Quantitative Precipitation Forecast
Issued by NWS

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000
FXUS04 KWBC 021904
QPFPFD

QUANTITATIVE PRECIPITATION FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
303 PM EDT SUN AUG 02 2015


PRELIM DAY 1 QPF DISCUSSION
VALID AUG 03/0000 UTC THRU AUG 04/0000 UTC
REFERENCE AWIPS GRAPHICS UNDER...PRECIP ACCUM - 24HR


DAY 1...


...FLORIDA AND THE SOUTHERN ATLANTIC COAST...

AFTERNOON THUNDERSTORMS IN FLORIDA WILL HAVE A TENDENCY TO
MAXIMIZE ALONG THE EAST COAST...BUT ONLY BRIEFLY...AS
SOUTHWESTERLY FLOW ALOFT PROMOTES REASONABLY QUICK PROGRESSION
OFFSHORE. A LONGER LIVED FOCUSING MECHANISM WILL CONTINUE TO FAVOR
RAIN OVER THE WEST AND NORTHWEST COAST...NEAR AND NORTH OF TAMPA
BAY. THE GREATEST CONCERN FOR HEAVY RAIN IS JUST TO THE SOUTH OF A
SURFACE LOW PRESSURE CENTER...WHERE LOW LEVEL CONVERGENCE AND LOW
LEVEL INFLOW OFF THE GULF WILL BE MAXIMIZED FOR QUITE SOME
TIME...ESPECIALLY TONIGHT...AS THE LOW MOVES VERY SLOWLY EASTWARD.
THIS INCLUDES THE STRETCH OF COAST FROM NEAR AND NORTH OF TAMPA
BAY UP THROUGH CEDAR KEY AND STEINHATCHEE. CONVECTION HERE MAY BE
SHALLOW AT TIMES...BUT STILL HIGHLY EFFICIENT AT RAINFALL
PRODUCTION GIVEN WARM RAIN PROCESSES AND TRAINING. THE HIGH
RESOLUTION MODELS HAD GENERALLY OVER-FORECAST THIS EVENT UP TO
THIS POINT IN TIME...WHICH MAY BE RELATED TO RESOLUTION...AS THE
WEAKLY UNSTABLE ENVIRONMENT LENDS ITSELF TO SMALLER CONVECTIVE
ELEMENTS THAT DO NOT TRAIN ACROSS THE SAME POINTS SO EASILY.

CONDITIONS SUPPORTING HEAVY RAIN SHOULD INCREASE
TONIGHT...HOWEVER...WITH THE LOW LEVEL WIND FIELDS STRENGTHENING
ONSHORE...OWING TO A SLIGHT EASTWARD SLIDE OF THE SURFACE
LOW...AND IN RESPONSE TO NORTHERN STREAM JET FORCING THAT WILL
SUPPORT A MORE BROAD SCALE AMPLIFICATION OF THE EXISTING UPPER
LEVEL TROUGH.

THE SAME COULD BE SAID FOR THE COAST OF SOUTH CAROLINA...AND
POTENTIALLY PARTS OF ADJACENT GA/NC...WHERE DEEP MOISTURE HAD
REMAINED IN PLACE. DESPITE SOMEWHAT MARGINAL LAPSE RATES AND
INSTABILITY...STRONG HEATING HAD YIELDED LOCALLY STRONG AND SLOW
MOVING CELLS WITH HEAVY RAIN AS OF MIDDAY. AFTER AN EVENING
LULL...ACTIVITY SHOULD INCREASE AGAIN TOWARD MORNING...WITH THE
BROAD SCALE PATTERN AMPLIFYING TO BRING STRONGER SOUTHERLY FLOW
ONSHORE...AHEAD OF THE APPROACHING SURFACE LOW OVER FLORIDA. SOME
OF THE 00Z HI-RES MODELS INDICATED HEAVY RAIN FOR THE SC COAST
MONDAY MORNING...AND NOW MORE OF THE 12Z GUIDANCE HAS TRENDED IN
THIS DIRECTION.

WPC BLENDED THE PREVIOUS FORECAST OVER THE SOUTHEAST U.S. TOWARD
THE 12Z HI-RES MODELS.


...MIDWEST/GREAT LAKES/OH VALLEY...

MOISTURE AND INSTABILITY AHEAD OF A COLD FRONT CROSSING THE GREAT
LAKES AND MIDWEST DURING DAY 1 WILL FEED DEVELOPING
CONVECTION...WHICH MAY PRODUCE LOCALLY HEAVY RAINFALL...ESPECIALLY
ACROSS THE GREAT LAKES. THE DEEPEST FORCING WILL TRACK TOWARD NEW
ENGLAND...WHILE THE GREATER INSTABILITY WILL REMAIN CENTERED BACK
TOWARD THE MIDWEST STATES. THE BEST COMBINATION IS IN
BETWEEN...WITH NUMEROUS MODELS PLACING A 24-HR QPF MAXIMUM ACROSS
MICHIGAN...WHERE MIDDAY CONVECTION HAD ALREADY ESTABLISHED
OUTFLOWS TO INTERCEPT INCREASING SOUTHWESTERLY FLOW LEVEL FLOW
FROM AN UNSTABLE SOURCE REGION.

MODELS HAD TRENDED TOWARD FAIRLY GOOD AGREEMENT...AND THE WPC
FORECAST WAS BASED LARGELY ON THE DETAILS OF THE 12Z NAM
CONEST...12Z GFS...AND THE 00Z SSEO MEAN AVAILABLE OUT THROUGH
MONDAY MORNING.


...WESTERN UNITED STATES...

MONSOONAL MOISTURE IN THE SOUTHWEST STATES REMAINS CONNECTED TO A
PLUME EMANATING FROM THE EASTERN PACIFIC UP THROUGH SONORA.
PORTIONS OF THE MOISTURE ARE THEN DIVERTED INTO THE GREAT BASIN
AND SOUTHERN PLAINS...FOLLOWING A MID LEVEL SHEAR AXIS LAID OUT
ROUGHLY WNW TO ESE. THE HIGH MOISTURE CONTENT AIR...COMBINED WITH
MARGINAL INSTABILITY AND LIFT FROM A SHORT WAVE CROSSING THE
SOUTHERN ROCKIES AND GREAT BASIN...IS EXPECTED TO PRODUCE YIELD
RELATIVELY GENEROUS COVERAGE OF CONVECTION TODAY THROUGH
MONDAY...ESPECIALLY OVER EASTERN UT AND WESTERN CO. PRECIPITABLE
WATER VALUES HERE WILL BE SLIGHTLY ABOVE CLIMATOLOGICAL
VALUES...AND WILL SUPPORT A RISK OF FLASH FLOODING. SOME OF THE
HIGH RESOLUTION GUIDANCE SUGGESTS ISOLATED RAINFALL TOTALS ABOVE
1.5 INCHES WILL BE POSSIBLE. LOCATIONS RECEIVING THE MOST RAINFALL
WILL LIKELY BE DETERMINED BY VERY SMALL SCALE CELL MERGERS AND
ACCIDENTAL RATHER THAN ORGANIZED TRAINING...GIVEN A RELATIVE LACK
OF STRONG INFLOW NEAR CLOUD BASE.

THERE IS SOME UNCERTAINTY CONCERNING HOW WIDESPREAD THE HEAVY RAIN
THREAT WILL BE...BUT WESTERN CO AND SOUTHEAST UT SEEM TO BE IN THE
AREA WITH THE BEST COMBINATION OF LIFT/MOISTURE SUNDAY
EVENING...WITH THIS COMBINATION THEN MIGRATING TOWARD NORTHERN UT
/ NORTHWEST CO / SOUTHWEST WY ON MONDAY.

FARTHER WEST...INSTABILITY AND MOISTURE COULD SUPPORT SCATTERED
CONVECTION WITH LOCALLY HEAVY RAINFALL ACROSS PORTIONS OF NORTHERN
NV/CA AND SOUTHERN OR...THEN MIGRATING DEEPER INTO CENTRAL AND
NORTHEAST OR ON MONDAY. A PLUME OF RICH MID LEVEL MOISTURE...BUT
MARGINAL INSTABILITY FOR SURFACE BASED PARCELS...SHOULD KEEP THE
MORE SUBSTANTIAL PRECIPITATION AMOUNTS TIED CLOSELY TO THE HIGHER
TERRAIN. SOME OF THE MORE AGGRESSIVE HIGH RESOLUTION GUIDANCE
SUGGESTS THAT ISOLATED ONE INCH AMOUNTS ARE POSSIBLE...ALTHOUGH
AMOUNTS LESS THAN 0.50 INCHES WILL BE MORE COMMON.

THE EASTERN EXTENT OF THE MONSOONAL MOISTURE SITS ATOP THE
SOUTHERN HIGH PLAINS...WHERE MOISTURE AND INSTABILITY HAVE
GRADUALLY FADED THE PAST FEW DAYS UNDER THE INFLUENCE OF REPEATED
LOCAL SCALE CONVECTION AND SOME DRYING AROUND A SURFACE HIGH
LOCATED IN THE MID MISSISSIPPI VALLEY. THROUGH MONDAY ADDITIONAL
SMALL SCALE CONVECTIVE CLUSTERS AND INDIVIDUAL THUNDERSTORM
DEVELOPMENT WILL BE MAINLY CONFINED TO EITHER SIDE OF AN AXIS FROM
SE CO TO W TX AROUND LUBBOCK. IT IS ALONG THAT AXIS THAT THERE IS
A FAIR MODEL CONSENSUS FOR HYDROLOGICALLY SIGNIFICANT 24-HOUR
AREAL AVERAGE TOTALS EXCEEDING A QUARTER INCH.

THROUGHOUT THE WESTERN U.S...WPC QPF BLENDED THE PREVIOUS FORECAST
TOWARD THE 12Z WRF-ARW AND THE 12Z GFS.

BURKE/HAYES

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

24HR QP VT 04/00Z
 0.01 549159 548154 546150 544144 539142 536139 535133 534127
      531121 527113 524109 520112 519118 515121 511122 507119
      503119 500123 498133 498140 500144 506154 513159 521166
      525174 522189 522196 522204 523205 529205 531201 533195
      536190 539186 541182 541173 544168 547164 549159
 0.01 519702 517691 514677 510668 503660 498651 493649 488651
      484651 478655 470665 447694 441703 437707 434711 428720
      422732 414747 408754 404758 402762 401768 398772 391780
      383788 377798 374806 372817 372823 372826 374828 379829
      382832 385838 385842 383846 379850 375854 372859 375868
      378876 381878 383879 384882 378890 378897 380900 383900
      384903 385912 388924 392936 397947 401954 404957 405960
      404964 403969 403975 404983 404991 407005 411015 414020
      415027 417035 419040 423046 427046 429041 430036 431026
      432021 432015 431007 429001 425990 423984 420979 416974
      414968 418945 422919 423914 426909 428904 432900 439892
      443887 446880 449873 454874 456872 458873 461876 463876
      463872 462863 461844 462837 464833 470821 476811 481805
      486798 491787 495776 498767 500753 500748 501744 504740
      512729 515725 517718 519710 519702
 0.01 483211 479210 474210 469210 467211 463210 459209 457206
      455203 458200 461197 469197 464196 463193 463191 464186
      463182 464176 462170 467163 473166 479165 481165 483161
      484156 481152 475150 471145 471142 474142 481143 487143
      489140 487136 476130 470126 467119 463110 461103 456088
      453078 451072 448067 444062 438059 435061 431060 427058
      420053 415048 412043 408042 396034 388022 383015 379011
      373009 368006 365004 363001 360996 357991 354988 351987
      343986 339989 334993 330995 328998 323003 318018 313026
      313033 313041 314044 314049 313060 314066 316073 316076
      316081 314084 312082 310076 305074 296072 287070 273066
      263062 258060 251061 249062 248066 248071 250074 252079
      256083 266091 273095 283096 293097 299099 305103 304108
      317123 320128 322128 323123 324109 327105 330104 334104
      337106 344109 345112 345116 351122 354122 355117 355113
      353110 350105 347101 347096 347082 345075 347073 349073
      354075 355082 353088 353093 354096 358098 359100 362110
      364112 367113 369112 372113 373117 372120 369127 371133
      379140 382143 382152 380159 379165 380169 381176 383182
      387188 389191 387192 384188 380187 378189 381195 387199
      397210 403218 405222 404227 405235 406239 409241 413243
      419242 425239 430234 441231 453228 458227 461226 465222
      483211
 0.01 451180 450174 450165 446161 444162 444159 436149 436142
      435139 436133 438127 436125 433127 430132 427139 426145
      426153 427160 429168 432171 435177 439181 442178 442182
      444185 447185 449182 451180
 0.01 435184 434181 433177 432174 430171 429168 427166 426163
      426167 426170 427172 428177 429180 431182 433183 435184
 0.01 445043 445041 445038 445036 443035 442033 440033 438034
      436035 436038 436040 438041 439043 439044 441044 443043
      445043 445043
 0.01 400683 397676 392677 386678 385675 382676 360681 355688
      350695 334723 330730 325737 314752 310757 306763 301768
      298772 293773 281775 276774 272774 263776 257779 253781
      247784 242788 240791 239795 238799 240803 245811 250817
      254825 258834 261841 262851 264862 264874 265897 268921
      269925 269930 266936 262956 263960 267961 272968 279964
      285958 287954 289953 292954 294952 295941 296937 294933
      295920 297911 298897 298887 303872 305863 306852 309842
      311833 317826 323821 334812 340806 344798 350792 354785
      363767 368753 374737 381720 391702 393699 397694 398688
      400683
 0.01 308041 308040 306038 304038 302038 302040 304042 306043
      306042 308041 308041
 0.25 508706 507693 505685 502678 498671 496663 492662 489664
      485669 478678 469687 464691 461696 453710 438727 434732
      432740 429746 424753 421756 419761 419766 421768 425765
      428764 429770 429775 429779 421789 415800 412805 411813
      410822 408829 406836 402843 398853 396859 394861 391860
      388859 386862 387867 389870 394873 398881 403882 407880
      411883 415888 419893 423891 428886 431884 433880 437871
      443858 449845 451838 452828 454813 455806 457799 462785
      464778 468770 475763 479759 483753 488739 495726 498721
      504719 507714 508706
 0.25 452139 451138 450137 448136 446137 446138 446139 447140
      447142 449142 450141 451140 452139
 0.25 435218 436216 436213 436211 434210 432209 431207 429205
      428204 426203 426205 426206 426208 427211 427212 427213
      428216 429218 431219 433218 435218 435218
 0.25 447109 447098 442096 439098 439102 437102 434097 431094
      428092 426096 432101 433104 431105 425104 420104 415101
      414099 415096 417092 415089 411090 409090 407089 405084
      407078 410075 409070 406065 405055 399048 396050 393049
      389047 387048 384047 382044 377043 374040 373034 369025
      365021 360020 357022 356027 357033 360036 364039 366043
      370048 372053 379058 381062 381065 379065 370061 366062
      368067 371073 374084 377089 376092 376098 379100 381098
      384095 387093 390094 393098 393105 391112 392116 396116
      399115 406120 413115 423118 429119 434118 440113 446112
      447109
 0.25 425018 426011 425006 424000 422995 420991 417988 413989
      413996 413001 415007 416012 418016 420021 422022 425018
      425018
 0.25 417769 418766 417764 416764 415766 415767 414769 416771
      417769 417769
 0.25 411178 411171 409168 406166 401163 398161 396159 393161
      394166 395170 398175 401178 404180 409180 411178
 0.25 413926 413921 412918 410915 408914 407915 405919 405924
      404926 405929 406933 407933 409931 411929 413926
 0.25 404801 404799 403797 402797 400796 399797 398798 397799
      396800 396803 396805 398807 399807 400807 401805 402804
      403803 404801
 0.25 371722 371719 370716 366714 360716 355719 348723 344728
      334737 328744 321755 316767 313773 309780 303787 298791
      294792 287790 281792 276797 273799 268799 262799 257801
      252804 252809 253811 256813 261813 267813 270814 269816
      266823 268835 271850 273857 276863 279868 280873 280879
      280894 281902 280909 281927 283927 284923 282920 284916
      286917 288912 291896 294864 299855 302841 304827 308821
      316819 324813 334805 342796 346791 350784 353775 358762
      362749 368734 371722
 0.25 353027 353023 353018 350013 345010 342010 340011 334014
      335023 332028 328029 331031 335030 341028 348029 353027
 0.25 335058 334056 333056 332055 330055 329055 327055 327057
      328058 330058 332058 334058 335058
 0.25 295088 293081 290079 287078 278076 271073 263072 261072
      258075 257078 259080 265084 270089 278092 287092 294090
      295088
 0.50 500708 499700 494692 491692 489696 484705 481714 477724
      472731 465729 457732 454742 452753 448763 450768 453770
      457772 460768 464761 466757 469753 476747 482741 489721
      494715 500708
 0.50 494673 494671 493671 492669 490670 489671 487672 486674
      485674 484675 483677 481680 483682 484682 485681 486680
      488678 489678 491678 493677 493676 494675 494673
 0.50 459719 455719 451723 445732 439740 433748 426756 429758
      431759 431764 433769 436763 441755 442749 446744 452735
      456726 459719
 0.50 453799 454792 452786 448785 443787 439788 435791 428798
      423806 420809 416811 414816 416820 419823 424822 431819
      431825 429832 426841 422852 418860 416866 417870 419871
      423872 426869 433863 439856 444848 448838 449824 451814
      453800 453799
 0.50 436114 438112 437110 437109 435109 434109 433110 432111
      431113 433115 434116 436114 436114
 0.50 431113 429110 426107 419107 412106 409098 407098 404102
      403105 399106 400109 403111 405115 408112 410110 414110
      421114 427116 431113
 0.50 423011 423008 423006 422003 422002 421001 420999 419997
      418999 417001 417003 418006 418007 419008 420010 422012
      423011
 0.50 400097 400095 399094 398093 396092 395094 396095 397096
      397097 399098 400097
 0.50 401072 401069 399069 396069 394067 391068 390070 390075
      390077 393078 394075 396073 397074 400074 401072
 0.50 380094 381092 381090 380088 379090 379092 379094 380095
      380094
 0.50 383051 383050 382049 381048 379048 379049 379051 381053
      383053 383051
 0.50 380078 380076 380074 379074 378073 376071 375069 375066
      373065 371064 370066 371067 373068 374071 374073 374075
      374076 374078 375080 375081 377081 379080 380078
 0.50 362729 361725 356725 351726 348729 342737 336745 326761
      318778 314785 312790 310795 309800 310807 312813 315816
      322812 331805 336800 342791 347784 351773 356753 362733
      362729
 0.50 371043 370041 371038 371036 370032 369030 366027 364026
      361027 360029 361032 363034 365036 367038 369041 371043
      371043
 0.50 349018 349015 347015 345016 344017 345018 347018 349018
      349018
 0.50 300819 300812 296809 292807 288810 286813 281815 274822
      272827 271832 272838 274842 280850 284853 287853 291852
      294850 297845 299834 298827 299820 300819
 0.50 289087 288083 285080 279079 274078 270077 265076 268081
      270083 274085 278088 282089 287089 289087
 0.50 289891 289885 289879 288874 285872 284877 284883 284889
      284896 285902 286906 288902 288897 289893 289891
 0.50 277809 276805 272802 268801 263801 257803 254805 254809
      258809 262808 267807 271808 276809 277809
 1.00 447809 445809 445810 447810 447809
 1.00 446834 446829 445824 444820 441822 440825 439827 438832
      438835 438839 439843 441845 442844 444840 445836 446834
 1.00 408107 408105 407104 407105 406107 407109 408107
 1.00 351747 351742 349739 345740 342743 336754 329766 325779
      323784 321792 318798 316806 319809 326806 330802 334798
      341786 346774 348767 349758 351747
 1.00 296819 297816 293814 288817 283820 278823 274828 274834
      277840 281842 288842 292842 294839 294832 294826 296819
 1.00 283084 281083 280084 281085 282085 283084
 1.50 339773 338764 335762 334765 332774 334781 329787 326792
      322799 321802 321804 324805 329800 334795 337789 338784
      338782 339774 339773
 1.50 294820 294817 292818 288820 284821 280823 276826 275830
      277835 279838 284837 288835 291833 292828 293824 294820
 2.00 335789 333788 331789 330789 330790 328792 328793 327794
      326795 326797 325798 324799 324801 325802 326801 327800
      329799 329798 330797 331796 332795 333793 334791 335789
      335789
 2.00 291828 292824 290821 289823 285823 283823 281824 278825
      276828 276830 277832 279834 280836 284836 286834 288833
      290831 291828
 3.00 285831 285829 284828 282829 281829 282831 282832 284832
      285831

$$





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