Quantitative Precipitation Forecast
Issued by NWS

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000
FXUS04 KWBC 200723
QPFPFD

QUANTITATIVE PRECIPITATION FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
300 AM EDT WED AUG 20 2014


PRELIM DAY 1 QPF DISCUSSION
VALID AUG 20/1200 UTC THRU AUG 21/1200 UTC
REFERENCE AWIPS GRAPHICS UNDER...PRECIP ACCUM - 24HR


DAY 1

...NORTHERN PLAINS...

THE WELL DEFINED HEIGHT FALLS AND ASSOCIATED AXIS OF ABOVE AVERAGE
PW VALUES WILL BE PRESSING INTO THE NORTHERN PLAINS WEDNESDAY AND
WED NIGHT.  MODEL CONSENSUS IS FOR THE HEAVY PRECIPITATION
POTENTIAL TO DEVELOP TODAY OVER THE NORTHERN PLAINS WITH THE
ORGANIZING CONVECTION WEDNESDAY AFTERNOON IN A REGION OF FAIRLY
UPPER DIFFLUENT FLOW AND STRENGTHENING LOW LEVEL INFLOW INTO THE
WARM FRONTAL BOUNDARY FORECAST OVER THE NORTHERN PLAINS. FROM A
SYNOPTIC SCALE STANDPOINT...THIS AREA WILL BE THE BENEFICIARY OF
FAVORABLE DYNAMICAL FORCING FOR DEEP-LAYER ASCENT AS THE UPPER
DIVERGENCE INCREASES IN THE DIFFLUENT FLOW PATTERN ALOFT WEST OF
THE H5 RIDGE AXIS AND DOWNSTREAM OF THE TROUGH. MOREOVER...THE
ACTIVITY DURING THE DAY WED WILL BE ENHANCED BY A VORT MAX
CURRENTLY ACROSS WY THAT WILL BE LIFTING NE INTO THE NRN
PLAINS...ONE THAT WILL BECOMING CONVECTIVELY-ENHANCED UPON MOVING
INTO THE NRN HIGH PLAINS. THERMODYNAMICALLY...INCREASING/DEEPENING
S-SW FLOW WILL MAKE FOR EFFICIENT MOISTURE TRANSPORT INTO THE
AREA...AS PWATS CLIMB TO NEAR 1.75 INCHES WHICH IS BETWEEN 2.5 AND
3 STANDARD DEVIATIONS ABOVE NORMAL FOR LATE AUGUST (NEAR THE 99TH
PERCENTILE). THESE HIGH PWATS AND DEEP WARM CLOUD LAYERS (WET BULB
ZERO HEIGHTS ABOVE 10KFT) WILL MAKE FOR HIGH RAINFALL EFFICIENCY
LATER THIS AFTERNOON INTO THE EVENING WHEN DEEP LAYER INSTBY WILL
BE MOST ROBUST (MUCAPES GENERALLY 1000-2000 J/KG...EXPECT LOCALLY
UP TO 3000 J/KG ACROSS ND PER THE LATEST ARW).

DESPITE THE FACTORS FAVORING HEAVY RAINFALL...THERE IS A FAIRLY
LARGE SPREAD IN THE MODELS WITH RESPECT TO WHERE THE HEAVIEST
RAINS OVER THE NORTHERN PLAINS MAY BE TOWARD THE END OF THE
FORECAST PERIOD...ONCE AGAIN LEADING TO LOW CONFIDENCE IN QPF
DETAILS.  AT THE SAME TIME...THERE IS A SIGNAL IN MOST OF THE
GUIDANCE FOR THE POTENTIAL FOR HEAVY TO ISOLATED EXCESSIVE AMOUNTS
ACROSS THESE AREAS...WITH LOCALIZED AMOUNTS OF 3+ INCHES NOTED
FROM THE HIGHER RESOLUTION GUIDANCE. A BLEND OF THE 00 UTC HIGH
RES GUIDANCE...ALONG WITH THE IN-HOUSE PSEUDO BIAS CORRECTED MEANS
WERE USED FOR QPF DETAILS.


...EASTERN GREAT LAKES INTO THE UPPER OHIO VALLEY AND NORTHERN
APPALACHIANS...

A SURFACE FRONTAL BOUNDARY WILL SLOWLY PUSH EASTWARD FROM THE
EASTERN LAKES AND UPPER OH VALLEY INTO THE NORTHERN MID-ATLANTIC
AND NORTHERN APPALACHIANS DURING THIS PERIOD.  AN AXIS OF
1.5-1.75" PWATS ALONG AND AHEAD OF THIS FRONT IN A REGION OF UPPER
LEVEL DIFFLUENCE/UPPER LEVEL DIVERGENCE EAST OF THE UPPER TROUGH
AXIS AND IN THE VICINITY OF THIS FRONT WILL SUPPORT POTENTIAL FOR
ORGANIZED FRONTAL CONVECTION ACROSS THESE AREAS. THE ACTIVITY WILL
BECOME ENHANCED IN TERMS OF BOTH AREAL-COVERAGE AND INTENSITY
DURING THE PEAK HEATING HOURS TODAY AS MUCAPES CLIMB TO AROUND
1000 J/KG. MODERATE TO HEAVY RAINFALL TOTALS ARE DEPICTED...WITH
AREAL AVERAGE AMOUNTS FROM .75 TO 1.25 INCHES...HOWEVER LOCALLY
HIGHER AMOUNTS (2-4+ INCHES PER THE HIGH RES GUIDANCE) WILL LIKELY
CAUSE SOME RUNOFF ISSUES GIVEN THE RELATIVELY LOW FFG OVER THIS
REGION.


...LOWER MISSOURI VALLEY...

SOME CONCERN HERE THROUGH WED MORNING ACROSS PARTS OF NEBRASKA
INTO IA/NRN MO AS LOW LEVEL JET INCREASES TO OVER 30 KTS INTO E/W
FRONTAL BOUNDARY NEAR THE KS/NEB BORDER (MADDOX "FRONTAL" TYPE
HEAVY RAINFALL SIGNATURE). THE MODELS CONTINUE TO SHOW MSTR
DEEPENING ALONG AND NORTH OF THE LLVL BNDRY OVERNIGHT WITH PWATS
INCREASING TO OVER 1.50 INCHES IN A NW/SE AXIS ACRS ERN
NEBRASKA...NEAR 5H RIDGE CREST AXIS. THE DIVERGENCE ALOFT...WHICH
TYPICALLY INCREASES JUST WEST OF THE UPPER RIDGE AXIS...SHOULD GET
A BIT OF A BOOST WITH THE INCREASED UPPER LEVEL CONFLUENCE TO THE
N-NE AND THUS ADDED FORCING WITHING THE RIGHT ENTRANCE REGION OF A
SHARPENING (ALBEIT SUBTLE) UPPER JET STREAK. THE EXPECTATION IS A
RATHER QUICK EXPANSION OF ELEVATED TSTMS IN A NW-SE FASHION
PARALLELING THE ELEVATED WARM FRONT...WITH THE LOW-LEVEL INFLOW
AND 850-300 MB MEAN (STEERING) FLOW BECOMING MORE ALIGNED WITH
TIME EARLY THIS MORNING... FAVORING MORE UPWIND PROPAGATION WITH
TIME WITH CELL REGENERATION/TRAINING A GOOD BET. SOME OF THE
LATEST HIGH RESOLUTION GUIDANCE (INCLUDING THE LAST SEVERAL HRRR
RUNS AND MOST RECENT WRF-ARW AND WRF-NMMB) CONTINUE TO SUPPORT THE
POTENTIAL OF LOCALIZED AMOUNTS BETWEEN 3 AND 5 INCHES ACROSS THIS
AREA... THOUGH AREAL-AVERAGE RAINFALL IS EXPECTED TO RANGE FROM
.5O TO 1.25 INCHES IN A RELATIVELY NARROW CORRIDOR.

HURLEY


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

24HR QP VT 21/12Z
 0.01 552017 545996 542985 535981 526973 520969 510962 501959
      497957 492956 490953 486952 478947 472942 460930 450919
      444913 438905 428889 422879 418869 408847 403837 400832
      403829 406827 410827 414829 419828 423829 426833 430838
      433840 437840 440842 444842 448845 450849 451855 453860
      455867 458870 462871 464873 466868 465861 462857 460852
      456837 457835 461832 464832 466834 468834 471836 472838
      478845 483852 485855 490858 493858 497858 496850 492825
      489812 487804 486799 482787 480782 478778 465759 463753
      460748 453740 447736 440735 436734 433735 425738 421740
      417742 413745 411749 392752 386753 383755 378757 376762
      377770 372772 366777 363782 358784 356784 355782 356776
      357769 356761 352762 349767 341768 338770 333771 330773
      324775 321777 322781 325782 331782 335780 338782 337785
      328798 325803 321806 309807 307806 305803 303799 299800
      296802 293807 292812 293820 290824 285827 284831 286835
      293835 294831 296836 298845 297868 297877 296887 293908
      291919 288930 290939 291944 297943 302941 303934 307923
      310913 313901 315892 315882 316873 316861 316851 317846
      323845 329844 334845 333856 326861 324865 324868 326868
      334864 345863 356867 360870 363873 366878 372880 377881
      381884 383886 385891 386898 389903 395920 410950 414960
      412963 410970 408981 406992 408000 410006 411008 417009
      428013 432023 439041 443045 444050 441061 440065 437069
      439076 440079 436081 427079 421071 419067 415064 414058
      409056 406054 401053 395059 391063 387065 383069 380074
      377078 377087 377090 379091 387090 392094 392098 394100
      396104 394110 392112 387113 379116 367115 362114 356112
      350108
 0.01 350108 347101 344096 342093 337093 335094 334099 333108
      334111 330111 323110 318112 316114 316117 315125 323126
      326135 330140 332142 332145 328149 327157 328164 328168
      331170 336174 341180 345180 346177 347168 347154 348149
      350147 355143 358141 362141 371143 387146 392145 398146
      411152 407159 408164 413161 417156 420155 423155 427151
      439159 441161 444160 450156 455154 460156 467165 476174
      481178 490181 499178 504176 508172 511170 514171 520173
      525167 526163 525161 526158 528139 526126 523119 521110
      522104 521099 519090 514084 510081 509078 511075 514071
      518066 523063 529060 535056 539053 542046 546033 550023
      552017
 0.01 510249 511241 511236 508230 506227 500221 492215 487213
      483214 481219 482223 489229 495236 499245 503254 504256
      506255 508251 510249
 0.01 496082 495079 495074 493071 492069 491071 489073 488075
      485078 487080 488085 489088 489091 491093 492091 493089
      495084 496082
 0.01 423086 421084 420083 418085 419088 421088 423086
 0.01 381062 382054 377053 370057 362063 353068 344071 338073
      336075 339079 345079 350077 353075 358072 364072 374073
      378069 380063 381062
 0.01 331053 331049 325048 321046 315045 312045 314041 317038
      317035 315032 312030 306028 303025 299027 294026 287022
      270014 267013 262011 256012 236015 234017 232021 230031
      229041 228055 229063 234068 241073 246081 258090 265095
      269098 276099 282103 288108 291112 290116 288119 288123
      289125 297126 304123 309117 311112 311109 309108 301107
      300099 299094 299088 302076 303071 304067 310060 314056
      322055 327054 331053
 0.01 277809 277805 275802 272798 268798 266796 260795 250797
      241804 238809 235814 241825 244830 249828 255828 260826
      261822 257819 254818 257817 263818 265819 269819 272816
      277809
 0.25 529015 530009 530002 527994 521989 515985 506984 501982
      489978 482975 479969 469954 462944 454932 445922 434911
      425901 421897 418891 416882 412874 404858 390835 388833
      384833 378837 373842 370846 366844 361844 359846 357849
      357854 363865 368870 371871 375871 378870 381871 388876
      397887 403896 408903 413907 416909 417913 419924 422934
      425939 428946 429954 428965 424973 421980 417990 418995
      422996 427995 433994 439995 443000 445009 447020 452027
      464034 472042 478046 485048 492047 502047 520032 524028
      526023 529015
 0.25 511154 512148 513141 513130 512126 509122 505117 502114
      497115 492119 487124 484124 481122 480112 476106 473103
      471103 468106 466110 469119 473126 481138 486144 489152
      489157 491162 498162 505161 510157 511154
 0.25 476807 476801 475795 472787 465775 461768 456762 447753
      443749 437745 431745 427748 423755 418761 406762 397763
      388765 385768 384772 383778 373790 368794 365800 364803
      366807 369809 372812 377815 384815 388814 391812 395811
      397814 401815 405815 412812 419809 422808 425810 429813
      432815 435814 440810 449808 460812 465814 471814 475811
      476807
 0.25 459113 460109 459105 456100 452095 447094 436096 430097
      429101 426107 423112 418123 417131 419135 422133 427122
      438119 445127 451124 455120 459113
 0.25 410105 410103 410101 410098 409096 408095 407096 406097
      406098 405100 405102 405105 407107 409106 410105
 0.25 410922 410920 410919 410917 409915 408914 408912 407910
      406910 405908 405907 403907 403908 402910 402913 402915
      403917 403918 404919 405921 405922 407924 409925 410924
      410922 410922
 0.25 302044 302040 298037 288036 268033 258031 250031 244032
      242035 240044 238049 238056 239061 242064 252076 260081
      266085 271086 277086 284084 288081 290077 289068 289064
      290057 294052 302044
 0.25 261813 261809 260805 258803 256802 254801 252802 249804
      248806 250808 253810 255811 257812 259813 261813
 0.50 518017 519010 518004 515993 513990 510992 507001 503009
      500011 496010 490007 486005 485002 475987 472979 469969
      466961 461952 454940 448933 442926 436922 432922 429925
      429930 429937 433947 434950 433955 431964 423982 422990
      427992 431991 439989 443991 446995 450000 453003 454008
      454014 456018 463023 476031 492038 499039 504037 509033
      513027 518017
 0.50 508148 507141 506135 503133 498132 493131 489132 487136
      489140 491145 493148 496151 501153 504152 508148
 0.50 467801 467797 466793 463787 458777 452766 444760 441756
      436753 431752 429755 426760 423766 419769 415768 410767
      403768 392771 378789 378795 379798 383800 392798 401802
      411803 418802 424799 430798 436799 440801 446801 457803
      464805 467801
 0.50 447116 448114 448111 447109 446107 444106 442104 441105
      440105 439106 438107 437108 436109 437111 438112 440112
      441113 442113 443115 443116 445118 446118 447116
 0.50 410894 410884 409877 404864 398853 391844 386840 381841
      377845 376850 377858 380863 388871 395879 403887 407893
      410894
 0.50 281078 283074 281071 279065 274062 272060 273056 281049
      280045 278044 271043 258043 252042 247040 245040 245044
      249048 252053 253059 256064 257069 260074 265078 271080
      277081 281078
 1.00 491023 491020 490018 489018 488016 486015 485015 483015
      481015 480017 480018 479019 479022 480024 481025 483027
      484027 486026 488026 489026 491025 491024 491023
 1.00 472999 469990 466984 459981 458977 460976 459967 457957
      453950 450945 444939 442940 440945 441951 441958 438964
      433971 430978 428981 430985 436984 444981 447983 450986
      454992 460993 466994 471999 472999
 1.00 468013 467011 466011 465010 463010 462011 462013 463016
      464016 466015 468013
 1.00 414781 414776 412774 409773 405775 403776 400778 399780
      399784 401785 403785 407787 408787 410786 413784 414781
 1.00 402873 402868 400864 398860 395856 392851 390849 385849
      383852 384856 387861 389864 391867 395871 398874 402874
      402873

$$




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