Quantitative Precipitation Forecast
Issued by NWS

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000
FXUS04 KWBC 241812
QPFPFD

QUANTITATIVE PRECIPITATION FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
211 PM EDT MON AUG 24 2015


PRELIM DAY 1 QPF DISCUSSION
VALID AUG 25/0000 UTC THRU AUG 26/0000 UTC
REFERENCE AWIPS GRAPHICS UNDER...PRECIP ACCUM - 24HR


DAY 1...

...GREAT LAKES/EAST COAST...

A FRONTAL ZONE ARRIVING INTO NEW YORK AND THE MID ATLANTIC REGION
WAS BRINGING WITH IT A RELATIVELY NARROW ZONE OF ENHANCED MOISTURE
CONTENT. THE ADDED MOISTURE...ALONG WITH SUFFICIENT HEATING SHOULD
YIELD ENOUGH INSTABILITY FOR SCATTERED TO NUMEROUS THUNDERSTORMS
THIS AFTERNOON AND EVENING. POOR MID LEVEL LAPSE
RATES...HOWEVER...WILL INHIBIT UPDRAFT STRENGTH AND THE OVERALL
COVERAGE AND EFFICIENCY OF RAINFALL. THESE LAPSE RATES ARE NOT
LIKELY TO IMPROVE MUCH...AS DEEP LAYER LIFT WILL BE MARGINAL
JUDGING BY WEAK HEIGHT FALLS AHEAD OF AN ALREADY STACKED UPPER
CYCLONE. WITH THE STACKED SYSTEM BEING WELL HANDLED BY THE
MODELS...RUN TO RUN QPF CHANGE WAS MINIMAL. WE BLENDED TOWARD THE
12Z GFS AND WRF-ARW FOR SOME OF THE DETAILS...EXPECTING GENERALLY
0.10 TO 0.75 INCH AREAL AVERAGE AMOUNTS TODAY THROUGH TOMORROW
ALONG THE NORTHERN HALF OF THE EAST COAST...WITH HEAVIEST AMOUNTS
OVER NEW ENGLAND.

FARTHER DOWN THE COAST...NARROW BROKEN BANDS OF THUNDERSTORMS ARE
EXPECTED AHEAD OF THE SLOW MOVING TRAILING FRONTAL ZONE BOTH TODAY
AND TUESDAY...AGAIN AMOUNTING TO 0.10 TO 0.75 INCH AREAL AVERAGE
AMOUNTS OVER THE CAROLINAS. IN FLORIDA LIGHT BUT INCREASINGLY
WESTERLY LOW LEVEL FLOW WILL FAVOR CONVERGENCE OVER NORTHEAST
FLORIDA THIS AFTERNOON...WITH SEA BREEZES MEETING IN THE CENTER OF
THE PENINSULA FARTHER SOUTH. ON TUESDAY THE SURFACE FRONT WILL
SINK INTO THE STATE...CONFINING THE HEAVIER AREAL AVERAGE AMOUNTS
TO THE WARM SIDE OF THE FRONT OVER THE CENTRAL AND SOUTHERN
PENINSULA. WPC FOLLOWED THE 00Z SSEO MEAN INITIALLY...AND THEN THE
12Z GFS ON TUESDAY.


...TEXAS / LOUISIANA...

THERE IS A VARIETY OF MODEL QPF SOLUTIONS OVER TEXAS AND
LOUISIANA...BUT MOST DEPICT ONE AXIS OF PRECIPITATION AHEAD OF A
SLOW MOVING COLD FRONT IN CENTRAL/SOUTHEAST TX TO SOUTHERN
LA...AND A SECOND AXIS WITH ITS ORIGIN IN MID LEVEL
MOISTURE/ASCENT OVER NORTHEAST TX TO NORTHERN LA. MODELS WERE
TRENDING DRIER IN THE VERY EARLY TIME FRAME THROUGH THIS
EVENING...AND MORNING SOUNDINGS WERE NOT VERY UNSTABLE EXCEPT AT
LAKE CHARLES. WE MAINTAINED A LOCAL QPF MAXIMUM IN THE VICINITY OF
SOUTHWEST LA...BUT CONSTRICTED QPF CONTOURS ELSEWHERE. EXPECT THE
SURFACE BASED CONVECTION TO PUSH OFFSHORE OVERNIGHT...BUT ELEVATED
CONVECTION MAY BE SUSTAINED EAST OF I-45 INLAND AND EXTENDING UP
TO NEAR A WEAK MID LEVEL TROUGH AXIS OVER NORTHEAST TX. MODELS ARE
A LITTLE MORE GENEROUS WITH PRECIPITATION ON TUESDAY AFTERNOON AS
A SHARPER MID LEVEL WAVE DIGS INTO THE REGION FROM THE NORTH. WPC
BLENDED THE PREVIOUS FORECAST TOWARD THE 12Z GFS...WRF ARW...AND
WRF-NMM...WITH SOME INFLUENCE ALSO FROM OUR LATEST IN-HOUSE
ENSEMBLE.


...SOUTHWEST STATES...

MONSOONAL MOISTURE WAS RUNNING CLOSE TO AVERAGE...WITH NO MORE
THAN 2 STANDARD DEVIATIONS FROM CLIMATOLOGY SHOWING UP IN THE GEFS
STANDARDIZED ANOMALIES PLOTS FOR PRECIPITABLE WATER THROUGH EARLY
TUESDAY. THE GREATEST MOISTURE CONTENT WAS HUGGING THE SOUTHERN
PERIPHERY OF UPPER RIDGING...FROM SOUTHWEST TEXAS ACROSS SOUTHERN
NM/AZ...AND INCREASING TOWARD SOUTHERN CALIFORNIA. THE PREVIOUS
DAY...THE 0.75 PW CONTOUR...EXTENDING FROM FAR SOUTHERN COLORADO
TO NORTHERN ARIZONA...HAD MARKED THE NORTHERN EDGE OF CONVECTION
CAPABLE OF PRODUCING LIGHTNING. THE WHOLE MOIST PLUME AT THE
SOUTHERN EDGE OF THE RIDGE IS FORECAST TO BALL UP ON THE
SOUTHWESTERN FLANK OF THE RIDGE THROUGH TUESDAY...WITH PW VALUES
FALLING OVER PARTS OF CO/NM...AND INCREASING FARTHER WEST. PW
ANOMALIES WILL RISE TO 2.5 STAND DEV OVER SOUTHERN CA BY TUESDAY
AFTERNOON. IN THE EARLY STAGES OF THIS PROCESS...POST FRONTAL
UPSLOPE FLOW GIVES SOME CONCERN FOR HEAVY RAINFALL OVER SOUTHERN
NM AND SOUTHWEST TX THIS EVENING. OTHERWISE...THE POTENTIAL FOR
LOCALLY HEAVY DOWNPOURS WILL SHIFT INTO AZ/CA LATE THIS
EVENING...AND BEGIN TO BUILD NORTHWARD TUESDAY AFTERNOON. THE
PREVIOUS WPC FORECAST HAD THIS REGION HANDLED WELL. WE MADE MINOR
ADJUSTMENTS TOWARD THE HRRR IN THE EARLY HOURS AND THEN THE 12Z
NAM.

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

BURKE

24HR QP VT 26/00Z
 0.01 539829 539812 538807 535805 530803 526803 522807 519807
      518806 513798 508792 501784 495778 488774 482769 479766
      474764 470763 465764 459770 453776 449779 447784 445788
      444793 439803 436811 435816 437821 444827 440849 441855
      444860 447864 450866 454863 459863 462873 463878 462885
      460896 460902 462907 469911 472912 475910 479907 484905
      494904 500901 505898 508895 512892 514888 517884 521882
      527876 530873 532869 536859 538842 539829
 0.01 521773 521766 521759 519753 519748 519742 517738 514731
      517726 515719 511711 507704 504700 501697 495694 492692
      490687 488680 485678 473672 465674 458677 449681 443687
      439693 433698 425708 420714 413718 404721 400722 398724
      396729 395733 390739 385745 381752 384754 385756 384758
      376764 368745 365746 362748 357752 348762 339774 334780
      329788 315793 311795 307796 296797 282795 272796 261797
      254796 250791 247792 244795 242801 240808 240817 243827
      249831 255831 258833 266835 271832 268826 281825 285826
      288828 294834 296842 296846 294848 286860 280872 272888
      265903 263908 263913 264924 272935 274943 274952 280964
      278968 278974 280977 284978 290975 295976 296978 293989
      292995 292000 294004 298006 303013 306014 310014 313009
      315004 319005 322006 327006 331006 333001 333997 332991
      329984 326978 325974 327969 333966 336960 336950 297903
      292909 290909 289904 285898 285893 286891 298864 305850
      307842 307836 305833 294819 292816 297815 304816 313817
      314822 318824 323830 335824 341821 346815 351809 355804
      364790 367786 370783 373784 378783 391774 406765 412761
      420759 435754 442751 450748 454748 459749 466753 479762
      484766 491770 503775 507777 513778 518777 521773
 0.01 496842 494833 493825 491818 490815 488814 486816 483819
      480820 478822 475828 474832 475838 477845 480849 483851
      487850 491847 496842
 0.01 461183 462176 462170 459166 455168 451178 447187 442195
      438204 435208 436211 443205 449200 455194 458190 459185
      461183
 0.01 455118 453107 452095 449092 445091 442091 437093 433093
      429091 426089 426091 427096 431099 433101 434104 437105
      443099 447101 449107 449112 451117 453120 455118
 0.01 450078 450068 449063 446055 443050 438047 432047 430051
      433056 437060 440065 442072 446077 450078
 0.01 430786 429783 426784 422787 419793 416799 413805 412810
      413817 416817 418819 421815 422808 425801 428795 429788
      430786
 0.01 413104 411099 408094 406098 403103 400105 397107 394109
      386112 377113 372115 370117 367116 363113 361109 363105
      367101 369099 367094 369090 367090 364086 362082 379084
      383086 386085 386074 388073 391073 394069 395065 398062
      404056 406054 403053 398053 395054 393052 390043 385042
      382045 376050 370049 367045 364042 361044 349053 343053
      337052 335048 336040 333036 329035 323040 319049 314055
      309061 308066 310067 319064 322065 320067 316071 312079
      306084 296081 288078 280076 272072 267070 263070 258072
      256077 255082 256086 262092 268092 272094 274103 278111
      283116 288118 291121 291127 295130 300132 303136 306138
      310139 314142 320144 324146 326148 323151 320152 309150
      302153 305156 310158 318165 328167 333169 338172 341174
      342178 347178 350177 354176 355173 351169 351165 353164
      362163 367163 371165 378164 379162 375159 370153 366149
      366146 368144 372138 385128 392121 396117 399115 408112
      413104
 0.01 400028 399023 399016 397011 395009 392006 387006 383006
      381010 383015 386016 390018 393020 396025 400028 400028
 0.01 380192 380189 378187 376184 374183 370182 366182 363182
      361182 358183 360185 362187 366187 369188 373190 374192
      378193 380192
 0.01 345140 345139 343138 341136 341137 340139 341141 342141
      344141 345140
 0.01 351068 346063 341062 335062 332068 327068 326066 324067
      322070 322074 323078 327074 333072 340074 345074 347074
      349070 351068
 0.01 257010 257006 255003 250998 249995 249990 246983 244979
      241978 237979 235982 234986 235989 235994 237997 240004
      243011 246013 251013 255013 257010
 0.25 529841 527834 523829 519827 515829 509841 505852 502857
      498863 494868 493873 493878 494880 499882 506880 509877
      517867 524857 527852 529844 529841
 0.25 510750 509744 507741 504738 506729 508725 506720 498712
      488706 483702 479698 468692 469688 466688 460691 451701
      444705 439709 433713 427715 421719 418724 417730 423730
      431730 438728 441729 441732 439735 442737 449735 453733
      454731 456723 459721 462719 470718 474720 484730 486737
      490742 495747 499750 505752 510750
 0.25 477790 476784 472781 465782 457788 451794 446802 445805
      445812 447814 452815 454818 454823 456822 457815 460805
      463796 468794 473794 476792 477790
 0.25 455850 455847 454846 453845 453844 451844 450845 449846
      448848 448849 447850 448851 448853 450854 451855 451856
      452855 453854 454852 455851 455850
 0.25 425796 425795 423795 422796 422798 421799 422800 423799
      424798 425796 425796
 0.25 413732 412730 411729 409728 407727 405727 404727 403727
      402730 402732 402733 403734 404734 406734 408735 409735
      410736 411735 412734 413732 413732
 0.25 367759 362757 358759 355761 348771 341781 333793 330798
      325803 323801 321802 320805 324805 325808 331806 336802
      341797 346796 350792 356781 364769 367759
 0.25 359129 358125 356120 351115 344107 343103 343098 343092
      344085 342083 339083 335084 335089 336095 337106 340115
      343122 347131 351133 354133 359129
 0.25 332142 332141 332140 331138 330137 329135 328135 327136
      326137 325139 326141 328142 330143 331143 332142
 0.25 323163 325161 324160 322159 320159 318160 320161 322162
      323163 323163
 0.25 333058 334056 332055 330055 330056 332058 333058
 0.25 318984 318979 317977 314976 312979 311981 310984 307985
      306987 305992 307992 310990 313990 315989 317986 318984
 0.25 310945 309939 307933 303920 301914 299913 296914 294919
      293926 293935 291941 288946 285951 284955 288956 288961
      289964 292965 299965 304963 306956 308950 310945
 0.25 298118 298116 298115 297113 296113 296115 298118 298118
 0.25 296101 294094 290091 288086 286084 283084 275082 272082
      271085 277087 282090 282095 280098 281101 285103 292102
      296101
 0.25 287810 286806 283805 278803 272802 265803 258804 254806
      253808 258810 262814 267816 272819 274818 273816 278815
      283815 287810
 0.50 520850 518845 513848 511851 508856 507859 504865 504868
      507870 510867 512864 515859 517855 519851 520850
 0.50 500723 500718 497717 492713 483708 472701 466700 462701
      449707 442711 440714 441718 447717 453715 460712 464711
      468711 479716 488722 494724 500724 500723
 0.50 430719 429718 427718 426719 424720 422722 422723 423723
      424723 426723 428722 428721 429720 430719
 0.50 360767 359763 356765 354767 353769 351772 350774 348777
      348779 344785 342789 345787 348784 350781 352778 353776
      355773 357771 358769 360767
 0.50 353128 352126 352125 350124 348125 349128 349130 351130
      352130 353129 353128
 0.50 299926 299927 299926
 0.50 302947 302945 302943 301941 299940 299941 297942 297943
      297945 297946 298947 299949 299950 299949 301949 302947
 0.50 283808 282808 280807 278806 276806 274806 273807 273808
      271810 273810 275811 276811 277811 278812 280812 281811
      282810 283808

$$




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