Quantitative Precipitation Forecast
Issued by NWS

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000
FXUS04 KWBC 231849
QPFPFD

QUANTITATIVE PRECIPITATION FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
248 PM EDT SUN APR 23 2017


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


DAY 1...

...SOUTHERN-CENTRAL APPALACHIANS / SOUTHEASTERN U.S. / MID
ATLANTIC...

A POSITIVELY-TILTED UPPER TROUGH WILL CONTINUE TO DEEPEN AS IT
PIVOTS SOUTHEAST DURING DAY 1...WITH DECENT MODEL CLUSTERING OF A
CLOSED MID-UPPER LOW GRADUALLY TRAVERSING THE SOUTHEASTERN STATES.
IN DUE TIME...THIS TROUGH TAKES ON A NEGATIVE TILT LATER
TONIGHT/EARLY MONDAY MORNING WHICH SHOULD RESULT IN INCREASING
MAGNITUDE OF UPPER DIFFLUENCE E-NE OF THE UPPER LOW WHICH BECOMES
BETTER FOCUSED WITH TIME.  IN ADDITION...THE APPROACH OF A JET
STREAK WILL PUT THE CAROLINAS TO MID ATLANTIC REGION IN A
FAVORABLE POSITION FOR INCREASED UPPER DIVERGENCE.   THE EVOLVING
SYNOPTIC PATTERN WILL FAVOR A RATHER BROAD SWATH OF HEAVY RAINFALL
ACROSS EASTERN PORTIONS OF THE LOWER OH VALLEY AND TN
VALLEY...ALONG WITH THE CENTRAL-SOUTHERN APPALACHIANS... ADJACENT
PIEDMONT...AND MUCH OF THE SOUTHEAST.

WPC QPF STARTED WITH FAIRLY LARGE PERCENTAGE OF CONTINUITY AND
THEN MADE CHANGES BASED ON THE 12Z GFS/NAM AND THE LATEST ECMWF
AND THE 12Z WRF ARW.  THAT RESULTED IN HIGHER AMOUNTS OVER PARTS
OF NORTH CAROLINA COMPARED WITH THE OVERNIGHT WPCQPF...WITH THE
BIGGEST DIFFERENCE COMING FROM THE MODELS SHOWING CONVECTION
REDEVELOPING ON MONDAY AFTERNOON BEFORE THE AXIS OF HIGHER
PRECIPITABLE WATER MOVES OUT.  AS A RESULT...THE HIGHER PCPN
VALUES SEEMED REASONABLE ALONG WITH THE FACT THAT THE HIGH QPF WAS
SHOWN BY MULTIPLE MODELS.  SINCE IT APPEARED THAT THE SEVERAL OF
MODELS WERE SUFFERING FROM CONVECTIVE FEEDBACK/GRID SCALE
PROBLEMS...WE WERE NOT INCLINED TO INCREASE AREAL AVERAGE AMOUNTS
TO 6 OR MORE INCHES AS SHOWN BY SOME OF THE MODELS EVEN THOUGH
ISOLATED POCKETS MAY GET THAT MUCH RAINFALL.

TO THE SOUTH OF THERE...WE ATTEMPTED TO MAKE FEW CHANGES TO THE
RAFL FORECAST WHERE MOISTURE WILL BE ABUNDANT AND THE UPPER LEVEL
SUPPORT WILL BE STRONG.  FORECAST SOUNDING SHOW PRECIPITABLE WATER
ANOMALIES AND H85 TO H70 MOISTURE FLUX ANOMALIES SOME 2 TO 2.5
STANDARD DEVIATIONS ABOVE CLIMATOLOGY WILL BE IN PLACE.  THIS AS
THE SYSTEM WILL BE ABLE TO DRAW IN BOTH GOMEX AND GULF STREAM
MOISTURE...LEADING TO AN EXPANSIVE (POLEWARD) AREA OF ANOMALOUS PW
INTO THE UPPER LAYERS (500-300 MB).
IN TERMS OF THE QPF...WPC NOTED A FAIRLY BROAD AREA WITH
AREAL-AVERAGE AMOUNTS BETWEEN 2-4" IN A CORRIDOR FROM PARTS OF
WESTERN NORTH CAROLINA INTO SOUTH CAROLINA...SURROUNDED BY 1 TO 3
INCH AMOUNTS.  BECAUSE OF THE ANTICIPATED MINIMAL CONVECTIVE
CONTRIBUTION ACROSS MUCH OF THIS REGION (ESPECIALLY NORTHERN
AREAS).

WILL CONTINUE WITH A MODERATE RISK FOR EXCESSIVE RAINFALL ACROSS
THE NC-SOUTHERN VA PIEDMONT INTO THE APPALACHIANS AND INCLUDING
FAR NORTHEAST TN....WITH A SURROUNDING BROAD SLIGHT RISK AREA.


...KEYS/SOUTH FLORIDA...

THE CONVECTIVELY-AIDED SHORTWAVE LOW HUGGING THE SOUTHEAST CORNER
OF THE FL PENINSULA WILL CONTINUE TO MOVE SLOWLY NORTHEASTWARD.
THE MODELS HAVE NOT BEEN PERFORMING PARTICULARLY WELL WITH
PLACEMENT OR AMOUNTS. THE FORECAST WAS LARGELY BASED ON SHORT TERM
EXTRAPOLATION PLUS THE FACT THAT THE THERMODYNAMIC PROFILES POINT
TO EFFICIENT RAINFALL PRODUCING CELLS UNTIL THE STORMS PULL AWAY
FROM THE COAST. A QUICK LOOK AT THE THE LATEST PARALLEL HREF 40KM
NEIGHBORHOOD PROBABILITY OF THE 24 HOUR QPF EXCEEDING 5 INCHES IS
STILL AROUND 50% WITHIN THE MAJORITY OF THE SLIGHT RISK AREA.

BANN

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

24HR QP VT 25/00Z
 0.01 519274 520268 519263 515253 509237 507232 506226 505220
      506213 506209 509207 513205 518207 522205 527201 531197
      532184 531179 530175 529172 531170 532170 532165 531159
      529151 522149 518146 516143 516129 515123 514118 510111
      510107 510102 512097 513089 514085 515077 515070 515063
      516059 518055 521052 526050 530044 533040 535035 536029
      537025 537019 537015 536010 533007 531002 528999 525999
      522996 520994 520991 519983 519956 519939 520926 520910
      520902 519897 514874 512866 508860 504854 498852 494853
      490856 487861 486868 482869 481871 478870 474867 472865
      469865 467868 467874 468878 466882 463885 459892 460906
      463918 464921 463925 462928 462933 459944 455952 452969
      453974 451978 448986 447024 450035 453042 455047 457052
      455052 454050 451046 446041 444037 443033 438028 433025
      431025 431030 434035 436038 438040 435042 434044 433049
      433056 435060 438070 442077 439086 436088 433087 428084
      426080 426073 425068 424065 422064 418062 415043 415039
      412042 411045 411052 409056 402055 400058 401061 398069
      396073 397077 399088 403094 400101 396108 389114 385117
      384123 386127 391126 397123 401122 403125 406131 408135
      407141 405144 402144 396142 394146 393152 393158 394163
      393169 390173 389176 392179 395182 399184 404189 403196
      403200 400201 396201 392198 378189 373184 370183 364184
      362186 364187 370193 376198 379205 381212 382215 385217
      390218 393217 398220 397222 395224 387223 378221 375222
      375227 381235 388251 393257 394268 394276 395280 398282
      410293 416297 424301 433304 443306 457305 461304 464302
      471297 478292 481290 480285 478275 478271 478265 477260
      478254 479251 481250 485252 494263 503278 509286 514286
      516283
 0.01 491698 490692 488689 487683 487678 487668 484664 480663
      478668 475674 472680 470688 465700 461708 459714 457721
      458729 464733 466735 469735 473734 475731 480726 486714
      489707 490698 491698
 0.01 484196 483193 481191 478188 477184 475182 472183 470185
      467188 465190 465194 467198 470201 473199 476196 478195
      480198 482198 484196
 0.01 402699 357701 354710 351716 348724 343732 327753 317765
      313770 306776 301780 295783 288786 278787 259789 253790
      248791 244795 241807 245813 250817 257820 257827 259829
      263831 257837 248845 246848 246853 247857 249859 253861
      254866 255869 258872 261872 264870 270865 282858 287854
      294851 302848 309847 319847 323847 324849 324853 327855
      331855 334856 339863 342869 343873 345877 347879 351881
      354881 357880 361878 365876 370872 373866 379852 385835
      389829 393819 395814 396806 397800 399798 403791 405787
      406781 407773 406764 402753 399735 399726 401718 402699
 0.01 294060 294055 292051 290049 285048 276045 271041 264036
      263035 264032 265029 266023 263020 257018 252020 249022
      243026 234037 234049 235056 240062 247065 256069 263071
      272073 277074 280076 283075 286072 290066 294060
 0.25 511154 512146 512141 508131 505127 504125 502126 499129
      497133 493145 491157 491170 492176 494181 498184 501182
      504178 505171 508161 511154
 0.25 507047 508040 506034 502033 499034 495037 492039 490045
      492051 495054 499054 502052 505050 507047
 0.25 490221 490219 490218 489216 488216 487215 486215 485215
      484217 483219 484221 486222 488222 490221 490221
 0.25 507955 508939 508926 507919 506914 502907 499905 495906
      489910 482915 479924 475944 469964 466974 466986 468991
      472992 480994 488996 493997 497995 500988 503978 507956
      507955
 0.25 474219 474214 470212 466211 462209 460206 455204 453201
      453196 455189 458182 461172 464166 468158 468150 465142
      460136 459129 460119 465102 465098 462094 457091 453090
      450091 444096 441102 440106 442108 447113 453117 455126
      455132 450139 445145 441150 437156 437159 439161 444167
      446175 446181 444184 442186 442192 443197 446199 449203
      447208 442211 436212 429211 426211 425208 427205 428199
      429195 431192 433193 435189 433175 431166 428165 426167
      423169 422174 421179 423183 425186 426191 423198 403212
      401214 403218 405224 404227 401228 397229 394232 392235
      393239 395245 403256 405259 406265 407272 410280 416286
      421289 429292 437295 443296 451296 456293 459286 458274
      457267 457263 458258 461249 465244 467238 470228 472222
      474219
 0.25 433109 432105 427105 423106 419108 416110 416113 417118
      419123 422126 425126 427122 429118 432114 433109
 0.25 410110 411108 411106 411105 409103 410101 409100 409101
      409103 409105 409106 409108 410110 410110
 0.25 397779 397770 395764 392759 388754 383747 379744 376737
      375726 371723 368722 364723 357729 353732 351736 339756
      334765 331768 326770 320772 316775 308783 292795 284801
      276797 265797 262799 265802 277803 280803 283804 286808
      277813 277816 279818 283818 296816 303815 311815 315815
      315819 310829 308834 308839 313839 319836 324834 330834
      337841 344847 351848 357845 365840 373833 379825 385814
      393794 397786 397779
 0.25 273056 272055 270054 268054 267053 265053 263052 261051
      259051 258051 258052 257053 257055 258055 259056 261057
      263058 264058 266059 268059 270059 271058 272058 273056
 0.50 508146 506145 505143 504145 505147 506147 508146 508146
 0.50 502949 502941 502937 499931 497932 491938 487940 485944
      482954 477964 476970 477977 481978 486978 491977 496975
      498972 501962 502949
 0.50 468220 466216 460213 457211 453212 449214 444215 440215
      437216 428219 423222 422226 421230 418229 412228 409230
      406233 402235 399239 400244 402247 411254 416261 420271
      422275 427277 437279 441278 441273 441268 444265 450258
      452252 455248 461242 463235 463231 464226 468220
 0.50 392785 393778 392773 391768 388764 382762 376766 369769
      364770 361767 352760 345755 340761 336767 332772 317778
      307787 300791 295796 293799 294803 299806 306809 314810
      321812 321816 320819 320823 318823 312828 310835 312836
      314835 316832 321827 329827 336829 340832 348835 351836
      356835 367828 372824 378818 382811 384804 389793 392785
 0.50 369734 368733 367732 366732 365732 364733 363734 363735
      363738 364738 365737 367737 369735 369734
 0.50 293813 291813 291814 292814 293813 293813
 1.00 462223 461220 459218 454217 448219 440221 437226 441229
      447231 442232 428238 415234 410235 407239 409242 413245
      420247 428248 442244 450243 453241 455238 454234 450232
      448229 452228 458226 462223
 1.00 385784 384777 382776 378777 369781 364782 359781 352775
      348772 341774 332777 325778 320781 313787 305793 301796
      300799 301801 312803 320806 325809 326810 326813 325818
      324821 327822 338823 346827 352828 359826 367822 371818
      374814 378805 380799 382793 385784
 1.50 449224 448223 446223 446224 448224 449224
 1.50 422243 424241 422240 421238 419238 418237 416238 414238
      414241 415242 417242 418243 420243 422243 422243
 1.50 375794 374790 370790 363791 356788 351782 348780 343779
      336779 325781 320785 313791 310793 309797 312799 316801
      323803 329809 330813 330816 330818 332819 336819 343821
      352823 361822 365820 368816 371810 374801 375794
 2.00 371804 371799 368796 363795 356792 351789 347784 343781
      334780 327782 321786 318791 315797 320800 331807 335812
      336815 339816 351820 354821 359820 364817 369811 371806
      371804
 3.00 364807 364803 362801 359798 353797 350795 347790 344786
      340784 335782 327786 324790 323794 324797 327801 331803
      336806 339808 346814 351816 357815 362812 364808 364807
 4.00 359810 360807 359805 358804 356804 354804 353805 351806
      351807 350809 351811 353812 355812 357811 359810 359810
 4.00 342794 342790 340787 338785 334785 331787 329789 328791
      328794 329796 332798 334799 338798 340797 342794
 5.00 338793 338791 338788 336787 335787 333789 331791 331792
      332792 332794 334794 335794 337793 338793

$$





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