Quantitative Precipitation Forecast
Issued by NWS

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000
FXUS04 KWBC 010653
QPFPFD

QUANTITATIVE PRECIPITATION FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
253 AM EDT SUN MAY 01 2016


PRELIM DAY 1 QPF DISCUSSION
VALID MAY 01/1200 UTC THRU MAY 02/1200 UTC
REFERENCE AWIPS GRAPHICS UNDER...PRECIP ACCUM - 24HR


DAY 1

LOWER LAKES---MID ATLANTIC INTO NY STATE AND NEW ENGLAND

SEVERAL AREA OF LOW PRESSURE MOVING WEST TO EAST ALONG THE FRONTAL
BOUNDARY NORTH OF THE OH RIVER AND SOUTH OF THE LOWER LAKES WILL
ACCENTUATE LIFT FROM THE LOWER LAKES INTO THE MID ATLANTIC---NY
STATE AND NEW ENGLAND DAY 1.  WITH PW VALUES REMAINING ABOVE
AVERAGE IN THE VICINITY OF THIS BOUNDARY---WIDESPREAD MODERATE TO
HEAVY PRECIP TOTALS LIKELY ACROSS THESE AREAS.  CONFIDENCE ON THE
SHORTER TERM QPF DETAILS IS LOW GIVEN THE SPREAD IN THE LATEST
GUIDANCE.  THE IN HOUSE ENSEMBLE QPF MEAN AND HI RES ENSEMBLE
MEANS WERE USED FOR DETAILS TO ATTEMPT TO MITIGATE THE SPREAD IN
THE LATEST GUIDANCE.  THIS RESULTS IN A BROAD REGION OF .25-.50"+
AMOUNTS ACROSS THESE AREAS---WITH THE LIKELIHOOD OF HEAVIER
TOTALS---AS PER MOST OF THE GUIDANCE BUT IN MANY DIFFERENT
LOCATIONS.

CENTRAL TO SOUTHERN APPALACHIANS INTO THE SOUTHEAST

TO THE SOUTH OF THE WEST TO EAST ORIENTED FRONT AND AHEAD OF THE
EASTWARD MOVING COLD FRONT FROM THE MID TO LOWER MS VALLEY INTO
THE TN VALLEY---EQUALLY LOW CONFIDENCE WITH QPF DETAILS STRETCHING
ACROSS THE CENTRAL TO SOUTHERN APPALACHIANS INTO THE SOUTHEAST.
PW VALUES 1-2+ STANDARD DEVIATIONS ABOVE THE MEAN WILL SUPPORT
POTENTIAL FOR WIDESPREAD MODERATE TO LOCALLY HEAVY PRECIP TOTALS
FROM THE CENTRAL TO SOUTHERN APPALACHIANS INTO THE SOUTHEAST.
HOWEVER---WITH SUCH SPREAD IN DETAILS AMONG THE LATEST
GUIDANCE---CONFIDENCE IS LOW WITH DETAILS RESULTING IN THE IN
HOUSE QPF ENSEMBLE MEAN USED PRIMARILY.

SOUTHEAST TX INTO LA

LOW LEVEL INFLOW IS FORECAST TO BACK EARLY THIS MORNING TO A MORE
SOUTHERLY DIRECTION INTO THE LA COAST AND UPPER TX COAST DAY 1.
THIS SHOULD SUPPORT INCREASING CONVECTIVE POTENTIAL ALONG AND TO
THE SOUTHEAST OF THE SLOW MOVING FRONTAL BOUNDARY STRETCHING FROM
SOUTHEAST TX INTO THE LOWER MS VALLEY.  THERE IS A MODEL SIGNAL
FOR HEAVY TO EXCESSIVE RAINFALL AMOUNTS ACROSS THESE
AREAS---ALTHOUGH THERE IS A LARGE DEGREE OF SPREAD MODEL TO MODEL
AND A LOT OF RUN TO RUN VARIABILITY.  SUBSEQUENLTY---CONFIDENCE IS
ON THE LOWER THAN NORMAL SIDE---WITH THE HI RES ENSEMBLE MEANS
USED PRIMARILY---RESULTING IN THE MAX AXIS FROM SOUTHERN
MS---ACROSS SOUTHERN LA AND INTO THE UPPER TX COAST.  WITH THE
RECENT VERY HEAVY RAINFALL EVENT OVER PORTIONS OF SOUTHEAST TX
INTO SOUTHERN LA HAVING LOWERED FFG VALUES----ADDITIONAL RUNOFF
ISSUES ARE POSSIBLE.  SEVERAL MODELS ARE SHOWING MODERATE TO HEAVY
PRECIP TOTALS EXTENDING FARTHER TO THE NORTHWEST INTO NORTHEAST
TX/SOUTHERN AR IN ASSOCIATION WITH LIFT TO THE SOUTHEAST OF THE
HEIGHT FALLS EJECTING INTO THE SOUTHERN PLAINS THIS PERIOD.  AT
THE MOMENT---GIVEN NO CLEAR CONSENSUS FOR THESE AMOUNTS---DAY 1
QPF KEPT PRECIP TOTALS ON THE LIGHT SIDE HERE.

SOUTHWEST---SOUTHERN ROCKIES INTO THE SOUTHERN HIGH PLAINS

THE INITIALLY WELL DEFINED CLOSED LOW OVER THE SOUTHWEST WILL
PRESS STEADILY EASTWARD SUNDAY THROUGH THE SOUTHWEST---BECOMING
MORE SHEARED SUNDAY NIGHT INTO EARLY MONDAY AS IT PUSHES INTO THE
SOUTHERN TO CENTRAL PLAINS.  MODEL CONSENSUS IS FOR MODERATE TO
ISOLATED HEAVY PRECIP TOTALS IN THE FAVORED TERRAIN REGIONS OF THE
SOUTHWEST AND INTO THE SOUTHERN ROCKIES. TO THE EAST OF THE HIGHER
TERRAIN---THE LATEST HI RES ARW AND NMMB ARE SHOWING A MORE
DEFINED STREAK OF MODERATE PRECIP TOTALS FROM EAST CENTRAL NM INTO
THE TX PANHANDLE AND NW OK.  CAN NOT SAY WITH CONFIDENCE THAT THIS
HI RES DETAIL IS NOT POSSIBLE---BUT GIVEN THE RELATIVE SMALLER
SCALE OF THESE PRECIP AREAS---CONFIDENCE IS NOT GREAT WITH LIGHTER
PRECIP TOTALS DEPICTED.

MID RIO GRANDE VALLEY OF TX

THERE IS FAIRLY GOOD MODEL AGREEMENT FOR MODERATE TO HEAVY PRECIP
TOTALS LATE SUNDAY AFTERNOON INTO SUNDAY  NIGHT OVER OVER THE MID
RIO GRANDE VALLEY OF TX.  LOW LEVEL EASTERLY FLOW IS FORECAST TO
FOCUS INTO THE STATIONARY FRONTAL BOUNDARY OVER THIS REGION IN THE
0000 TO O600 UTC PERIOD MONDAY---SUPPORTING POTENTIAL FOR
INCREASINGLY ORGANIZED CONVECTION AND LOCALLY HEAVY PRECIP TOTALS.


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

ORAVEC

24HR QP VT 02/12Z
 0.01 482698 480683 476676 471670 469668 466667 461670 456670
      447670 434655 428651 420647 411650 405653 401657 394663
      390670 382683 374698 366713 353728 347735 343744 339751
      335760 332768 330774 329780 326797 325802 322806 315813
      309828 307837 306840 306847 302868 299878 297884 294889
      283903 275918 275922 277925 277929 275931 270940 266949
      260964 253980 251989 247998 256016 318044 323076 327079
      328086 328091 326098 326104 328108 334115 344131 348137
      352139 356138 358136 360130 366124 373119 378112 382103
      385095 390091 393088 395082 397076 398071 396066 398060
      407057 410056 411055 409049 380033 376034 370034 366032
      363027 363023 365022 368023 375020 379017 379012 380007
      378003 375982 375974 374970 374962 372958 369955 366954
      362957 358961 355966 350967 345967 341965 337962 337959
      343954 358944 363936 365932 363927 355911 355900 355893
      356888 357882 359877 367873 374867 380858 386878 388881
      389882 394885 398896 402906 403911 404917 398933 398957
      398969 398976 399981 403991 409996 415996 418993 424985
      429979 432976 434970 437954 438941 440928 441916 445899
      449879 450868 453857 456845 457833 460820 463815 464810
      468798 468793 468785 468773 467759 469753 471749 475743
      478719 482698
 0.01 399213 397207 394202 388195 381188 372182 363177 359178
      357183 362190 370197 378203 386210 392213 398214 399213
 0.01 343182 344180 344178 344175 344173 343171 343170 341170
      340170 340172 340175 339177 340177 340179 340181 341182
      343183 343182
 0.01 275809 275803 272799 268798 266798 262801 258803 257807
      259811 262815 266816 270814 274812 275809
 0.25 461723 459718 457715 452707 449704 444702 434701 426698
      422697 420693 421680 420674 418667 416664 412663 409665
      406668 394686 389694 383703 375719 367737 366741 367748
      367760 366764 366771 367778 366783 365789 362789 356790
      349790 345792 342794 336801 334805 332811 329821 323841
      319849 316854 315859 312867 307875 298894 290908 288912
      286919 285933 284943 284949 284956 287960 290960 295961
      300960 315951 320942 325934 328926 331915 336892 341884
      345877 350867 354857 358848 363841 369834 376828 383822
      387820 389819 390822 389831 390838 395849 399855 405862
      413868 417870 421869 425858 427847 428840 429835 432824
      435816 440806 446799 452798 456795 460743 460731 461723
 0.25 423931 423928 423926 423924 422922 421923 421924 420926
      419928 419929 418931 418933 418935 419938 421938 422935
      423933 423931
 0.25 384083 383077 382071 378065 373063 370062 367063 369069
      370077 370084 373090 375096 378097 380095 382089 382084
      384083
 0.25 371052 368051 367049 363047 362047 358046 354046 353047
      351051 352053 354056 357057 361057 363056 366055 368053
      371052
 0.25 351117 350112 348108 346105 345101 344094 342091 338091
      337097 338102 339106 341111 344114 347117 351117
 0.25 313017 314012 313009 306006 298003 289002 283999 280999
      277001 275004 275009 280014 287017 294020 301021 306022
      310022 313017
 0.50 452755 453747 452740 450732 449727 449721 447715 443712
      437713 427716 415715 408717 404720 401725 400730 401737
      403739 397741 390747 387751 384756 381780 370797 367805
      361815 349830 344837 341842 339846 338852 340854 347847
      350844 352841 356829 358825 362825 368826 371822 376814
      380803 384793 385788 389784 392782 396779 402770 407762
      409758 416755 421756 423759 428762 431767 436775 440778
      446777 449772 450766 452755
 0.50 416686 416681 414677 410677 408680 399691 389702 385708
      382716 377730 375740 375743 377746 382744 385741 387737
      390730 393724 399719 402713 410700 413694 416686
 0.50 425794 423789 421785 417784 412786 408788 405790 404794
      406798 408801 412805 415806 418802 420799 425796 425794
 0.50 412737 410737 409737 410739 412737 412737
 0.50 379080 379078 379076 379074 378071 377069 376069 375068
      374068 373070 373071 372073 373075 373077 374079 374080
      375082 377082 379081 379080
 0.50 326896 326891 326885 324882 321881 320881 318879 313878
      310879 305886 302893 299899 295904 291910 289918 288929
      289939 290950 291952 296952 303950 308945 312939 315932
      320917 325902 326896
 1.00 315911 316905 315898 313895 307895 302902 297908 294912
      293916 292929 292933 293937 294941 297945 305941 308937
      310933 312924 315913 315911
 1.50 312916 312907 311905 308903 304904 302907 300912 299918
      297924 296931 296934 297936 299939 301939 304935 307930
      309924 311918 312916
 2.00 303928 303927 301928 300931 301931 302931 303929 303928

$$




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