Quantitative Precipitation Forecast
Issued by NWS

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000
FXUS04 KWBC 240658
QPFPFD

QUANTITATIVE PRECIPITATION FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
258 AM EDT MON APR 24 2017


PRELIM DAY 1 QPF DISCUSSION
VALID APR 24/1200 UTC THRU APR 25/1200 UTC
REFERENCE AWIPS GRAPHICS UNDER...PRECIP ACCUM - 24HR


DAY 1...

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

A HEAVY RAINFALL EVENT WILL CONTINUE TODAY...FOCUSED MAINLY ACROSS
PORTIONS OF NORTH AND SOUTH CAROLINA. OVERALL AN IMPRESSIVE
SETUP...WITH BOTH CONDITIONS ALOFT AND IN THE LOWER LEVELS
CONDUCIVE TO HEAVY CONVECTIVE RAINFALL. IN THE UPPER LEVELS THE
CLOSED LOW MOVING SOUTHEASTWARD WILL CONTINUE TO TAKE ON MORE OF A
NEGATIVE TILT RESULTING IN INCREASED ASCENT OVER NC/SC. ALSO NOTE
IMPRESSIVE DIFFLUENCE AT 250 MB...WHICH SHOULD AID IN THE
MAINTENANCE OF CONVECTION THROUGH THE DAY. IN THE LOWER LEVELS A
STRONG COASTAL FRONT EXTENDS ALONG THE CAROLINA COAST...WITH
INSTABILITY ALONG/SOUTH AND JUST NORTH OF THIS BOUNDARY. STRONG
EASTERLY FLOW INTO AND OVER THIS BOUNDARY WILL HELP MAINTAIN A
STRONG CONVERGENCE AXIS...AND ALSO HELP MAINTAIN INSTABILITY INTO
THE BOUNDARY. PRECIPITABLE WATER VALUES WILL CONTINUE TO INCREASE
TO AROUND CLIMATOLOGICAL RECORD VALUES ACROSS PORTIONS OF SC/NC AS
MOISTURE FROM THE TROPICAL WAVE OFF OF FLORIDA IS WRAPPED WEST
INTO THE CLOSED LOW.

THE EXPECTATION IS THAT THE HEAVY CONVECTIVE LINE MOVING ACROSS SC
AS OF 06Z WILL CONTINUE SLOWLY MOVING EAST INTO THE MORNING.
HOWEVER AS THE CLOSED LOW DIVES SOUTHEAST AND BECOMES INCREASINGLY
NEGATIVELY TILTED...EXPECT THE NORTH/SOUTH CONVERGENCE AXIS
RESPONSIBLE FOR THIS CONVECTIVE LINE TO SLOW ITS EASTWARD
PROGRESSION. THIS SHOULD ALLOW FOR CONTINUED CONVECTIVE
REGENERATION OVER EASTERN SC THIS MORNING...WITH THE ACTIVITY
SLOWLY MOVING EASTWARD INTO SOUTHERN NC WITH TIME. THE COMBINATION
OF PROLONGED SYNOPTIC SUPPORT AND ONLY SLOW EASTWARD PROGRESSION
OF THE CONVERGENCE AXIS...AND WIND FIELDS CONDUCIVE TO SOME
SOUTHWARD BACKBUILDING OF CONVECTION INTO THE INSTABILITY...BOTH
POINT TOWARDS THE LIKELIHOOD OF TRAINING CONVECTION. WHICH GIVEN
THE VERY HIGH PWAT VALUES...WILL LEAD TO SOME IMPRESSIVE RAINFALL
TOTALS INTO THIS EVENING.

SOME MODEL DIFFERENCES EXIST WITH REGARDS TO THE EXACT AXIS OF
HIGHEST QPF AMOUNTS. AT LEAST SOME OF THE DIFFERENCES ARE RELATED
TO EXACTLY HOW MUCH CONVECTION IS ABLE TO PROPAGATE EASTWARD WITH
TIME. THE HIGH RES ARW PROPAGATES THE MOST...PUSHING THE HEAVIEST
TOTALS MORE INTO SOUTHERN NC. THE HIGH RES NMMB ON THE OTHER HAND
IS THE LEAST PROGRESSIVE SOLUTION...KEEPING THE HEAVIEST AMOUNTS
OVER CENTRAL SC. AT THIS TIME THINK SOMETHING IN BETWEEN THESE TWO
EXTREMES IS PROBABLY THE MOST LIKELY OUTCOME. THE 0Z 3KM NAM AND
NSSL WRF PROBABLY REPRESENT THIS MIDDLE GROUND SOLUTION THE BEST.
WPC QPF GENERALLY FOLLOWED A MULTI MODEL BLEND...ALTHOUGH WAS
WEIGHTED TOWARDS THE HIGH RES CONSENSUS. THOUGHT MUCH OF THE NON
CAM GUIDANCE (GFS/NAM/ECMWF) MAY HAVE BEEN A BIT TOO FAR INLAND
WITH THEIR HIGHEST AMOUNTS...AND PROBABLY A BIT TOO FAR
SOUTHWEST...AS THEY MAY BE FAILING TO CORRECTLY PROPAGATE
CONVECTION SLOWLY EASTWARD. LOOKING AT AREAL AVERAGED AMOUNTS
MAXING IN THE 4-6" RANGE ALONG THE NC/SC BORDER NEAR THE COAST.
WOULD ANTICIPATE SOME ISOLATED 6-10" TOTALS IN THIS VICINITY AS
WELL WHERE TRAINING ENDS UP MAXIMIZED. THE FACT THAT THE CLOSED
LOW WILL REMAIN MOVING WILL PREVENT RAINFALL TOTALS FROM BEING
EVEN MORE EXTREME. OVERALL THE NEW WPC QPF ENDS UP PRETTY SIMILAR
TO OUR PREVIOUS FORECAST.

FURTHER NORTH FROM NORTHERN NC INTO VA RAINFALL WILL BE MORE
STRATIFORM IN NATURE. GOOD UPSLOPE FLOW WILL CONTINUE DECENT
RAINFALL INTO THE SOUTHERN APPALACHIANS INTO THE MORNING. HOWEVER
BY LATER TODAY THE SYSTEM BEGINS TO CUTOFF A BIT FROM THE FLOW AND
WE START TO LOSE THE BETTER MOISTURE AND DYNAMICS. THUS EXPECT
RAINFALL INTENSITY TO DECREASE ACROSS THE APPALACHIANS BY THIS
TIME. OUR PREFERRED HIGH RES CONSENSUS DOES CUT BACK A BIT ON
AMOUNTS TODAY IN THE STABLE AIR ACROSS VA.


CHENARD

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

24HR QP VT 25/12Z
 0.01 531197 532182 530175 530171 532170 532165 531160 530154
      529151 526150 519148 516142 516129 515120 512114 510110
      510104 514085 515075 515072 514069 511066 506065 502065
      500067 490073 479077 468078 461067 459060 457050 457039
      455031 453022 450017 441004 438997 436995 433993 421991
      419988 419984 418980 418975 417966 416961 416957 403956
      395956 391956 389960 389970 393975 396979 399980 404981
      406983 406995 405004 402018 399024 398027 398032 400041
      397048 393053 389057 385057 382055 377055 379061 378064
      375065 372062 367063 365066 367069 372073 374079 374084
      376087 376095 375105 376108 379108 381106 381100 383096
      385094 392094 399092 400099 395103 392109 387112 383114
      381117 377123 376127 378129 386129 391127 396126 397132
      397138 395142 393144 392149 393158 394162 392167 388170
      387178 388183 391186 393184 395182 398183 403188 404193
      403199 400201 396200 390196 369182 364184 361185 357183
      354181 351182 348183 346186 345189 344195 348199 355189
      360188 364187 369192 377203 380208 383212 390215 395219
      397222 395224 387224 378221 375221 374225 381237 385242
      388250 392256 398262 407272 411276 414279 415278 420276
      424273 434271 447266 458260 463263 467260 473254 476246
      480242 487239 490234 486231 481228 479223 482221 489222
      496224 498227 500226 503223 506211 508207 510206 514206
      517206 520205 523205 531197
 0.01 535877 535864 534852 532834 528819 526810 522802 518797
      511798 501804 497818 495825 494830 494835 490852 489856
      488861 487867 484865 484861 482852 481847 480843 479839
      478837 474838 472840 473851 477866 479873 473877 468880
      463885 450909 445923 448926 454924 458925 460928 459930
      458936 455950 452969 454974 457974 458979 458002 459010
      461016 465020 468025 472033 475039 480044 484048 494054
      506055 511051 515046 519026 519021 521017 521009 521004
      520001 520994 520983 519979 519973 519960 520948 523934
      527919 531902 534888 534880 535877
 0.01 487195 483192 480190 477185 474182 471186 469190 469195
      470198 472200 474196 478194 481198 484199 486197 487195
 0.01 436785 422787 420787 420784 423780 425777 425774 428765
      429760 428753 429748 428743 424732 423729 420730 418731
      415729 413719 414710 413698 412692 413687 414676 413671
      410669 401670 383679 369689 357700 346713 339720 333726
      322737 320739 317744 313749 309757 307762 306767 308773
      306776 298780 290783 281785 270787 267790 265795 262802
      258807 249812 240815 238818 238823 239828 242830 250827
      258824 262822 261827 259832 259838 264839 267837 271837
      276834 282831 287825 294821 304819 322823 327824 329830
      331834 331841 330846 331847 333851 337853 340856 343857
      351857 356855 358852 360847 357845 356842 357839 360835
      363832 365828 370823 376827 380830 383830 387828 391826
      396807 397800 400796 407792 411789 414791 416797 415801
      413805 414812 414814 416814 420813 424810 428807 432802
      435793 436785
 0.01 341168 339166 336167 335169 334164 330165 326167 323168
      324171 327173 333173 337172 339170 341168
 0.01 276809 274808 273808 272810 273811 275811 276809
 0.25 524876 523863 521855 518846 513842 509844 508849 506857
      502863 497869 480894 477903 475912 475922 475927 477930
      478937 477943 478949 481957 481962 479966 474972 473976
      474980 476983 476987 471994 473998 476996 478994 482994
      485000 485006 488009 493002 496995 505983 510965 511954
      514945 518926 519902 522888 524876
 0.25 511149 505122 503117 500113 499116 499120 499129 497133
      495130 493125 488119 485118 482120 479122 475123 472120
      470117 470112 473108 473102 472095 471089 468085 464082
      462078 456069 454064 453059 452052 451044 447034 443028
      440022 439017 437014 434015 432021 428023 426027 426032
      429044 430057 432063 433071 434078 437082 442079 444079
      444082 438089 435094 431092 427090 423092 422095 425101
      420103 415104 410103 407102 405104 400112 398113 399115
      401118 404122 405125 409126 414126 419128 419133 415144
      406149 402152 401155 401158 406168 411176 415182 417187
      420190 421193 420196 413200 412204 415208 418211 423213
      422219 422225 423232 417230 413227 408230 403231 398232
      393233 393237 399244 403247 407248 410251 414253 424252
      442248 452244 460240 467236 471232 471229 473222 476217
      477212 474210 471211 466209 463207 454206 455200 458194
      464184 466178 467172 468159 467153 465148 463143 462140
      463135 465128 468127 478129 482134 484139 487143 492142
      495141 496144 496149 498155 498161 496170 495179 496185
      497188 500189 503184 503168 508159 511149
 0.25 448209 443206 440202 437201 432198 428201 427206 429211
      430215 431217 432214 435216 439215 442213 446211 448209
 0.25 452139 450132 447126 444122 440120 434121 431125 428132
      429140 430147 433149 436148 442147 447146 451141 452139
 0.25 430233 429232 427231 426230 425229 424229 423229 424230
      424232 425233 427233 429234 430233
 0.25 406217 405214 402211 399207 396203 393201 389199 386199
      384200 386205 390208 393210 396212 399216 405217 406217
 0.25 422020 422015 421013 418012 416013 414015 412017 410019
      409021 408026 409030 412030 414028 416026 418024 421022
      422020
 0.25 419046 418045 417044 415043 414043 413043 411045 412047
      413049 415050 417048 418048 418046 419046
 0.25 416071 416065 412062 409061 406056 402056 399058 393062
      389066 387070 386072 384070 382071 379074 378077 381079
      384077 388075 393075 397075 401077 406077 409075 413074
      416071
 0.25 400723 400716 397713 391716 384717 375715 371713 368713
      362717 351727 343732 339737 331750 314775 312778 311783
      307788 304794 305797 308799 321806 326812 330820 332823
      336825 339825 342827 348831 352832 356830 358827 360823
      364818 369813 375808 378805 383803 387799 392793 396784
      392768 391757 392751 393748 395740 397735 400723
 0.25 349840 348839 346839 346840 345842 344842 344845 345845
      347845 347844 348842 349840
 0.50 516884 517875 516867 514864 510864 506867 503871 498881
      488896 486903 485908 483922 486933 489946 489961 491967
      491975 490981 491985 494987 495985 498980 500974 502969
      504965 506960 508946 511934 512903 513895 514892 516884
 0.50 470220 470217 468215 463214 455214 438216 429218 425219
      424224 427228 431231 434234 432236 428237 425237 416233
      411232 408234 406238 408242 413245 418245 427245 434244
      442241 443238 442236 438234 443231 451229 454228 456231
      463231 466227 468222 470220
 0.50 469105 469095 469093 467091 464089 455073 452069 450065
      450058 450051 447041 443039 442033 440030 435030 433033
      435037 441042 440046 437048 435061 436074 443074 447078
      449082 449095 450100 452105 452110 450114 453118 457115
      459111 462110 466109 469105
 0.50 457182 455181 455179 455177 455174 454173 453171 452173
      452176 452177 454179 454180 454181 454184 455184 456184
      457182 457182
 0.50 453188 454186 453184 451185 449186 448186 447187 446188
      445189 445191 445192 447193 449192 451190 453189 453188
 0.50 443166 445164 445162 444160 443159 442157 441156 439155
      438154 436154 435155 434157 435160 436162 437163 438164
      439166 440166 441167 443166 443166
 0.50 448114 447109 445104 443101 438100 434102 430103 427105
      423107 426112 427116 428119 431119 434116 436114 441114
      447114 448114
 0.50 429173 429171 429169 427169 425169 425170 427171 428173
      429173
 0.50 433099 432099 432097 431095 431094 429093 428094 429096
      430097 431098 432099 432100 433099
 0.50 421178 421176 421175 419175 417176 416177 417178 419179
      420179 421178
 0.50 420119 420115 417114 414114 410113 408111 407107 405109
      406112 408114 408117 410119 413121 416121 419121 420119
 0.50 389787 388782 387779 383776 380772 379767 380764 380756
      378750 375743 372738 367734 360734 355733 350734 341742
      334752 321774 318779 316785 314791 313794 314798 318802
      323804 327809 330814 334820 338823 349829 352829 355828
      357822 359817 364812 372803 376798 382797 387792 389787
 1.00 504908 503907 503906 502903 501903 500904 499906 499907
      498909 498911 498914 499916 500915 502914 502913 503911
      503909 504908
 1.00 462223 461220 456217 452218 447218 443218 438219 436221
      437225 442226 446225 451225 455225 460225 462223
 1.00 450073 449070 449068 448067 448065 447064 446063 445060
      444058 444057 443058 443060 443062 442064 441065 440067
      441069 441070 443071 445072 446073 448074 450073 450073
 1.00 421240 421239 420238 419237 418236 416236 415236 414237
      413238 414240 415240 417240 419241 421241 421240
 1.00 368759 364750 361747 357746 352747 350750 347753 344756
      337760 334763 333767 325779 317795 318798 320801 327804
      331811 334814 337815 339812 343811 350811 355810 359808
      365803 368800 367794 365782 363765 368759
 1.00 351824 349824 348824 349824 351825 351824
 1.50 362760 362758 360757 359757 358756 357755 355755 353756
      351757 350758 349760 349762 350763 352764 352765 354766
      355766 356767 358766 359765 359764 360763 361762 362760
 1.50 363798 363790 362783 359778 355776 353772 349768 343768
      337771 330777 324785 323791 320795 322800 327802 333809
      342808 348808 355807 362800 363798
 2.00 360796 360790 358784 352777 351773 347770 342771 337773
      331778 326786 326791 324795 325799 329801 335808 338804
      343804 348804 353804 356802 359799 360796
 3.00 356795 356789 354786 349780 346774 341773 337775 334781
      331788 327794 326797 329798 332800 334799 338798 342799
      349801 355797 356795
 4.00 353793 351788 348785 347778 344776 339777 339782 336785
      335789 332793 332796 337796 342797 347797 352795 353793
 5.00 348793 349791 348789 347788 346788 344788 342786 340785
      338786 337788 337791 337793 339793 341795 343794 344794
      346795 348794 348793
 5.00 345781 345779 345778 344779 345781 345781

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