Quantitative Precipitation Forecast
Issued by NWS

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000
FXUS04 KWBC 010632
QPFPFD

QUANTITATIVE PRECIPITATION FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
232 AM EDT FRI MAY 01 2015


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


DAY 1...

...CENTRAL APPALACHIANS TO THE ATLANTIC COAST FROM MD TO SC...

INCREASING WESTERLY FLOW WITHIN THE NORTHERN STREAM WILL PUSH
ALONG A CLOSED LOW THAT WAS DIGGING INTO THE CENTRAL APPALACHIANS
THURSDAY EVENING. THE LOW WILL PASS THROUGH NORTH CAROLINA AND
SOUTHEAST VIRGINIA EARLY FRIDAY...PRODUCING AN ORGANIZED SWATH OF
PRECIPITATION NORTH AND EAST OF THE TRACK...WITH A SHOWERY REGIME
NEAR AND SOUTH OF THE TRACK AND TRAILING THE MID LEVEL CENTER.
LINGERING LOW LEVEL MOISTURE AND SEASONABLY STEEP LAPSE RATES
SHOULD SUPPORT LOOSELY ORGANIZED RAIN FROM SHALLOW CONVECTIVE
CELLS IN THE MOUNTAINS AND EASTERN FOOTHILLS BACK ACROSS WV/VA AND
PORTIONS OF ADJACENT STATES THIS AFTERNOON. THERE WAS LITTLE
CHANGE TO WPC QPF AFTER INCORPORATING SOME OF THE TRENDS AND
SMALLER SCALE DETAILS SEEN IN THE 00Z NAM/GFS AND THE WRF-NMM.


...GREAT BASIN / CENTRAL ROCKIES / CENTRAL PLAINS...

THUNDERSTORMS SHOULD PROVE TO BE GOVERNED MORE BY LOW LEVEL
BOUNDARIES...TERRAIN AND DIURNAL HEATING IN THE CURRENT REGIME.
BUT ONE MID LEVEL SHORTWAVE WILL HELP TO ORGANIZE LIGHT AREAL
AVERAGE PRECIPITATION AMOUNTS FROM ERN NE AND FAR NE KS INTO IA
AND POSSIBLY NRN MO. THIS WILL OCCUR AT THE EASTERN EDGE OF WHAT
LITTLE INSTABILITY IS FORECAST TO DEVELOP TODAY...BUT ACTIVITY
COULD BE SUSTAINED OVER ROUGHLY THE SAME REGION INTO THE NIGHTTIME
HOURS OWING TO THE PLAINS LOW LEVEL JET AND APPROACH OF ANOTHER
LOW AMPLITUDE SHORTWAVE. MEANWHILE...THE MODELS ARE FORECASTING
GREATER ORGANIZATION OF CONVECTION AND A POTENTIAL SMALL MCS OVER
EASTERN COLORADO. THIS SIGNAL EXISTS IN SEVERAL MODELS...INCLUDING
THE 12Z ECMWF AND SEVERAL OF THE 00Z HI-RES MODELS. IT MAKES SENSE
WITHIN THE PATTERN...WITH MODEST BUT TIMELY POST-FRONTAL UPSLOPE
BENEATH SUFFICIENTLY ENERGETIC WESTERLY FLOW. GIVEN THE MODEL
AGREEMENT WE BEGAN TO SIGNAL A BROADER AREA OF AT LEAST 0.25 INCH
AREAL AVERAGE PRECIPITATION IN SE CO / FAR NE NM.

FARTHER WEST...CONVECTION WILL AGAIN BE LOCATED NEAR AND DOWNWIND
OF THE HIGHEST TERRAIN ANYWHERE FROM THE SIERRAS TO THE WASATCH
AND OVER ERN AZ / WRN NM. THE ACTIVITY IN AZ/NM HAD ACTED NEARLY
MONSOONAL ON THURSDAY...ALTHOUGH OBVIOUSLY OF MUCH LESSER MOISTURE
CONTENT...WITH SHALLOW THUNDERSTORMS NEAR THE 700 MB RIDGE
CENTER...DROPPING PRESUMABLY 0.10 INCH AMOUNTS IF MESONET
OBSERVATIONS ARE TO BE BELIEVED. THE MODELS SHOW A STRONGER QPF
SIGNAL ON FRIDAY...AND WE RELIED MAINLY ON THE NAM FOR COVERAGE.


...NORTHWEST U.S...

MOST PRECIPITATION IN THIS REGION WILL REMAIN NORTH OF THE
CANADIAN BORDER...WITH THE COLUMBIA RIVER BASIN IN BRITISH
COLUMBIA CATCHING A SMALL AREA OF 0.10 TO 0.25 INCH PRECIPITATION.
WE MAY INTRODUCE A SMALL AREA OF MEASURABLE PRECIPITATION  FROM
CENTRAL ID INTO WESTERN MT...BUT MAY SCALE BACK THE COVERAGE IN
OUR FINAL ISSUANCE LATER THIS MORNING. THE PATTERN WOULD APPEAR
SUPPORTIVE OF HIGH BASED CONVECTION INITIATING SOME OF THE TALLEST
TERRAIN...IN A REGION WHERE THE 600-500 MB LAYER IS FORECAST TO
MOISTEN AHEAD OF A LOW AMPLITUDE SHORTWAVE TROUGH. THE DRY LOW
LEVEL AIR...HOWEVER...MAY BE TOO DRY TO OVERCOME...WITH LITTLE OR
NO PRECIPITATION SIGNAL IN THE MODELS.

BURKE

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

24HR QP VT 02/12Z
 0.01 536207 537199 537189 536171 532149 530131 531124 533117
      533110 530104 526099 523102 518116 513129 512138 510143
      508143 506146 506151 504155 502155 500157 499161 499170
      502184 515206 520217 510214 510220 512226 515227 517227
      522224 527223 529223 531221 532216 534214 536207
 0.01 518268 520255 518246 514238 510230 506223 500216 497216
      495218 495224 495228 498237 501247 504255 502256 499255
      496252 493245 488244 487249 489257 493266 501281 504284
      507285 513279 518268
 0.01 480236 480234 480232 478232 477233 476234 475235 475237
      475238 477239 478238 479237 480236
 0.01 474151 475141 472138 471133 471124 474116 475104 476091
      473085 471087 469090 465097 463102 462106 460115 459128
      457147 451166 451176 453179 456179 459178 460174 467170
      470163 472158 473153 474151
 0.01 469935 469930 467927 465925 457920 453917 449913 443913
      439916 435918 431919 426923 424928 421931 417931 416924
      414916 413910 410903 406903 399908 396913 394918 394934
      394953 392960 392969 392979 394984 396989 397998 393010
      393021 392024 388024 384021 381008 378003 374005 368016
      363029 357037 349044 342049 332053 330056 332058 334059
      337057 341057 345060 356065 360067 366066 370067 371069
      373075 374080 375081 381081 386080 391080 394081 396083
      394088 390102 382110 383115 388114 396116 397118 399120
      397122 397126 397133 392145 391159 383165 381174 378178
      374181 369181 363181 365186 369190 376192 385200 391202
      395201 395199 393196 389191 386186 384182 384178 385174
      389171 392170 395173 402174 405172 412163 416160 419154
      419147 414144 411144 408141 406136 405131 406127 406119
      409114 411107 412097 409092 405093 403094 402091 402086
      404081 406078 410075 414069 415064 419054 417047 413043
      409041 404042 397042 395039 396036 403035 408032 409026
      407020 405015 403009 404000 410001 412996 412990 412986
      414982 420981 428976 435971 440966 444962 452955 461945
      466940 469935
 0.01 427762 426757 423760 421764 417764 412767 408770 402776
      396779 391780 389778 388776 386772 384765 383757 384750
      385745 387740 388735 389724 387706 383694 379686 372679
      368676 363674 358675 355678 350685 345694 341704 338714
      328757 327766 326772 326777 329783 329787 331793 335795
      351802 360808 361814 360819 362823 367823 372822 376819
      393808 400802 407795 415787 419784 422782 427762
 0.01 368093 368089 367086 363083 357071 351070 346072 336076
      331078 329081 330084 336094 342105 346108 347105 347101
      345096 344087 348086 351086 355087 358089 362092 368093
 0.25 519183 519180 520178 518175 516177 516179 515182 516184
      516185 517185 518185 519184 519183
 0.25 379718 378708 373699 370696 366694 361695 359698 356707
      354717 348734 347738 347744 353752 358758 357763 356770
      357774 359778 363787 367788 370785 374776 376765 375753
      378744 379739 379732 379718
 0.25 387047 387042 386038 382031 375033 375030 377027 376025
      373028 371030 370034 366039 362045 362048 367049 374048
      378046 381047 384048 387047
 0.25 382802 381800 378798 375798 373799 370801 369803 367805
      367809 369811 371811 375810 376809 378807 381805 382802
 0.50 375717 375711 372706 370704 364705 361707 360711 357721
      355730 353740 353744 356748 363753 367753 371750 373747
      375743 376733 375719 375717
 0.50 372772 372770 372768 371765 370765 369765 368766 367768
      367771 367773 367775 367777 368778 370778 370777 371774
      372772
 1.00 371740 371734 371727 370720 366718 363720 361724 360729
      359734 359741 362743 366745 370743 371740
 1.50 369734 368733 368732 366730 364731 364733 364735 364737
      365739 366739 367738 369736 369734

$$





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