Quantitative Precipitation Forecast
Issued by NWS

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143
FXUS04 KWBC 171900
QPFPFD

QUANTITATIVE PRECIPITATION FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
159 PM EST FRI NOV 17 2017


PRELIM DAY 1 QPF DISCUSSION
VALID NOV 18/0000 UTC THRU NOV 19/0000 UTC
REFERENCE AWIPS GRAPHICS UNDER...PRECIP ACCUM - 24HR


DAY 1

...EASTERN U.S...

THE BROAD TROUGH COMING THROUGH THE WEST WILL GRADUALLY SPIN UP A
SHARPLY DEFINED SURFACE LOW AND FRONTAL WAVE THAT IS FORECAST TO
PROGRESS THROUGH THE GREAT LAKES AND OHIO VALLEY FROM TONIGHT
THROUGH SATURDAY. WHILE THE STRENGTHENING WARM CONVEYOR BELT WILL
SUPPORT AN EXPANSION AND INTENSIFICATION OF RAINFALL OVER THE
EASTERN U.S...FRONTOGENETICAL FORCING ALOFT WILL ALSO SUPPORT AN
EXTENSION OF LIGHT ACCUMULATIONS BACK WEST THROUGH THE CENTRAL
PLAINS STATES. A FEW BANDED STRUCTURES WILL BE DIFFICULT TO
ANTICIPATE AHEAD OF TIME...AND WILL DETERMINE WHICH AREAS IN THE
PLAINS RECEIVE A FEW TENTHS VERSUS A FEW HUNDREDTHS...BUT WITH A
LACK OF ICE/SNOW THERE SHOULD BE LITTLE IMPACT.

RAINFALL WILL BE HEAVIER IN THE WARM SECTOR...PARTICULARLY ACROSS
PARTS OF IL/IN/OH...ALONG THE NORTHERN PERIPHERY OF A 1.25 INCH PW
PLUME ACCOMPANIED BY MODEST 500 J/KG MUCAPE VALUES PER THE NAM.
DEEP CONVERGENCE AND UNIDIRECTIONAL FLOW SETS UP FOR A TIME EARLY
SATURDAY...PERHAPS ALLOWING FOR WEST TO EAST TRAINING OF SOME
CONVECTIVELY ENHANCED PRECIPITATION FROM FROM ABOUT CHAMPAIGN
ILLINOIS THROUGH NORTHERN INDIANA AND OHIO. CONSENSUS GLOBAL MODEL
MASS FIELDS POINT TOWARD THE WRW-ARW AND EMC WRF-ARW2
SOLUTIONS...AS WELL AS THE HREF MEAN...AS HAVING A GOOD HANDLE ON
PLACEMENT. THIS FIT WELL WITH THE INHERITED WPC GRIDS...WHEREAS
THE OVERALL GLOBAL MODEL CONSENSUS AND ESPECIALLY GFS AND NAM ARE
LIGHTING UP TOO FAR NORTH AWAY FROM THE CAPE AXIS WITH THEIR
HEAVIER AMOUNTS. THUS...WPC ADJUSTED THE QPF PATTERN SLIGHTLY
SOUTHWARD...RESULTING IN A REDUCTION OVER LOWER
MICHIGAN...ALTHOUGH THE SYNOPTIC FORCING WILL STILL LEAD TO
AVERAGE AMOUNTS 0.50 INCHES TO 1.25 INCHES THERE. THE MORE
CONVECTIVELY ENHANCED SWATH FARTHER SOUTH IS FORECAST TO RECEIVE
1.50 TO 2.25 INCHES ON AVERAGE...WITH AMOUNTS TAPERING OFF WITH
EASTWARD EXTENT INTO PENNSYLVANIA WHERE WARM ADVECTION WILL
DOMINATE WITHIN AN ATMOSPHERE MARKED BY LESSER INSTABILITY.

GIVEN THE POTENTIAL FOR TRAINING OVER IL/IN/OH EARLY SATURDAY
THERE IS AT LEAST SOME RISK OF FLASH FLOODING FROM ISOLATED 3-PLUS
INCH TOTALS...THOUGH PW ANOMALIES AND EVENT DURATION LOOK FAIRLY
TAME.


...ROCKIES AND WASATCH...

THROUGH 00Z THIS EVENING AND BEYOND THE TAIL END OF THE MID LEVEL
FRONTAL ZONE AND CONTINUED HEIGHT FALLS WILL SWEEP THROUGH
UTAH...COLORADO...AND ADJACENT STATES...HITTING THE HIGH TERRAIN
ESPECIALLY WITH LIGHT TO MODERATE ADDITIONAL PRECIPITATION
AMOUNTS. IN SOME LOCATIONS HEAVY SNOW MAY CONTINUE THROUGH
TONIGHT...MOST PROMINENTLY IN THE COLORADO ROCKIES. INTENSITY AND
COVERAGE SHOULD DIMINISH SHARPLY BY LATE TONIGHT AND BE DONE BY
EARLY SATURDAY. WPC QPF LEANED TOWARD THE 12Z HREF MEAN AS WELL AS
THE WRF-ARW AND THE MORE GENEROUS VERSIONS / GREATER COVERAGE OF
LIGHT PRECIP / OF OUR IN-HOUSE ENSEMBLE. THIS APPROACH RESULTED IN
ALMOST ZERO NET CHANGE TO THE QPF IN THESE AREAS. SEE WPC WINTER
WEATHER PRODUCTS AND LOCAL FORECAST OFFICE INFORMATION FOR SNOW
RELATED HIGHLIGHTS.


...PACIFIC NORTHWEST...

THE NORTHWEST CATCHES A BRIEF RESPIT...AND THE 00Z TO 00Z 24-HR
QPF ACTUALLY TRENDED A LITTLE DRIER. MODERATE AND HEAVY RAINFALL
PICK UP AGAIN BY DAY 2 GOING INTO SUNDAY...HOWEVER...OVER WESTERN
WASHINGTON. THIS WILL THEN LEAD INTO A VERY ACTIVE PERIOD LEADING
UP TO THANKSGIVING DAY. DETERMINISTIC 7-DAY FORECAST TOTALS ALONG
THE WEST COAST INCLUDE 2 TO 5 INCHES OF RAIN AT LOW ELEVATIONS AND
8 TO 12 INCHES AT THE HIGHEST ELEVATIONS IN NORTHERN CALIFORNIA
AND WESTERN WASHINGTON AND OREGON.

BURKE


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

24HR QP VT 19/00Z
 0.01 535206 535198 533191 527180 521167 518163 515161 510164
      503162 490160 491165 488165 488162 483156 479153 470145
      466141 461142 459140 461138 458137 451136 455140 456142
      455147 455151 458153 466160 471164 478165 481166 484169
      487173 498179 505188 520208 523212 529213 535206
 0.01 517267 519254 520247 519241 518236 516232 512225 509222
      506219 502211 495206 490205 489203 483204 475207 462213
      456214 448217 445220 445223 451225 458227 461228 467227
      472223 477223 481224 485225 487226 488229 484232 479229
      477227 474227 468232 453235 449234 445234 442237 443240
      446242 451244 456244 461247 470248 472248 475252 478272
      482279 487286 491292 496294 500295 504294 506292 511285
      514275 517267
 0.01 501155 500150 498146 494140 489135 485130 476127 470124
      469129 470133 470138 473141 482142 486147 493151 499155
      501155
 0.01 496848 495844 495838 494824 486808 484804 481801 480794
      478787 473780 468772 465764 463759 460756 457755 454751
      453740 452735 453729 456721 454708 452703 448702 443699
      436698 426700 423703 419704 413706 410708 404715 399723
      396731 394738 391747 390751 390757 392769 391779 390783
      387787 383794 381804 380811 378815 374818 361827 355832
      349840 339854 330867 323879 316894 308909 306915 306921
      307924 313924 316923 324920 339911 343909 346911 346916
      345920 339926 335932 334936 334941 337947 341952 344954
      348955 350951 351948 352945 359947 363941 363928 364922
      367924 369925 372924 376927 377933 377938 379945 382955
      386961 389965 390970 390981 390994 390001 388006 388015
      389020 388026 389031 388037 385045 382048 378048 370050
      366050 362052 358054 356057 357059 360060 365058 368056
      374056 377057 378058 379060 374060 368059 358067 360070
      365071 367075 370077 373086 374091 373094 371095 365090
      360089 357090 354095 357098 362100 372112 370118 367119
      362119 360121 362123 370127 373136 375140 377137 379132
      382131 387127 393122 398118 406117 409114 409111 410098
      408098 405108 403111 401109 398107 394110 392110 388113
      383113 381110 381106 383104 385101 388100 394098 394094
      399090 403083 408077 415076 417071 419068 420070 423072
      426076 430082 433085 437086 445072 432062 427054 420047
      416040 415034 419033 423035 428035 431033 435033 440027
      443022 445017 445011 446002 444982 443969 442963 444960
      457919 464905 474896 484882 488873 492863 496848
 0.01 496949 496944 494937 491929 486921 482909 480906 477904
      475907 474915 477922 480932 484942 487950 491953 494952
      496949
 0.01 466112 464109 464112 466112 466112
 0.01 461104 461101 460101 460104 461104 461104
 0.01 454105 455100 453097 450095 447094 444095 442096 440093
      437093 436095 424089 424091 427094 431099 430104 426104
      419104 420108 423111 421114 417113 414113 414116 416118
      420119 431112 434111 439111 445113 450109 446104 448103
      452104 454105
 0.01 434938 433931 431935 430940 428947 427952 427959 426964
      425971 428970 430969 431966 431959 432954 432947 433940
      434938
 0.25 526196 526193 525189 524185 522183 521181 518178 515179
      513181 514185 517187 519188 521191 523193 524195 526196
 0.25 508259 510249 510241 505229 499216 495215 492217 491222
      491232 489235 487236 482239 480240 477238 481246 485258
      489270 494276 497277 500277 504273 506266 508259
 0.25 479137 478137 479137 479137
 0.25 471153 470152 469150 468150 467149 466149 467152 467153
      469154 470154 471153
 0.25 474833 473826 471818 465804 453779 447770 437761 434756
      429752 422744 414739 409740 404746 401753 400760 398773
      398781 396786 392792 389799 391807 391816 390822 388826
      385831 380836 370842 360851 354859 347868 339878 333890
      332893 332896 336893 340890 345891 351890 357885 364883
      367884 373893 375895 376900 379900 383905 385913 387919
      389923 392925 395926 403925 410925 414921 422909 426896
      433888 437884 442882 455876 463866 468856 472843 474833
 0.25 409068 405065 402063 401060 400058 397056 393060 391064
      390063 388068 387074 394073 394068 396066 398065 399069
      398074 401074 403069 409068
 0.25 383076 383074 381075 381076 381077 383077 383076
 0.25 374066 373065 371064 370063 368063 367063 368064 369065
      371066 373067 374066
 0.50 507248 507241 506237 500227 498224 495223 493228 493233
      494238 493240 489238 485240 485250 487259 490265 493269
      496271 499271 502264 503257 504252 507248
 0.50 392071 391068 389070 390071 392071
 0.50 465831 465825 463818 460813 456809 450800 444793 420759
      415751 411749 408749 406751 404757 403764 402776 401781
      399786 397791 395799 396807 395814 394826 393831 392837
      388840 382843 377844 372847 365853 359861 353870 349881
      349884 352882 369870 377864 381862 384862 386863 389876
      390893 393906 396906 399903 408898 416891 423883 427880
      430878 434875 437871 443861 446855 449852 456847 460844
      463839 465831
 1.00 502238 501236 500235 500234 499235 499237 499238 500240
      502238
 1.00 496257 496254 495253 494251 492249 491248 490250 489252
      490255 490256 490258 491259 492261 494262 496260 496257
 1.00 432816 432809 429803 426793 423789 419786 415783 411783
      407785 405789 403795 402799 401813 400818 400825 401832
      400840 399851 394874 394881 395888 399887 402884 407875
      413868 418859 420854 421848 423837 427829 432816
 1.50 427817 426811 423801 422796 418795 416793 413793 410796
      410803 408812 406822 405827 406834 401853 398871 398877
      396882 397885 399883 408868 412861 415851 415840 415828
      418825 421824 425822 427817 427817
 2.00 412840 412835 409836 407841 406848 405852 404857 403862
      403869 404866 407862 408858 410854 412849 412842 412840

$$





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