Quantitative Precipitation Forecast
Issued by NWS

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000
FXUS04 KWBC 210659
QPFPFD

QUANTITATIVE PRECIPITATION FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
259 AM EDT SUN AUG 21 2016


PRELIM DAY 1 QPF DISCUSSION
VALID AUG 21/1200 UTC THRU AUG 22/1200 UTC
REFERENCE AWIPS GRAPHICS UNDER...PRECIP ACCUM - 24HR


DAY 1

SOUTH CENTRAL TO SOUTH TEXAS

VERY HEAVY TO EXCESSIVE RAINFALL POTENTIAL WILL CONTINUE INTO THE
NEW DAY 1 TIME PERIOD ACROSS SOUTH CENTRAL TO SOUTH TX FROM IN THE
VICINITY OF 100W NEAR THE U.S./MEXICAN BORDER--NORTHEASTWARD NEAR
OR JUST TO THE EAST OF SAN ANTONIO.  MODEL VERIFICATION SO FAR
POINTS TO A NORTHWARD BIAS IN THE MODEL QPFS.  WHILE MANY OF THE
MODELS AREA SHOWING THIS BIAS---THEY ALSO SHOW LITTLE MOVEMENT TO
THEIR PRIMARY AREA OF POTENTIALLY VERY HEAVY RAINFALL AMOUNTS
DURING THE UPCOMING DAY 1 PERIOD.  THE DAY 1 QPF WENT WITH THE
IDEA OF A FARTHER SOUTH ADJUSTMENT TO THE MODELS---SHOWING LITTLE
MOVEMENT THROUGH THE DAY ON SUNDAY.  AFTER THAT---WHILE CONFIDENCE
DECREASES WITH THE EVOLUTION---THERE ARE SIGNS THAT A MCV FROM
THIS CONVECTION MAY BEGIN TO PRESS MORE TO THE WEST NORTHWEST TO
THE WEST OF 10OW ALONG THE BORDER REGION.  THE 1200 UTC AUG 20TH
ECMWF WAS LIFTING SHORTWAVE ENERGY FARTHER NORTHWARD INTO NORTH
CENTRAL TX---ALONG WITH ITS PRECIP MAX.  THE 0000 UTC ECMWF HAS
TRENDED AWAY FROM THE NORTH CENTRAL TX MAX---WITH HEAVIER TOTALS
OVER SOUTH CENTRAL TX---ALTHOUGH ITS MAX AMOUNTS ARE OVER FAR
NORTHEAST TX/NW LA.  AT THE MOMENT---WE ARE SHYING AWAY FROM THE
IDEA OF LIFTING PRECIP QUICKLY NORTHEASTWARD---CONCENTRATING THE
HEAVIEST AMOUNTS FARTHER TO THE SOUTH ACROSS SOUTH CENTRAL TO
SOUTH TX---MORE IN LINE WITH THE GFS---GFS REFORECAST---UKMET---HI
RES ARW---NSSL WRF AND NAM CONEST.  WHILE THE PLACEMENT OF THE
MAXIMA IN THE MODELS HAS NOT BEEN PERFECT---THEY HAVE SIGNALED
OVER THE PAST FEW RUNS FOR VERY HEAVY AMOUNTS---WITH THIS SAME
SIGNAL CONTINUING IN THE UPCOMING DAY 1 TIME PERIOD.  WITH THE
SLOW MOVEMENT TO THE IS CONVECTIVE AREA EXPECTED TO CONTINUE INTO
THE NEW DAY 1 PERIOD---SERIOUS FLOODING PROBLEMS MAY PERSIST
ACROSS THESE AREAS---WITH ADDITIONAL LOCALIZED MAX AMOUNTS OF
5-10"+ POSSIBLE.

DESERT SOUTHWEST INTO THE SOUTHERN HIGH PLAINS

A STREAM OF SHORTWAVE ENERGY STRETCHING FROM SOUTHERN CALIFORNIA
INTO THE SOUTHWEST AND SOUTHERN HIGH PLAINS WILL SUPPORT ANOTHER
ROUND OF WIDESPREAD SCATTERED CONVECTION ACROSS THESE AREAS DAY 1.
 MODEL CONSENSUS FOR MAX TOTALS IS FROM SOUTHWEST TX INTO CENTRAL
TO WESTERN NEW MEXICO IN THE VICINITY OF THE STATIONARY FRONTAL
BOUNDARY FORECAST TO REMAIN DRAPED FROM WESTERN NM INTO SOUTHWEST
TX.  AREAL AVERAGE MODERATE TOTALS DEPICTED---WITH LIKELIHOOD OF
HEAVIER TOTALS AND ISOLATED RUNOFF ISSUES IN THE VICINITY OF THIS
FRONT.  ISOLATED RUNOFF ISSUES ALSO POSSIBLE WESTWARD INTO CENTRAL
TO SOUTHERN ARIZONA WITH THE NEXT ROUND OF SCATTERED CONVECTION
ACROSS THIS REGION LATE SUNDAY INTO THE EARLY MORNING HOURS OF
MONDAY.

CENTRAL APPALACHIANS---MID ATLANTIC INTO THE NORTHEAST/NEW ENGLAND

NO MAJOR MODEL DISAGREEMENTS WITH THE EASTWARD PUSH OF THE
AMPLIFIED UPPER MS VALLEY TROF.  THIS SYSTEM EXPECTED TO PUSH
STEADILY EAST NORTHEASTWARD THROUGH THE LAKES/OH VALLEY---MID
ATLANTIC AND NORTHEAST.  A NARROW AXIS OF ABOVE AVERAGE PW
VALUES---2 TO 2.5 STANDARD DEVIATIONS ABOVE THE MEAN---WILL
PERSIST ALONG AND AHEAD OF THE ASSOCIATED FRONT.  STRONG FRONTAL
CONVERGENCE IN THIS HIGH PW AXIS WILL SUPPORT POTENTIAL FOR
ORGANIZED FRONTAL/PRE-FRONTAL CONVECTION---WITH MODERATE TO HEAVY
PRECIP TOTALS FROM THE CENTRAL APPALACHIANS---THROUGH THE MID
ATLANTIC AND INTO THE NORTHEAST/NEW ENGLAND.  THE QUICK MOVEMENT
OF THE FRONT AND ASSOCIATED CONVECTION SHOULD BE A LIMITING FACTOR
FOR VERY HEAVY TOTALS---WITH ONLY A MARGINAL RISK OF RUNOFF ISSUES.

ORAVEC

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

24HR QP VT 22/12Z
 0.01 551148 553136 554123 554109 552099 548094 545092 542092
      536096 534099 533104 529124 526133 525137 524144 523157
      517160 513160 510161 508164 507169 506181 503191 499198
      497203 496208 496217 494224 493233 497240 504254 511270
      514274 517273 518269 520265 522259 524246 527237 531231
      535223 538213 543194 545184 547169 551148
 0.01 544776 544768 542764 541755 540749 533721 518714 518707
      517698 515691 512688 507682 503680 501673 498667 496664
      488661 483661 477662 472663 467664 458668 447672 430681
      420685 410689 386695 375696 366700 360706 357716 354727
      353731 356733 354737 351741 344747 328759 325764 324768
      326783 328788 333788 338786 341783 346774 349770 351769
      353771 353776 352787 352794 348797 343803 338812 330818
      324823 316831 312834 309835 306833 300827 292824 284821
      280819 278818 280816 286815 288814 289811 286805 279799
      275796 271795 258796 253797 251802 252808 250812 252816
      256818 272826 280831 285838 285844 287848 288855 289862
      287872 285884 283894 283901 283907 285912 284917 282928
      277937 274942 273947 269955 263963 251976 245982 239990
      234997 231009 231014 229018 228028 227043 228049 229060
      231069 237073 249085 253087 256090 261094 273106 278111
      285116 294118 300119 303121 311126 316131 321136 328142
      334147 344149 349150 352151 354149 361146 365137 366126
      365119 362109 361105 360102 361099 366094 369089 372087
      376085 382085 386083 385074 387069 389068 393064 393059
      393055 392050 383048 377047 374046 362043 348040 340039
      337040 331040 323041 317040 315039 311035 309031 309025
      311018 317003 321997 325988 324984 323978 323971 323964
      325958 325955 327951 330945 330941 334932 352905 370876
      375869 379862 383854 387847 392837 396830 401823 406817
      410811 412814 415821 416823 420823 422826 422832 419842
      418849 415854 415861 419865 422867 430869 435870 440873
 0.01 440873 444877 446880 449882 457881 463876 463873 467871
      474870 489864 491862 495861 500856 509844 519833 523827
      525825 528820 534806 539788 544776
 0.01 507279 506271 504265 502259 498254 496248 493246 492254
      493261 496267 499274 501279 504280 507279
 0.01 502988 502983 501978 498970 500960 501949 501937 501931
      499926 499916 495906 492899 490896 487894 482894 480897
      480904 480910 481914 482920 483924 484928 483932 481939
      480951 482960 489975 492984 495990 500991 502988
 0.01 475783 472782 468782 460784 454786 447788 440790 433793
      431795 430798 427805 426810 427815 427821 429826 432831
      437837 447843 451842 454840 457838 459835 461829 463821
      466814 469808 471800 473792 475783
 0.01 394205 393200 391197 388193 385190 382187 379185 373183
      372188 373193 375196 380199 383202 387204 392205 394205
 0.25 540186 541177 541170 541159 543152 544135 543127 541127
      539128 536132 533138 531146 530157 530166 527172 519179
      517184 515193 514199 515202 518203 520213 519218 517219
      510217 507219 504224 502229 504236 508248 515256 518253
      520246 520239 520231 522225 525221 532211 534207 537199
      540186
 0.25 532766 532758 531753 527742 522734 516728 510721 504717
      498707 494699 487696 483695 483691 484685 483680 479676
      476675 471676 466679 457685 442694 403703 395718 387724
      383728 383732 381734 380737 380741 383743 388744 387748
      383751 375755 366758 363762 363769 374782 379787 382789
      379792 374794 372797 367804 348837 346845 346852 350854
      355852 359850 363849 365851 367852 370852 373848 379840
      382832 383820 385810 385804 386798 387794 390790 397784
      404790 410790 414787 429782 434777 438775 443773 461767
      467767 471768 476769 481769 488771 494777 497780 497784
      495787 490789 485798 483808 481820 482827 485831 489834
      493834 500829 513819 519812 523804 525799 525795 524794
      517798 515798 515794 516787 520777 528772 531770 532766
 0.25 352128 352121 349114 344108 341106 342101 341092 338086
      336082 336078 338070 341065 343060 343056 338052 331050
      324052 319054 310052 306053 303054 297056 294057 290057
      285053 278050 272046 269044 268041 268033 270029 273028
      283029 290031 295029 300023 303015 306009 307003 307998
      305991 304983 304972 304963 304957 302952 301949 299948
      297949 293954 288958 280968 270978 260986 250996 246000
      242006 236018 232025 231033 231042 232051 234056 237062
      242068 246071 257081 262086 267090 278097 287098 294097
      299093 303087 305083 308082 317083 320082 323082 328086
      332092 335099 339105 340113 342122 345129 349132 352128
 0.25 309899 309897 309896 309897 309899 309899
 0.25 306926 306924 306922 304921 303922 303924 302926 303927
      305928 306926
 0.50 533195 533192 533190 532187 530187 529186 527187 526187
      525189 524190 525191 526193 526194 527196 529198 530199
      532197 533195
 0.50 511739 509736 506734 499732 493733 487737 490747 493754
      495757 497763 502767 505767 507764 511757 509745 511739
 0.50 486737 483735 478735 470734 464735 465733 468724 475718
      477714 477708 471701 471693 473690 475686 473684 470684
      461688 444697 436700 428702 417703 413706 412711 410721
      401725 397728 400731 408735 411735 414737 408743 399748
      390752 382756 374758 370761 371765 374767 380768 388769
      395772 399773 403775 410782 416780 424777 442768 449764
      457760 468758 477755 480749 477743 481739 486737
 0.50 336058 335056 334055 332054 330054 329054 327055 326057
      326059 326061 327061 328062 330063 332062 334061 334060
      336058 336058
 0.50 318078 320074 320070 317066 313065 309066 304067 299069
      294067 290064 282062 278061 273057 265051 258043 252034
      249031 244028 238029 235033 234040 235046 238057 240062
      244065 252072 268085 274087 278088 290085 293083 296079
      300075 307076 318078
 0.50 300008 302003 301998 299989 299981 299970 298966 296963
      293962 290963 281972 270981 265986 260991 257996 253004
      258009 265008 276017 281020 285022 290022 296018 300010
      300008
 1.00 456712 454712 451712 449712 446711 442712 439714 443715
      444715 447717 448720 450719 453716 455715 456712
 1.00 433754 431753 428754 424754 421754 417755 416755 414755
      411757 411761 413762 415763 418762 422762 424760 427759
      430758 432757 433754
 1.00 295010 296003 294998 293993 293989 295977 294970 292969
      289970 281976 274982 268989 266993 262997 267003 271006
      276009 279012 285014 289014 293012 295010
 1.00 264068 265064 264062 259057 256055 251050 247047 243048
      243052 245058 249062 253065 258068 262069 264068
 1.50 292981 293976 292972 286974 281980 276984 272991 272995
      272001 278004 284008 287007 289005 290001 289997 290989
      292981
 2.00 290981 290975 286976 283980 281983 278987 276991 276997
      280998 284995 286992 288988 290983 290981

$$





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