Quantitative Precipitation Forecast
Issued by NWS

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656
FXUS04 KWBC 260715
QPFPFD

QUANTITATIVE PRECIPITATION FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
314 AM EDT MON SEP 26 2016


PRELIM DAY 1 QPF DISCUSSION
VALID SEP 26/1200 UTC THRU SEP 27/1200 UTC
REFERENCE AWIPS GRAPHICS UNDER...PRECIP ACCUM - 24HR


DAY 1...

...TEXAS / SOUTHWEST U.S....

CLOSED MID/UPPER LOW WILL REMAIN NEARLY STATIONARY ACROSS NW
MEXICO AND BAJA THIS PERIOD...WHILE THE NORTHERN STREAM TROUGH
CONTINUES TO AMPLIFY INTO A MID-UPPER CLOSED LOW ACROSS THE UPPER
GREAT LAKES. THE MODELS CONTINUE TO SHOW WEAK SUPPORT FOR UPPER
FORCING ACROSS TX IN BETWEEN THESE TWO SYSTEMS... WITH AN UPPER
LEVEL SHEAR AXIS AND A QUASI-STATIONARY SURFACE BOUNDARY OVER
SOUTH TX AND WEAK UPPER DIFFLUENCE EAST OF THE UPPER LOW ACROSS
SOUTHERN AZ/NM INTO WEST TX. MEANWHILE...THE MORE ANOMALOUS PWS
(2.00+ INCHES) WILL CONTINUE TO PRESS SOUTH WITH TIME TOWARD THE
TX GULF COAST...WHILE MODEST PW ANOMALIES (AROUND 1.5 STANDARD
DEVIATIONS ABOVE NORMAL) ALIGN W-E ACROSS SOUTHERN AZ/NM INTO WEST
TX. INSTABILITY WILL ALSO BECOME MORE CONFINED TOWARD SOUTH TX AND
THE GULF COAST WITH TIME DURING THE PERIOD...WITH ONLY MIN MAL
CAPES (200-400 J/KG) ACROSS FAR SOUTHERN AZ NORTH OF THE UPPER
LOW. IN TERMS OF THE QPF...THE 00Z GFS AND ESPECIALLY ECMWF HAVE
TRENDED LIGHTER DURING THE DAY 1 PERIOD ACROSS SOUTH-CENTRAL TX
AND AREAS WEST INTO THE SOUTHWEST...WHICH IS NOT SURPRISING GIVEN
THE WEAKENING SYNOPTIC SUPPORT AND LACK OF DEEP INSTABILITY.
HIGHEST AREAL-AVERAGE TOTALS FROM 12Z MON-12Z TUE WERE BETWEEN
0.50-1.0" ALONG THE RIO GRAND EAST OF THE BIG BEND FROM DRT TO
LRD...WITH A SECONDARY AXIS ALONG THE SOUTH TX GULF COAST BETWEEN
CRP AND BRO WHERE THE INSTABILITY AND 2+ INCH PWS WILL PERSIST.
THE HIGH-RES CAMS SHOW LOCALIZED 3-5" TOTALS ON THE MEXICAN SIDE
OF THE RIO GRANDE...WITH A FEW POCKETS OF 3-5" AMOUNTS ALONG THE
LOWER AND MIDDLE TX COAST. OUTSIDE OF THE ARES ALONG THE RIO GRAND
(NEAR DRT) HIT HARD BY THE RECENT HEAVY RAINS (THUS HAVING LOWER
FFG)...THE RISK FOR FLASH FLOODING DURING DAY 1 APPEARS TO BE
MARGINAL AT BEST.


...EASTERN U.S. FROM THE EASTERN LAKES...NORTHEAST...AND
MID-ATLANTIC REGION...

A NARROW RIBBON OF HIGHER PW VALUES...1.5-1.75 INCHES...WILL SWEEP
EASTWARD TOWARD THE EASTERN SEABOARD AHEAD OF A STRONG COLD FRONT.
AVAILABLE INSTABILITY...HOWEVER...WILL BE RATHER MEAGER AHEAD OF
THE FRONT...WITH MUCAPES AVERAGING 500-1500 J/KG AHEAD OF THE
FRONT LATER TODAY...MAINLY ALONG THE WESTERN SLOPES OF THE
APPALACHIANS. WPC QPF WAS COMPRISED FROM A BLEND OF CONTINUITY
(PREVIOUS FORECAST) AND THE 00Z GFS AND ECMWF. BOTH THE GFS AND
ECMWF SHOW MINIMAL TIMING DIFFERENCES COMPARED TO PREVIOUS RUNS
(12Z SUN ECMWF WAS A BIT FASTER).HIGHEST AREAL-AVERAGE AMOUNTS
BETWEEN 0.50-1.00" WERE NOTED.


...SOUTHEAST U.S. FROM SOUTH CAROLINA TO FLORIDA

A CIRCULATION ALOFT OVER THE SOUTHEAST WAS BEST DEFINED AT 250
MB...AND THE DIFLUENT REGION EAST OF THE LOW OPENS UP OVER THE
ATLANTIC...ENSURING A LITTLE GREATER COVERAGE OF HEAVY DOWNPOURS
JUST OFFSHORE OF FLORIDA UP TO SOUTH CAROLINA. THUNDERSTORMS WILL
ALSO FORM INLAND...WITH THE TYPICAL DIURNAL TRENDS...AND GREATER
COVERAGE DURING THE DAYTIME HOURS. AREAL AVERAGE AMOUNTS LOOK TO
BE IN THE 0.10 TO 0.25 INCH RANGE...THOUGH WITH FAIRLY RICH
MOISTURE IN PLACE A FEW HEAVIER EMBEDDED DOWNPOURS ARE LIKELY.

HURLEY

GRAPHICS AVAILABLE ON THE WEB AT
WWW.WPC.NCEP.NOAA.GOV/QPF/QPF2.SHTML

24HR QP VT 27/12Z
 0.01 501320 501315 498315 495319 491320 490317 491309 489303
      485298 482294 480289 480283 481273 479268 480261 483258
      486252 488244 490227 486223 485217 486212 491211 496213
      498218 504220 508217 510207 511202 511196 508190 507183
      509178 512173 515169 519166 524167 528170 530171 532170
      537161 544157 550159
 0.01 567941 566947 563951 557955 550960 545961 539963 529963
      518963 508963 504962 500960 493954 486949 472935 470930
      468927 461920 458919 457915 455910 454905 453900 455895
      456887 452877 448867 438865 434861 436857 438853 442849
      445846 447841 445839 441840 435841 431843 426844 419849
      405862 397869 390877 385885 380893 370907 359925 349944
      339959 334968 331976 327987 326001 324014 324022 326028
      325034 326040 326045 328048 331048 338054 338066 343087
      344092 344099 343106 340112 338115 334117 323115 321114
      320117 319124 322134 324138 325143 319153 318160 315161
      304159 297153 293149 290149 289145 289139 290130 292126
      291121 287110 286106 285098 282090 277082 270075 265068
      261061 258051 255048 253043 253037 251032 243026 240023
      238019 236009 232002 230993 230965 264911 267904 272908
      276916 279918 281917 282914 284910 283903 286895 290889
      293886 294887 296877 295867 293860 294855 293849 293843
      292837 289835 285834 277832 273831 267832 259831 251829
      244826 241825 242821 242811 243805 244802 250798 258793
      265792 270789 284779 288773 294767 295758 296753 298749
      303743 309739 313737 319736 326738 334741 340745 345750
      349760 350772 348780 343787 343790 344792 346794 349795
      352794 355790 358783 362775 365768 371752 374744 376739
      375733 373729 374724 379716 384711 387709 392708 406700
      414695 422689 429687 439684 446678 449670 453661 455661
      458663 460666 461669 463673 464670 466677 468682 472690
      478696 483703 492713
 0.01 492713 496717 499719 506729 511738 517747 522757 527767
      532779 537791 541801 547811 549817 553821 559828
 0.01 364867 361865 358866 352867 343873 339876 336880 330887
      327891 325896 323901 322904 329906 335906 344901 349899
      352894 356885 359880 361874 364867
 0.01 338919 334917 330917 323916 318916 318922 319932 319941
      317948 317952 319951 323945 326938 330932 335926 338919
 0.01 330837 328835 326836 324836 323838 321840 320842 320845
      320847 320849 322850 323849 323848 325846 326844 327842
      328840 328839 330837
 0.01 308136 309134 307132 305129 303131 303133 303135 304138
      306138 308136 308136
 0.25 525254 519249 514242 509236 505234 501235 499239 496248
      492256 491259 491263 494271 496280 498288 505289 512288
      513288
 0.25 542198 540197 537194 536192 535189 532188 530189 528191
      526195 525198 525201 526205 528208 529211 530215 531218
      533221 534223 535225
 0.25 560870 560858 557848 552837 546824 538811 531799 525783
      521777 517773 512769 506767 499764 501768 499771 495774
      486779 482786 482791 483796 487802 495801 500803 504807
      512817 516823 519832 522838 524844 524849 522858 520865
      519873 516880 510883 503884 495885 489887 485884 483875
      483863 481855 481842 477832 472798 469783 464779 458776
      453772 447769 442764 438758 438748 438745 436744 431746
      428750 418759 412760 408757 407751 410746 421737 426731
      426722 425718 423715 417714 411716 405719 401724 397731
      391741 384752 377764 372777 366790 357801 349811 343822
      342826 343830 345838 345846 345849 347850 353846 358841
      365831 372821 376816 381813 387810 394807 403805 410806
      401832 401835 405836 410832 420824 427821 435819 443820
      449820 454823 457831 456841 453850 454855 460852 465850
      467852 467856 468867 466876 461889 459897 459903 460907
      464913 470915 476929 480935 485939 496945 507948 515948
      523947 533943 539939 543934 547928 548923 548918 547909
      548901 550892 552883 560870
 0.25 495758 492754 488750 484745 481741 476738 475737 473740
      475743 480744 485748 489752 493756 495758
 0.25 343770 342764 341759 336754 330748 324745 320745 316746
      309751 303755 299763 297772 297781 295791 295795 297798
      302804 306812 310818 314818 317816 322809 325802 329796
      335790 339783 341775 343770
 0.25 324098 324092 323086 318077 313069 308059 309054 312050
      314044 313039 313012 317003 318996 319989 317982 313981
      309985 304987 300988 297986 292975 291970 294965 298956
      299950 299946 297939 295935 289933 283935 276940 272940
      271942 267945 263947 256947 251948 246950 241958 237967
      235971 235977 236983 235991 236997 239001 246007 249011
      250017 256024 258030 259035 261046 264057 268061 272064
      278070 284078 286081 291085 300089 307096 316102 322101
      324098
 0.25 259813 258813 257811 256811 255811 253811 251812 249814
      249816 249818 250820 252821 254820 255819 256818 257816
      257815 258814 259813
 0.50 525258 519255 516250 511246 508240 506240 504242 506250
      507256 506266 505268 501269 499271 500277 502283 506283
      511283 516284
 0.50 541202 540201 538202 537202 536204 535207 536208 536210
      537212 537213
 0.50 552857 551849 548843 544836 541831 538826 534823 532830
      531838 534843 538848 542853 545858 550859 552857
 0.50 540925 540921 539918 534916 531913 528907 528899 525894
      521891 516892 512893 507895 497896 492899 487901 478902
      476900 476896 477890 476883 474880 471881 465890 463895
      462903 466906 472905 475907 475911 476917 477924 480929
      487936 496939 502940 507940 527936 534931 540925
 0.50 477847 476847 475846 473847 473848 473850 473853 472855
      474856 474855 475853 475852 475850 476848 477847
 0.50 456808 455806 452804 450803 446803 443803 440804 437806
      435809 436813 439814 442814 445814 449813 452812 454811
      456808
 0.50 431766 430761 425763 421766 419772 418776 417781 413784
      408786 399791 391796 393801 399801 409797 419793 423791
      427786 424777 427774 430769 431766
 0.50 409730 409728 407727 405727 404728 403729 402731 402732
      402734 401737 402739 403739 405738 406736 407736 408733
      409730
 0.50 400751 399746 393747 387755 383763 378772 376783 371792
      360805 354813 349822 349834 351838 355836 367821 372814
      378805 382797 387788 389785 391779 389774 391771 395762
      400753 400751
 0.50 335773 335765 333759 329754 325751 318751 313754 308757
      304761 302768 302774 304791 305798 307803 311807 316805
      320802 323797 326792 331788 334783 335776 335773
 0.50 314088 312081 309075 300067 296062 294056 292049 285046
      275040 269037 267039 267044 265050 267056 279061 284066
      287072 290077 296080 307087 311090 314088
 0.50 305019 306014 306011 303005 298001 291999 286996 281991
      282986 284983 287979 285962 285959 282956 274957 268959
      261958 255958 253958 250960 246963 243969 242976 249976
      256975 260979 262982 263986 257987 251985 247984 243985
      239990 239995 243000 248004 258012 262016 265021 268027
      273030 279033 288034 297033 302032 304025 305019
 1.00 522262 521262 519261 518260 516260 514260 513261 513263
      512266 512268 512271 512274 514275 515277 517278
 1.00 501926 500924 497922 494921 492921 489919 487919 486921
      486922 487925 489927 492927 496928 499928 501926
 1.00 361816 361814 359814 358814 357815 356817 356818 355819
      354821 354822 353824 353826 352828 353829 355829 355828
      356827 357826 358824 359823 359822 360821 361818 361816
 1.00 327779 326771 325763 323761 319761 315761 312763 310765
      308771 310778 312786 312794 314796 315794 317791 319787
      323784 327779
 1.00 300015 300008 295005 289003 282002 277001 271998 260994
      255991 251990 248991 244995 247000 257006 261010 265014
      269018 274021 279022 285022 291020 296018 300015
 1.00 280976 279972 278970 276968 274967 270966 266967 265968
      263972 265974 268976 270976 274977 277978 280976
 1.50 318770 317768 316767 314768 314770 315771 316770 318770
 1.50 296012 293008 289006 280005 275003 271001 262000 255994
      251993 249996 251000 254002 261006 267013 272017 278018
      281017 291015 296012
 1.50 274970 272969 270970 269970 269972 270972 272973 272972
      274970 274970
 2.00 288012 285009 280008 276007 273004 269002 266003 265007
      267011 271014 274015 278014 282012 287012 288012
 2.00 255998 253997 253998 255998 255998
 3.00 273009 273008 271008 270009 271010 273011 273009

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