Quantitative Precipitation Forecast
Issued by NWS

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000
FXUS04 KWBC 060702
QPFPFD

QUANTITATIVE PRECIPITATION FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
201 AM EST WED DEC 06 2017


PRELIM DAY 1 QPF DISCUSSION
VALID DEC 06/1200 UTC THRU DEC 07/1200 UTC
REFERENCE AWIPS GRAPHICS UNDER...PRECIP ACCUM - 24HR


DAY 1

...SOUTHWEST U.S. / SOUTHWEST TEXAS...

A DEEP TROUGH HAD SETTLED INTO THE SOUTHERN U.S...ESTABLISHING A
CORRIDOR OF STRONG UPPER JET FLOW EXTENDING FROM THE PACIFIC
AROUND BAJA THROUGH SOUTHWEST TEXAS AND ON DOWNSTREAM TO THE EAST
COAST. VERTICAL PROFILES WERE VERY MOIST IN THE MID LEVELS AND
SHOULD MOISTEN IN THE LOW LEVELS THROUGH EVAPORATIVE COOLING AND
CONTINUED LARGE SCALE LIFT. THUS A FAIRLY EXTENSIVE PRECIPITATION
EVENT IS EXPECTED...PARTICULARLY OVER SOUTHWEST TEXAS...AND
UPSTREAM TOWARD THE MID LEVEL TROUGH AXIS...THROUGH NORTHERN
MEXICO...INCLUDING MORE OF THE RIO GRANDE BASIN / WGRFC AREA OF
CONCERN. PRECIPITATION MAY END UP A BIT BANDED WITH PERSISTENT
FRONTOGENETICAL FORCING IN THE MID LEVELS AND DECENT LAPSE RATES
IN 00Z SOUNDINGS...ALTHOUGH MODEL QPFS ARE NOT SHOWING A
PARTICULARLY STRONG BANDING SIGNAL. BETWEEN THE FRONTOGENESIS /
UPPER JET REAR QUAD FORCING...AND THE ARRIVAL OF ADDITIONAL
NORTHERN STREAM ENERGY INTO THE BASE OF THE TROUGH / I.E.
CONTINUED HEIGHT FALLS / PRECIPITATION WILL BE FAIRLY CONTINUAL
AND CONTINUOUS...STRETCHING ALL ALONG THE MID LEVEL FRONT AND
SLOWLY DROPPING SOUTHWARD. AT HIGH ELEVATIONS IN SOUTHWEST TEXAS
SOME OF THE PRECIPITATION WILL FALL AS ICE AND SNOW...WITH
DETAILED DISCUSSION IN THE WPC HEAVY SNOW DISCUSSION...QPFHSD.

THE QPF WAS RELATIVELY EASY TO HANDLE HERE GIVEN THE STRONG  MODEL
AGREEMENT. OUR QPF BLEND WAS MORE STRONGLY RELATED TO PREFERENCES
DOWNSTREAM INTO CENTRAL TEXAS AND FARTHER EAST...BUT GENERALLY
SPEAKING WPC STARTED WITH A 50/30/20 BLEND OF OUR IN-HOUSE
ENSEMBLE /00Z NAM/ WPC CONTINUITY. THIS APPROACH YIELDED VERY
LITTLE CHANGE TO THE QPF...AND DURING THE 30 HOUR PERIOD ENDING
12Z THURSDAY WE ARE FORECASTING AREAL AVERAGE LIQUID AMOUNTS
AROUND ONE INCH FROM THE EDWARDS PLATEAU / CONCHO VALLEY THROUGH
THE TRANS-PECOS REGION ON INTO CHIHUAHUA.


...SOUTHERN AND EASTERN U.S...

A DEEP AND SLOPING FRONTAL ZONE WILL BECOME ESTABLISHED BY
WEDNESDAY MORNING ACROSS THE SOUTHERN STATES AND EXITING THROUGH
THE CAROLINAS / LOWER MID-ATLANTIC STATES ALONG THE LEADING SIDE
OF THE DEEP TROUGH OVER EASTERN NORTH AMERICA. RAIN WILL BE MORE
OR LESS CONTINUOUS...OR OFF AND ON IN SOME LOCATIONS...THROUGH DAY
1...SUPPORTED ESPECIALLY BY MID LEVEL MOISTURE AND EITHER DEEP
LAYER ASCENT OR LOW LEVEL ADVECTIONS. THE DETAILS OF EACH 6-HOUR
PERIOD MAY BE DIFFICULT TO PIN DOWN AS PRECIPITATION STREAMERS
BECOME STRETCHED ALONG THE FRONTAL ZONE...BUT ON A 24-HOUR TIME
SCALE THIS ALL FALLS OUT FAIRLY SIMILARLY AMONG THE DETERMINISTIC
MODELS. A SHORTWAVE TROUGH THAT WAS ENTERING MONTANA AT 00Z
WEDNESDAY WILL QUICKLY DIVE THROUGH THE TROUGH AND GRAZE THE
SOUTHEAST STATES WITH ENHANCED HEIGHT FALLS AS WELL AS UPGLIDE ON
THE 300 K ISENTROPIC SURFACE...MAINLY THIS AFTERNOON/EVENING. THIS
WAVE MAY HAVE SOME INFLUENCE ON THE SURFACE BOUNDARY AND
ASSOCIATED UNSTABLE ENVIRONMENT NEAR NORTH FLORIDA TO SUPPORT SOME
CONVECTIVE PRECIPITATION THERE. BACK WEST...700 MB FRONTOGENESIS /
RIGHT REAR QUAD JET FORCING / LARGE SCALE HEIGHT FALLS APPEAR MOST
PERSISTENT OVER CENTRAL TO SOUTHEAST TEXAS...RESULTING IN A LOCAL
QPF MAXIMUM THERE. IN BETWEEN...AMOUNTS MAY BE MORE SUBDUED OVER
PARTS OF ALABAMA AND WESTERN GEORGIA WHERE DEEP LAYER FORCING WILL
BE LESS WELL SYNCED WITH LOWER LEVEL MOISTURE.

AGAIN...THE MODELS WERE SIMILAR...ESPECIALLY WITH THE 00Z GFS
COMING MORE IN LINE WITH THE OTHERS. FOR THE
SPECIFICS...HOWEVER...WPC RELIED MORE HEAVILY ON OUR IN-HOUSE
ENSEMBLE MINUS THE BIAS CORRECTION - WHICH PRESERVES LIGHT
AMOUNTS...AND THIS WAS CLOSE TO THE WRF-ARW AND ACTUALLY THE 00Z
NAM AS WELL.


...GREAT LAKES TO NEW ENGLAND...

THE ADVANCING FRONTAL ZONE AND ASSOCIATED RAINFALL WILL EXIT
THROUGH NORTHERN NEW ENGLAND EARLY THIS MORNING AFTER DUMPING
PERHAPS THREE QUARTERS OF AN INCH AVERAGE AMOUNTS ON DOWN EAST
MAINE. WE ARE THEN LEFT WITH LAKE EFFECT SNOWS AND PERHAPS A
LITTLE BIT OF SYNOPTIC SNOW AS SHORTWAVES PINWHEEL THROUGH THE
GREAT LAKES. A GOOD ALONG-LAKE FETCH SETS UP FOR ERIE AND ONTARIO
DURING DAY 1...AND 850MB TEMPS WILL BE VERY COLD...BUT THE EVENT
WILL BE QUITE SHALLOW...AND PW AMOUNTS VERY LOW AT AROUND 0.25
INCHES. WPC LEANED AS HEAVY AS WAS REASONABLE...USING MORE OF THE
HI-RES GUIDANCE TO DERIVE 24-HOUR LIQUID AMOUNTS OF NEAR A QUARTER
TO HALF INCH IN THE FAVORED LOCATIONS OFF THESE TWO LAKES AND
NORTHERN PARTS OF THE U.P. AND LOWER PENINSULA OF MICHIGAN.

BURKE

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


24HR QP VT 07/12Z
 0.01 469621 480632 485642 489654 490657 489663 488669 485673
      479678 470681 464681 456681 449682 443685 433687 429689
      426691 421692 418692 411691 405687 401695 402711 399719
      392734 383751 374765 367780 364787 360793 358799 357804
      357810 357815 356819 354828 351838 347847 339863 336872
      333881 329899 327909 327919 327939 326949 325960 326971
      329980 332991 334995 334002 334014 333026 332033 330037
      332041 335044 340048 345050 349050 357050 363047 371045
      377046 379049 379054 378056 376057 376060 378064 378073
      376076 372075 367073 361073 356082 343092 341096 338098
      334092 332089 329088 324087 321091 321096 320100 318101
      311098 307105 303113 297120 292121 285116 283112 283105
      279103 277100 274096 271094 267086 263085 261081 257075
      257069 259066 262059 264055 264050 264038 262021 263011
      267003 269996 267992 263990 259986 255982 254978 253974
      253972 253963 252948 253937 256918 266904 268899 273891
      274887 278884 283880 290875 297869 300868 299866 294868
      290869 287872 283873 280871 277868 273866 271864 270858
      271855 273852 276845 280838 285833 294822 304811 309805
      314798 316794 315792 311793 306794 301796 297798 293800
      291801 287800 284798 286795 292790 296785 301778 309765
      315751 322738 342709 346703 351698 364685 374675 377673
      381671 391669 397673 400674 402674 403671 405663 408657
      413646 420637
 0.01 503908 504885 502876 499868 495865 491871 488878 487886
      485894 482899 479907 478911 478917 483922 487927 486936
      486947 486952 487955 491955 492953 496952 497949 499942
      502921 502913 503908
 0.01 482708 481703 479699 473696 467700 464705 447726 440739
      434751 430769 426774 424780 421788 418797 415812 416823
      420830 422825 424817 426807 428800 434787 434782 436779
      440772 443766 446759 451745 451738 453732 464722 474717
      480712 482708
 0.01 488866 487851 484847 481842 480835 478832 475829 470829
      467832 464831 464829 463823 465818 468799 471788 470784
      467779 463777 459777 452774 448782 444793 443798 440801
      436804 434806 433812 433814 436815 443821 448827 450831
      450837 447839 444841 443843 438852 432854 425850 421848
      418851 417856 417863 423867 433867 456865 460873 461878
      461885 460890 459898 456909 455914 455922 457923 460920
      465920 467915 471904 475895 480887 488866
 0.01 470053 468045 464038 460033 456027 446017 442014 438007
      429994 427989 423982 419977 417975 415978 415989 417996
      409012 404014 399018 396020 393018 389017 388020 389027
      394032 397032 400035 405040 409047 411052 414055 418055
      423061 426063 427061 432059 436057 440060 441063 439067
      435072 436074 440072 444075 448081 455071 460065 466063
      470053
 0.01 453103 454095 452092 449089 444088 440086 435085 435088
      438093 439096 442101 444104 449105 453103 453103
 0.01 416066 415061 413060 411061 408064 406064 407061 407057
      404055 400056 397058 393061 391065 388068 388071 390072
      394069 396065 400062 401066 398069 397073 399076 403076
      405072 410072 413073 414068 416066
 0.01 395796 394794 395791 393791 391793 389794 386796 384798
      383801 381804 380806 380808 382807 385804 387802 388800
      392799 393798 395796
 0.01 396906 396901 396899 394895 392894 390892 388895 388897
      387899 387904 389906 389909 392911 394908 396906
 0.01 394851 393844 388845 385852 383857 382863 380870 381879
      381884 383884 385886 386884 388879 389872 391865 392858
      392853 394851
 0.01 354066 355062 353060 350058 347057 339056 336056 334059
      328060 325061 323063 322068 326070 331067 337066 344067
      349069 354066
 0.01 278805 276801 270797 264796 259796 253798 249802 252807
      255808 256810 259812 262812 269811 274808 278805
 0.25 495881 494880 493881 493882 495881 495881
 0.25 471658 471652 470648 467644 463640 458637 453635 448635
      443637 438641 428649 425654 423660 423668 426673 430672
      436670 448665 455663 460662 466662 470661 471658
 0.25 474845 473842 471840 468840 466844 466847 465851 463856
      463864 464867 466867 468863 468856 469851 471847 474845
 0.25 474882 471882 470885 468886 466888 465893 465895 463900
      463903 465905 467902 468898 469895 470892 471888 472885
      474882
 0.25 457788 455785 452787 449791 448797 446802 445806 444812
      447814 450815 452814 454811 455803 456798 457793 457788
 0.25 453850 454847 453846 451846 449846 448848 448850 448853
      450853 451852 453850 453850
 0.25 444756 445754 445752 443750 442750 440752 439753 438754
      438755 437758 437760 437763 438765 440765 441763 442762
      443760 443759 444757 444756
 0.25 432785 432780 429781 427781 424787 423794 423796 422797
      420804 419811 420815 421813 424806 425801 428793 430788
      432785
 0.25 389698 388691 383688 375689 370693 362700 353710 328744
      322753 315764 310775 310782 317782 323780 328780 327787
      324793 313809 298826 291834 287839 284845 283850 284854
      288859 293860 298858 302854 305850 307849 311848 314853
      312860 306872 304878 300884 297887 292890 287893 284896
      279905 266923 262933 259940 259950 260958 259965 260970
      265972 269970 272966 275965 276969 278982 277997 274011
      272018 271028 272034 274042 276056 266074 269078 272081
      274086 278089 289094 293095 297095 302091 308082 311077
      314070 317058 322049 323020 323014 323006 320990 319983
      318973 318957 319940 320926 324900 327870 328861 329856
      334843 341821 343815 345809 349800 351794 354788 361776
      366765 371754 375742 379730 383720 386710 388703 389698
 0.50 458649 458645 457643 453641 448644 445647 442650 438653
      436656 437661 442662 446661 449659 453656 456653 458649
 0.50 453796 453794 452794 452796 453797 453796
 0.50 441757 440757 441759 441757
 0.50 455791 454790 453791 454793 455791
 0.50 430786 429784 427785 426786 426788 426790 426789 428788
      429787 430786
 0.50 380700 377698 371700 363706 356713 351720 346730 340738
      329751 322759 319763 316769 317772 318774 321775 329770
      333768 337767 340770 340776 337787 330794 324802 316812
      309820 301826 298829 295834 291843 290847 292851 295850
      299846 305838 311831 316825 322823 329823 333820 336816
      340808 344799 346794 349789 354780 359772 363762 366752
      369741 372731 375721 379709 380700
 0.50 322883 321877 321872 319868 317868 314871 312875 306886
      301895 299900 297904 294905 288903 284907 281912 277916
      274919 272923 270931 267937 265943 264950 265956 264960
      264965 267965 268959 274946 276942 279941 281942 283946
      283952 283966 280997 278009 276018 276026 277034 279040
      282044 283053 282060 280068 277072 271072 272075 279078
      281084 286088 292089 298088 303084 305078 311049 315037
      316020 316005 314990 313984 313976 313960 314944 316928
      319900 322883
 1.00 370714 364715 359720 355726 352733 348740 345748 350748
      353746 358741 361734 364728 367721 370714
 1.00 306011 307003 308996 307983 307969 308956 308941 307928
      307914 305914 302918 297926 292935 290947 291960 287983
      288986 290987 292991 292004 291010 289015 287020 288026
      296031 299032 301025 304017 306011
 1.00 296082 296080 296079 295077 294077 292076 291077 290077
      289079 288080 288081 288082 288083 290084 292084 293083
      294083 296082 296082
 1.00 292062 293060 292058 290056 288057 288058 288060 288062
      288063 290063 292063 292062
 1.50 303987 303979 303973 302964 301956 300949 297952 297960
      296968 296977 295983 296989 299991 302989 303987

$$





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