879 533871 531866 529862 526860 523862 516866
      507881 502888 499896 494903 489909 479920 474927 469935
      464942 460947 454952 447957 435965 428968 421973 409982
      395990 383997 377001 369004 353009 338014 325021 318024
      310027 295032 289036 287040 289043 295047 305048 312052
      316053 320052 334045 396029 401029 406030 412036 418039
      426039 457031 467032 471031 474029 479024 484017 500987
      504978 509970 516954 520946 524936 526928 528918 531899
      534885
 0.50 419116 418114 415114 412112 409109 405110 401112 398114
      395117 399120 402121 407123 411122 415120 418117 419116
 0.50 254730 256737 259741 266747 270750 274752 283754 293758
      298758 303757 312751 315748 317743 317733 315721 310710
      304703
 0.50 298868 297863 295859 290851 287848 283847 276851 272859
      272865 273871 276880 280890 282892 286895 288895 291893
      294889 294885 297874 298868
 1.00 521905 522899 521894 519891 516890 514889 512890 508898
      503913 500921 497916 494916 492919 488925 484930 479934
      473936 469942 466948 462952 451960 443969 433977 428980
      422982 410989 399993 387999 376005 352014 347016 342020
      328025 319033 317034 316038 318040 322042 335037 351037
      357036 363034 375029 402023 415021 427017 438012 449007
      457006 465006 471005 475001 484992 488986 491980 494973
      497964 502949 505943 506939 510937 513933 516926 521905
 1.00 258727 260733 262737 267743 273748 281752 289754 298755
      303754 307751 310747 311743 312732 311726 307716 302708
      300706
 1.50 484964 485957 484951 480952 476953 470952 462957 440981
      412996 408998 404999 400998 395999 387002 380005 373010
      366013 350019 347021 348022 350026 348028 346031 346033
      348034 353033 357032 364030 372027 390023 398021 404016
      419010 433004 448996 461987 467983 471981 474977 481972
      484964
 1.50 260727 262732 264737 269742 275747 283751 292752 296753
      301752 305749 306746 308741 308736 308726 304716 299709
      297707
 2.00 421999 420998 419998 417999 418001 420999 421999
 2.00 418001 417000 415000 413000 413001 411002 411003 411004
      413004 415003 416003 417002 418001
 2.00 404005 400004 395004 385007 380009 379013 377016 372018
      363022 359025 357028 368026 378024 388021 392019 395018
      396016 398011 402008 404005
 2.00 263724 263729 265734 269740 275745 280748 286750 294751
      299751 303749 306743 307737 307732 306727 303719 300713
      294708
 3.00 268722 268732 269737 271739 276743 282746 290748 297748
      302744 305737 305729 301721 298715 292710
 4.00 270721 270729 271734 272737 278741 284745 290747 294747
      297745 303740 304733 303728 301724 298718 292713 288711
 5.00 272721 272729 273734 276739 282741 286743 291745 298743
      302739 303736 303732 302727 299724 296718 291715 287713
 6.00 274720 274728 275733 279738 283741 289743 295743 300740
      302736 302732 301728 297724 294718 289716 283715 281715
 7.00 302734 301730 298728 295724 292719 287717 280718 277720
      277726 276732 279737 283740 289742 293742 296740 301736
      302734
 8.00 300732 295729 293723 289719 284718 279721 278728 278734
      281738 287740 292740 297737 300732
 9.00 296735 294731 293725 291721 288719 282720 280723 279728
      279734 283737 286739 291739 295737 296735
10.00 295735 293731 293727 292724 290721 288720 284720 281723
      280725 279728 280732 281734 283736 285737 289738 290739
      292738 295735

$$




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