Quantitative Precipitation Forecast
Issued by NWS

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FXUS04 KWBC 200702
QPFPFD

QUANTITATIVE PRECIPITATION FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
258 AM EDT MON MAY 20 2013


PRELIM DAY 1 QPF DISCUSSION
VALID MAY 20/1200 UTC THRU MAY 21/1200 UTC
REFERENCE AWIPS GRAPHICS UNDER...PRECIP ACCUM - 24HR


DAY 1...

...PLAINS/UPPER MIDWEST/UPPER MS VLY...

EXTREMELY COMPLEX FCST... FEATURING THE INTENSIFYING AREA OF LOW
PRESSURE OVER THE DAKOTAS... TWO SMALL SCALE MID-LEVEL LOWS/MCVS
IN CEN NE AND CEN IA... COUNTLESS SMALL SCALE SHORT WAVE
DYNAMICS...AN ANOMALOUS POWERFUL COLD FRONT AND DEEP TROPICAL
MOISTURE WILL SETUP HEAVY RAINFALL FROM THE NRN TIER OF THE
COUNTRY SOUTH INTO THE CENTRAL/SRN PLAINS. THE MOST ORGANIZED
RAINFALL AT THE MOMENT AND LIKELY TO PERSIST FOR THE NEXT SEVERAL
HRS IS TRUE SYNOPTIC SCALE FORCING ACROSS A GOOD PART OF ND BACK
INTO ERN MT/WY... AS DEEP MOISTURE OVERRUNS INTO THE COLD SECTOR
TO COMBINE FOR A HEALTHY DEFORMATION ZONE OF MDT TO HVY RAINFALL
AND OROGRAPHIC ENHANCEMENT IN MT/WY. THE GUIDANCE HAS A SOLID
HANDLING OF THIS STEADY RAINFALL WITH 1 TO 2 INCH AMOUNTS AND
LOCALIZED HEAVIER AMOUNTS. THE RAIN RATES SHOULD DECREASE OVER
TIME AS THE UNSTABLE CONVECTIVE DEVELOPMENT OVER THE PLAINS INTO
THE UPR MS VLY EVENTUALLY TAKES OVER THIS AFTN/EVENING AND THRIVES
OVERNIGHT. THE GUIDANCE REALLY VARIES... ESPECIALLY ON THE
HANDLING OF THESE TWO MID-LEVEL CIRCULATIONS AND THE LOCATION OF
THE HEAVIER QPF AMOUNTS. WPC FOLLOWED A COMPROMISE OF THE DATA...
BASICALLY A CONGLOMERATE OF THE GFS/ECMWF AND INTERNAL PSEUDO BIAS
CORRECTED GUIDANCE FOR A HEAVY RAINFALL AXIS FROM ERN IA/MN INTO
NRN WI... ANOTHER FROM ERN SD/ERN ND AND NWRN MN AND FINALLY A MAX
FROM CENTRAL/ERN OK NEWRD TO CENTRAL MO. IN ALL OF THESE
LOCALES... 1 TO 2 INCH AMOUNTS ARE POSSIBLE WITH LOCALLY HIGHER
NUMBERS... AS THIS REMAINS A SLOW LARGE SCALE SYSTEM OVERALL WITH
VERY FAVORABLE FACETS FOR HEAVY RAINFALL.

...SOUTHEAST...

ANOTHER COMPLEX AREA... AS A TRAPPED MID-LEVEL LOW NEAR THE SRN
APPALACHIANS FUELED A HEAVY
RAINFALL COMPLEX OVERNIGHT ACROSS NRN/NERN GA WITHIN INCREASING
WARM ADVECTION REGIME. AS THIS ACTIVITY HAS WEAKENED... MORE
UPSTREAM DEVELOPMENT OVER ERN TN/NWRN GA NEAR THE EDGE OF A MOIST
DECAYING DEWPOINT BOUNDARY HAS DEVELOPED AND BEGAN TRAINING AND
PROPAGATE SOUTH AND EAST TO PARTIALLY CLIP THE AREAS IMPACTED
OVERNIGHT IN GA. THE GUIDANCE INCLUDING THE HI-RES OUTPUT HAS
HANDLED THIS ACTIVITY OVER THE PAST 6 TO 12 HRS MARGINALLY AT BEST
AND THE FOCUS LATER TODAY INTO TMRW APPEARS BE SETTING UP OVER
SC/CENTRAL NC... AS SMALL POCKET OF COOLER AIR ALOFT WITH DAYTIME
HEATING INTERACTS WITH POOLING PW MAX FOR SLOW MOVING CONVECTIVE
RAINFALL. WPC FOLLOWED A COMPROMISE OF THE GFS/ECMWF AND INTERNAL
PSEUDO BIAS CORRECTED GUIDANCE.

...NEW ENGLAND...

A SHORT WAVE OVER ERN CANADA WILL SLIDE DOWNSTREAM TOWARD NOVA
SCOTIA/CANADIAN MARITIMES AND PRODUCE SOME WARM
ADVECTION/OVERRUNNING SHOWERS AND ISOLATED HEAVIER RAINFALL ACROSS
NEW ENGLAND THIS AFTN THROUGH TMRW. THE GUIDANCE AGREES THE MAX
ISENTROPIC LIFT NEAR A WARM FRONTAL BOUNDARY WILL LIFT FROM
INTERIOR NEW ENGLAND THROUGH MAINE. THIS IS WHERE WPC PLACED A MAX
OF A .50 TO 1 INCH RAINFALL FOR THE NEXT 24 HRS.

HURLEY

GRAPHICS AVAILABLE ON THE WEB AT WWW.WPC.NCEP.NOAA.GOV

24HR QP VT 21/12Z
 0.01 498647 497641 495636 490628 485623 480620 476617 470614
      461611 457610 454612 444622 440627 437634 435637 432638
      426641 423644 423647 420652 421658 423661 422664 416669
      403680 384696 382700 384706 386710 390711 397707 401705
      404706 409703 416700 419704 420708 421712 420716 419729
      418735 418740 418746 421754 421768 420778 420781 421785
      423789 424793 423800 421805 417811 415816 412830 409839
      406844 401846 395855 390858 387862 382865 379871 376876
      369880 365883 360887 356898 353907 349916 340933 328948
      325952 324957 324964 327967 330968 325970 318972 314975
      308982 306988 301991 296995 293996 288001 287007 285009
      286012 290013 300009 308006 320003 329999 335994 340994
      344995 350000 354997 357994 364986 379974 384971 387967
      393956 400947 410938 418931 424942 425951 422956 419961
      415963 413968 412974 407983 406988 409992 413997 413999
      415990 418983 421979 427979 429980 430982 429989 427991
      424993 422008 421015 421025 420041 417049 415051 411051
      404050 401045 399043 398038 396034 386015 384012 377011
      374010 371013 368018 364017 362015 357015 356021 357023
      359023 362023 365026 365032 364035 361035 357033 354037
      355041 357047 357054 361055 364058 367065 372068 377081
      380086 385089 389092 393090 398089 401092 402098 401107
      400112 402115 406118 410119 414118 416114 418112 424112
      430112 432114 434117 436118 439117 444113 447116 449119
      452122 450126 448128 444128 441130 439132 438136 438144
      441148 444151 447154 450155 450151 448145 448139 451135
      458136 466138 470137 474137 486140 489144 495147 499151
      505154 510156 514159 519160 520157 511136 509133 508128
      506123 504110 501104 496103 494106 491108 485106 481104
      480102 476098 470093 465091 461085 463080 475075 479074
      481072 486068 491064 494061 497059 499053 506041 508036
      510027 512013 515997 516987 517981 517971 517960 517946
      517936 516926 513902 511885 508867 503844 499833 497827
      493816 490810 485792 483777 479762 475745 472737 472730
      470723 467718 462715 461712 463709 465705 469701 474698
      478702 482704 483698 484681 483675 484670 488671 490672
      493670 497657 498647
 0.01 518268 519261 519255 517248 513242 516238 513231 509226
      506224 504227 502219 500214 494211 489213 482212 476211
      473213 470213 460216 454218 450221 438226 431233 427239
      424246 422252 421258 425266 428269 435279 448287 456290
      459291 461290 467288 471285 481278 486276 491273 499276
      505277 510275 514271 518268
 0.01 442715 439708 435706 431704 427702 425702 424705 427712
      430719 432726 433731 432734 435736 438731 441726 441720
      442715
 0.01 410757 407746 405743 402741 397742 391746 384749 379747
      372738 366733 361730 356728 351730 342741 339746 337751
      334757 332764 329769 323772 319776 312780 306784 300785
      294785 288783 280779 264767 257766 250770 247773 245778
      243783 242789 241800 242812 249817 267826 273829 278830
      287831 292834 296838 298840 299844 300848 302850 307853
      314853 318856 318853 318848 320845 324842 327839 330838
      336836 344832 348833 350836 353840 356836 359830 365832
      371833 377833 383831 387827 394823 400820 401818 400813
      398803 398797 399793 402791 402781 401775 404770 407767
      409762 410757
 0.01 319913 318909 315907 310905 306900 307893 305890 301894
      295899 294902 294906 295915 298924 301930 307930 312926
      315924 317920 319914 319913
 0.25 472672 470666 467661 461657 456655 449654 443656 439662
      432671 428677 428681 431684 438685 445684 452677 455676
      459677 465677 471675 472672
 0.25 511256 509251 509250 507247 506249 506253 506254 508257
      511256
 0.25 509952 507930 505911 503893 501878 497859 492844 484820
      472792 469787 466784 460778 456773 453768 449766 443770
      439779 438783 440791 440797 439804 437810 435815 427832
      409869 407874 402877 394880 377889 369895 364904 355917
      350927 345936 338951 336956 337960 339964 338969 331975
      329978 328981 330985 336985 342985 346986 351987 356986
      362980 375966 380960 385953 393945 400937 410922 416915
      422906 426903 432900 437900 440902 444907 447914 449919
      450927 449939 447950 446956 444961 441965 440973 440999
      437011 432024 432032 435043 440054 447062 450065 455065
      462063 468062 475060 479058 482055 490048 493045 496040
      500029 504014 506003 508989 509979 509967 509952
 0.25 472250 471247 468247 467248 467251 470252 472250
 0.25 379774 379770 377767 375764 368764 358767 350772 343779
      335782 327784 319788 313791 308792 302793 294793 287790
      262781 257782 253784 248789 246792 247797 252802 256804
      257806 259812 265815 270817 283823 287823 290822 290819
      286814 285811 287809 290808 293809 308811 312812 316812
      321814 336815 342814 347812 355807 360805 364801 367796
      368791 370787 374783 379774
 0.50 505980 505971 505961 504944 502930 500916 496884 495876
      492869 489861 479839 474830 469824 453819 449820 448823
      442829 429845 424852 421859 416868 411875 406881 401886
      396889 390891 383896 378899 374900 368904 358918 354925
      351932 347941 344949 342967 340976 342979 346982 354983
      359979 367972 372965 380953 384947 391940 397934 401928
      412914 417907 421899 424890 428882 435877 441877 446878
      448882 454892 456898 456904 456914 454920 454926 454941
      454949 452960 448971 447982 446988 447994 449003 452014
      452021 451024 439036 439040 440044 443048 450052 459054
      468053 474053 479051 484045 489038 493029 498016 502005
      503998 505988 505980
 0.50 365778 362776 357776 350782 340788 331790 321794 316797
      314799 316801 324801 331805 339805 348801 357794 362787
      365782 365778
 0.50 295800 290795 285793 278791 273790 267789 261791 258796
      263800 268801 274803 280805 286805 294803 295800
 1.00 500945 498931 496922 492914 490912 489907 491897 490885
      488873 485867 477850 473842 470839 467840 461846 459850
      459854 464860 467865 470869 471873 472881 472892 474903
      476906 480909 485912 486912 487917 484922 481926 479931
      476937 468948 467952 469955 471957 474958 477960 478963
      479969 479981 482994 481005 483011 485012 489010 492006
      494000 497994 500986 501977 499956 500945
 1.00 412898 412892 411890 407891 397898 393901 390905 389912
      386917 383918 378917 376916 376912 375908 372907 368911
      365915 359924 354933 350943 348955 347961 347968 347973
      349976 353977 356976 361973 364969 367965 371956 377946
      383937 390930 398921 405914 408910 410905 412898
 1.00 278797 277796 276795 274795 271796 271797 272797 274797
      277798 278798 278797
 1.50 485885 485881 484877 483872 482871 479869 478870 477874
      477875 477880 477884 477889 478893 479896 481897 483895
      485890 485888 485885
 1.50 494982 495978 494973 493972 490973 489974 489979 489983
      491985 494984 494982
 1.50 406904 404901 401902 398904 397906 396908 395911 396914
      397914 398914 400912 402909 403908 405905 406904
 1.50 379933 378930 376930 370930 368928 368925 368921 366919
      364923 365926 362926 359931 355940 351950 350961 351968
      355970 359969 361966 363963 368955 373946 377937 379933
 2.00 366951 367947 366944 366940 364937 363936 360938 358941
      357942 355944 355946 353948 352950 352954 352957 352961
      355963 358963 360960 361959 363957 364955 365953 366951

$$
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