Quantitative Precipitation Forecast
Issued by NWS

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000
FXUS04 KWBC 300654
QPFPFD

QUANTITATIVE PRECIPITATION FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
253 AM EDT SAT APR 30 2016


PRELIM DAY 1 QPF DISCUSSION
VALID APR 30/1200 UTC THRU MAY 01/1200 UTC
REFERENCE AWIPS GRAPHICS UNDER...PRECIP ACCUM - 24HR


DAY 1

SOUTHEAST TX INTO THE LOWER MS VALLEY

THERE ARE A LOT OF UNCERTAINTIES ON HOW THE ONGOING VERY HEAVY TO
EXCESSIVE RAINFALL EVENT OVER NORTHEAST TX...NW LOUISIANA INTO
SOUTHWEST ARKANSAS WILL EVOLVE AT THE BEGINNING OF THE UPCOMING
DAY 1 TIME PERIOD.  TIMING OF THE EAST SOUTHEAST PUSH OF THE
ORGANIZED CONVECTION VARIES AMONG THE LATEST GUIDANCE---BUT THERE
SHOULD BE INCREASED PROGRESSION EARLY DAY 1 AS HEIGHTS FALL
SLIGHTLY ACROSS THE WESTERN TO CENTRAL GULF COAST AREA AND THE
CURRENT STRONG LOW LEVEL SOUTH SOUTHWESTERLY FLOW VEERS TO A MORE
SOUTHWESTERLY DIRECTION.  DAY 1 QPF LEANED TOWARD THE CMC GEM FOR
THE BEGINNING OF THE DAY 1 PERIOD---WITH ITS TIMING FASTER THAN
THE NMMB---BUT A LITTLE SLOWER THAN THE ARW AND HRRR.  AFTER
THIS---THE ARW BECOMES VERY PROGRESSIVE WITH THIS CONVECTION TO
THE EAST SOUTHEAST PUSHING IT THROUGH ALL OF SOUTHEAST LA BY 0000
UTC---MUCH FASTER THAN ITS PREVIOUS RUN.  WHILE THE ARW OFTEN DOES
BEST WITH LARGE SCALE ORGANIZED CONVECTION---LOWER CONFIDENCE WITH
IT WHEN IT SHOWS SIGNIFICANT RUN TO RUN CHANGES.  THE NSSL WRF AND
CMC GEM WERE SLOWER THAN THE ARW FOR THE 2ND SIX HOUR PERIOD AND
WERE FOLLOWED.  WHILE HEAVY PRECIP AND RUNOFF ISSUES ARE LIKELY
INTO THE BEGINNING OF THE DAY 1 PERIOD ACROSS
LOUISIANA...SOUTHWEST MS---TOTALS LIKELY WILL NOT BE AS GREAT AS
HAS BEEN OBSERVED OVER PORTIONS OF TX/AR AS INCREASED PROGRESSION
IS EXPECTED EARLY DAY 1 AND LESS ORGANIZATION TO ANY ADDITIONAL
CONVECTION AFTER 0000 UTC SUN ACROSS THE LOWER MS VALLEY AS THE
BEST LARGE SCALE FORCINGS LIFT NORTHEASTWARD.

OH VALLEY INTO THE CENTRAL APPALACHIANS

WITH THE STRONGEST UPPER DIFFLUENCE EXPECTED TO LIFT NORTHEASTWARD
FROM THE LOWER MS VALLEY EARLY DAY 1 AND INTO THE OH
VALLEY/CENTRAL APPALACHIAN ARE LATER DAY 1---THE EMPHASIS FOR
ORGANIZED CONVECTION IN THE 0000-1200 UTC SUNDAY TIME PERIOD WILL
ALSO BE LIFTING  NORTHEASTWARD.  THERE ARE DIFFERENCES AMONG THE
MODELS WITH RESPECT TO THE AXIS OF THE HEAVIEST TOTALS ACROSS THE
OH VALLEY INTO THE CENTRAL APPALACHIANS DUE TO TIMING
DIFFERENCES---BUT A STRONG MODEL SIGNAL FOR HEAVY TO ISOLATED
EXCESSIVE RAINFALL TOTALS ACROSS THE OH VALLEY INTO THE CENTRAL
APPALACHIAN REGION.  THE CMC GEM...NSSL WRF AND IN HOUSE QPF
ENSEMBLE MEAN WERE USED PRIMARILY FOR THE QPF AXIS DETAILS.

LEE OF THE CENTRAL ROCKIES INTO THE CENTRAL PLAINS AND MID MS
VALLEY

MODERATE TO HEAVY RAINFALL AMOUNTS ALSO POSSIBLE TO THE NORTH AND
NORTHEAST OF THE SLOW MOVING CLOSED LOW FORECAST TO DRIFT EASTWARD
THROUGH THE CENTRAL PLAINS TOWARD THE MID MS VALLEY REGION.
OVERALL THERE IS GOOD AGREEMENT WITH THE AMOUNTS AND AXIS OF THIS
PRECIPITATION AREA.  THE IN HOUSE QPF ENSEMBLE MEAN WAS FOLLOWED
TO MITIGATE AND SMALLER DETAIL DIFFERENCES.  LATE SEASON
ACCUMULATING SNOWS POSSIBLE ON THE WESTERN PORTION OF THIS
PRECIPITATION AREA FROM SOUTHEAST WY INTO FAR SW SOUTH DAKOTA AND
WESTERN NEBRASKA.  SEE THE LATEST QPFHSD FOR ADDITIONAL WINTER
WEATHER INFORMATION ACROSS THIS AREA.

SOUTHERN GREAT BASIN---SOUTHWEST INTO THE SOUTHERN ROCKIES

THERE IS FAIRLY GOOD AGREEMENT WITH THE EVOLUTION OF THE NEXT IN
THE SERIES OF STRONG CLOSED LOWS AMPLIFYING ACROSS THE WESTERN
U.S.---WITH THE NEXT CLOSED LOW FORECAST TO DROP SOUTHEASTWARD
FROM THE SOUTHERN GREAT BASIN INTO THE SOUTHWEST.   A DEVELOPING
COMMA HEAD/DEFORMATION PRECIPITATION BAND TO THE NORTH AND
NORTHEAST OF THIS CLOSED LOW WILL SUPPORT MODERATE TO ISOLATED
HEAVY PRECIP TOTALS FROM SOUTHERN NV--FAR SOUTHERN UT---CENTRAL TO
NORTHERN AZ---SOUTHWEST CO INTO NW NM.


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

ORAVEC

24HR QP VT 01/12Z
 0.01 527169 523162 517154 505142 498136 492134 487131 482129
      478124 476121 474114 475100 472091 468085 459083 456078
      454072 454056 452032 451019 449006 447995 447981 447914
      450901 450894 451889 454877 454863 453837 452822 452814
      452809 451794 448782 442762 440755 437751 433749 429745
      422740 419738 412737 397735 390734 386737 382738 372743
      370747 368753 366757 364762 361771 358781 355784 351786
      344790 342794 339795 326796 314798 310801 309804 312817
      320831 318839 317843 317850 316863 309870 296878 275904
      264920 263927 264931 264938 266943 264954 266958 266964
      266969 268972 277975 282975 285973 293967 300962 308958
      324951 337942 347937 352936 357934 365928 368925 370921
      372917 376916 383920 387945 391968 394991 397015 399024
      398030 396034 394039 390043 386046 380046 376043 373039
      370035 366033 349032 344032 340034 336037 333040 331045
      331050 334055 337058 338062 337067 336078 333082 330085
      326087 327090 323100 322104 324107 332113 335123 340132
      335144 335149 337154 340157 339160 337160 331159 328160
      325163 326166 331167 335169 341176 343181 346185 352179
      355176 358176 362178 364182 367186 370189 373192 377192
      381195 387196 389193 387188 381181 380175 380165 382160
      383152 387141 397122 400118 404119 411123 412129 408132
      405134 402137 398140 397145 399150 402153 408159 413155
      417156 422155 425153 428148 429141 429136 431133 432140
      434145 437156 442159 444162 446167 448172 449175 449177
      445181 443183 442188 446190 449194 451195 454192 458186
      462183 464178 467170
 0.01 467170 469165 474164 479167 482169 487172 490173 495175
      500176 505177 510178 515179 518178 521178 524174 527169
 0.01 421102 422093 421084 418079 411078 409080 406079 402079
      390082 385095 384102 384106 386108 389108 393107 398106
      406098 406093 408091 408096 410098 410103 412109 418107
      421102
 0.25 441854 438827 439813 439804 437796 434784 431776 427766
      424761 420759 405752 394753 389753 385754 381758 379762
      376769 365785 360792 354798 345805 340812 335832 335838
      336843 339854 340857 339860 336863 330868 314881 301893
      290905 280919 276929 275934 276942 275948 276953 281959
      287959 292958 300954 309950 315945 330933 337927 344923
      352918 359914 367909 373905 378902 383902 387906 387911
      389917 393919 395922 397927 400936 406945 408950 409955
      406963 405969 405975 407989 414038 417047 422053 426056
      430055 434042 437039 439033 441021 441995 441980 441966
      440948 439935 439906 440878 441854
 0.25 432092 431091 430090 429089 428088 428089 428090 428092
      429092 431093 432092
 0.25 376130 376122 373116 370112 370104 370098 371091 373084
      377080 377072 375065 374058 372053 368050 362049 357051
      356055 359066 357072 353074 347085 344090 340091 340099
      340106 342118 344123 347128 352131 356135 358139 359146
      357152 359156 363156 368153 370142 373135 376130
 0.50 438990 438975 438964 437947 437931 436919 435912 435906
      436899 435890 435878 436852 436844 434838 433832 431824
      431817 430809 428797 428786 425775 421766 413764 409761
      404760 398763 395766 388771 383777 371790 348820 345829
      343841 345845 349848 352850 354854 355859 355866 353874
      350879 347883 343886 339887 336888 336885 334880 329879
      323881 316884 309889 302895 297900 291908 286917 283926
      281933 279944 281949 283952 285956 289955 297952 306947
      313943 321937 327930 338919 344914 352910 367898 374893
      378891 381892 385893 388896 392906 394910 397913 401921
      405933 409942 412954 412960 412964 411978 411991 413003
      414014 416027 420037 423041 427042 431036 435024 437011
      438990
 0.50 362110 364108 363105 363103 362101 361100 360098 360097
      359098 359100 358102 358105 358107 359108 360109 360110
      362110 362110
 1.00 434987 435978 434971 430957 424945 419938 419945 419952
      417959 417968 417985 418994 419001 422008 424013 426015
      428016 431011 433004 434995 434987
 1.00 425869 425863 422862 418867 415869 412866 408861 404860
      402864 402870 403876 409879 413885 418889 422889 423886
      423874 425869
 1.00 403790 403786 402785 398785 395786 390789 387792 379800
      373808 371814 368820 362829 362833 366838 369843 370851
      366863 361873 358878 357885 357889 359891 363887 368878
      375871 382861 388854 392849 395843 394830 392823 391816
      396805 400797 403790
 1.00 343906 341904 336903 328904 323904 320902 318899 316894
      311892 306895 300900 297906 292921 289929 287937 288942
      289945 296948 303946 308942 319934 328924 333917 337911
      343906
 1.50 431992 431987 432983 432978 431975 429972 427973 426975
      425980 425985 424989 424994 425999 426001 428001 429999
      431994 431992
 1.50 332915 329910 322910 317908 312905 310898 307897 302900
      300905 297918 297927 296935 295941 297945 303944 307941
      316934 325926 331917 332915
 2.00 326922 326917 323915 313913 308911 306908 302910 301914
      301922 299929 297933 298941 300943 303942 307940 313935
      319930 325924 326922
 3.00 321924 317923 314922 310922 306924 303927 301931 301937
      303940 307937 310935 312932 316929 319926 321924

$$





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