Quantitative Precipitation Forecast
Issued by NWS

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000
FXUS04 KWBC 191840
QPFPFD

QUANTITATIVE PRECIPITATION FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
240 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 538196 534195 530196 515197 507197 498199
      491200 484202 469210 461212 455211 453209 452205 453199
      455193 460185 463179 461173 460166 459160 458155 456151
      452143 450139 450133 450128 450125 452123 455120 456116
      456102 455096 454093 454087 453082 452071 449065 448060
      447046 447034 445023 443012 440998 439980 435958 435946
      432937 433926 433911 432906 431899 428889 422868 416842
      414837 410833 405833 401836 398840 395844 392848 386851
      382852 379854 375856 372859 367863 360869 355875 347879
      339882 334883 328884 322883 320878 321874 321867 323863
      323855 322849 320843 317838 319831 319827 321827 324832
      336822 341822 344820 346816 348811 347802 345798 345794
      356781 366768 370759 371754 371747 373736 375731 377726
      378723 377715 366716 363717 361719 358714 355709 352706
      346701 341702 338703 330717 321732 314748 310757 308766
      307771 307777 306782 303787 299792 298798 300803 298807
      296812 290813 283813 277813 270812 263809 260811 259815
      259818 261821 267827 273830 289837 291839 292842 294846
      294854 294860 295874 296887 296893 298900 299913 301920
      303924 306929 308933 311936 311942 312954 315960 318969
      312975 306983 302990 297995 291002 286003 280003 269000
      265001 263005 260008 260013 262014 263017 263025 270030
      282034 291036 296036 299035 307033 312033 318033 326036
      331037 334034 335027 333023 333019 337018 343019 348021
      357027 361031 364034 367039 371040 375042 378040 383040
      386038 394032 399030 403033 405043 403047 400049 393051
      382051 377050 372048 367048 362048 361052 363054 366057
      371057 374058 377060 378062 378066 376071 379076 384077
      388082 395088 398090 399096 400102 397105 391112 392117
      392119 395120 398119 403120 403127 403131 401134
 0.01 401134 392145 390150 389157 387164 385168 381174 378177
      373176 369177 365179 362180 359181 359183 360187 362189
      368194 381206 395215 398218 398222 391225 387229 387234
      390237 399242 409245 418247 426247 430246 432243 434238
      438234 443230 449225 456222 464219 471219 480222 485224
      488227 495233 504247 514264 521248 526237 529226 540200
 0.01 527700 526691 525684 520673 514659 508648 496631 488622
      484619 479619 469623 462632 459637 456641 451645 446651
      441659 441663 445667 449670 454672 457676 450679 437694
      428702 422706 415708 408713 407726 408735 410741 413744
      420742 436729 438726 442726 445727 444730 445734 442737
      436739 434744 435748 437754 442755 450748 453744 457737
      459731 460729 463729 467732 469736 476747 479746 483741
      491718 493711 495708 497709 503708 508708 519706 524704
      527700
 0.01 479238 480236 480234 479233 479231 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 449172 447167 446159 443153 440149 437146 435145
      433149 431154 424162 423174 423182 420187 412195 409199
      407205 411218 410222 408224 404226 395231 395234 397236
      403236 414235 433227 439220 440218 438216 436210 435203
      438195 440190 441183 441176 444172 446174 447177 449178
 0.25 435035 437026 436017 434002 431983 429975 426967 414947
      409941 405936 402929 400926 400922 401917 403910 405902
      407896 410889 410885 410880 405875 401874 397874 390875
      385878 377887 371890 365894 351899 346901 343905 339908
      339910 339924 337931 334939 328949 326955 325965 325975
      326984 326992 320994 310999 302007 296011 295014 296017
      300021 310023 323025 325025 326021 327012 329005 331003
      334003 343003 350000 360995 367995 371999 377003 384004
      397002 402003 407006 411011 415016 419029 422037 424039
      427042 433040 435035
 0.25 389199 389197 388194 386194 385193 384193 383193 381195
      381197 382198 383200 384200 385201 387201 389199
 0.25 355750 355743 352737 348736 344738 337746 332754 327764
      322773 322778 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 428187 428188 429187
 0.50 403979 403973 405966 403957 401949 393942 391939 390935
      391924 389916 387911 381907 375907 371909 368914 362917
      361913 359911 355910 352912 349916 347924 345932 338939
      331952 329958 328964 328973 330982 335991 337993 341994
      348993 353991 358987 362984 371984 375988 378994 380996
      384996 387995 390993 398987 401983 403979
 0.50 322016 322013 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 386947 384943 380940 378939 375940 372943
      370947 370952 366960 363963 359961 357944 355941 350940
      345941 341943 336951 333955 332960 331966 332973 333978
      335984 341989 347989 351987 357982 361979 366978 369974
      369967 367965 368963 371963 380965 386961
 1.50 362976 356969 354966 352960 352956 353952 352946 348945
      345946 341949 336956 334960 333965 333971 335975 341981
      346982 350980 354978 357979 362976
 2.00 350974 351971 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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