Quantitative Precipitation Forecast
Issued by NWS

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000
FXUS04 KWBC 210640
QPFPFD

QUANTITATIVE PRECIPITATION FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
239 AM EDT SUN MAY 21 2017


PRELIM DAY 1 QPF DISCUSSION
VALID MAY 21/1200 UTC THRU MAY 22/1200 UTC
REFERENCE AWIPS GRAPHICS UNDER...PRECIP ACCUM - 24HR


DAY 1

EASTERN GREAT LAKES--APPALACHIANS---SOUTHEAST AND CENTRAL GULF
COAST

THE SURFACE FRONTAL BOUNDARY STRETCHING FROM THE GREAT LAKES INTO
THE OH VALLEY---TN VALLEY AND LOWER MS VALLEY AT THE BEGINNING OF
THE UPCOMING DAY 1 PERIOD WILL BE MOVING SLOWLY EASTWARD SUNDAY
INTO EARLY MONDAY---STRETCHING FROM THE EASTERN GREAT LAKES
THROUGH THE APPALACHIANS AND INTO THE CENTRAL GULF COAST BY THE
END OF THE FORECAST PERIOD.  ABUNDANT MOISTURE WILL REMAIN ALONG
AND AHEAD OF THIS FRONT WITH PW ANOMALIES 1.5 TO 2+ STANDARD
DEVIATIONS ABOVE THE MEAN.   THIS ALONG WITH CONTINUED VERY
DIFFLUENT UPPER FLOW IN THE BROAD WEST SOUTHWEST FLOW ALOFT TO THE
EAST OF THE MISSISSIPPI RIVER WILL SUPPORT ANOTHER DAY OF
POTENTIALLY WIDESPREAD MODERATE TO HEAVY PRECIP TOTALS FROM THE
EASTERN GREAT LAKES---APPALACHIANS---SOUTHEAST AND INTO THE
CENTRAL GULF COAST.  CONFIDENCE IS FAIRLY HIGH THAT THERE WILL BE
WIDESPREAD MODERATE TO HEAVY TOTALS---LESS WITH THE SHORTER TERM
QPF DETAILS.  THE WPC DAY 1 QPF LEANED MORE TOWARD THE IN HOUSE
ENSEMBLE MEAN AND HI RES ENSEMBLE MEANS TO MITIGATE THE WIDE RANGE
OF QPF DETAILS AGAIN EVIDENT IN THE LATEST SUITE OF MODELS.  MODEL
CONSENSUS FOR THE HEAVIEST TOTALS THIS PERIOD ARE IN THE VICINITY
OF THE SOUTHERN APPALACHIANS FROM THE UPSTATE OF SC---WESTERN
NC-EASTERN TN INTO SOUTHWEST VA WHERE 2-4"+ TOTALS ARE POSSIBLE.
THE OVERALL FAVORABLE PATTERN FOR WIDESPREAD MODERATE TO HEAVY
RAINS WILL ALSO SUPPORT A FAIRLY LARGE THREAT OF RUNOFF
ISSUES--ESPECIALLY ACROSS PORTIONS OF THE SOUTHERN TO CENTRAL
APPALACHIANS.

UPPER MS VALLEY INTO THE UPPER LAKES

THE COMMA HEAD/DEFORMATION PRECIP AREA ASSOCIATED WITH THE CLOSED
LOW LIFTING NORTHWARD INTO THE UPPER MS VALLEY/UPPER LAKES REGION
DAY 1 WILL CONTINUE TO AFFECT AREAS FROM FAR EASTERN ND INTO
NORTHERN MN AND THE UPPER LAKES REGION.  MODEL CONSENSUS IS FOR
THE HEAVIEST PRECIP TOTALS WITH THIS COMMA HEAD TO BE ACROSS
ONTARIO---WITH .10-.25"+ AMOUNTS AFFECTING FAR EASTERN
ND---NORTHERN MN INTO FAR NORTHERN WI AND THE U.P. OF MI.

NORTHEAST MEXICO INTO SOUTH TX

SOUTHERN STREAM SHORTWAVE ENERGY EXPECTED TO PUSH EASTWARD ACROSS
NORTHERN MEXICO AND INTO SOUTH TX SUNDAY AFTERNOON-INTO SUNDAY
NIGHT/EARLY MONDAY.  THERE IS A GOOD CHANCE OF ORGANIZED
CONVECTION AHEAD OF THESE HEIGHT FALLS AFFECTING THE U.S./MEXICAN
BORDER REGION FROM NORTHEAST CHIHUAHUA---NORTHERN
COAHUILA---NORTHERN NUEVO LEON AND INTO SOUTH TX TO IN THE
VICINITY OF 30N.  THERE ARE NUMEROUS MODEL QPF DIFFERENCES ACROSS
THESE AREAS BUT A CLEAR MODEL SIGNAL FOR POTENTIAL FOR HEAVY
PRECIP TOTALS AND ISOLATED RUNOFF ISSUES WHERE CONVECTION
MAXIMIZES.  SIMILAR TO AREAS TO THE EAST OF THE MISSISSIPPI
RIVER---IN HOUSE ENSEMBLE MEANS WERE USED TO MITIGATE THESE
DIFFERENCES.

NORTHWEST MID TO UPPER LEVEL FLOW EXPECTED FROM THE NORTHERN GREAT
BASIN/NORTHERN ROCKIES INTO THE CENTRAL ROCKIES DAY 1.  WIDESPREAD
SCATTERED CONVECTION LIKELY ACROSS THESE AREAS.  VERY LOW
CONFIDENCE WITH DETAILS---WITH LIGHT TO LOCALLY MODERATE AREAL
AVERAGE AMOUNTS DEPICTED.

ORAVEC

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


24HR QP VT 22/12Z
 0.01 536915 536899 535880 534866 533856 533847 532832 531824
      529818 528803 528796 526790 517766 509747 506738 503733
      502728 500723 496719 493715 489714 483708 476702 469698
      461701 426716 421718 417721 410729 403735 395742 381754
      370765 364771 357778 351784 347788 343792 331803 321805
      317807 314806 303806 293806 282804 272804 262806 258808
      256811 254816 254822 256824 260826 267830 276833 280835
      282840 284842 282845 278847 272852 267859 266869 266881
      275925 273936 270947 265951 260960 252977 251982 247985
      242987 239990 236993 233995 233998 236001 248012 256018
      262024 264028 265035 267040 271044 279058 287071 296074
      300076 305075 311075 315073 318070 325070 330071 335073
      341070 355062 359059 361057 364057 368055 372055 375054
      378054 381056 391058 394067 393081 392089 391097 390102
      388105 386105 380112 378117 377119 377123 380127 385126
      392123 397123 402124 412124 418129 421131 424128 427120
      433113 437110 438105 439101 440096 433088 427080 422073
      419066 422063 424063 439075 445082 449086 454086 459075
      460072 459066 458064 459062 462065 468071 474072 478069
      480066 484063 490064 494066 497067 501067 504065 506060
      508055 509047 507040 505036 501028 496027 492028 487029
      483026 475019 471018 467020 462026 458029 454031 449031
      447029 437028 436038 442046 441052 439057 438061 436063
      435061 429056 425053 421053 417054 414053 408052 401044
      388033 384029 383027 384023 388014 398998 399993 401987
      401984 400978 398974 394972 386968 378972 375978 372981
      366987 359991 353996 350004 344010 338016
 0.01 338016 334021 331026 326029 322024 318011 317004 318996
      321983 323977 325969 327956 328939 326926 325919 324917
      325915 333907 340898 347889 356882 373867 377864 384861
      389859 394858 398856 402856 407857 417861 428866 437872
      442883 444886 444891 444901 448916 448920 445925 442930
      439936 437939 436942 440947 455962 469982 474985 479989
      482988 489988 500986 509980 510978 511972 512964 519955
      521946 523941 529928 536915
 0.01 423096 422093 419091 417088 417085 416083 414080 413082
      414085 414090 415092 417097 415101 414104 416105 418102
      419100 420097 423096
 0.01 406091 405089 405088 403086 402088 402090 403092 405092
      406091
 0.25 529902 529891 527876 522855 516838 513828 510820 503806
      502800 501795 500784 500772 496761 489745 485739 479734
      472733 464730 451725 440732 433735 430737 427740 424757
      424763 422767 419771 414772 408770 406767 407764 407754
      400753 394757 388763 377776 368784 358794 353799 346802
      340806 329808 322812 314813 278812 272811 268811 263812
      260815 261818 266821 281825 287828 293832 298837 299841
      298845 296849 291853 285854 278855 275857 273861 271865
      271871 272881 275898 278906 282911 289915 293916 293921
      288938 285945 282951 274965 270970 266972 266977 264982
      261985 255990 251994 244998 250002 255006 264019 269026
      273034 280044 283049 289054 296054 301054 305052 307048
      308044 308036 310026 309015 309007 309996 309984 310975
      311963 311949 312942 312935 311929 312924 314918 320902
      323893 326885 329878 333872 344864 350860 357857 362852
      369849 386842 400836 409835 417835 424834 433830 443829
      450829 456831 461834 464841 463849 460854 453857 445863
      443866 444871 449876 456879 463883 465885 466891 469901
      474908 478913 481916 482920 486927 489937 492945 497951
      500953 502953 504950 510944 516930 521925 524918 528910
      529902
 0.25 370026 371023 371021 370020 368019 367019 365019 364021
      363023 362025 361027 361029 360031 361033 362033 364033
      366032 368030 369028 370026 370026
 0.50 521900 521889 520881 516876 514875 511876 502870 497870
      492873 489879 486886 486894 487902 490917 493924 497929
      501932 505930 510926 513921 514918 517916 519910 521900
 0.50 482819 482814 481808 479801 475796 474793 475790 477782
      475775 471768 472764 472758 469751 465747 463740 457737
      454737 451738 447741 439750 435755 431761 424771 422776
      418780 412786 407788 401791 393792 392787 392785 388783
      375782 371786 368790 359799 349805 343807 336809 332809
      329811 324814 317816 310816 295816 289818 287821 289822
      298831 302836 306842 307847 307854 307860 309861 315863
      326857 338853 349851 354850 360846 370839 382833 394830
      407826 420821 425819 432820 444821 456823 468825 473825
      478824 482819
 0.50 480872 479868 477865 472865 469865 464862 457863 452865
      451870 454872 457874 463877 468878 473881 476880 478878
      480872
 0.50 313903 312889 311882 310876 307872 307868 306866 298874
      294884 293887 291888 290882 291868 286859 281857 277858
      275860 274865 274872 275889 278899 282903 286906 295905
      297909 298917 298925 297931 292941 287950 283959 277968
      274974 273980 272986 269990 259994 256998 257002 262012
      268019 275027 281035 289043 292044 297043 300039 302034
      304026 305019 300009 300002 300995 300964 300956 301950
      305939 309913 313903
 0.50 274818 273817 272817 270816 268816 266816 266817 268818
      269818 270819 272818 274818 274818
 1.00 467804 465797 463795 459793 458790 455789 450790 435794
      420795 412796 406801 400804 403808 409810 417810 425809
      431807 438806 443809 449811 456812 460812 463811 466809
      467805 467804
 1.00 389815 389811 387808 383807 379806 377804 377801 378795
      373796 365801 356806 348811 328817 306820 303824 305827
      312833 316835 320836 326837 330839 337844 347845 353844
      356841 362835 370829 378825 385820 389815
 1.00 292018 291014 289010 288004 287999 289995 289989 287985
      284982 280983 278987 279995 268996 264998 263002 264007
      267011 269014 272016 280020 283022 288022 292018
 1.50 372810 372808 370807 366808 359810 354813 349818 344821
      340826 327823 321822 312823 312826 315828 321829 327831
      335831 337829 339831 342838 347842 352840 360830 368820
      372810
 1.50 284010 285006 283003 281001 278000 275999 273999 271999
      268001 266003 267006 269009 270011 272013 276012 280013
      282014 283012 284010
 2.00 367813 364812 361813 359814 356817 354819 352820 350822
      351826 353827 356827 358825 360822 361821 364818 366816
      367813
 2.00 278007 277005 276005 275004 273004 271005 271006 271007
      272009 273009 274009 275009 276007 278007 278007

$$





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