Quantitative Precipitation Forecast
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000
FXUS04 KWBC 081859
QPFPFD

QUANTITATIVE PRECIPITATION FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
159 PM EST FRI DEC 08 2017


PRELIM DAY 1 QPF DISCUSSION
VALID DEC 09/0000 UTC THRU DEC 10/0000 UTC
REFERENCE AWIPS GRAPHICS UNDER...PRECIP ACCUM - 24HR


DAY 1


GULF COAST INTO THE SOUTHEASTERN U.S....MID ATLANTIC REGION...AND
NORTHEAST...

THE EJECTION OF AN INITIAL POSITIVELY-TILTED UPPER TROF ACRS THE
SRN PLAINS ACROSS THE LOWER MS VALLEY INTO THE SOUTHEAST BY SAT
MORNING WILL CONTINUE TO SUPPORT A RATHER WIDE SWATH OVERRUNNING
PCPN FROM THE GULF COAST REGION SPREADING THOUGH ERN PORTIONS OF
THE MID ATLC REGION BY FRIDAY NIGHT. THE UNSEASONABLY LOW LATITUDE
HEIGHT ANOMALIES ASSOCD WITH THE UPPER TROF (4-4.5 STANDARD
DEVIATIONS BELOW NORMAL OVER SOUTH TX AND THE WESTERN GULF COAST)
WILL CONTINUE TO SUPPORT SOME UNSEASONABLY EARLY SEASON SNOWS
ALONG THE WRN FRINGE OF THE PCPN SHIELD OVER THE GULF COAST REGION
THAT WILL SPREAD NEWD THROUGH PARTS OF THE SRN APLCNS INTO NRN
VA/SRN MD. SEE QPFHSD FOR MORE DETAILS ON SNOWFALL AMOUNTS.

THE HEAVIER QPF AXIS OF PCPN NORTH OF THE FRONTAL BOUNDARY IS
EXPECTED TO SHIFT FROM THE SOUTHEAST AND SOUTHERN APPALACHIANS
INTO THE MID ATLANTIC REGION AND EVENTUALLY COASTAL NEW ENGLAND.
THIS AS THE BROAD SCALE FORCING AHEAD OF THE AMPLIFYING UPPER
TROUGH GETS A SIGNIFICANT BOOST FROM THE STRENGTHENING
RIGHT-ENTRANCE REGION UPPER JET FORCING. THE ENSUING UPTICK IN
FRONTOGENESIS AND ATTENDANT ISALLOBARIC NW-W COMPONENT TO THE FLOW
AT LOW LEVELS WILL ULTIMATELY LEAD TO A TIGHTENING NW-SE QPF
GRADIENT, PARTICULARLY WEST OF I-95, WHICH COULD BECOME BUOYED
SOMEWHAT PER WHAT WOULD BE A DOWNSLOPE COMPONENT. IT SHOULD BE
NOTED THAT SOME OF THE HIGH-RES GUIDANCE DEPICTS THIS IDEA (I.E.
DRIER COMPARED TO THE NON-CAM GUIDANCE CONSENSUS), HOWEVER DESPITE
THIS THE HIGH-RES CAMS HAVE TRENDED WETTER ALONG THE THE I-95
CORRIDOR COMPARED TO THE PREVIOUS RUNS. THEREFORE, OVERALL, A
CONSENSUS APPROACH TO THE QPF WAS UTILIZED, LEAD BY THE 12Z ECMWF
AND GFS, ALONG WITH THE 15Z NBM AND LATEST WPC BIAS CORRECTED
ENSEMBLE QPF.

ACROSS FL...WITH THE APPROACHING HEIGHT FALLS FRI NIGHT COINCIDENT
WITH INCREASING SWLY 85H FLOW AND PWS INCREASING TO NEAR 2" ALONG
THE FRONT...EXPECT TSTMS TO INCREASE IN COVERAGE ACRS THE CNTL
PENINSULA AS THE COLD FRONT GRADUALLY PUSHES EWD ACRS THE STATE BY
SAT MRNG.  GIVEN THE DEEP LAYERED UNIDIRECTIONAL FLOW AND
SUFFICIENT SHEER...SOME TRAINING LINE ELEMENTS MAY OCCUR THAT MAY
LEAD TO LOCALIZED HEAVIER RAIN IN EXCESS OF 2 TO 3 INCHES.  WHILE
SOIL CONDITIONS ARE RELATIVELY DRY HERE...COULD NOT RULE OUT SOME
ISOLD RUNOFF ISSUES IN USUAL SLOW DRAINING AREAS.

GREAT LAKES AND INTERIOR NEW ENGLAND...

WHILE SOME MINOR TIMING DIFFERENCES EXIST...MODELS HAVE CONVERGED
WITH THE CLIPPER SYSTEM ROUNDING AND AMPLIFYING THE LONGWAVE
TROUGH BASE FROM THE UPPER MS VALLEY AND UPPER GREAT LAKES
EASTWARD ACROSS THE OH VALLEY ON SAT, BEFORE THIS WAVE PHASES WITH
THE SOUTHERN STREAM AND RESULTS IN MORE RAPID COASTAL
CYCLOGENESIS. PRIOR TO THE PHASING, ACCOMPANYING THIS FEATURE WILL
BE MAINLY LIGHT TO SPOTTY MODERATE LAKE ENHANCED SNOWFALL DOWNWIND
OF LAKES SUPERIOR AND MICHIGAN -- AS THE COMPACT AREA OF WAA/MOIST
ISENTROPIC ASCENT ABOVE THE LAKE-INDUCED CBL COMBINES WITH THE
RESIDUAL OVER-WATER INSTABILITY. BEHIND IT, MORE GENERAL ("PURE")
LAKE EFFECT SNOWS WILL ENSUE FROM WEST TO EAST AS VERY STRONG COLD
ADVECTION IS USHERED IN BEHIND THE SFC LOW, LEADING TO STG LOW
LEVEL LAPSE RATES AS 85H TEMPS DROP TO -18 OVER LAKE SUPERIOR ON
SAT. MODELS GENLY SHOW DECENT AGREEMENT HERE AND SO CHANGES FROM
CONTINUITY WERE RELATIVELY MINOR.  FOR MORE DETAILED INFORMATION
OF SNOWFALL AMOUNTS..PLEASE SEE QPFHSD.

HURLEY/SULLIVAN

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


24HR QP VT 10/00Z
 0.01 459624 463635 467644 468649 467652 465662 460681 457692
      455700 451708 446716 438731 435737 430743 418756 411762
      405768 400773 395780 384795 377808 374811 375814 378814
      388813 403815 411813 419809 425803 425797 426792 428787
      431783 433782 433787 431791 430795 432797 436789 438784
      437777 437772 438766 441758 443754 446751 449752 447755
      450756 454752 456749 458744 462738 466732 467728 467723
      470713 471709 474706 490708 497711 501717 505726 507740
      506751 504762 502765 497766 490765 487763 483766 479769
      478774 471791 469801 467804 467809 466814 465822 466829
      467835 470843 475852 480859 482863 483869 483881 480890
      476895 476901 474905 469912 464917 454930 451933 447935
      438935 435933 433926 426922 421917 419912 418908 418904
      415903 412901 406895 393888 390883 387879 383879 376876
      373874 371871 369867 369860 366858 363859 358860 354861
      352860 352857 354854 366842 369839 370835 374828 376825
      375822 373819 371820 367823 364827 357841 354847 349852
      337862 325872 319879 313886 302897 291908 278918 270919
      266919 263916 259911 260900 260891 261887 260881 250872
      244867 237862 235858 232856 227855 226851 223843 222836
      220812 220802 220792 220783 222777 237770 268754 283745
      291741 297737 310726 322715 327709 333704 343693 366669
      384648
 0.01 483338 484336 485336 485334 487332 489330 490328 491328
      493326 495325 495324 497323 497322 499321 499320 501319
      502318 505311 508299 512292 514280
      514274 513270 509262 503259 499257 496258 489259 483260
      478264 472267 467271 455277 449281 445285 433293 422300
      411305 406308
 0.25 437632 442637 447643 449649 449656 448667 447675 445683
      442693 439699 430714 420728 412739 403754 394767 385780
      377793 373799 368806 358819 348830 343836 341836 340832
      335826 332824 329825 315833 301842 291849 277858 268861
      259861 244856 238852 234847 228842 227833 226813 228804
      228795 232790 239786 253779 268771 282763 294755 307746
      331726 342715 352704 371678 381665 391653 397647 404642
 0.25 504299 506293 507286 506281 504276 496272 492271 489272
      483275 477279 471283 464285 461288 459292 453298 448301
      442306 440310 441314 447319 464324 472324 479323 486322
      493319 498314 502304 504299
 0.25 470878 469875 468873 467871 466868 466866 465864 464864
      463866 462868 462869 462871 462873 462874 464875 464876
      466878 466879 467880 468881 469880 470878
 0.25 469893 469890 468889 467890 466892 466893 465895 465897
      465898 464900 464903 465904 466903 467900 467898 468895
      468894 469893
 0.25 456832 455823 454820 454816 453806 452796 451792 450792
      448798 445805 442808 439815 441822 444823 448822 451822
      453823 454828 455833 456832
 0.25 454867 453855 450852 446853 440855 436854 431851 427850
      420857 416859 410860 408861 408865 410869 415872 419874
      430874 438873 441873 444875 447877 451875 453869 454867
 0.25 441829 440827 439827 438827 436828 436830 438832 440831
      441829
 0.50 503291 504286 504282 502279 498278 492277 490278 488283
      486294 481297 472305 467308 461306 457306 451309 451311
      455312 462314 475317 481316 487315 492313 496309 503293
      503291
 0.50 439655 439650 436646 431642 424641 420641 415642 408646
      402652 392662 353711 343721 332732 309751 296760 284769
      278773 273777 257784 244792 238796 233801 231809 231817
      231838 233842 236845 242849 256854 263858 269856 281850
      295841 307833 318824 329813 341804 353795 360792 366791
      372786 376780 386768 394754 409726 417713 425698 432684
      435677 438668 439661 439655
 0.50 417865 415865 414865 413866 414866 416866 417865
 1.00 430661 429655 427652 421651 415654 409658 400668 391679
      372700 353719 333739 312756 308761 302765 291774 283783
      277787 271790 260798 256803 251808 246811 241816 239822
      238832 239837 240840 246844 252844 259843 265845 269847
      273845 280843 285839 307823 312818 319815 323812 327806
      330799 334794 337787 342782 355775 367769 374767 380762
      387751 394739 402725 414699 427674 429666 430661
 1.50 424662 423658 421657 417660 412663 408667 396682 383697
      369711 340737 333743 326750 320757 314764 306771 303775
      302780 303783 300787 293794 291798 297798 301798 306796
      314791 322785 328777 336772 343766 351760 360754 368748
      371747 375749 376752 379750 381748 392730 398721 402713
      411693 420676 422668 424662
 1.50 303814 301811 298809 295807 294805 292805 290809 288814
      273816 267808 258811 251815 246822 246831 247836 250838
      258835 266831 274828 278830 280835 284833 297824 302819
      303814
 1.50 289803 287804 286804 287805 289804 289803
 2.00 413675 412671 410671 406674 399685 392695 385703 378712
      376714 379714 383710 389709 390716 393717 395715 398709
      404699 409686 413675
 2.00 363733 361731 357732 350735 344739 339744 329754 321765
      314777 310784 313784 316781 321778 326773 338763 347754
      352747 357741 362738 363733

$$





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