Quantitative Precipitation Forecast
Issued by NWS

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000
FXUS04 KWBC 031829
QPFPFD

QUANTITATIVE PRECIPITATION FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
229 PM EDT TUE MAY 03 2016


PRELIM DAY 1 QPF DISCUSSION
VALID MAY 04/0000 UTC THRU MAY 05/0000 UTC
REFERENCE AWIPS GRAPHICS UNDER...PRECIP ACCUM - 24HR


DAY 1

...SOUTHEAST AND FLORIDA...

A SHORTWAVE TROUGH WAS EXITING THE CAROLINA COASTLINE...BUT A
LONGER WAVELENGTH TROUGH AXIS REMAINED BACK WEST TOWARD THE
MOUNTAINS...AND THE DIURNAL HEATING CYCLE HAD ALREADY LED TO
RENEWED CONVECTIVE INITIATION FROM VIRGINIA TO GEORGIA AS OF 18Z.
MUCH OF THE AFTERNOON/EVENING PRECIPITATION EVENT WILL BE BROADLY
FORCED BY GRADUAL UPPER HEIGHT FALLS WITHIN ONLY LOOSELY CONFLUENT
AND PRIMARILY WESTERLY LOWER TO MIDDLE LEVEL FLOW. THUS...IT IS
HARD TO HAVE TOO MUCH CONFIDENCE IN THE QPF DETAILS...EXCEPT THAT
AREAL AVERAGE PRECIPITATION SHOULD INCREASE WITH TIME AND AS THE
AFTERNOON STORMS HEAD ONTO THE COASTAL PLAIN...AS CELL MERGERS AND
LOCAL UPSCALE GROWTH WILL LEND TOWARD GREATER COVERAGE OF MODERATE
RAIN AND SOME HEAVY DOWNPOURS. THIS COULD YIELD SOME FLASH FLOOD
CONCERNS OVER PARTS OF THE CAROLINAS WHICH HAD RECEIVED A FEW
BOUTS OF HEAVY RAIN IN RECENT DAYS. THE MODELS ALSO SUGGEST THAT
ONE OF THE MORE ORGANIZED SWATHS OF PRECIPITATION WILL OCCUR DOWN
ACROSS SOUTHERN AL/GA AND FAR NORTHERN FL...WHERE THE EXIT REGION
OF A SUB-TROPICAL JET WAS NOSING INLAND FROM THE GULF. WPC
ADJUSTED THIS SWATH SLIGHTLY FARTHER SOUTH BASED ON TRENDS IN THE
HRRR AND OTHER HI-RES MODELS. ON WEDNESDAY THE COMBINED EFFECTS OF
NORTHERN AND SOUTHERN STREAM FORCING WILL BRING A COLD FRONT INTO
FLORIDA ALONG WITH FAVORABLE HEIGHT FALLS AND DIFLUENT UPPER FLOW.
THIS SUGGESTS A ROUND OF HEAVY RAIN...ESPECIALLY FOCUSED OVER
CENTRAL FLORIDA...BUT ALSO PROPAGATING OR DEVELOPING TOWARD SOUTH
FLORIDA DURING THE AFTERNOON. THE MODEL QPF SIGNAL HAS BEEN
INCREASING...WITH MOST GUIDANCE PREDICTING AT LEAST 1.5 TO 2.5
INCH AREAL AVERAGE PRECIPITATION OVER CENTRAL FLORIDA...FROM EARLY
MORNING THROUGH THE EARLY AFTERNOON. WPC STARTED WITH CONTINUITY
AND LEANED TOWARD THE ECMWF AND WRF-ARW.


...MID ATLANTIC AND NORTHEAST...

EACH DIURNAL CYCLE SHOULD BRING RENEWED CONVECTIVE ACTIVITY OVER
VIRGINIA. INSTABILITY DECREASES EACH DAY...WITH CAPE THIS
AFTERNOON CLIMBING TO AROUND 750 J/KG AT MOST...AND CAPE ON
WEDNESDAY CLIMBING ONLY TO AROUND 500 J/KG OVER A MORE NARROW ZONE
EAST OF THE PIEDMONT. MODELS INDICATE RELATIVELY GOOD COVERAGE
TODAY OF QUARTER INCH AVERAGE PRECIPITATION...WITH POTENTIAL FOR
EMBEDDED HEAVIER TOTALS...WITH COULD COME LOCALLY CLOSE TO FLASH
FLOOD GUIDANCE IN SOME OF THE RECENTLY WET AREAS. IN ADDITION TO
THIS GENERALLY NW-SE MOVING CONVECTION EACH DAY...A SYNOPTICALLY
DRIVEN AND MAINLY STRATIFORM PRECIPITATION EVENT WILL DEVELOP
ALONG THE MID ATLANTIC AND NEW ENGLAND COASTS AND EXTENDING
INLAND...AS LOW PRESSURE FORMS AND DEEPENS AHEAD OF THE LARGE
SCALE TROUGH AXIS OVER THE GREAT LAKES. THE APPROACH TO QPF HERE
WAS SIMILAR TO THAT OVER THE SOUTHEAST...USING TRENDS IN OUR
IN-HOUSE ENSEMBLE...AS WELL AS PUTTING MORE WEIGHT ON THE DETAILS
OF THE ECMWF AND WRF-ARW.


...GREAT LAKES AND OHIO VALLEY...

IN A HIGHLY AMPLIFIED PATTERN...A CLOSED NORTHERN STREAM LOW WILL
DIG INTO THE WELL ESTABLISHED LONGWAVE TROUGH AXIS OVER THE GREAT
LAKES AND OHIO VALLEY. THIS IS OCCURRING WELL BEHIND THE FRONTAL
BOUNDARY THAT WAS ALREADY PUSHING TOWARD THE ATLANTIC AND GULF
COASTS...SO THE AIRMASS WAS DRIER...WHICH GIVES US REASON TO LEAN
ON THE CONSERVATIVE SIDE WITH QPF. WIDESPREAD 0.25 INCH AMOUNTS
ARE ANTICIPATED AHEAD OF THE BETTER MID LEVEL DIFLUENCE ON THE
EAST SIDE OF THE CLOSED LOW...CENTERED ON LOWER MICHIGAN. A FEW
SPOTS WILL LIKELY RECEIVE MORE THAN 0.50 INCHES...BUT VERY LITTLE
GUIDANCE SUGGESTS MORE THAN AN INCH. THE GUIDANCE CONSENSUS PAINTS
THE AXIS OF GREATEST QPF FROM LOWER MICHIGAN INTO IN/OH...WHERE WE
FOCUSED DURING THIS CYCLE...MAKING SLIGHT REDUCTIONS TO QPF
FARTHER WEST IN IL/KY.


...WEST COAST...

THE FULL LATITUDE TROUGH INITIALLY OFF THE WEST COAST IS EXPECTED
TO SPLIT INTO TWO DISTINCT PIECES THIS PERIOD.  THE NORTHERN
PORTION WILL PUSH OFF INTO WESTERN B.C...WHILE THE SOUTHERN
PORTION BEGINS TO CLOSE OFF...NEAR THE NORTHERN CALIFORNIA COAST.
THE MODEL CONSENSUS IS FOR GENERALLY LIGHT TO MODERATE PRECIP
TOTALS AHEAD OF EACH PORTION OF THIS EVOLVING TROUGH. THE WPC
FORECAST WAS ALREADY IN GOOD SHAPE...RESEMBLING MANY OF THE HIGH
RESOLUTION MODELS...AS SOME OF THIS PRECIPITATION WILL BE
CONVECTIVE. WE MADE A FEW MINOR ADJUSTMENTS TO FOLLOW TRENDS IN
THE NAM/GFS...BUT OTHERWISE MADE VERY LITTLE OVERALL CHANGE. SOME
OF THE HEAVIER AMOUNTS THROUGH WEDNESDAY ARE EXPECTED IN NORTHERN
CA AND SOUTHERN OR...WHERE THE PATTERN OPENS UP AND BECOMES MORE
DIFLUENT TO THE NORTHEAST OF THE DEVELOPING CLOSED LOW.

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

BURKE

24HR QP VT 05/00Z
 0.01 538202 540193 540186 536176 532164 530159 526154 518148
      507145 503147 500150 494158 489159 484158 481160 481165
      483172 482180 482187 481195 477199 473201 468201 463202
      457200 455196 456190 458185 461182 463177 465162 463158
      462156 459155 454151 448150 446155 447161 450173 448178
      444180 436184 427187 425190 421192 412194 398191 394191
      389192 378187 370182 365181 361183 359185 362189 370194
      376201 386208 395214 396216 395219 391221 388221 387224
      386230 388234 391237 396240 400244 404246 408248 415249
      417250 417252 415254 412253 406250 401248 396247 387246
      382248 379251 368252 359254 352259 348261 347266 349271
      354274 366279 375277 392272 397270 401270 409268 418266
      429262 444251 452249 460245 465245 470246 479247 483247
      483240 484237 486236 488235 490238 493240 491242 486242
      485245 487250 491259 493264 497268 499274 501278 503281
      507281 510276 512269 512264 516259 517229 517220 520217
      523215 528215 534209 538202
 0.01 486225 486224 484223 483223 481222 479222 478222 476222
      475222 474224 475227 477226 479226 480227 482228 483228
      485227 486225
 0.01 500816 500810 497808 492802 487801 480801 472803 466806
      462809 457810 447812 438813 430812 424811 423806 424803
      425791 426786 429783 434778 440773 447769 450762 455747
      454738 453732 451729 444724 442720 442714 445706 448695
      450687 450679 446673 440672 434667 430661 425654 423652
      419652 408650 400649 397648 393649 381662 372674 367681
      364688 358701 350713 339722 329731 317742 311746 303750
      296754 293756 289756 279759 269762 261770 258777 257781
      254783 248786 243792 235801 232806 229814 225821 222829
      223839 222847 221857 223863 230876 237875 240881 239890
      240900 240908 246910 248912 251909 255905 265891 274880
      285869 290865 293866 295869 297872 300872 306869 310867
      312864 316858 322847 328833 332825 337817 345805 348803
      352804 358806 366804 367809 365813 360818 354823 350829
      346834 339845 338853 337858 337864 337876 340885 346900
      349903 352901 356897 361890 364887 368887 379889 380898
      380904 381907 382914 385920 387924 391927 398927 401925
      404925 405928 407933 409936 416940 423943 426942 428940
      433935 437928 440922 444914 445904 457875 459871 461870
      462873 462880 461886 461896 465898 467897 470895 470889
      469873 469867 470863 470855 475848 479843 485841 491836
      494833 497827 498820 500816
 0.01 417163 418159 414158 410162 407163 403165 400162 400164
      403167 404171 406170 408166 412164 415165 417163
 0.01 417149 416146 412146 409147 405146 402144 400145 394149
      390148 388150 384156 384161 385161 391156 394155 397152
      404151 406149 408148 410150 415151 417149
 0.01 361985 360982 358979 352976 341971 336966 334960 332958
      328958 323962 318966 315971 315980 317984 318991 320997
      324004 325007 327008 332005 337000 341996 346992 351987
      353986 357985 361985
 0.01 257000 257995 256992 254989 250989 247991 247996 240994
      233992 231993 232997 233005 235013 237016 241016 248018
      252018 252014 252011 254008 256001 257000
 0.25 528199 527196 525193 523190 520189 517189 514189 512190
      511194 513196 515198 517200 518203 520205 523206 525204
      527201 528199
 0.25 508251 509243 509238 508232 506227 503224 500222 496221
      494222 494225 495230 497234 499238 502242 504247 506251
      508251
 0.25 491214 488209 481207 471210 466212 461215 459216 456215
      449213 446212 445210 445207 447204 446200 444201 442205
      436209 433211 430210 426208 424215 420219 411224 406226
      400226 397227 397231 402234 406238 412241 425245 430246
      436245 441242 443239 441237 443228 448226 452223 456219
      466221 475216 483214 491214
 0.25 478236 478233 476232 476235 477238 478236
 0.25 486821 482818 475820 463826 454830 441828 432821 425820
      418823 415826 413829 413833 414835 411838 407841 403845
      400852 396856 391860 389865 390868 394868 403861 420874
      429865 438858 443856 449852 454848 459844 464842 470839
      479830 483826 486821
 0.25 438883 438880 438878 438875 437873 437872 435871 433871
      431873 431876 430878 430881 430883 430885 430886 432887
      434887 435887 437885 437884 438883
 0.25 426762 426760 426758 425756 425755 423754 423753 421753
      419754 418755 417757 416758 415760 415762 415764 417767
      419767 420766 422766 424765 425763 426762
 0.25 412219 412218 411216 410214 409213 407213 405213 404214
      403216 404218 406219 408220 410219 411219 412219
 0.25 410681 409673 406670 402668 398668 393669 390671 385675
      382679 377689 372697 367705 360713 353719 346724 339731
      332739 326745 317750 308756 301764 296771 290776 277779
      273781 268785 262791 252797 246802 242810 237812 234815
      231823 229828 229832 231836 231842 229853 229856 231861
      236863 241863 244863 246865 249869 250880 250883 253882
      260876 268868 284856 289849 293841 298822 301810 303805
      309805 310810 310814 308818 307825 307840 309846 311847
      313845 316835 318825 319818 321814 325804 330796 333790
      334783 336780 340779 345780 350778 356772 360769 362770
      364777 367781 375788 379790 383786 385783 388777 388765
      389759 387756 386756 382757 378755 373755 369756 366757
      365753 367749 373740 380732 390727 391727 393730 393736
      389746 389750 391752 397751 405747 409743 411739 412732
      413725 411719 409718 407719 400719 398718 399715 405696
      409687 410681
 0.25 405829 405822 402818 399816 395815 390817 388820 385824
      385829 388829 391826 395825 398828 401830 405829
 0.50 436223 434220 432221 432222 432223 434224 436223
 0.50 423239 424233 420230 417230 412229 408230 403229 400229
      401231 406233 409236 414238 417240 421240 423239
 0.50 426843 425841 424841 424843 425844 426843
 0.50 396682 394679 392678 387681 383686 379693 372706 364716
      354724 348727 342732 333743 329747 324751 313758 308763
      304768 296781 293782 285782 278784 273787 262796 256799
      253802 250805 244815 239818 237823 237833 235841 237848
      240849 245847 249843 252846 252854 253860 255864 258865
      265863 277855 281850 283846 285838 287832 294819 295810
      294805 294801 297794 300796 307797 310797 312800 315805
      318804 320800 326788 326779 331774 336771 343769 346772
      348772 354768 358763 360753 362748 366743 374733 383722
      389709 393702 395696 396682
 0.50 383775 382772 380770 378768 376767 373765 370765 369768
      368770 370774 372777 374778 375779 379779 382777 383775
 0.50 312839 312837 312835 311833 311835 311837 311839 312841
      312839
 0.50 446218 445218 444218 445218 446218
 1.00 387696 388693 386692 385694 383696 383697 382699 381699
      380702 380704 380707 381708 383707 383706 384704 385703
      386701 387698 387697 387696
 1.00 367728 363727 358729 350731 346734 343737 340744 329755
      321759 318762 316766 311771 308774 306778 306781 307787
      310789 313787 313782 315778 319772 326768 333767 340763
      344760 345756 350750 356746 361739 365732 367728
 1.00 287820 285806 284802 282800 279800 278803 271811 268816
      265821 262825 262831 261840 259846 257850 257854 258856
      270853 274842 277836 280832 284829 287823 287820
 1.00 263813 263811 262809 260808 258809 257809 256811 256812
      256814 256816 257817 258817 259818 259817 261816 261815
      262814 263813
 1.50 357737 356736 355735 353736 350736 348737 348739 350739
      354740 355739 356739 356738 357737
 1.50 340757 340755 338754 336754 335755 334756 333758 333759
      332760 331761 332762 334761 335761 337760 338760 339759
      340757
 1.50 281821 282819 282817 281815 280813 280811 278810 278811
      277812 276813 275814 274816 273817 273818 273820 274820
      276821 276822 278824 279823 281822 281821
 1.50 269841 269839 269837 268835 268834 266834 265835 265837
      265839 265841 265843 266844 267843 268842 269841

$$





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