Quantitative Precipitation Forecast
Issued by NWS

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663
FXUS04 KWBC 241807
QPFPFD

QUANTITATIVE PRECIPITATION FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
206 PM EDT WED MAY 24 2017


PRELIM DAY 1 QPF DISCUSSION
VALID MAY 25/0000 UTC THRU MAY 26/0000 UTC
REFERENCE AWIPS GRAPHICS UNDER...PRECIP ACCUM - 24HR



DAY 1

...OH VALLEY/CENTRAL APPALACHIANS/GREAT LAKES/ MID ATLANTIC/NEW
YORK/NEW ENGLAND...

THE MODELS SHOW A PARENT CLOSED LOW MOVING NORTHEAST OUT OF THE OH
VALLEY TOWARDS THE LOWER GREAT LAKES TONIGHT INTO THU. UPPER
DIVERGENCE MAXIMA IN THE LEFT EXIT REGION OF THE UPPER JET
CROSSING THE CENTRAL APPALACHIANS SUPPORT MAXIMA IN THE MID LEVEL
DEFORMATION ZONE OUT IN ADVANCE  OF THE LOW.  THE MODELS SHOW A
DEFINED QPF MAXIMA IN THE VICINITY OF LK ONTARIO/ADJACENT ONTARIO
DURING THU.

IN THE CENTRAL APPALACHIANS...THE LOW TO MID LEVEL FLOW WILL BE
BACKING IN RESPONSE TO THE APPROACHING UPPER TROF. AN UPSLOPE
COMPONENT OF FLOW WILL AID DEVELOPMENT OF SHOWERS IN TERRAIN OF
WV/VA/PA THE REST OF TODAY INTO THU. RUNOFF ISSUES MAY BE POSSIBLE
IN WESTERN VA/ADJACENT WV WHERE FFG VALUES ARE LOWER.

THE DEVELOPMENT OF A TRIPLE POINT LOW MAXIMIZED LOW LEVEL
CONVERGENCE ALONG THE I95 CORRIDOR WITH WIDESPREAD RAINS EXPECTED
FROM THE WASHINGTON DC TO NEW YORK CITY CORRIDOR TONIGHT TO EARLY
THU...INTO INTERIOR NEW YORK AND SOUTHERN NEW ENGLAND DURING THE
DAY THU.  DIFFERENCES IN QPF RELATE TO PHASING DIFFERENCES BETWEEN
THE DECAYING INLAND PARENT LOW AND DEVELOPING TRIPLE POINT LOW.
MANUAL PROGS USED A MULTI-MODEL BLEND WITH CONTINUITY. FURTHER
SOUTH...SHOWERS/STORMS THIS EVENING IN THE CAROLINAS AND GEORGIA
MOVE OFFSHORE IN TANDEM WITH THE PASSAGE OF THE LOW LEVEL COLD
FRONT.


...CENTRAL TO SOUTHERN FL...

THE MODELS FORECAST A ZONE OF CONFLUENT LOW LEVEL FLOW STREAMING
ACROSS THE PENINSULA WITH 1.5-2 INCHES OF PRECIPITABLE WATER
AVAILABLE AS THE BAND DEVELOPS TO THE SOUTH IN TANDEM WITH THE
AXIS OF THE LOW LEVEL JET DROPPING SOUTH TONIGHT.  THE STRENGTH OF
THE LOW LEVEL JET AT 40-50 KT SUPPORTS LOCALIZED STRONG
CONVERGENCE AND A PERIOD OF HEAVY RAINS ACROSS SOUTH CENTRAL TO
SOUTHWEST FLORIDA.
THERE IS A STRONG MODEL SIGNAL FOR BANDS OF SHOWERS/STORMS---BUT
STILL A LOT OF SHORTER TERM DETAIL DIFFERENCES WITH THE EVOLUTION
OF THIS PRECIP.  TO MITIGATE THESE DIFFERENCES--WPC LEANED MORE
TOWARD THE STORM SCALE ENSEMBLE MEAN---DEPICTING A BROAD REGION OF
1-2" AREAL AVERAGE AMOUNTS.  WITH THE POTENTIAL FOR A PERIOD OF
TRAINING OF CELLS IN THE MOIST WEST SOUTHWESTERLY LOW LEVEL
FLOW---LOCALLY HEAVIER TOTALS AND ISOLATED RUNOFF
ISSUES---ESPECIALLY OVER URBANIZED AREAS---ARE POSSIBLE.  THE WRF
NMMB/NAM CONUS NEST AND NSSL WRF SHOW ISOLATED BANDS OF
3-5"---ALTHOUGH IN DIFFERENT LOCATIONS...RESULTING IN LOW
CONFIDENCE OF WHERE THEY MAY OCCUR.

...NORTHERN PLAINS/GREAT BASIN/CENTRAL ROCKIES AND HIGH PLAINS...

A CLOSED LOW WILL BE PUSHING EASTWARD ACROSS SOUTHERN ALBERTA AND
INTO SOUTHERN SASKATCHEWAN THURSDAY.  THE TRACK OF THIS CLOSED LOW
WILL KEEP THE BULK OF THE SIGNIFICANT PRECIP NORTH OF THE BORDER.
LIGHT RAIN IS EXPECTED WITH THE COLD FRONT AS IT DRIFTS EAST
ACROSS THE NORTHERN PLAINS...INCLUDING EASTERN MT ACROSS ND INTO
WESTERN MN.  LIGHT TO LOCALLY MODERATE PRECIP ALSO POSSIBLE
FARTHER TO THE NW OVER NW MT THIS EVENING WITH SHOWERS IN THE
GLACIER NATIONAL PARK ASSOCIATED WITH THE UPPER TROF AXIS PUSHING
EASTWARD BEFORE THE STRONGER LOW LEVEL CONVERGENCE DEPARTS THE
REGION AND COVERAGE DECLINES THU MORNING.

FARTHER TO THE SOUTH---SCATTERED TO NUMEROUS SHOWERS DEVELOP AS A
COUPLET OF UPPER DIVERGENCE/LOWER LEVEL CONVERGENCE DEVELOPS IN
NORTHERN UT AND CROSSES NORTHERN CO/ADJACENT SOUTHERN WY.  LIGHT
TO LOCALLY MODERATE AREAL AVERAGE TOTALS EXPECTED HERE ALSO. THE
12Z NAM HAS AN HIGHER TOTALS IN NORTH CENTRAL CO AND A MODEL
CONSENSUS WAS USED FOR QPF DUE TO THE UNCERTAINTY INVOLVED.

PETERSEN

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


24HR QP VT 26/00Z
 0.01 414639 425640 435643 439648 442654 447669 450676 451685
      451692 453698 456707 458712 460714 463713 464708 462702
      460692 470686 472679 475674 478679 479684 478688 477694
      474698 471703 473708 480722 481730 483733 483738 485747
      487754 491770 492778 493787 494799 495811 496820 495829
      493843 489856 483867 472868 468869 467872 464879 462884
      456886 452882 452877 450871 450863 447859 443861 432866
      429868 425874 412892 407895 401897 396899 391896 386893
      383889 378886 374884 368881 362880 356879 353879 351881
      344888 339891 333891 329888 327882 325875 324864 326859
      330855 332851 329846 316851 310846 309838 302838 294840
      290843 282850 272858 264864 258868 255871 250874 248876
      244876 237871 228865 225862 225856 226841 226833 226824
      229813 233802 245786 259770 267761 275753 282745 290734
      296726 300719 308711 317704 336687 355672 363665 368662
      372659 393645
 0.01 562087 563037 563023 562013 555993 554989 552985 547981
      534975 526968 515957 506949 500946 494942 482936 462936
      456933 451933 438940 434944 430947 419956 415962 408966
      405967 406970 408973 407977 411992 409996 406000 406005
      401006 393008 389008 386010 380013 378008 376006 373005
      372013 374020 379026 383030 385038 387047 384052 381053
      378053 372050 373054 377056 380059 378062 376066 375072
      372079 372082 375085 378092 378096 380095 384095 386096
      385099 383099 382103 377107 379110 382109 384109 385112
      384114 382114 379115 375121 373125 373130 376132 379130
      382134 382141 381149 383154 385155 390156 394158 395166
      395170 397173 404177 407177 410176 414172 416163 419155
      421147 420143 420136 422126 424100 425095 426092 428092
      431097 432101 433106 431111 431116 432118 433117 436117
      437119 439122 440127 434142 433150 434152 438153 441160
      443164 443170 443174 442178 437184 437189 438192 438197
      440201 442203 444202 445198 447195 450195 452193 454188
      460184 465186 469186 471183 472178 469177 466178 464176
      460170 458162 462156 466159 468162 475166 479171 479177
      478184 478190 475194 471201 467201 464204 459207 458219
      460223 463225 468222 473219 476216 480217 484220 491222
      497221 500213 503203 506197 511190 514189 517190 521193
      522200 523205 511206 506210 504215 503219 504229 506238
      507246 509249 512251 516252 518249 519247 520241 521235
      523230 527225 537210 540186 538175 540170 540167 539154
      543149 547143 551135 552127 554119 558101 562087
 0.01 486075 485070 482065 481052 472053 466055 456054 452053
      449051 449049 445039 445029 449008 448005 446998 443995
      439995 436992 432993 429997 426995 418000 413006 412009
      413011 416013 420017 422022 432023 428030 424034 423037
      424041 430059 433069 434074 432080 430085 433087 436086
      442084 445086 449087 449083 446079 442076 440071 438067
      440066 442065 446068 449071 451075 455079 454083 456086
      455095 457098 459099 460096 466089 469085 471080 472075
      475079 477082 481081 485078 486075
 0.01 448986 448983 447981 445983 445985 447987 448986
 0.01 389095 389093 387094 385095 387097 388097 389095
 0.01 381085 381084 379084 377085 379087 380087 381085
 0.01 365157 365155 365154 363154 361154 360156 361157 362158
      364158 365157
 0.25 557087 559067 559056 558047 556030 551021 545011 538001
      536997 531993 527991 521989 511987 505986 500983 495981
      488981 479983 475987 473992 475998 479999 483999 489998
      492998 493002 491009 491018 494029 498034 503038 513043
      516048 517054 517058 515066 512069 506071 501074 498077
      495082 493089 490104 486120 484125 481130 479134 480138
      485140 496143 499149 501156 504161 509165 519168 525170
      529170 534166 535163 536157 534149 531145 527137 534129
      541120 548111 553100 556093 557087
 0.25 479812 479804 478799 474787 470777 465763 459754 454747
      450745 446744 443745 438747 434750 432751 429750 428743
      430738 436729 437725 437716 430697 428689 427679 426667
      424662 421658 413655 403655 396657 391660 383665 374672
      360684 353690 346696 338703 329709 322715 315723 310730
      305736 278764 272770 266776 259783 254785 251788 241802
      237812 235823 236827 236833 235845 234855 235858 238861
      248858 256854 265849 273842 279836 285829 290821 295814
      301808 310803 320802 324804 328808 335814 342819 346822
      347826 353835 355838 359839 363845 364849 368860 375868
      380875 385878 390878 401874 407870 414863 420856 424853
      428852 438846 447843 452842 458840 474832 477828 479823
      479812
 0.25 471111 472108 472106 471104 470104 469105 468107 468108
      467110 467111 469111 471111 471111
 0.25 414068 414057 409052 402057 397064 396071 394075 391078
      393080 397090 405093 406100 408100 410097 409091 411080
      414068
 0.25 410045 410044 409042 408040 406039 405038 404040 404042
      405042 406044 407047 408048 409047 410046 410045
 0.50 554086 555075 554065 552058 549052 545048 541041 537027
      532013 528008 523006 518009 512009 506011 501016 502021
      507026 514026 519029 523033 527039 531053 532056 532061
      532067 530071 523081 516091 513097 512102 513107 519119
      524122 530121 539114 543111 547105 552095 554086
 0.50 466807 464801 462795 456786 453779 452772 447757 443755
      440755 434758 430760 426763 423765 420765 416763 413760
      410755 412750 418741 419735 422731 424728 424723 421716
      394722 394716 396711 402702 409695 414690 416684 416677
      416670 412666 408665 403664 398665 388670 380675 370682
      352696 335711 323723 309739 292754 279768 272776 265782
      258788 255792 251795 247798 244802 241807 238813 238818
      241819 243823 243827 240839 239850 241853 245853 255848
      263842 273836 280829 285820 290812 296804 300801 305799
      318798 329798 336795 339790 345782 350779 352779 353782
      354789 353795 354803 356808 359811 364813 363817 360821
      359823 362825 367827 366831 367836 369842 370848 373851
      377864 380867 384870 390871 396869 403864 410855 413850
      415845 416842 419839 425838 437836 444831 447826 452822
      459816 463815 464812 466807
 1.00 546090 543084 540084 536088 532092 527095 524099 527105
      532107 537105 541102 544096 546090
 1.00 442791 442776 441769 440767 438767 433774 429782 424789
      421793 420797 418802 419809 419815 422819 425821 430821
      434817 435813 439803 442793 442791
 1.00 410786 411782 409777 406773 399763 395759 393761 392769
      387773 382777 375776 370777 367780 364782 364787 366795
      367800 369801 376800 388795 393792 397791 408788 410786
 1.00 397696 391688 385687 381690 374699 368705 348717 340723
      333730 317746 310752 304760 289774 285778 281780 272785
      263790 255799 250806 253818 252830 253836 260836 270831
      277826 282817 287806 292798 297794 301793 305791 311790
      324789 330788 334784 340777 346769 348763 350756 352752
      354746 357737 360725 368716 370712 374710 378712 384712
      388709 392704 397696
 1.00 394856 395851 393847 391845 390843 388842 384843 382844
      381846 379850 381854 383857 384859 385861 389862 391860
      393858 394856
 1.50 344766 344760 342757 338755 335756 330760 323765 318768
      315771 314775 318782 325783 332779 337774 342769 344766
 1.50 282808 283804 282800 279799 276801 272804 267808 264812
      262817 261825 264828 267828 272826 276822 279817 282811
      282808

$$





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