Quantitative Precipitation Forecast
Issued by NWS

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000
FXUS04 KWBC 251834
QPFPFD

QUANTITATIVE PRECIPITATION FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
233 PM EDT SUN SEP 25 2016


PRELIM DAY 1 QPF DISCUSSION
VALID SEP 26/0000 UTC THRU SEP 27/0000 UTC
REFERENCE AWIPS GRAPHICS UNDER...PRECIP ACCUM - 24HR


DAY 1...

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

THE ANTICIPATED HEAVY RAIN EVENT WAS UNFOLDING IN TEXAS. THE MOST
FOCUSED AND EXPANSIVE HEAVY RAIN HAD OCCURRED EAST OF THE BIG BEND
VARIOUS OVERNIGHT OUTFLOWS AND AN MCV LIFTING OUT OF MEXICO WERE
SUPER-IMPOSED ON THE INCREASINGLY DIVERGENT FLOW ALOFT AS AN UPPER
LOW CLOSES OFF IN MEXICO. THE LOW ITSELF...HOWEVER...WILL
IMMEDIATELY BEGIN RETROGRADING...RESULTING IN A NET LOSS OF
GRADIENT AND WIND SPEEDS THROUGH A SIGNIFICANT DEPTH OF THE COLUMN
OVER TEXAS. AT THE SAME TIME...HOWEVER...COLD POOLS WILL CONTINUE
TO ENCOURAGE THE MOST ROBUST CONVECTION TO PROPAGATE SLOWLY
EASTWARD NEAR THE I-35 CORRIDOR...FINDING THE CAPE GRADIENT ALONG
WITH MODEST LOW LEVEL INFLOW. THE VERY RICH TROPICAL MOISTURE IN
PLACE...PW VALUES AROUND 2 INCHES...WILL SUPPORT INTENSE LOCAL
RAIN RATES AND SOME WARM RAIN PROCESSES...WHILE THE ABSENCE OF
COORDINATED DEEP LAYER ASCENT SHOULD TEND TO RESULT IN SOME
FRACTURING AND OVERALL LAZY APPEARANCE OF THE CONVECTION.

WE WOULD EXPECT ADDITIONAL HEAVY RAINFALL TO FORM BACK TO THE WEST
IN BETTER PROXIMITY TO UPPER FORCING...AND AS BACKED LOW LEVEL
FLOW ENCOUNTERS THE HIGHER TERRAIN...BUT GIVEN THE EXTENT OF
ONGOING OUTFLOWS...THIS MAY OCCUR STRADDLING THE RIO GRANDE...WITH
A GOOD DEAL OF THE HEAVY RAIN OCCURRING IN MEXICO TONIGHT AND
MONDAY...THOUGH THIS WILL STILL BE OF CONCERN TO RIVER FORECASTS
IN THE UNITED STATES. THAT BEING SAID...THERE WERE MODEL SOLUTIONS
THAT STILL WANT TO PRODUCE VERY RAIN ON THE U.S. SIDE...SUCH AS
THE 12Z GFS. GIVEN THE OBSERVATIONAL TRENDS...WPC FAVORED THE
OLDER 06Z GFS...AS WELL AS THE 12Z UKMET AND SOME OF THE HI-RES
MODELS...AGAIN STRADDLING THE RIO GRANDE...ALTHOUGH CERTAINLY
SHOWING POTENTIAL FOR VERY HEAVY RAIN AND FLASH FLOODING TO OCCUR
NEAR AND SOUTH OF DEL RIO.

IN A BROADER SENSE...WPC FOLLOWED THE TREND OF MOST GUIDANCE TO
SUPPRESS HEAVIER AMOUNTS FARTHER SOUTH...WHILE MAINTAINING THE
SHAPE OF THE QPF WITH LITTLE CHANGE. WE DID INCREASE AMOUNTS ALONG
THE SOUTHEAST TEXAS COAST PER OUR BLEND FAVORING THE GFS/ARW. THE
WESTWARD EXTENT OF MEASURABLE PRECIPITATION IS PRETTY WELL AGREED
UPON IN THE MODELS AND ENSEMBLES...WITH AREAL AVERAGE AMOUNTS OF A
TENTH UP TO A HALF INCH FORECAST ACROSS FAR SOUTHERN NEW MEXICO
AND SOUTHEAST ARIZONA THROUGH MONDAY AFTERNOON.


...EASTERN U.S. FROM THE OZARKS TO THE GREAT LAKES AND
APPALACHIANS...

A NARROW RIBBON OF HIGHER PW VALUES...1.5 INCHES OR SO...WILL
SWEEP EASTWARD THROUGH THE MIDWEST / GREAT LAKES INTO THE NORTHERN
MID ATLANTIC AHEAD OF A STRONG COLD FRONT. AVAILABLE
INSTABILITY...HOWEVER...WILL BE GREATEST THIS EVENING FROM
MISSOURI INTO THE SOUTHERN GREAT LAKES...BUT WILL THEN BE HIT AND
MISS FARTHER EAST DEPENDING UPON MESOSCALE EVOLUTION OF
PRECIPITATION AREAS AND CLOUD COVER. THE WARM SECTOR IS NARROWED
BY PERSISTENT RIDGING OVER THE NORTHEAST...AND A SLOWLY RETREATING
WARM FRONT IN THE OHIO VALLEY. AS SUCH...QPF EXPECTATIONS ARE ON
THE LIGHT TO MODERATE SIDE. THE MODELS ARE IN GENERALLY GOOD
AGREEMENT ON THE LARGE SCALE...AND WPC BEGAN WITH A 20/20/30/30
BLEND OF PREVIOUS WPC / UKMET / GFS / WRF-ARW.


...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 0.50 INCH RANGE...THOUGH WITH FAIRLY RICH
MOISTURE IN PLACE A FEW HEAVIER EMBEDDED DOWNPOURS ARE LIKELY.

BURKE

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

24HR QP VT 27/00Z
 0.01 540205 538196 535189 531181 524179 522180 518179 513181
      510184 509191 509201 513208 516217 518220 521221 525223
      527226 531228 534226
 0.01 549922 549907 545899 543895 541893 535888 532885 531883
      531879 533875 535870 536858 532847 528835 524825 512815
      505808 499804 491802 487801 484799 482795 481787 481781
      479779 473773 467768 462763 456758 445760 439761 435761
      416767 405771 398774 390779 384784 377789 373791 368791
      361788 358787 355789 353798 349799 346799 345796 341790
      339788 339785 339780 346773 353767 356762 355758 351755
      346753 335755 331753 329753 329749 325742 321743 318745
      315754 305755 294765 289771 280775 265767 256766 248769
      245770 242773 241777 241783 239787 239791 240798 239803
      235807 233811 234823 236827 239831 245830 249828 254833
      260836 264843 268844 272842 276842 280843 285844 288847
      290851 290858 289868 288875 288881 286886 287892 290898
      299901 297905 296910 298914 299920 298923 295924 292925
      286926 283928 279926 274926 269930 264936 261939 260943
      248953 241972 240976 237979 236985 236990 239000 242008
      245017 249024 253031 257039 256048 258055 264070 270077
      275084 283098 290112 292115 297117 301118 305116 311122
      317123 321122 327118 329114 331114 335114 339113 341110
      342099 343086 340078 333074 332073 332070 335065 336060
      336054 333046 331033 331027 332021 341006 344000 348990
      350985 353982 359974 367961 375947 380940 385933 387928
      389924 396918 405906 411900 416899 420897 440891 449889
      449897 449903 448908 448915 450925 455931 455935 458939
      464959 479967 488970 493971 497970 512962 516959 519955
      525951 532946 538941 546934 549922
 0.01 520269 519250 517233 513227 511224 508223 501222 498223
      494222 491225 489236 488241 489245 489254 484257 479261
      479267 481269 480275 482283 484289 491292 497293 503293
      506293 509291 511289 513287 517281
 0.01 375853 374851 369855 362861 355868 347875 340882 333887
      324893 320902 317915 316920 316928 317933 317939 316942
      318945 320946 323947 328945 330941 333936 335930 337919
      339914 342910 348901 354893 359885 362880 364874 374855
      375853
 0.01 329870 329863 328857 327853 325847 320848 317851 318857
      320861 321866 321870 321875 325874 328871 329870
 0.01 292803 290801 290799 288798 288799 287802 287804 289805
      291805 292803
 0.25 537923 536917 532915 525912 513899 508891 502884 499883
      496879 493874 496870 505868 511862 513860 517856 517849
      516842 512834 505827 491815 467795 462785 455782 448779
      443777 437778 418781 406782 401783 396786 382797 375801
      371804 365805 362804 359806 355808 353813 350822 349826
      349833 346840 349843 352840 355837 360834 367827 377814
      383809 388807 392809 400812 408810 417812 420814 422816
      422820 424824 422827 418835 412843 407850 395861 382876
      381881 384884 387883 390885 392888 395889 397888 404882
      411877 417877 421878 430878 439877 447875 454874 459875
      463877 464881 463888 461896 460904 462912 464917 468919
      472929 475947 478950 484950 492947 502948 512947 519943
      526936 532930 537923
 0.25 504276 505273 505271 505269 503268 503267 502266 500265
      498265 498266 498268 498270 498271 499273 500274 500275
      502276 504276 504276
 0.25 508248 509246 510243 510241 509238 508236 506236 505237
      504238 503239 503241 502244 502246 503248 503249 504251
      506251 507250 508248
 0.25 489891 489889 488888 486888 486889 485890 483891 482892
      481892 482893 483894 485893 487893 488892 489891
 0.25 376882 374881 370885 366889 362894 359899 356903 355909
      360905 364901 367897 371892 374887 376882
 0.25 350949 350946 348946 343949 334954 329956 322956 317956
      311956 306956 304952 302946 300940 297936 291934 285935
      280937 273943 265950 257958 250965 249970 246975 247979
      244984 243990 244997 250006 250012 254015 258019 259025
      262036 263043 265049 270058 276066 288085 300100 308102
      314101 318098 320093 322087 320073 317063 319057 323053
      327050 326042 324030 325017 325010 327005 337000 339995
      339988 335978 337971 339967 345957 350949
 0.25 335773 335768 333765 327764 318763 312762 300769 295774
      294778 296784 298791 299802 300809 298817 305819 314819
      321816 326810 328814 330816 334815 334811 334806 332800
      330792 328784 329780 332777 335773
 0.25 342867 341864 340865 339867 341868 342867
 0.25 307846 306839 304835 302834 299835 296838 296841 298845
      299849 300855 301859 304862 306859 307852 307848 307846
 0.25 293822 293820 292819 291818 290818 288817 286817 285818
      283819 281821 281822 281823 283824 285825 287825 289824
      290824 291824 292823 293822
 0.25 288835 288833 286832 284832 282832 280832 278832 277834
      279836 281836 282837 284837 286836 288835 288835
 0.25 284785 283783 279783 273785 271783 270778 265773 261772
      254773 249778 246784 245789 245794 246796 249803 251812
      254822 260820 267822 269820 268817 264812 266808 274806
      279802 283797 283790 284785
 0.25 272834 271832 269834 268835 270836 271836 272834
 0.25 264827 263825 263824 261824 260823 259823 259825 260826
      260827 262828 263827 264827
 0.50 522928 522924 522920 520915 513907 507900 503897 498900
      490906 484913 481917 480924 481930 486934 494938 498939
      504940 514938 522931 522928
 0.50 511846 509839 505834 495825 491822 485820 479819 474813
      470811 465807 459805 452804 446804 441808 440810 442813
      444818 441823 441828 443831 443836 445839 446842 444846
      432850 425852 422853 419856 426857 428859 426861 422865
      421868 423870 428873 436872 444871 450868 462863 468863
      474867 479868 485865 497859 505853 510849 511846
 0.50 470895 471890 470887 468888 466891 465895 464898 463901
      463905 465908 466910 468910 468905 469903 470898 470895
 0.50 427786 424785 421785 419784 415784 412784 408786 407788
      406792 408794 409797 412798 414798 416797 420795 421794
      424791 426789 427786
 0.50 402790 402788 401788 401790 402791 402790
 0.50 376803 374803 372805 372806 372808 373809 374808 376805
      376803
 0.50 364827 364825 363823 363820 364818 363816 362816 361816
      360819 359820 359821 358823 356825 356826 356828 356829
      358830 360829 362829 363827 364827
 0.50 332772 331769 327768 322768 316767 313767 311770 304771
      299775 299781 301787 303793 305801 307807 306814 311814
      315814 317811 318804 318802 321801 323802 326801 326797
      326792 323784 321779 321777 324777 330774 332772
 0.50 332969 331965 327965 318962 312963 308965 305968 301974
      297981 295984 292987 288988 282988 277991 268989 260987
      255987 254992 258998 262006 261011 262015 265023 267043
      269051 274057 279062 283069 292082 298086 306089 310090
      313087 313081 313076 311067 305062 303054 303051 307049
      315047 319046 320042 320033 320026 320020 319011 319999
      318990 320986 323986 327985 328979 332969
 0.50 298044 297042 297041 296042 297042 298044 298044
 0.50 294949 294943 292940 290939 284939 280943 277947 273952
      267953 264958 259960 255964 255972 252973 251976 255974
      256972 259971 268977 273979 277980 281978 287970 290966
      293960 294949
 0.50 279796 279792 276789 272789 270787 268785 267779 262775
      257776 255777 252780 250784 248790 252796 256801 259804
      263804 270804 276801 279796
 0.50 259809 260807 259805 258804 256804 255806 255808 255810
      256810 258810 259809
 1.00 510924 510921 509918 506916 504915 500915 498916 496919
      495921 495927 497929 499930 502931 505930 508929 510926
      510924
 1.00 493845 493843 491841 491840 491841 490843 489843 488845
      488846 490846 491845 493845 493845
 1.00 484849 485844 484839 483836 481838 479841 478842 475845
      473847 472850 473854 475856 477857 480858 482855 483852
      484849
 1.00 466839 467836 466834 465832 465831 464829 463829 462829
      460829 459830 457832 457835 458837 459839 460842 461843
      463843 464842 465841 466839 466839
 1.00 318791 317787 316785 312784 310782 309780 309775 306775
      304776 305779 305782 305784 305787 308790 310791 311792
      315792 318791
 1.00 316973 317971 316970 314969 312970 311971 311973 312975
      314976 315975 315974 316973
 1.00 309077 309076 308074 307074 306074 306076 307077 309078
      309077
 1.00 312032 313028 313023 311016 309010 308001 306993 305990
      302988 291995 280995 277996 272995 266993 264994 264998
      267005 267013 270019 275022 283023 296028 302030 306034
      311035 312032
 1.00 287960 287955 283956 279958 276962 273964 269966 268969
      270972 274974 277975 279972 281968 284964 287961 287960
 1.00 283037 283034 283032 281030 279029 277030 276032 275034
      274036 275038 277039 278039 280038 282037 283037
 1.00 274797 275795 275793 273793 272793 271794 270795 269796
      269798 270798 272798 273798 274797
 1.00 264790 264788 264786 264784 264782 262780 261781 259782
      258783 257783 256785 255785 254787 252789 252790 254791
      256791 257791 258791 260792 262792 264790 264790
 1.50 307026 306020 304015 299006 296002 293999 287998 280998
      276999 271998 267996 267999 269000 271004 271011 272018
      276020 282020 285020 288022 292025 297026 302025 307026
      307026
 1.50 262788 262786 261785 259786 259787 260788 261788 262788
 2.00 300021 300016 299013 295007 289003 282000 275001 274003
      275006 275011 274014 275017 283018 288020 290022 293023
      298023 300021
 3.00 295021 296019 296017 295014 294013 294012 293011 291011
      289012 289014 290016 291017 291018 292020 293021 294021
      295021

$$





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