Quantitative Precipitation Forecast
Issued by NWS

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000
FXUS04 KWBC 191835
QPFPFD

QUANTITATIVE PRECIPITATION FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
233 PM EDT TUE MAY 19 2015


PRELIM DAY 1 QPF DISCUSSION
VALID MAY 20/0000 UTC THRU MAY 21/0000 UTC
REFERENCE AWIPS GRAPHICS UNDER...PRECIP ACCUM - 24HR


DAY 1

MID SECTION OF THE NATION

NEGATIVELY TILTED HEIGHT FALLS WILL CONTINUE PUSHING FROM THE
CENTRAL/SOUTHERN ROCKIES AND EVENTUALLY OUT INTO THE SOUTHERN AND
CENTRAL PLAINS BY TUE EVE.  WIDESPREAD MODERATE TO HEAVY RAFL
SHOULD CONTINUE THROUGH THE EVENING GIVEN A COMBINATION OF STRONG
SYNOPTIC SCALE FORCING NEAR THE HIGHLY DIFLUENT MID AND UPPER
LEVEL FLOW EAST OF THE NEGATIVELY TILTED TROF...AND IN ASSOCIATION
WITH NUMEROUS SHOWERS AND THUNDERSTORMS OVER THE SOUTHERN PLAINS.
THE MODEL LARGE SCALE MASS FIELDS WERE IN PRETTY GOOD AGREEMENT IN
THE 19/12Z RUNS...BUT THE MODEL PCPN FIELDS WERE NOT IN NEARLY
SUCH GOOD AGREEMENT.  THERE WAS BETTER AGREEMENT IN THE NORTHERN
AREA OF PCPN WHICH WAS SYNOPTICALLY DRIVEN...BOTH IN TERMS OF PCPN
AMOUNTS AND IN PLACEMENT/EVOLUTION OF THE PCPN.

THE QPF FOR AREAS OF OK INTO NORTH TX WAS NOT NEARLY AS WELL
CLUSTERED.  ONE SIGNAL THAT SEEMED TO BE CAPTURED WAS A SLOWER
EASTWARD MOTION THAN FORECAST IN THE OVERNIGHT MODEL RUNS.  DURING
THE OVERNIGHT MODEL RUNS...THE GFS AND THE NSSL WRF WERE IN
AGREEMENT THAT THERE SHOULD BE FAIRLY GOOD COVERAGE OF SHOWERS AND
THUNDERSTORMS ROUGHLY ALONG OR JUST NORTH OF THE RED
RIVER...ALTHOUGH THE PCPN MAX IN THE 19/00Z GFS WAS SOME 100 MILES
EAST OF THE QPF MAX IN THE 19/00Z NSSL WRF.  THE MANUAL QPF
GRAPHICS TENDED TO BE SLOWER THAN THE GFS MAX IN THE 20/06Z TO
20/12Z TIME FRAME.  THE GFS CONTINUED THE IDEA OF A QPF MAX IN THE
AREA...ALTHOUGH SLOWED DOWN...WHILE THE NSSL WRF BACKED AWAY FROM
THE VERY SLOW MOTION IT ADVERTISED EARLIER AND WAS LOOKING MORE
LIKE THE NAM IN NOT SHOWING A SOUTHERN MAX.  GIVEN THAT THE FLOW
IS SOUTH TO SOUTHEAST AT H85 THIS EVENING AND INTO THE EARLY
PORTION OF THE OVERNIGHT WHICH WILL BE IMPINGING ON A STALLED OUT
FRONT...DID NOT FOLLOW THE NAM/NSSF WRF OVERNIGHT.

BY WEDNESDAY...WINDS BECOMING SOUTH TO SOUTHWEST IN THE LOW LEVELS
SHOULD HELP THE SYSTEM BECOME LESS OF A RAIN PRODUCING SYSTEM.

DAY 1 QPF SHOWS MAX PRECIP TOTALS 1-2"+ ALONG THE RED RIVER AND
SOUTHERN/SOUTHEAST OK TOWARDS THE ARKLATEX.


W TEXAS...

LOW LEVEL FLOW BECOMES SOUTHEAST OVER W TEXAS DURING THE DAY ON
WEDNESDAY...AND THE AIRMASS BECOMES INCREASINGLY UNSTABLE EAST OF
THE DRYLINE.  FELT THE BETTER CHANCE WAS UP NEAR THE REMNANTS OF A
LOW LEVEL BOUNDARY VS NEAR THE MOUNTAINS NEAR THE MEXICAN
BORDER...ALTHOUGH CONFIDENCE IN THE PLACEMENT WAS LOW.


GREAT BASIN

PCPN SHOULD BECOME INCREASINGLY SCATTERED OVER THE GREAT BASIN AS
THE MAIN TROF AXIS MOVES EAST AND MID/UPPER LEVEL HEIGHTS RESPOND
ACCORDINGLY.  UNTIL THEN...WIDESPREAD AND GENERALLY LIGHT PCPN
SHOULD CONTINUE UNTIL THEN WITH A PREFERENCE FOR QPF IN/NEAR THE
HIGHER TERRAIN.

NEW ENGLAND

A SYSTEM MAKING ITS WAY EASTWARD AND EVENTUALLY OFF SHORE WILL
TAKE MOST OF THE PCPN WITH IT.  THE AIRMASS WAS UNSTABLE ENOUGH
FOR SHOWERS THIS AFTERNOON AND EVENING OVER THE INTERIOR PORTION
OF NEW ENGLAND AND PARTS OF NY.  ONCE SHOWERS TAPER OFF LATER THIS
TONIGHT...ENOUGH DRY AIR GETS DRAWN INTO THE SYSTEM TO END THE
PCPN.

BANN

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

24HR QP VT 21/00Z
 0.01 540200 540195 537196 534195 530196 513197 492199 476206
      469210 461212 455211 453210 452206 452201 454195 463178
      460168 459160 458154 456150 452143 450137 450131 450124
      454121 456116 456107 457098 455093 453079 450068 448061
      448053 447047 447039 447029 444017 440996 439985 439978
      438973 437966 436961 435949 434943 432937 431934 433930
      433924 433909 430898 429890 427883 423869 419857 418849
      417844 413836 410833 406833 403834 399839 395844 389850
      381852 367862 354875 346880 335883 328884 325884 322883
      321878 321872 321866 323861 323855 322849 318839 317834
      319831 319827 322827 324832 326833 328830 330826 334822
      343821 347813 348810 347804 345799 344794 350788 356781
      362773 368765 371759 371752 371746 371742 373736 375731
      378723 377717 376714 365716 362719 359716 354707 348702
      344701 339703 335708 325725 315744 311755 309758 308764
      306783 300790 298794 298797 299800 301802 299804 297809
      295812 290813 280814 271813 264809 260812 258816 260820
      267827 276832 286836 290838 292843 294845 294849 294856
      294867 295877 296889 298899 299914 302923 307929 311939
      312952 314959 317963 318968 312975 299993 294000 290002
      284003 278003 275003 273001 269000 265001 263005 260008
      260012 262014 263025 270029 278033 282035 288036 299036
      305033 316033 327036 333036 335031 333019 337018 343018
      352024 358027 364034 367038 370040 375042 379040 383040
      387037 394032 398030 402031 404036 405040 405043 404046
      402049 395051 384051 378050 374050 372048 363047 361052
      364054 369057 376059 378061 378066 376071 389084 396089
      399092 399097 400100 399103 396106 391112 392119 397120
      401118 403119 403123 403131 398138
 0.01 398138 393144 390149 389155 389161 386164 382172 380176
      375176 371176 367179 359181 360188 367193 372197 375200
      380205 386210 394214 397218 399220 398222 391225 386228
      387232 390236 397242 406245 416246 424247 429246 431243
      436236 442231 448226 452223 455222 462221 469219 479221
      484223 487226 494232 496235 499240 503246 509255 513262
      514263 516259 525238 532219 536207 540200
 0.01 527700 526691 525684 519669 514659 508648 494628 488622
      484619 479619 473621 469624 460634 458639 454642 446651
      441660 440662 443665 447668 456673 458674 456677 450679
      444687 435696 427704 415708 407714 408718 406722 407730
      411742 415743 420742 438726 444726 444730 445735 442737
      436739 434744 435749 438755 444754 448749 451745 455742
      457737 459731 460728 463730 468733 471740 474745 476747
      483741 487729 492715 494709 498709 504707 508708 521705
      524703 527700
 0.01 479238 480236 480234 479233 478231 478230 476232 475235
      476236 477238 479239 479238
 0.25 485653 483646 481643 477641 474641 469643 466647 464650
      463656 466657 471658 475659 478659 483658 485653
 0.25 449178 449171 446165 445158 443153 440149 436146 431154
      424163 423174 423183 419187 412195 409200 407203 407208
      411218 410222 408224 403226 395231 395234 397236 405236
      414235 433227 441220 438216 436210 435202 438194 441189
      441183 441175 446173 447178 449178
 0.25 435038 436028 436017 433998 431984 429976 427968 420958
      412945 405936 402930 398924 408894 410888 410880 405875
      398874 391875 385877 381883 378886 375888 366894 353899
      348900 343905 339908 339913 338926 337932 334939 328948
      326958 325965 326980 327988 326991 324992 313998 306002
      302007 298009 295015 298020 305022 312023 319024 323025
      326024 326013 329006 331003 340003 346002 357996 360995
      365995 371998 376002 383004 386004 394002 399002 405005
      410009 414015 417022 419029 421034 424039 428042 432041
      435038
 0.25 389199 389197 388195 386194 385193 384193 383193 381195
      381197 382198 383200 384200 385201 387201 389199
 0.25 355750 355746 355742 352737 348736 344738 337746 332754
      327764 322773 323779 327781 330781 334778 340770 347763
      353754 355750
 0.25 293023 294021 294018 293016 292016 291016 289016 288016
      287016 285016 283016 282018 282020 283021 284022 285023
      287024 288024 290024 292023 293023
 0.50 429187 430185 429184 428185 427186 426187 426189 428188
      429187
 0.50 403979 403972 405969 405963 403956 401949 392940 390938
      390934 391924 389915 385910 380907 375907 371909 366916
      362916 359911 355910 351912 348919 347925 345932 341936
      337941 331952 329958 328967 328975 330982 332986 337993
      342994 348993 353991 359986 364984 371984 375988 378994
      381996 385996 391993 398986 402983 403979
 0.50 322016 322014 320011 316010 313010 310011 307012 305013
      305017 307019 309020 312020 315020 318020 321018 322016
 0.50 322005 322003 320003 319005 320005 322005 322005
 1.00 386961 387954 386946 380940 378939 375940 372943 370947
      370952 368956 366961 363963 359961 357944 355940 348940
      345941 341943 335952 332960 331967 332974 335984 338987
      342989 348989 351987 358981 366978 371964 382965 386961
 1.50 362976 356969 353966 352960 352956 353952 353948 352946
      348945 344946 341949 336956 334960 333965 333971 335975
      341981 346982 350980 354978 357979 362976
 2.00 350974 351967 350963 348956 346952 343952 341954 338958
      336962 335967 337971 340973 344976 350974 350974
 3.00 343967 343965 343964 341963 340965 341966 342967 343967
      343967

$$





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