Quantitative Precipitation Forecast
Issued by NWS

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000
FXUS04 KWBC 050700
QPFPFD

QUANTITATIVE PRECIPITATION FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
200 AM EST TUE DEC 05 2017


PRELIM DAY 1 QPF DISCUSSION
VALID DEC 05/1200 UTC THRU DEC 06/1200 UTC
REFERENCE AWIPS GRAPHICS UNDER...PRECIP ACCUM - 24HR


DAY 1

...EASTERN U.S / INCLUDING EAST TEXAS...

EARLY TUESDAY MORNING A 983MB SFC LOW WAS LIFTING THROUGH LAKE
SUPERIOR. CYCLOGENESIS HAD OCCURRED IN SUCH A WAY...WITH COMPLEX
STREAM INTERACTION ALOFT...SO AS TO PRODUCE MESOSCALE AREAS OF
HEAVIER PRECIPITATION RATES...AND NOT SO MUCH THE CONSOLIDATED
SWATH OF SNOWFALL THAT WAS EARLIER ANTICIPATED. THE TRENDS
CONTINUE TO PUSH THE HEAVIER WRAP-AROUND SNOWS DURING THE MATURE
PHASE...INTO ONTARIO...WHILE ADDITIONAL MODERATE SNOWS WILL START
TO DIMINISH OVER THE ARROWHEAD OF MINNESOTA BY 12-15Z. IN THE
POST-FRONTAL REGIME THIS TURNS INTO A LAKE-EFFECT
EVENT...PARTICULARLY FOR THE KEWEENAH PENINSULA AND PARTS OF
NORTHERN LOWER MICHIGAN. FARTHER SOUTH AND EAST THE MID LEVEL DRY
SLOT WILL LIMIT VERTICAL MOISTURE DEPTH...BUT A DEVELOPING LONG
FETCH ACROSS LAKE ERIE EVENTUALLY SHOULD KICK IN WITH ORGANIZED
PRECIPITATION...THOUGH INITIALLY THIS WILL BE RAIN. FOR MORE
DISCUSSION ON THE WINTRY WEATHER SEE THE WPC HEAVY SNOW
DISCUSSION...QPFHSD.

THE DEVELOPING CYCLONE WAS PUSHING A COLD FRONT THROUGH THE
EASTERN U.S...AND AS OF 06Z A FAIRLY SOLID SQUALL LINE WAS MOVING
INTO WESTERN TENNESSEE AND SOUTHERN ARKANSAS. LESSER INSTABILITY
FARTHER NORTH AND LESSER FORCING FARTHER SOUTHWEST WILL RESULT IN
SOME BREAKS...ALTHOUGH MOST LOCATIONS WILL SEE RAIN AS THIS SYSTEM
SWEEPS STEADILY EASTWARD THROUGH TUESDAY. THE WRF-ARW2 WAS
HANDLING THE PROGRESSION AND INTENSITY PARTICULARLY WELL. LOOKING
AHEAD INTO THE DAYLIGHT HOURS...AND JUDGING BY SIMULATED
REFLECTIVITY AND FORECAST SOUNDINGS...ROBUST CONVECTION SHOULD BE
CONFINED SOUTH OF INTERSTATE 40 AND WEST OF THE MOUNTAIN AREAS. AS
FORCING SPILLS OVER INTO THE CAROLINAS THE MOISTURE RETURN APPEARS
INSUFFICIENT TO YIELD MUCH...IF ANY...CAPE. THUS THE TREND WAS
TOWARD LESSER AMOUNTS FROM EASTERN NC UP THROUGH VIRGINIA TO THE
DELMARVA. FARTHER NORTH THERE MAY BE VERY SLIGHT CONVECTIVE
ENHANCEMENT OWING TO STRONG DEEP LAYER HEIGHT FALLS OVER THE
NORTHERN MID ATLANTIC INTO NEW ENGLAND...THOUGH THUNDER IS NOT
LIKELY. THE QPF DISTRIBUTION MAY LAY OUT VERY SIMILAR TO THE 12Z
ECWMF AND ECMWF ENSEMBLE MEAN. THE GFS HAS NOT BEEN THE BEST AT
HANDLING THE SOUTHERN LATITUDES...AND MAY BE A BIT OVERDONE WITH
AMOUNTS IN NEW ENGLAND GIVEN THE QUICK PROGRESSION.
GENERALLY...HOWEVER...LOCALLY HIGHER TOTALS ARE EXPECTED IN NEW
ENGLAND OWING TO WARM ADVECTION-FORCED PRECIP QUICKLY FOLLOWED BY
THE FRONTAL ZONE AND HEIGHT FALLS. ANOTHER MAX WILL BE ACROSS THE
SOUTH WHERE SOME INSTABILITY IS TO BE FOUND. WPC USED ROUGHLY A
40/40/20 BLEND OF THE ECMWF/WRF-ARW2/WPC CONTINUITY.


...SOUTHWEST / INCLUDING SOUTHWEST TO CENTRAL TEXAS...

WITH AN ONGOING LARGE SCALE PATTERN CHANGE...AND BUILDING RIDGE
ALONG THE WEST COAST...SOME SHORTWAVE ENERGY WILL SLIDE BENEATH
THE RIDGE INTO A WEST TO EAST ORIENTATION. THIS SETS UP A
FAVORABLE SITUATION FOR RAIN AND WINTRY MIX PRECIPITATION ROOTED
IN THE MID LEVELS...AND FORCED BY THE UPPER JET ALONG WITH A LOW
AMPLITUDE RIPPLE IN THE WEST TO EAST FLOW. DETERMINISTIC AND
ENSEMBLE MODEL QPFS AND ASSOCIATED PROBABILITIES ALL POINT TO TWO
SWATHS...ONE FORCED MORE IN THE MID LEVEL FRONTAL ZONE FROM
EASTERN AZ TO NEAR LAMESA TX...AND ANOTHER WITHIN THE LOWER LEVEL
FRONTAL ZONE...ENHANCED BY SOME NORTHEASTERLY SFC WINDS /
UPSLOPE...OVER FAR SOUTHERN AZ/NM AND SOUTHWEST TEXAS. EVENTUALLY
THIS JET FORCING SHOULD LEAD TO DEVELOPMENT DOWNSTREAM INTO THE
TEXAS HILL COUNTRY AS THE PATTERN EVOLVES. GETTING THE PLACEMENT
OF THESE AXES CORRECT WILL NOT BE EASY...AND THERE IS SOME NORTH
TO SOUTH SPREAD IN THE GUIDANCE. SIMILAR TO OTHER
AREAS...HOWEVER...WPC LEANED MORE HEAVILY TO THE ECMWF AND ITS
ENSEMBLE...AS WELL AS THE 00Z WRF-ARW2 AND HREF MEAN. SEE THE
HEAVY SNOW DISCUSSION FOR DETAILS ON THE ICE/SNOW POTENTIAL IN
SOME PARTS OF THIS REGION.

BURKE

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


24HR QP VT 06/12Z
 0.01 537083 535069 532061 528055 520043 510034 501028 491019
      488015 486013 481009 478007 475006 472001 469996 466989
      458978 453973 449966 442957 437952 434947 430942 427934
      422919 417905 413894 411897 411903 412911 415920 415925
      417928 417940 418947 419963 423973 424976 424981 425985
      426990 425995 422999 425011 430015 433020 437026 438029
      438033 436035 436039 437049 438052 439057 441065 443067
      442071 441072 444075 445079 447082 450083 453080 452068
      450062 449059 451057 452060 458060 464058 469063 475068
      476069 479067 481065 486067 493076 496083 496094 496097
      500098 502098 504095 506091 508089 510088 515087 519088
      522091 524089 527089 531090 534090 537083
 0.01 508682 505674 503665 501658 498654 493645 491641 488639
      480634 477632 472634 460638 439645 423659 416664 408671
      393683 380692 373697 368704 343733 318762 312769 305775
      297781 290784 277792 263788 264793 263797 261797 257797
      253800 252802 256805 261805 260808 257812 256816 261823
      266823 269820 272815 276812 281805 287805 292806 302803
      310800 314802 319800 323797 327794 329792 331794 327801
      321809 315815 301829 286841 282844 279848 274858 271865
      269875 270880 274882 270888 267892 267895 267905 279914
      280918 280922 279928 274936 271945 264951 259961 257964
      253967 248974 247982 247991 249995 253997 258001 262003
      268003 275000 278999 281996 284994 288994 291998 292002
      294010 296023 299033 300040 300047 298060 297065 295073
      292079 291084 294095 297103 303109 307111 311110 320106
      323105 328107 332113 336117 341117 344115 348114 349108
      347103 346097 345094 346087 347082 347074 345062 346049
      345038 342026 338016 335008 327003 325004 324001 323995
      321984 320980 320974 321966 322953 327946 331938 337930
      343922 348914 354906 359899 363892 368884 373877 378867
      390849 391846 394843 399839 411826 424812 428809 431808
      433810 435814 440815 444815 448818 451824 452829 451836
      447840 444844 442850 437851 432852 427852 424855 425858
      428860 436864 448867 451864 455864 458867 458874 456886
      454900 454908 456913 459917 463919 471923 476930 481930
      484932 484934 487942 490946 494947 497945 499939 498935
      507937 510936 514934 518926 522915
 0.01 522915 523909 523899 522881 520873 518868 515862 512858
      504851 500847 497842 494838 492832 484824 481820 476819
      471815 468811 464799 468794 471789 481769 485757 487750
      490744 494733 496728 497724 497719 499705 505696 507687
      508682
 0.01 453100 452098 452095 452094 450092 448094 448097 449099
      450100 451101 453101 453100
 0.01 242823 242821 242819 241817 241815 240815 239813 239811
      238811 237812 236813 236814 235816 236818 236820 237822
      238824 239824 241824 242823
 0.25 509053 508047 505044 500043 498043 495041 494038 489035
      487035 490038 492041 494046 498048 502050 505052 509053
 0.25 492682 491673 489667 486660 483657 477654 471652 466651
      458653 451655 445658 433667 423677 414687 408695 400702
      394707 390708 387706 387701 385698 382699 380702 362718
      352729 345739 341748 340755 341762 338767 335762 334758
      331756 327760 320769 311779 307784 304791 306792 310791
      315789 323784 329779 332774 335769 337769 339771 346770
      353767 357763 361758 361763 358771 346794 344806 337815
      321836 313846 300851 294854 289858 285862 283869 284879
      284885 286886 289885 295883 298882 300884 300891 297898
      294912 290923 286929 284937 278949 276955 275960 271972
      270978 272982 274983 279981 284976 301960 310951 318941
      344900 358881 366868 373857 398814 405803 413795 423786
      423792 426795 430789 432784 436780 444773 453763 459761
      465760 471758 475755 477746 478737 481730 483721 485712
      487707 490695 491688 492682
 0.25 506890 506883 503879 498877 496872 492859 491853 488848
      483838 480834 476831 458837 455840 452845 451852 455852
      462848 465854 466861 468866 468871 468874 464886 461898
      462903 467907 470905 474900 482894 490897 500898 505896
      506890
 0.25 463824 463822 463821 462819 461819 461820 460822 460823
      460825 461827 462828 462827 463825 463824
 0.25 387781 386776 384775 381776 378778 377780 375783 374785
      373789 372792 373797 374796 377794 379792 380791 382789
      384786 386783 387781
 0.25 338093 339089 339087 340085 341080 340076 340074 338073
      335075 333077 331079 332083 334086 335088 336091 337093
      338093
 0.25 338065 338063 339060 338058 338056 336057 335058 334060
      334062 333063 333064 333066 331068 331069 330070 330073
      330075 331076 332075 333075 334073 335071 336069 337067
      337066 338065
 0.25 325083 327077 326072 323061 321052 320048 316045 314047
      312051 312062 311073 307083 305093 306098 310100 317095
      322088 325083
 0.25 310000 310996 311992 311988 311983 311979 311975 308974
      306976 305979 304982 304985 303990 303994 303998 304001
      306004 309002 310000
 0.25 300796 299794 297795 295795 293796 293797 293799 294799
      296799 297798 299797 300796
 0.50 485684 486678 484671 481666 478663 471659 463658 455659
      447665 440672 436678 432687 430697 427702 423705 417710
      408725 404734 402739 399742 392746 389750 388755 390760
      393762 396762 396766 394770 394774 397776 400779 404781
      409780 413777 417769 420763 426762 430764 436769 440770
      443767 446760 450750 451747 449743 447741 445734 448730
      451731 453732 453736 454743 456748 460750 464751 468749
      470744 471735 476726 481704 484694 485684
 0.50 486864 486856 485851 483847 480842 478838 474837 471840
      470846 472853 474855 477860 479865 481869 483869 486865
      486864
 0.50 481877 481872 477872 474875 471878 469883 467888 467895
      470895 474892 476889 479884 481879 481877
 0.50 393800 395798 394796 393797 391798 390800 391802 393800
 0.50 381743 381741 381739 380738 378739 377741 376742 375744
      374747 373749 374750 376749 378749 378748 379747 380746
      381744 381743
 0.50 378714 377711 373712 368716 361725 353733 350738 349745
      350747 354747 356748 356751 352755 350761 350764 354762
      357758 358752 361746 365742 368737 368732 370727 377717
      378714
 0.50 386809 382808 377808 372810 368814 360820 356819 354818
      353815 349815 347819 345830 342835 338836 332838 329842
      326850 323861 318870 312877 308883 304892 304897 303903
      301907 299912 285949 293953 296956 299953 299944 304935
      314937 319929 324921 335906 347890 357876 367860 372852
      376842 377836 379830 382820 386809
 0.50 350764 348763 347764 346765 347767 349766 350764
 0.50 331765 331763 328761 327763 324767 322769 319774 317777
      316781 312785 314786 318784 321782 325778 327775 329770
      331766 331765
 0.50 322898 322896 320894 318896 317898 317899 316900 315903
      314905 314907 314909 315911 316909 317908 317907 319905
      320902 321900 322898 322898
 0.50 297866 298863 297862 295863 293863 291864 290865 289866
      288867 288868 287870 288872 290873 292872 293870 294870
      294868 295867 297866 297866
 1.00 474677 472672 468669 463669 457670 452672 448676 445680
      443686 441699 439711 439717 442713 446710 450707 454705
      458701 466693 472685 474680 474677
 1.00 470716 470714 468712 467714 467717 467719 469718 470716
 1.00 439728 438720 435721 430724 428726 429729 430733 429737
      429745 432752 434758 437759 439755 438751 438743 436736
      438731 439728
 1.00 364840 355841 350842 347845 341854 337863 333874 333882
      333890 333893 332897 334897 336895 340889 345882 350874
      355865 360854 360849 362843 364840
 1.50 343865 345860 346858 346856 344858 343860 342861 341862
      341863 340865 341866 343865

$$





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