Quantitative Precipitation Forecast
Issued by NWS

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000
FXUS04 KWBC 011839
QPFPFD

QUANTITATIVE PRECIPITATION FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
239 PM EDT TUE SEP 01 2015


PRELIM DAY 1 QPF DISCUSSION
VALID SEP 02/0000 UTC THRU SEP 03/0000 UTC
REFERENCE AWIPS GRAPHICS UNDER...PRECIP ACCUM - 24HR


DAY 1...

...PACIFIC NORTHWEST...

A DEEP TROUGH WILL CONTINUE TO LEAN INTO THE WESTERN
U.S...ALTHOUGH HEIGHT FALLS AND PROGRESSION OF A FRONT THROUGH
EASTERN WA/OR AND ADJACENT STATES WILL BE ACCOMPANIED BY
RELATIVELY LITTLE PRECIPITATION. HEAVIER AMOUNTS WILL FALL IN THE
NORTHERN CASCADES AND OLYMPIC RANGE...DEEPER INTO THE COOL AIR
WHERE CONDITIONS WILL BECOME INCREASINGLY UNSTABLE AND CONDUCIVE
TO SHOWERS. THERE HAS BEEN LITTLE TREND IN THE MODEL
GUIDANCE...ALTHOUGH AVERAGE AMOUNTS FROM THE GLOBAL MODELS AND
SREF ARE TRENDING SLIGHTLY WETTER IN THE NORTHERN CASCADES.


...GULF COAST AND SOUTHERN ATLANTIC COAST...

MODERATE PRECIPITATION WILL BE ORGANIZED NEAR AND EAST OF THE LONG
AGO REMNANTS OF ERIKA OVER NORTHERN FLORIDA...AND EXTENDING ALONG
A MID LEVEL TROUGH AXIS OFFSHORE OF SOUTHEAST GEORGIA. IN THE
SHORT TERM DIURNAL THUNDERSTORMS SHOULD BE OUTFLOW DOMINATED.
OVERNIGHT...HI-RES MODELS ARE SPLIT AS TO WHETHER PRECIPITATION
FLARES UP NEAR THE CENTER OF THE WEAK WARM CORE SYSTEM MOVING
ONSHORE INTO NORTHERN FLORIDA. THE CENTER DID FLARE UP OFFSHORE
LAST NIGHT...AND THE WRF-ARW BEING ONE OF THE MORE TRUSTED
MODELS...WE CONSERVATIVELY INTRODUCED SOME HEAVIER PRECIPITATION
NEAR AND EAST OF TALLAHASSEE. EVEN THE MORE AGGRESSIVE MODELS ARE
NOT ESPECIALLY HEAVY...BUT GIVEN THE TROPICAL MOISTURE IN
PLACE...SOME SMALL SCALE INTENSE RAIN RATES MAY OCCUR.

AN UNRELATED MID LEVEL TROUGH AXIS WILL REMAIN STATIONED ALONG THE
WESTERN GULF COAST THROUGH WEDNESDAY. SCATTERED AFTERNOON
THUNDERSTORMS EXTENDING INLAND MAY MERGE WITH A BROAD OUTFLOW
BOUNDARY TO PRODUCE A RELATIVE PRECIPITATION MAXIMUM IN BETWEEN
HOUSTON AND LAKE CHARLES THIS AFTERNOON. OVERNIGHT EXPECT
CONVECTION TO REFORM JUST OFFSHORE WITHIN THE TROUGH AXIS.
MODERATE TO HEAVY RAIN IS FORECAST TO STRADDLE THE COAST AND
OCCASIONALLY DRIFT INLAND THROUGH MIDDAY WEDNESDAY.


...SOUTHWEST...

NO SIGNIFICANT CHANGES TO THE BROAD SCALE FLOW OVER THE
SOUTHWEST---EASTERN GREAT BASIN INTO THE CENTRAL TO SOUTHERN
ROCKIES. SCATTERED MONSOONAL CONVECTION IS AGAIN LIKELY IN THE
AXIS OF SLIGHTLY ABOVE AVERAGE PW VALUES STRETCHING FROM NORTHWEST
MEXICO INTO THE SOUTHWEST STATES AND CENTRAL TO SOUTHERN ROCKIES.
PRECIPITATION WILL BE ORGANIZED ON SMALL SCALES...SO CONFIDENCE IN
THE DETAILS IS LOW...AND WE MAINTAINED ONLY LIGHT AREAL AVERAGE
QPF...USING THE 12Z NAM TO MAKE SOME SMALL ADJUSTMENTS.


...EASTERN U.S. TO THE NORTH OF I-40...

MUCH LIKE THE REST OF THE COUNTRY ASIDE FROM THE PACIFIC
NORTHWEST...THE HEAVIER AND MORE GREATLY ORGANIZED PRECIPITATION
IN THE NORTHERN PART OF THE EASTERN U.S. WILL OCCUR ON SMALL
SCALES WITH AN ASSOCIATED LESSER DEGREE OF PREDICTABILITY. ONE
SWATH OF PRECIPITATION WILL STRETCH FROM WESTERN IOWA TO THE UPPER
PENINSULA OF MICHIGAN ALONG AN AXIS OF FRONTOGENESIS AHEAD OF A
LOW AMPLITUDE SHORTWAVE IN SOUTHWEST FLOW. THOUGH DEEP LAYER
FORCING WILL MIGRATE NORTHWARD WITH TIME...LOW LEVEL INFLOW
ENCOUNTERING OUTFLOWS MAY CAUSE PRECIPITATION TO PERSIST BACK TO
THE SOUTH. A SECOND ORGANIZING INFLUENCE WAS A WEAK CLOSED MID
LEVEL LOW DRIFTING THROUGH THE OHIO VALLEY. A PRECIPITATION
MAXIMUM WILL BE FAVORED ON THE WESTERN FLANK...WHERE WARM
ADVECTION AND 850-700 MB SPEED CONVERGENCE WILL BE MAXIMIZED.
THUNDERSTORMS DRIVEN MORE BY THE HEATING CYCLE WILL OCCUR AHEAD OF
THE LOW...FARTHER EAST. THERE WAS NOT MUCH SPECIFIC AGREEMENT
AMONG THE MODELS AS TO WHERE TO PLACE 0.25 INCH OR GREATER AMOUNTS
ON A 24 HOUR TIME SCALE. WPC BLENDED THE PREVIOUS FORECAST TOWARD
THE 09Z SREF AND LATEST IN-HOUSE ENSEMBLE...WHOSE PLACEMENT
MATCHED FAIRLY WELL TO EXPECTATIONS FOR LOW LEVEL INFLOW AND DEEP
LAYER ASCENT BASED ON THE GFS. ALSO RECEIVED SOME INPUT FROM LOCAL
OFFICES IN THE UPPER MIDWEST.

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

BURKE/ORAVEC

24HR QP VT 03/00Z
 0.01 473619 484651 489662 494676 496686 495689 495695 494712
      492719 491729 491736 491741 491746 491754 491764 489772
      487780 485785 483789 483794 481808 480816 481828 479848
      476862 474868 473873 474877 481887 483889 484893 484904
      477915 474919 471922 466927 463933 462937 459940 456941
      456947 455955 452962 447972 439982 429990 420995 415996
      413996 412992 412983 413975 416969 418961 414961 408964
      403967 400970 389976 385976 388969 398947 405936 411927
      415921 421917 423915 423909 423900 423880 421873 420867
      418868 414871 409873 404872 399869 391860 385857 381857
      381852 383837 383828 381823 379819 375820 370824 364825
      361825 359823 359819 360816 359808 360801 364797 366794
      367791 368784 368780 370777 373773 376771 379770 387769
      397775 406782 410786 414792 418796 420797 420801 419808
      416813 415816 415820 417825 419827 431833 440839 448848
      455857 459860 462853 464847 467841 466836 464836 460832
      459823 459817 457814 455809 453811 450811 451808 451801
      450796 447789 446780 446773 448765 451759 453752 454745
      454737 455721 456712 457706 460698 459686 458670 454653
      452647 450640 451627
 0.01 548167 550155 551149 550143 548136 546133 543131 541129
      538131 534137 526147 521150 518149 515148 502143 494141
      491137 484131 481130 479132 480137 480142 477144 466146
      464147 463152 461162 455166 452168 451171 444186 445193
      447194 449192 449190 452187 458185 468175 473172 477173
      480175 484180 485184 487186 488192 486197 480200 475201
      470204 465207 462209 459210 448213 424220 422222 422224
      427226 428228 426231 416234 415241 417243 419245 424246
      430248 433247 437248 465253 475263 485274 489278 492280
      495283 501287 508289 512285 516279 520269 520261 520251
      520245 522240 526234 530231 534226 537219 539207 541195
      542185 545179 548167
 0.01 504972 504961 504951 500946 496942 487929 479924 475930
      475936 473939 470957 470968 470973 472977 472985 475994
      477997 479997 482997 484995 489978 491980 494980 497980
      500978 504972
 0.01 415066 416061 412059 409056 406053 402051 399053 395055
      395057 399056 404056 407061 408065 410068 414068 415066
 0.01 401078 401073 400071 393066 386056 385051 390050 392050
      394048 389040 388038 385038 383040 381039 378037 378033
      380030 387028 389026 390022 390011 391004 392000 392991
      387990 382996 379004 375010 373017 369023 367030 363039
      362043 359045 353048 349048 345050 343052 339052 334055
      329055 326056 324059 324064 326071 325078 322081 318081
      310079 307078 303076 298077 288076 278074 271071 266068
      255060 244054 238051 233055 232059 233063 238069 246079
      251083 257086 263091 268095 277105 282110 284112 289113
      295117 299122 303126 311127 315126 320126 325122 332119
      336115 342109 345105 347097 352090 356093 360094 359089
      357086 357082 361074 365069 367067 369069 372076 374080
      377083 381081 384078 386077 388079 401078
 0.01 380044 378042 376040 375042 376044 378046 380044
 0.01 376060 375057 374056 372055 370056 368057 370059 371061
      373061 375062 376060
 0.01 355927 355919 352914 348910 344907 340904 335901 328902
      322904 315913 312924 316937 319941 323943 330943 334941
      339937 345935 350934 354930 355927
 0.01 344788 343781 341777 335773 330772 330770 329757 328751
      326746 325740 323737 318730 313731 311736 309746 309756
      309768 308778 307784 305788 299793 290796 287794 287791
      266793 255794 250795 244797 238802 236810 236815 238818
      239824 241829 247835 254837 265837 269838 273840 286849
      292855 300858 304857 308854 313848 319841 322832 336798
      341792 344788
 0.01 312949 313944 311941 306936 304933 302929 301920 297911
      294905 285893 283890 279889 272890 267896 264903 260920
      260925 262928 266933 270936 272939 275946 275952 274957
      270962 267965 263966 259967 255968 239971 233975 231982
      232990 232996 234999 238005 244009 251011 256011 260010
      264009 267006 270000 271995 273993 279989 285983 289978
      299967 312949
 0.25 534212 535200 533191 525177 522169 518163 507153 498162
      492165 489168 490173 494181 495185 499187 507189 512194
      516200 520208 523216 528220 532218 534212
 0.25 516264 517256 516248 513236 501214 498210 494207 485207
      475211 472215 470218 473220 485224 487226 489228 491234
      492237 489238 484238 476230 467233 464233 462235 460238
      461241 472246 481254 489262 496272 498276 502280 506281
      509275 516264
 0.25 472670 472663 470655 469648 467644 465639 461641 461646
      461653 463660 464665 465672 467677 470678 471676 472670
 0.25 461225 460221 458219 456218 452218 450219 449219 445220
      445222 446224 449226 452225 455224 458225 461225
 0.25 457901 457898 456896 455893 454894 453896 453897 454898
      454901 455903 456901 457901
 0.25 455918 456915 456913 455910 455908 455907 454906 453905
      452906 451906 450907 448908 446910 446911 445913 446916
      447917 447918 448919 450920 452921 453921 454920 455919
      455918
 0.25 445937 446935 446933 446930 445928 445927 443925 442925
      440925 440927 440928 440929 440930 441933 441935 442936
      443937 445937 445937
 0.25 439952 438945 434940 428938 424939 424942 425949 428955
      427961 426968 428970 430968 435966 438959 439952
 0.25 406850 405848 404845 402841 401839 399837 396836 395838
      393840 393843 395846 397848 399850 402850 406850 406850
 0.25 396786 394784 390782 385782 381784 378789 377793 375797
      375800 376802 381800 384798 388796 393794 395791 396786
 0.25 340096 340093 340091 339089 339087 339085 339084 339082
      338081 336082 334083 333084 333086 334088 335090 335091
      335093 336095 338097 340096 340096
 0.25 328105 328101 325097 320097 316098 312100 309102 308109
      309115 310118 315118 319116 321112 322108 326110 328106
      328105
 0.25 325764 324754 323748 321744 318743 317746 316751 315765
      313781 310787 308794 307800 302806 297809 291809 284809
      275810 266812 260813 264817 270819 282823 288825 280826
      277828 278833 282837 286842 290845 296849 302848 307845
      311839 315826 318820 318810 319803 321797 323790 325782
      325764
 0.25 299943 299936 298926 296920 292914 288910 281909 276913
      274915 273919 276924 281929 285941 284948 281956 279961
      277969 280973 284973 286971 292960 296955 299947 299943
 0.25 247998 247996 247994 247992 248990 247988 246986 244984
      242984 240985 239987 239989 239991 239993 239995 240997
      240998 242999 244999 246999 247998
 0.50 531213 531211 532208 532206 532203 532201 532200 530198
      530197 529196 528195 526194 524194 524195 523197 523200
      523203 523205 524208 524210 526212 527213 529215 530215
      531213 316110 315109 314109 315110 316110
 0.50 513255 513249 512244 510237 507232 502222 496213 488211
      482211 478213 478216 480218 484221 489224 492229 497239
      503248 506258 509261 511261 513255
 0.50 518185 518180 518177 514171 511166 506163 501165 498167
      495169 495174 496180 499183 503183 507185 514188 518185
 0.50 503275 501270 500266 494259 491248 489244 485241 482239
      479236 475234 472239 474244 477247 485253 493258 495262
      496267 501275 503275
 0.50 322769 322767 321765 321763 319765 320766 320767 321769
      322769 322769
 0.50 321771 320770 318771 318772 318774 319775 320774 321771
 0.50 320782 319780 318782 318783 317785 316786 316787 315789
      315792 317792 317791 318789 319787 319785 320783 320782
 0.50 308833 307824 303820 301815 291813 280813 278816 283819
      288818 294819 298822 299824 298826 292827 286829 287836
      290839 293843 298846 302844 306839 308833
 0.50 295949 294949 292948 290949 289949 288950 288952 287954
      287955 286956 287958 288958 289958 290956 292954 292953
      293952 294951 295949
 0.50 294933 294931 294929 294926 294924 294923 293922 292921
      291920 290919 288919 286919 286920 286922 286923 287925
      287927 288929 288931 289933 290934 291935 292936 293935
      294934 294933
 1.00 506177 507174 505172 504174 504176 505177 506177
 1.00 301838 302836 301834 300833 299833 297834 297835 295836
      296838 297840 299839 301838 301838

$$




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