Quantitative Precipitation Forecast
Issued by NWS

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000
FXUS04 KWBC 122219
QPFPFD

QUANTITATIVE PRECIPITATION FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
518 PM EST TUE DEC 12 2017


FINAL DAY 1...DAY 2 AND DAY 3 QPF DISCUSSION
VALID DEC 13/0000 UTC THRU DEC 16/0000 UTC
REFERENCE AWIPS GRAPHICS UNDER...PRECIP ACCUM - 24HR


DAY 1

...NORTHEAST...

A MID/UPPER LEVEL TROUGH WILL TAKE ON AN INCREASINGLY NEGATIVE
TILT AS IT MOVES INTO THE NORTHEAST THROUGH TONIGHT. WILL SEE
SURFACE LOW REDEVELOPMENT NEAR THE MAINE COAST...WITH AN
INTENSIFYING LOW MOVING NORTH INTO CANADA ON WEDNESDAY. WILL
CONTINUE TO SEE SNOW/SLEET WITH THIS SYSTEM ACROSS INTERIOR
CENTRAL/NORTHERN NEW ENGLAND...WITH MORE OF A SNOW TO RAIN
SCENARIO ACROSS EASTERN NEW ENGLAND. SOME WEAK ELEVATED
INSTABILITY WILL CLIP CAPE COD THIS AFTERNOON AND MOVE INTO
DOWNEAST MAINE THIS EVENING. THIS MAY ALLOW FOR A FEW EMBEDDED
HEAVIER CONVECTIVE CORES RESULTING IN SOME ISOLATED 0.5" IN AN
HOUR TOTALS. MODELS WERE IN CLOSE ENOUGH AGREEMENT THAT A MULTI
MODEL BLEND SEEMED TO SUFFICE FOR QPF. THIS RESULTS IN AN
ADDITIONAL 0.5"-1" OF QPF AFTER 0Z ACROSS PORTIONS OF CENTRAL AND
NORTHERN MAINE.

LAKE EFFECT SNOW WILL CONTINUE INTO TONIGHT OFF OF LAKE ERIE AND
ONTARIO. FOLLOWED CLOSE TO A HIGH RES MODEL BLEND FOR THIS
ACTIVITY.

SEE THE QPFHSD (HEAVY SNOW DISCUSSION) FOR MORE DETAILS.


...UPPER MS VALLEY INTO THE GREAT LAKES REGION...

A CLIPPER SYSTEM WILL BRING A SWATH OF SNOW TO PORTIONS OF THE
UPPER MS VALLEY INTO THE GREAT LAKES REGION TONIGHT INTO
WEDNESDAY. MODELS HAVE ALL COME INTO AGREEMENT ON A MORE INTENSE
SYSTEM WITH HIGHER QPF AMOUNTS. THIS TREND SEEMS TO BE RELATED TO
THE INTERACTION OF TWO SHORTWAVES...ONE THAT WILL MOVE ACROSS THE
DAKOTAS AND INTO THE MS VALLEY TONIGHT...AND THE OTHER PUSHING
INTO MN ON WEDNESDAY. THE SOUTHERN OF THESE TWO SHORTWAVES HAS
BEEN TRENDING STRONGER...RESULTING IN MORE INTERACTION WITH THE
NORTHERN WAVE. THIS RESULTS IN BROADER AREA OF MID/UPPER LEVEL
FORCING AND GREATER COVERAGE OF MORE SATURATED CONDITIONS. WILL
ALSO SEE GOOD FRONTOGENETIC FORCING AND OMEGA WITHIN THE DENDRITIC
SNOW GROWTH ZONE MOVE ACROSS THIS SYNOPTICALLY FAVORED LOCATION.
THUS ANTICIPATE WE WILL SEE A BROAD SWATH OF LIGHT TO MODERATE
SNOW...WITH A NARROWER CORRIDOR OF MODERATE TO HEAVY SNOW.

MODELS ARE GENERALLY IN GOOD AGREEMENT ON THIS EVOLUTION. SOME
DIFFERENCES IN THE EXACT QPF AXIS EXIST...AND WITH SYSTEMS SUCH AS
THIS WILL PROBABLY CONTINUE TO SEE SOME SLIGHT SHIFTS RUN TO RUN.
FOR NOW STAYED CLOSE TO A BLEND OF THE 12Z NAM/GFS/NAM NEST/ARW2
AND THE 0Z ECMWF. THIS RESULTS IN LIQUID EQUIVALENT AMOUNTS
BETWEEN 0.25"-0.5" FROM CENTRAL WI INTO SOUTHERN MI. STAYED AWAY
FROM THE HRW ARW AND NMMB...WHICH SEEM TO BE LAGGING TRENDS AND
APPEAR TOO DISORGANIZED INITIALLY WITH THE SYSTEM.

SEE THE QPFHSD (HEAVY SNOW DISCUSSION) FOR MORE DETAILS.



DAYS 2/3...

WPC QPF WAS PRIMARILY BASED ON A BLEND OF THE ECMWF...GFS...AND
UKMET...WITH GREATER WEIGHT PLACED ON THE ECMWF AND GFS.

...GREAT LAKES AND MID ATLANTIC...

THE CLIPPER SYSTEM MENTIONED IN THE DAY 1 PERIOD WILL CONTINUE TO
DIG FROM THE GREAT LAKES INTO THE MID ATLANTIC REGION DURING THE
DAY 2 PERIOD (WEDNESDAY NIGHT AND THURSDAY)...WITH A SOUTHEASTWARD
CONTINUATION OF THE SWATH OF SNOW. UPWARD TRENDS IN QPF FROM MANY
OF THE AVAILABLE MODELS IS REFLECTED IN A SIMILAR UPWARD TREND IN
THE LATEST WPC QPF. ALTHOUGH THE DURATION OF THE EVENT WILL NOT BE
LONG...STRONG FORCING SHOULD BE ABLE TO COMPENSATE TO PRODUCE SOME
LIQUID EQUIVALENT TOTALS OF AT LEAST 0.25 INCHES NEAR OR JUST
NORTH OF THE TRACK OF THE 850MB LOW IN PORTIONS OF OH/PA. THERE IS
SIGNAL IN ALL OF THE OPERATIONAL MODELS FOR A SMALL BAND OF PRECIP
APPROACHING 0.25 INCHES...AND A STRONGER SIGNAL IN WPC INTERNAL
BIAS-CORRECTED ENSEMBLE GUIDANCE. THE COMBINATION OF A STRONG
UPSTREAM +PV ANOMALY AND MODERATELY STRONG FRONTOGENETIC
CIRCULATION SHOULD YIELD SOME BANDED PRECIPITATION AND MAY LEAD TO
SHARPER GRADIENTS THAN ARE DEPICTED IN THE CURRENT FORECAST. SEE
THE QPFHSD (HEAVY SNOW DISCUSSION) FOR ADDITIONAL DETAIL ON
SPECIFIC WINTER WEATHER IMPACTS.

COLD AIR ADVECTION IN THE WAKE OF THE CLIPPER...AND STEADIER WNW
LOW-LEVEL FLOW...SHOULD REACTIVATE LAKE EFFECT SNOW ACROSS THE
GREAT LAKES REGION. THE COLDER TEMPERATURES WILL BE CONCENTRATED
OVER THE NORTHERN LAKES WHICH IS ALSO WHERE THE LARGEST
LAKE-INDUCED INSTABILITY WOULD BE LIKELY. MODELS HAVE MORE QPF IN
THE FAVORED REGIONS FURTHER NORTH...AND THIS PATTERN WAS FOLLOWED
WITH WPC QPF. LARGE SCALE SUPPORT SHOULD BE PROVIDED BY ANOTHER
DIGGING WAVE DURING THE DAY 3 PERIOD...WHICH MAY PRODUCE BROADER
LIGHT PRECIPITATION THAN WOULD BE EXPECTED IN A TYPICAL LAKE
EFFECT PATTERN.

...GULF COAST REGION...

MODELS SHOW SOME VARIABILITY WITH THE PLACEMENT OF THE QPF AXIS
ACROSS THE NORTHERN GULF OF MEXICO AND ADJACENT PORTIONS OF SOUTH
TEXAS AND NORTHERN MEXICO. THIS WILL OCCUR IN A REGION OF
INCREASING ASCENT NORTH OF A SURFACE COLD FRONT AND IN THE RIGHT
ENTRANCE REGION OF A SUBTROPICAL JET STREAK. WPC QPF WAS TRENDED
WETTER BASED ON THE TRENDS IN MOST OF THE MODEL GUIDANCE. FOR
PLACEMENT...TRIED TO STRIKE A BALANCE BETWEEN THE ECMWF (FURTHER
NORTH) AND GFS (FURTHER SOUTH). GIVEN THE STRONG SURFACE HIGH
SETTLING INTO THE RIO GRANDE VALLEY...THE TREND MAY BE FOR THIS TO
END UP TOWARD THE SOUTH END OF MODEL SPREAD...BUT CONFIDENCE WAS
NOT HIGH ENOUGH TO PLACE GREATER WEIGHT ON A PARTICULAR SOLUTION.

CHENARD/LAMERS

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

24HR QP VT 14/00Z
 0.01 492612 493614 494614 495616 496616 497618 498620 500622
      502624 502626 504628 505631
      512646 514658 516666 522683 524704 521718 517727 513733
      500742 486746 471753 465755 460759 454764 452770 448777
      448782 447785 448795 448800 450804 452811 453817 455821
      453829 450831 446833 448843 451850 459861 462863 464859
      466856 466851 468850 469855 469860 472863 475862 477865
      481869 485884 494897 498901 503906 507911 510917 514926
      517936 519946 518954 517960 515964 512968 510970 507970
      504972 503971 498969 494967 491969 492975 495977 501982
      509991 514997 512000 507999 498998 495997 492997 492001
      489004 485003 484000 477988 472990 468994 464994 462992
      458988 438968 438964 437961 433955 429949 424945 421942
      420939 419933 421931 425930 429929 429926 429919 429914
      427909 427901 425893 421891 418893 411896 408896 406894
      402890 398883 395873 394867 392863 392854 397841 398839
      398835 394830 389825 386820 380818 374817 366816 369813
      374808 378803 389793 401786 407784 413780 424772 419757
      419749 420745 421743 423741 423736 418733 420730 424728
      427725 431724 432721 433717 435713 434706 433701 430696
      426696 423697 417701 413707 412715 410721 406727 401732
      397736 391738 384741 378747 371753 362750 359743 367737
      369731 365722 362719 358710 357708 359702 362694 366688
      370682 374676 383664 388658 393654 397649 403642
 0.01 477147 477141 474136 473131 470125 467117 465104 458097
      454094 450092 442086 435080 434075 431070 429068 424065
      421065 419069 417074 417081 425098 430107 433112 436115
      440125 443129 446133 451139 454144 457148 461151 466152
      470153 474149 477147
 0.01 446150 445145 442141 440137 438133 435130 433131 434138
      435143 436148 437153 441155 444152 446150
 0.01 430125 431121 430118 428112 425106 422101 417098 410097
      408101 412106 416109 420114 423119 426124 430125
 0.01 391806 393811 395820 397821 398820 397814 395808 394804
      392801 391803 391806
 0.01 251812 250808 249802 249796 248790 244791 242794 240797
      239802 238807 239813 241817 245817 247813 251812
 0.25 500703 500694 498685 494668 492662 490657 482646 476638
      471636 465638 453642 447645 442649 439653 434656 430659
      425664 423669 424677 427681 432684 434690 438693 442697
      446702 446717 450720 453725 457729 462730 467731 474730
      480728 485726 490723 494718 498711 500703
 0.25 478915 478912 478909 478907 477905 477904 476905 475905
      474905 472906 471907 470910 470911 470912 470915 470917
      472919 474919 475917 476917 477916 478915
 0.25 461922 458913 457904 459898 461893 459888 454878 449871
      445866 447862 440856 437853 435847 424829 422826 418824
      416829 416837 418844 420849 424860 427869 430881 439900
      449918 451923 454926 461922
 0.25 438762 438758 437754 435753 432754 430756 428758 428762
      429767 430769 431773 432776 433774 435771 436769 438765
      438762
 0.25 425791 424789 421788 417789 416791 414793 413798 415801
      417803 419805 422805 424801 424798 425794 425791
 0.25 399691 399688 398687 397686 396686 395687 394687 393688
      391690 390693 391695 392697 393699 395701 396699 396698
      397696 397695 398693 399691 399691
 0.50 494699 493686 489675 486668 482658 477651 475648 471647
      463649 453653 447657 443666 442671 444674 442683 441688
      443692 451694 459694 456705 457711 459714 464721 467722
      471722 481719 487715 492708 494699
 0.50 445894 444889 444887 443882 442880 440876 438875 436873
      435873 433877 433878 435881 437885 438887 440890 441893
      443895 445894
 0.50 436761 435758 435761 436761 436761
 1.00 486702 486697 485692 481688 480683 480678 479674 476675
      474677 473685 473690 472693 470701 471708 472710 475712
      481708 484704 486702
 1.00 473660 473657 473656 472655 471655 470656 469656 468658
      467659 467662 468664 469664 470663 472662 473660 473660

24HR QP VT 15/00Z
 0.01 524259 516259 506260 499263 491271 488273 483275 480277
      475280 469286 465289 463294 460298 460305 461318 462324
      465328 470332
 0.01 477618 485625 487629 491633 495634 498638 501642 504647
      509658 514670 519681 524693 529705 533717 538729 542742
      543744 554802 545804 534800 530801 524799 515791 505782
      499781 492777 486775 481771 476757 475740 475736 474733
      470729 466727 461726 457724 453725 446727 444727 442724
      441714 450706 456700 458689 460683 463675 468672 470667
      472662 472657 471655 466651 461650 454651 450654 449657
      446663 442667 437672 431676 427683 425692 423699 421709
      420714 419723 423727 425732 422735 421739 422743 425746
      427746 433749 435751 436756 437759 438763 436782 434789
      436798 437803 440804 442800 442796 442791 447792 450795
      453801 455806 455812 454816 454822 457827 460834 465839
      469838 475842 476845 477851 477858 479862 480873 480878
      480883 472910 470916 466920 464920 462918 460911 460904
      461899 462889 462877 459871 460864 456862 452864 449867
      449872 447874 447879 444884 441887 437890 430890 427888
      423884 413876 409871 407868 402867 398862 394854 389842
      389836 387832 386828 381828 376826 369827 365826 364818
      372811 375805 378799 382793 387788 393782 394779 391776
      389771 390764 391762 392756 391751 390748 385745 381745
      380744 376740 375733 371732 368733 363736 353744 350745
      348747 342753 331759 320752 317750 317745 318739 320725
      321719 322715 332708 339697 344692 350688 356683 362678
      382660 388652 397644
 0.01 554050 556041 555032 552020 544010 536000 532998 529994
      521989 508988 503989 499990 495989 492985 489982 485983
      481979 473972 467967 462966 451966 441971 432962 427961
      419961 409961 404964 402970 401977 401981 403984 406989
      412994 416995 420998 423001 427006 431018 439019 441017
      444017 448019 451020 452024 453030 450031 447031 440032
      436035 436043 439050 442053 447054 453054 456052 476037
      518054 523055 527053 533053 537059 542071 544071 547069
      551064 554050
 0.01 527949 527939 523931 520928 517926 514926 512928 509928
      502929 497932 493934 489934 482934 477937 474942 474947
      476950 481954 487955 491955 492957 497962 502967 509968
      514967 520965 523963 524960 527950 527949
 0.01 446099 446096 443094 437090 434087 432085 432081 434076
      434071 429066 426058 413047 408042 404040 405037 403035
      398034 395034 393032 391027 390020 388015 386015 386022
      384026 380026 377023 370023 367027 363027 360025 357026
      355031 355038 356044 357050 355053 355058 360060 358065
      360069 365073 373075 374081 377085 383081 387086 389084
      393084 395087 398085 401086 403089 405097 405103 403109
      401111 403114 407114 410110 414104 418105 421107 426108
      430107 434105 439105 442106 443103 446099
 0.01 314058 313049 311041 308034 303030 299027 295033 295038
      296042 298050 299053 299059 302065 304068 308068 312062
      314058
 0.01 292841 292835 291832 289832 280831 275836 272845 267853
      265856 266860 273865 275869 276874 280873 283871 287862
      289854 291849 291843 292841
 0.01 270058 271048 272036 271033 268030 265027 265021 263015
      256010 252010 250012 247016 245020 244028 240036 238057
      237067 237079 238086 241090 244088 249086 256081 260074
      266068 270058
 0.25 437632 437638 436643 430651 422658 416666 413675 409686
      406694 404706 402715 400721 396719 393716 391711 388708
      384705 381704 376705 369705 366703 364698 363694 365689
      368685 373678 379669 392655 404642
 0.25 518727 518716 517706 515698 513691 509686 506686 503688
      502695 503702 506706 508716 511723 512732 514734 517732
      518727
 0.25 416814 416811 416809 415807 415804 413802 412800 411799
      409799 409801 410802 410803 411805 411807 412810 412811
      412812 414814 414815 416814 416814
 0.25 409791 408787 407785 404784 401785 399787 398789 396791
      393794 395796 399797 400799 402800 406800 407797 409794
      409791
 0.25 406058 405058 404056 403056 402055 401055 400057 400058
      401060 402060 403062 405060 406058
 0.25 257065 257061 256059 253058 250057 247058 246061 245064
      246066 247070 249072 252071 254069 256067 257065
 0.50 403663 400657 396657 393659 387664 383670 378676 375683
      376687 378689 382689 385687 392683 398678 403672 404667
      403663

24HR QP VT 16/00Z
 0.01 503313 500309 495308 491308 485306 480304 476304 471305
      468304 464304 459303 450304 445302 442299 440293 441286
      442283 440281 435275 430268 427260 425254 424250 422240
      424236 427235 429234 431231 431224 459207 465208 469207
      475204 480202 483202 488202 492201 495200 496196 491191
      489185 486184 482181 480177 478175 475174 469180 457192
      450195 447192 444191 441189 441184 447179 447172 445167
      446153 460142 463142 466141 470133 471128 475126 478126
      481129 485131 486133 489134 493132 495130 496127 496122
      495116 493102 494099 497095 501083 505074 506065 507060
      507055 506052 506043 503032 501027 499023 494013 487998
      483990 480979 479975 478967 477956 472949 469940 472930
      472921 472917 471914 466915 463913 456908 453906 451902
      450899 452892 454887 454883 452879 444876 436876 429875
      424875 421878 415882 413882 412879 410874 409869 408863
      409857 409850 408845 405843 401835 403828 401823 399818
      395817 386819 376824 374822 373815 379795 381787 380775
      375768 370763 364760 359759 353761 347766 342775 324808
      316824 310833 307844 303858 303864 304867 305879 305888
      304899 302910 300922 297945 295969 296974 296980 295996
      296003 297006 299012 302012 304010 315039 316048 313057
      312070 311075 309079 305082 301083 296082 293078 289070
      286069 283069 281072 277080 274083 268083 261085 250083
      244078 240072 236065 236053 236044 236034 236009 238984
      235963 235956 234952 235947 235939 242921 246913 250906
      252903 253897 252883 252875 253866 256850 257846 257842
      259838 263827
 0.01 263827 271812 274803 273796 274790 274783 276774 279765
      282758 289742 291738 294735 302727 311718 318711 324706
      354684 367674 378663 393651 399646 405644 407651 406670
      404675 406682 408693 407703 405713 400723 400730 399735
      402739 403744 407753 407761 408766 411768 413767 421768
      424767 427765 427762 427760 429757 432757 435751 441747
      447742 448741 451745 452750 451755 449766 449773 448778
      453779 456776 456774 459775 462778 464782 466784 471791
      471801 474810 476817 477822 476828 476835 478851 478858
      481862 484867 484872 485879 483885 484890 487894 490899
      498904 502914 502927 499940 497947 495950 492952 491956
      493959 497962 502967 529989 553008 557010 562013 568022
 0.01 547178 547170 545166 542160 539156 534153 534144 532133
      529127 526123 524116 524107 526105 526100 527092 531088
      535093 537105 540111 543114 546120 549123 556130
 0.01 546790 546769 544752 535727 530714 526703 515682 508676
      503678 502682 500685 501689 502698 500711 499718 500721
      502724 502731 505736 509750 514762 519773 522775 525781
      531789 534792 537794 540796 544796 546790
 0.25 562083 556077 551069 546061 541054 535048 530039 528029
      528024 529022 533023 541026 549028 554030 557031 562038
      565042
 0.25 525258 522257 518257 514253 510243 505232 497225 494225
      494227 493233 492239 489244 487252 483255 483260 484266
      486271 490276 499280 510285 514286
 0.25 532203 532197 530192 528188 525185 521183 517182 515187
      515192 518197 520201 523204 528205 531205 532203
 0.25 471845 471843 469842 468842 467843 467846 468846 470847
      471846 471845
 0.25 457808 458800 456794 451796 449799 446804 443806 440810
      439815 441820 444823 448824 451821 453818 455813 457809
      457808
 0.25 456852 457847 456843 452844 451846 449848 447850 444853
      443856 441858 440861 441863 445863 448862 450861 452860
      454857 455855 456852
 0.25 387684 387678 385675 381675 376677 370679 365683 363683
      361686 356692 352696 343699 337703 332707 327712 324717
      316729 312735 310741 305755 300768 299775 298786 299790
      301793 305792 308790 316778 322767 331756 339744 347733
      356725 361719 366714 374704 387684
 0.25 288937 289925 288915 287904 286895 284884 282873 278872
      276875 276880 277886 268900 264915 261924 257932 250944
      246951 242959 242969 244977 246985 246990 244995 241001
      240004 239009 240019 242029 244036 248042 254047 258047
      262045 267041 271034 275027 277023 277016 278995 279985
      281975 285956 288945 288937
 0.50 522266 520266 518266 517268 516270 516273 517275 517276
 0.50 351709 350707 347707 341709 336709 334710 334715 332721
      330726 329733 334732 339728 343724 346719 349714 351709
 0.50 279949 280941 278935 278928 275925 270926 266930 261937
      258943 255948 250956 247961 245968 247973 250976 253982
      253986 248996 243006 242013 243020 244024 248030 252032
      259031 263029 266023 270013 271007 271999 270987 270982
      272976 276966 277955 279949
 1.00 268964 269960 269956 269952 268949 266951 265952 263955
      261956 259959 258962 257964 258966 261967 265967 267966
      268964
 1.00 262009 262004 262002 260000 257999 253000 251002 250004
      249006 248010 248014 249017 250018 253018 256017 258015
      260012 261011 262009

$$





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