Quantitative Precipitation Forecast
Issued by NWS

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416
FXUS04 KWBC 082041
QPFPFD

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


PRELIM DAY 1...DAY 2 AND DAY 3 QPF DISCUSSION
VALID DEC 09/0000 UTC THRU DEC 12/0000 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.


DAYS 2/3...

...EASTERN SEABOARD...

THE SOUTHERN STREAM TROUGH MOVING THROUGH THE DEEP SOUTH/GULF OF
MEXICO TODAY, RESULTING IN EARLY SEASON SNOW FOR PARTS OF THE
COUNTRY NOT ACCUSTOMED TO WINTRY PRECIPITATION, WILL PHASE WITH
NORTHERN STREAM UPPER DYNAMICS OFF THE MID-ATL/NERN SEABOARD LATE
SAT INTO SUN. THE ELONGATED AREA OF SURFACE LOW PRESSURE OFFSHORE
WILL BECOME CONSOLIDATED, DEEPEN AND LIFT NORTH INTO NOVA
SCOTIA/CANADIAN MARITIMES. THE POST-FRONTAL DEFORMATION ZONE WILL
BRUSH PARTS/EASTERN NEW ENGLAND WILL HEAVIER QPF. FOR THE MOST
PART, GUIDANCE IS RATHER SIMILAR ON THE PROGRESSION OF THIS SYSTEM
AND QPF AMOUNTS, SUGGESTING POSSIBLE .25 TO .75 INCH AMOUNTS FROM
EASTERN MA UP THROUGH MAINE AND PARTS OF NH AND WPC FOLLOWED THIS
ROUTE.

...UPPER MISSISSIPPI VALLEY INTO THE GREAT LAKES/APPALACHIANS...

IN THE WAKE OF THE PHASED STORM SYSTEM OFFSHORE OF THE NERN QUAD
OF THE COUNTRY, DEEP COLD CYCLONIC FLOW ACROSS THE WARM AND
UNFROZEN GREAT LAKES WILL LEAD TO HEAVY LAKE EFFECT SNOW LATE SAT
THROUGH SUN. THE GLOBAL MODELS AND ESPECIALLY THE HI-RES MODEL
GUIDANCE ARE PINPOINTING THE TRAJECTORY OF THESE INTENSE SNOW
BANDS VARIOUSLY, WEST TO EAST ACROSS LAKE SUPERIOR FROM THE
KEWEENAW PENINSULA TO NERN UP OF MI, SERLY OFF LAKE MICHIGAN IN A
COUPLE SPOTS INTO LOWER MI, AND PREDOMINANTLY SWRLY COMPONENT OFF
LAKES ERIE AND ONTARIO IMPACTING NWRN PA INTO SWRN NY STATE AND
INTO UPSTATE NY. FINALLY THE CYCLONIC FLOW WITH NWRLY WINDS INTO
THE APPALACHIANS COULD SPELL FAVORABLE OROGRAPHICS FOR HEAVY
SNOWFALL FROM SOUTH CENTRAL PA TO WESTERN NC.

THEN ON SUN EVENING THROUGH MON, A TRUE ARCTIC CLIPPER FEATURE
WILL DIG THROUGH THE UPPER MS VALLEY INTO THE GREAT LAKES/OH
VALLEY. EXPECT SIMILAR EFFECTS FROM SUCH A SYSTEM, RELATIVELY DEEP
SURFACE LOW, GUSTY WINDS, STRONG COLD ADVECTION AND MOSTLY
MOISTURE STARVED. THE AGREEABLE GLOBAL MODELS SUGGEST A
STREAK/AXIS OF HEAVIER SNOW FROM NORTHERN MN THROUGH WI INTO MI,
GENERALLY A .25 INCH OR LESS QPF AMOUNTS. BEFORE THE SYSTEM
ARRIVES, CONTINUED LAKE EFFECT AND PERHAPS SOME LAKE ENHANCEMENT
IS EXPECTED DOWNWIND OF THE EASTERN LAKES.

HURLEY/MUSHER


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

24HR QP VT 11/00Z
 0.01 485614 489616 491618 495621 496626 497636 496643 495647
      494655 493658 494662 494672 495682 495687 494691 492695
      489697 476705 458729 459734 458740 455747 452750 448752
      444759 441777 440779 440784 445783 451777 455771 460765
      463764 465764 471768 473770 474776 471783 466790 462798
      464802 467805 472811 475819 477827 479839 481847 484852
      481871 481878 479880 477888 472902 470900 468902 465905
      462906 462903 463899 461895 459891 462888 463882 464878
      459870 457864 455862 452863 444863 439866 434866 431869
      425869 417868 413866 411863 401855 399848 397844 393842
      390842 386836 382834 384827 379828 378835 373836 371838
      368840 362845 360844 364839 365830 363829 361832 358839
      352844 349846 348845 350839 347837 350834 352832 354827
      354823 357819 363814 369810 373804 379801 387792 401786
      406781 411779 414779 417776 425773 428767 423763 424752
      423750 421752 417752 403761 397763 391769 387772 384777
      374767 373764 370761 366757 361751 354750 348752 342757
      335761 329766 318777 309786 305791 301789 282772 277773
      274775 264777 257780 248782 240784 236784 234780 232772
      230767 231763 251747 256743 262738 274730 297713 309704
      316700 324696 332686 342678 370665 379662 385658 393655
      396653 401651 408648 411645 419638
 0.01 556062 556053 555047 552038 545018 541007 537998 533990
      528982 522974 517968 512962 505956 498950 496947 492944
      489942 486941 483939 479939 482949 486957 486959 481959
      474954 470955 472960 477965 485969 491975 498981 503986
      509993 511998 511002 510006 502010 498016 498021 499026
      506032 516046 523052 528060 534068 537075 540079 544079
      548077 550074 553066 556062
 0.01 522264 521254 521244 521239 519235 512228 500228 498232
      497235 497239 497243 495245 488248 483251 478256 473262
      468270 463274 452284 441293 435296 429301 424307 424309
      428311 433313 436311 442309 449307 454305 460301 467299
      471298 473299 472301 468304 465308 466312 473316 476315
      481317 488319 499311 507297 512289 516280 520272 522264
 0.01 491934 491932 489929 486927 484926 482924 479924 477922
      475922 477924 479927 480929 482932 484932 486935 489935
      491934
 0.01 452735 451733 450731 448732 447733 445734 445735 444737
      445738 447738 449738 451738 452735
 0.01 445836 444831 443829 440830 438832 437835 437840 436842
      436847 436852 438854 439851 440849 442846 442844 443839
      445836
 0.01 434833 433827 429827 425827 422825 419824 417828 412833
      409840 407843 404843 401844 401847 402850 405853 408852
      410849 413852 416852 418849 425848 428840 433835 434833
 0.01 260823 257819 252816 249812 245809 241805 239803 235803
      233808 236813 240817 243821 248824 250825 254825 260823
 0.25 468621 473626 477634 480641 483649 488669 485676 480682
      474687 469693 465697 459701 455703 453706 451706 443707
      435709 430709 426711 422713 419711 415705 412698 410694
      406693 401699 395704 389709 383714 374722 366726 358726
      350727 341730 331732 324736 313741 301747 287754 263768
      257771 250774 241776 238775 237771 240765 244760 253752
      265745 277737 291730 303723 315717 321713 326708 337698
      347691 359683 375676 389669 399662 411654 423644 442630
 0.25 515267 516257 515251 512244 510242 507243 504255 503257
      500258 494258 489258 484259 480262 477268 477276 483279
      488279 491284 493290 498292 503290 507287 510281 513274
      515267
 0.25 472855 471853 471848 470843 469840 468839 466841 466844
      465849 465853 465858 467861 469863 471863 472858 472855
 0.25 456806 455801 453796 450795 448797 446800 443805 441808
      440813 440816 442817 447817 449819 454820 455813 455807
      456806
 0.25 447712 447710 445708 444709 443711 442712 441713 441716
      443716 444716 445715 446714 447712
 0.25 437758 437757 436756 435755 433754 432756 432759 433761
      433763 434765 436764 436763 437760 437758
 0.25 431781 430778 429778 428779 427780 427781 426784 426785
      425786 425789 424791 423794 424796 425797 426796 427795
      427793 428791 429791 429788 430786 430783 431781 431781
 0.25 423862 422862 421861 419862 419863 421864 422863 423862
 0.25 389799 388797 386798 384798 383800 381802 380805 382806
      383805 385804 387803 388801 389799
 0.25 358834 358832 357830 356830 356832 355835 357836 358834
 0.50 459624 466627 469627 471632 474638 474644 478651 478660
      478666 476669 470673 458677 452680 446679 438682 433686
      422695 421691 422687 425679 426675 425670 424667 421667
      400685 388695 380702 369710 353716 339722 326727 314734
      302740 277755 266761 260764 256766 252767 250762 252759
      257754 267748 292735 317722 323719 329715 340707 363691
      387675 400667 410659 420651 427647 434644 443634 452626
 0.50 501275 500269 498266 494262 491260 487260 484261 480264
      481270 485273 490275 495277 499276 501275
 0.50 434761 434759 434758 434759 434761 434761
 0.50 428788 429786 427784 427786 426789 428789 428788
 1.00 461644 461639 459634 458631 455633 454635 453639 451642
      451644 450647 450652 453653 456651 458649 460646 461644

24HR QP VT 12/00Z
 0.01 543041 543029 543023 542019 542014 540010 537002 531988
      524977 512957 507952 504945 502939 499934 494921 489914
      485907 482889 480882 481874 479856 476842 469833 463821
      456808 447797 441781 441771 442764 446752 448744 449741
      449737 464720 471707 474699 475695 475690 473673 470674
      467682 453703 444709 440715 440721 430728 429731 430733
      433734 433738 431740 430744 429747 426748 420745 418750
      410757 406761 404766 403783 403786 400789 395792 389796
      385801 388806 393810 396814 400820 399829 400840 400850
      404854 407857 412859 407867 409871 409875 406882 407887
      413884 419900 422907 426912 429917 431921 431926 431932
      433935 435940 440941 443947 446950 448953 444954 448964
      452979 457986 460993 458998 456999 452998 450995 446992
      443987 439982 434977 425974 424976 425979 429983 433986
      432995 435000 439002 443000 444998 446001 449007 461013
      459016 459020 463024 465040 469041 471039 474039 475037
      477039 480047 482048 484045 489040 492042 494039 494035
      491027 489025 490021 490015 489012 490009 494008 495012
      496021 499029 505039 507043 511048 515053 521055 530056
      535054 539049 543041
 0.01 470986 470984 469982 467981 465979 464979 463979 462977
      460979 460981 462983 464984 465984 467986 469988 470986
 0.01 422699 421694 419691 415692 410697 408704 406712 404718
      401725 403734 405743 404750 406753 409752 413746 416740
      421736 424730 420728 415729 414726 417725 418712 420703
      422699
 0.25 531021 530015 528010 524002 519994 513986 508980 504978
      501977 502984 504988 509996 515004 519011 524018 527022
      529023 531021
 0.25 440755 440753 440752 438751 437753 436753 436756 435757
      435758 435761 435763 436764 438764 439762 439761 440760
      440757 440755 440755
 0.25 437866 436864 434863 433861 431861 430862 430864 431866
      431867 433868 434868 435869 436868 437866
 0.25 427791 427788 427786 426784 424785 423787 422788 422789
      421792 420794 420797 420799 420801 422802 423801 424801
      425798 426796 426793 426792 427791
 0.50 425794 425791 424790 424791 424794 425794 425794

$$





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