Quantitative Precipitation Forecast
Issued by NWS

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000
FXUS04 KWBC 201856
QPFPFD

QUANTITATIVE PRECIPITATION FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
255 PM EDT WED MAY 20 2015


PRELIM DAY 1 QPF DISCUSSION
VALID MAY 21/0000 UTC THRU MAY 22/0000 UTC
REFERENCE AWIPS GRAPHICS UNDER...PRECIP ACCUM - 24HR



DAY 1

...SOUTHERN PLAINS...

SHOWERS AND STORMS MAY DEVELOP ALONG AND NEAR THE RESIDUAL FRONTAL
BOUNDARY ACROSS CENTRAL TO SOUTH-CENTRAL TX AS MOIST SOUTHERLY TO
SOUTHEASTERLY FLOW IS EXPECTED AHEAD OF THIS FRONT. CONFIDENCE LOW
WITH QPF PLACEMENT AND AMOUNTS ALONG THIS PORTION OF THE FRONT
GIVEN THE WIDE SPREAD IN SOLUTIONS.
WITH RECENT HEAVY RAINS...ISOLATED RUNOFF ISSUES ARE POSSIBLE.

SHORTWAVE ENERGY MOVING OUT OF NORTHERN MEXICO ON THE SOUTHERN
EDGE OF THE WESTERLIES MAY IGNITE MORE ORGANIZED CONVECTION NEAR
THE BIG BEND---WITH THIS ACTIVITY THEN PUSHING SOUTHEASTWARD ALONG
THE RIO GRANDE IN THE EARLY HOURS OF THU.  THERE IS SUPPORT FOR
CLUSTERS OF SHOWERS/STORMS IN THE HI RES ARW--NMMB---ECMWF---UKMET
AND CMC GEM---ALTHOUGH THEY DO DIFFER WITH RESPECT TO HOW FAR TO
THE SOUTHEAST CONVECTION PROPAGATES.  HEAVY TO ISOLATED EXCESSIVE
RAINFALL AMOUNTS ARE POSSIBLE WITH THIS CONVECTION IN THE EARLY
HOURS OF THURSDAY.  WPC CONTINUES TO FAVOR A BLEND OF THE GLOBAL
MODELS ALONG WITH THE HI RES ARW---NSSL WRF AND CMC GEM.

AS THU PROGRESSES...LOW LEVEL SOUTHERLY FLOW DEVELOPS WITH
WARM/MOIST ADVECTION COMBINING WITH DEVELOPING 700 MB CONVERGENCE
TO RESULT IN SHOWERS IN THE HIGH PLAINS ON EASTERN NM AND WEST
TEXAS/PANHANDLE.  HIGHER AMOUNTS ARE FCST IN THE REGION NEAR THE
NM/TX BORDER WHERE LOW LEVEL SOUTHEAST FLOW TURNS UPSLOPE. MANUAL
QPF USED A MULTI-MODEL/HIGHER RESOLUTION ENSEMBLE BLEND.

...OH VALLEY/TN VALLEY/CENTRAL TO SOUTHERN APPALACHIANS/MID
ATLANTIC STATES TO LONG ISLAND AND ADJACENT COASTAL SRN NEW
ENGLAND...

MODEL CONSENSUS IS FOR A WELL DEFINED 700 MB WAVE TO TRACK FROM
THE MID MS VALLEY ACROSS THE OH VALLEY AND ACROSS THE CENTRAL TO
SOUTHERN APPALACHIANS THU AFTERNOON/EVENING.  700 MB THETA-E
ADVECTION AHEAD OF THE WAVE HELPS TO PRODUCE WIDESPREAD RISING
MOTION.  ABOVE AVERAGE PW VALUES WILL PERSIST AHEAD OF THE COLD
FRONT EXPECTED TO MOVE EAST ACROSS THE TN VALLEY AND APPALACHIANS.

OVERRUNNING RAINS TO THE NORTH OF THE ASSOCIATED WEAK SURFACE WAVE
PUSHING EASTWARD WILL BRING LIGHT TO MODERATE PRECIP AMOUNTS FROM
THE OH VALLEY AND THE CENTRAL TO SOUTHERN APPALACHIANS AND VA/NC.
THE NAM WAS FURTHER NORTH WITH CYCLOGENESIS IN THE COASTAL WATERS
DUE TO A FURTHER NORTH CYCLONE POSITION...SO THE FURTHER NORTH NAM
QPF AXIS WAS DISCARDED IN FAVOR OF THE OTHER MODELS.  THE HIGH RES
WRF ARW AND NSSL WRF SUPPORT THE ECMWF/UKMET HIGHER AMOUNTS IN
VA/NC FURTHER SOUTH THAN THE NAM/GFS....SO THE AFOREMENTIONED
GROUP WAS PREFERRED FOR MANUAL QPF.

...CALIFORNIA/OREGON/GREAT BASIN/SOUTHERN ID/WY ROCKIES...

A REGION OF ABOVE AVERAGE PW VALUES WILL REMAIN ANCHORED FROM
NORTHERN CALIFORNIA/OREGON INTO THE NORTHERN GREAT BASIN WITH
STANDARDIZED ANOMALIES OF 1-2 STD DEVIATIONS ABOVE NORMAL OVER THE
SOUTHERN OR CASCADES INTO ADJACENT NORTHWEST CA.  SCATTERED SHOWER
ACTIVITY LIKELY AGAIN IN THIS ABOVE AVERAGE PW AXIS WITH 700 MB
VERTICAL VELOCITY MAXIMA OVER THE SOUTHERN OR CASCADES LEADING TO
A RAINFALL MAXIMA IN THAT REGION. THIS COINCIDES WITH A MAX REGION
OF UPPER DIFFLUENCE.  ELSEWHERE...MAXIMA IN THE RANGES OF
NORTHEAST OR/SOUTHERN ID/NORTHWEST WY/NORTHERN NV COINCIDE WHERE
ASCENT IS AUGMENTED BY UPSLOPE FLOW AS 700 MB CONVERGENCE MAXIMA
ROTATE AROUND THE BROAD CIRCULATION CONTINUING ACROSS CA/NV AND
ADJACENT PORTIONS OF THE GREAT BASIN.  MANUAL QPF USED A
MULTI-MODEL AND 09Z SREF MEAN QPF.

PETERSEN

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

24HR QP VT 22/00Z
 0.01 520215 520212 518209 514205 507203 502206 499207 494207
      487204 480201 477201 472200 461202 458201 457197 457193
      459189 471166 473164 473161 473151 475129 475124 474119
      469112 464105 461099 455089 454083 452082 449081 447078
      443075 438073 432070 430063 426058 420054 414050 413043
      404028 400023 396022 393024 384029 379030 375030 373028
      363018 360013 354010 349007 347000 347995 347990 347980
      348971 350963 350949 348941 347926 346918 344910 340904
      342896 345891 349887 361882 367880 375878 389872 393872
      396869 403864 407861 408857 408852 407835 405828 402822
      401818 402816 405811 408803 410797 409785 409777 409766
      408758 409754 409748 410743 409733 406713 406705 404701
      398698 394698 388698 384703 382709 376712 372719 369723
      340728 331733 327736 322740 318744 315749 313752 312756
      314766 317771 318775 317778 314785 311790 305795 297797
      292798 288797 279798 277799 274798 269797 262796 255796
      250799 247803 247809 251813 264816 277819 283822 286824
      287828 290835 291841 290847 294856 295861 294868 292874
      292878 294881 295887 293894 291901 290909 292928 293932
      292937 288943 279954 270963 267966 262969 251974 246976
      241979 236983 231985 230003 234012 240021 245028 249036
      264048 275049 279051 285052 297053 305061 309068 316075
      320076 324079 331080 337083 345088 352090 362088 368089
      373093 376096 382097 385096 388098 389101 389105 387110
      382114 379119 373123 373129 378130 382129 387129 393129
      395132 394135 388139 386152 385157 384160 382160 377163
      374168 371170 366170 362167 360172 354181 356187 361192
      374203 380206 384209 388211 396213 401215 405217 408220
      405222 400222 395223 392224 390227
 0.01 390227 388230 387233 389235 392237 396239 404240 413243
      414246 417249 426253 434253 441251 444250 448247 453243
      456240 458234 460232 464232 467230 471231 473233 474237
      476241 481241 486236 498230 505229 511225 514224 518220
      520215
 0.01 483794 483784 482773 481766 479759 476727 475718 475709
      475701 474692 472690 469689 464695 461698 460704 458710
      457717 458734 458741 456749 455764 456781 457789 456798
      456805 456813 456820 458827 461830 463828 465829 469833
      472833 477828 479822 481809 483794
 0.01 377217 377214 375212 370210 368208 365204 362199 359197
      357196 354200 356204 359208 361210 365213 369215 374217
      377217
 0.01 350199 350197 350195 351192 351190 349189 349190 347191
      346191 346194 346196 347198 347199 349199 350199
 0.01 345182 345178 344171 343168 337167 334164 329163 325163
      323167 326168 330171 335172 338175 339179 343182 345182
 0.01 341805 340797 338796 336797 333802 329805 326808 324812
      322818 322823 319829 319836 319849 323852 327853 330848
      333846 336841 338836 341825 340810 341805
 0.25 453220 454215 450214 447211 445208 442207 435205 428201
      425201 423202 422207 425212 425215 422217 417219 413226
      408228 406229 404233 405234 409235 411235 414237 419242
      425246 431246 437243 441236 444230 448226 453220
 0.25 455179 456172 456164 456159 454154 450153 448158 447161
      448167 447175 445179 444185 449187 451188 453181 455179
 0.25 451109 451107 447105 444105 442106 439106 435106 432106
      430108 428106 428108 430110 433111 437110 440111 443112
      447113 449112 451109
 0.25 425165 425162 424161 423160 421157 420155 418155 418156
      417158 417161 416163 416165 416168 417168 418168 420166
      422165 424166 425165
 0.25 397205 395199 392195 385191 380188 375186 368183 364183
      363186 367190 372194 377197 382201 387203 393207 397205
 0.25 395745 393737 388731 382730 378734 373738 368745 363747
      357746 353746 344749 333754 330757 328760 328764 329768
      332774 336778 345788 350791 352796 350803 351806 354810
      358814 361821 360830 358838 359842 363842 368843 372843
      374840 378833 382820 385814 389807 394796 396788 394780
      392773 392766 395754 395745
 0.25 357040 355034 352028 348022 342016 334007 333000 334995
      335988 336978 337967 337961 337955 332945 327939 325934
      322917 322912 321907 320903 317900 315895 313888 313878
      312870 309864 306862 305865 303874 303883 302897 302907
      303914 306914 309916 310924 310933 308942 301968 292977
      285976 276976 268977 264978 262980 259984 258990 259002
      267014 271018 272019 269020 263019 261013 257008 255001
      250001 247002 244005 243008 261022 267025 276025 284026
      291029 308045 317054 323058 330062 336062 343061 346057
      349053 355047 357040
 0.25 355852 353848 349847 344849 340851 338854 335858 334863
      336867 338869 341868 344866 348863 351860 353856 355852
 0.25 262807 263805 261803 259802 257803 256803 256804 254806
      254808 256808 258808 260808 262807 262807
 0.50 442220 440218 437216 433215 430216 428218 427220 425222
      424227 426229 429230 431231 433232 436230 438228 439226
      441222 442220
 0.50 421236 421233 421231 420230 419230 419233 418233 417234
      418236 420236 421236
 0.50 386198 386196 385194 383193 381193 379193 379194 379195
      381197 382198 384199 386198 386198
 0.50 386760 386752 385747 372748 364754 354759 345764 343765
      342769 342774 345778 350779 357778 360782 361783 365783
      370781 374779 377774 384768 386760
 0.50 341041 342036 341031 338023 331014 324012 317014 314014
      312012 315007 321977 325976 327974 323968 320960 319954
      318949 316947 313948 310951 306964 305973 302982 300989
      297990 295988 288985 280984 272984 268986 266994 266999
      267003 270009 274013 287020 297026 301032 303035 306038
      311042 317044 324046 333045 339044 341041
 1.00 300010 300006 297002 294000 289998 284998 280999 279002
      280005 282008 285012 289014 292015 296014 300011 300010

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