Quantitative Precipitation Forecast
Issued by NWS

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000
FXUS04 KWBC 151839
QPFPFD

QUANTITATIVE PRECIPITATION FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
238 PM EDT SUN OCT 15 2017


PRELIM DAY 1 QPF DISCUSSION
VALID OCT 16/0000 UTC THRU OCT 17/0000 UTC
REFERENCE AWIPS GRAPHICS UNDER...PRECIP ACCUM - 24HR


DAY 1...

...CENTRAL GULF COAST...

SLOW-MOVING DEEP CONVECTION WAS LINED UP ACROSS PARTS OF SOUTHEAST
LOUISIANA AND SOUTHERN MISSISSIPPI AS OF 18Z. A
SMALL PLUME OF ENHANCED COLUMN MOISTURE WAS DRIFTING ONSHORE IN
THIS REGION...WITH PRECIPITABLE WATER HAVING RISEN JUST ABOVE 2.00
INCHES PER THE 12Z SLIDELL SOUNDING SPC MESOANALYSIS. SPOTTY
CONVECTION WITH HEAVY LOCAL RAIN IS EXPECTED TO MIGRATE VERY
SLOWLY EAST THIS AFTERNOON AND EVENING. INCREASING UPPER DIFLUENCE
IN THE LARGE SCALE PATTERN...ESPECIALLY THIS EVENING...COULD MAKE
FOR MORE PRODUCTIVE UPDRAFTS. AT LOW LEVELS...HOWEVER...INFLOW
WILL BE VERY WEAK AND
INCONSISTENT...AND WITH DEEP LAYER SHEAR LESS THAN 20 KNOTS CELL
STRUCTURES SHOULD STRUGGLE TO SHOW ANY ORGANIZATION. BRIEF INTENSE
RAIN RATES ARE POSSIBLE...BUT AT ANY GIVEN LOCATION THE
INSTABILITY SHOULD BECOME EXHAUSTED AFTER A RELATIVELY SHORT
TIME...CAUSING THE CELLS TO PROPAGATE ELSEWHERE. IN QPF TERMS THIS
IS DESCRIBED BY AREAL AVERAGE AMOUNTS AROUND 1.00 TO 1.25 INCHES
JUST TO EITHER SIDE OF NEW ORLEANS. LOCALLY...HOWEVER...EXPECT 2
INCH PER HOUR RAIN RATES AND ISOLATED TOTALS GREATER THAN 3 INCHES
THROUGH LATE EVENING.

A SEPARATE BROKEN LINE OF STORMS IS EXPECTED ALONG A COLD FRONT
THAT WILL SWEEP THROUGH THE SOUTHEAST STATES FROM THIS AFTERNOON
THROUGH MONDAY. DEEP LAYER ASCENT IS NOT WELL FOCUSED...AND WITH
INSTABILITY REMAINING WEAK...THE AREAL AVERAGE PRECIPITATION
FORECAST IS NEAR A HALF INCH OR LESS ASIDE FROM THE
AFORE-MENTIONED PORTION OF THE CENTRAL GULF COAST. WPC QPF LEANED
TOWARD THE 12Z GFS AND RECENT TWO RUNS OF THE WRF-NMMB. THE
WRF-ARW...WHICH USUALLY PERFORMS BETTER...WAS NOT INITIATING MUCH
CONVECTION...ESPECIALLY MONDAY AFTERNOON WHEN THE FRONT REACHES
EASTERN GEORGIA AND SOUTH CAROLINA.


...REST OF EASTERN U.S...

A MID-LATITUDE CYCLONE WAS LIFTING INTO SOUTHEAST CANADA...TAKING
MOST SYNOPTIC SCALE ORGANIZED PRECIPITATION WITH IT. THE
ASSOCIATED COLD FRONT WILL SWEEP THROUGH THE EASTERN U.S...AND
MOST GUIDANCE AGREES TO A SWATH OF AT LEAST QUARTER INCH RAINFALL
IN THE WEAKLY CONVECTIVE AND UPSLOPE ENHANCED ENVIRONMENT FROM
SOUTHWEST PA DOWN THROUGH EASTERN TN. STRONG HEIGHT FALLS AND SOME
TERRAIN ENHANCEMENT MAY ALSO SQUEEZE OUT QUARTER INCH AMOUNTS OVER
WESTERN AND NORTHERN NEW YORK. FARTHER EAST...THE MODEL QPF SIGNAL
IS MORE VARIABLE TOWARD THE COASTAL PLAIN FROM THE MID-ATLANTIC
STATES SOUTHWARD. TWELVE HOUR HEIGHT FALLS OF 50 METERS AND SOME
SENSE OF CONVERGENT/CONFLUENT MID LEVEL FLOW ARGUE FOR LEANING TO
THE WETTER GFS AND GEFS PROBABILITIES FROM SOUTHERN VA UP THROUGH
NJ. THE DIFFERENCES ARE STILL FAIRLY MINOR...BUT WPC USED A BLEND
OF CONTINUITY...THE 12Z GFS...AND THE WRF-NMMB...TO ARRIVE AT A
SMALL AREA OF HALF-INCH-PLUS PRECIPITATION STRADDLING VA/NC...WITH
QUARTER INCH AMOUNTS UP THROUGH EASTERN MARYLAND TO NEW JERSEY.

BURKE

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


24HR QP VT 17/00Z
 0.01 541203 539186 536181 532176 524168 518166 514168 507168
      504168 502170 499170 498172 498182 500188 504187 509187
      512192 514200 516206 519211 523216 526221 531221 535221
      537218
 0.01 527251 524249 522246 519239 512227 508221 504217 500214
      494215 488218 486220 485225 487233 486236 484237 481240
      480244 478253 478262 481269 481279 483286 487290 494294
      501296 507297 510296
 0.01 499616 495614 493615 486621 481628 477635 464670 462683
      458689 454697 449704 443711 440714 436716 429721 425723
      424723 424720 427711 429702 431696 431691 434687 434681
      433674 430672 426674 420680 416686 409694 404701 393713
      389721 381726 373732 359746 351760 343771 337777 336774
      346759 357745 365730 369721 371713 371708 368706 366706
      362708 356714 350721 345728 341734 332747 320763 311778
      304798 299802 288800 280792 270787 260786 256786 252790
      255796 255801 250804 250806 250811 253814 257818 265822
      272825 282827 286827 291829 292833 290837 285852 279869
      270883 263898 255913 252920 248927 242933 236938 234940
      232942 230950 231975 235978 241978 250976 263967 283938
      286934 290931 297927 307926 314922 322917 327910 337895
      343886 347879 357865 367849 377835 388818 399805 403802
      406801 407810 411813 414815 419816 421818 429824 436829
      441829 444831 450838 453841 455846 449851 445850 439851
      436853 431853 426852 420852 411854 410859 410864 417868
      427869 438868 442868 446865 453860 459859 462864 465868
      466873 466886 466893 465898 463903 465907 465915 467917
      467904 472895 477884 478879 478872 475862 479855 477849
      476842 472833 467824 461817 458813 454811 450809 448804
      446800 444798 441798 439801 443805 444807 443809 437810
      433808 429806 426802 425789 423787 419792 419797 417800
      413800 410799 410795 415789 422782 425779 429781 434776
      434771 437768 443762 447757
 0.01 447757 455750 463744 467741 471737 479731 486723 493715
      500707 503703 505698 511687 513682 513675 515661 515656
 0.01 269068 269066 268064 266062 266061 264061 262061 261061
      259061 257059 257061 259062 260063 260064 261066 262066
      263068 264068 265069 267069 269069 269068
 0.01 273011 273005 272001 268992 265984 263981 259979 253979
      250980 243986 240989 240993 242002 249008 254013 261017
      267018 271016 273011
 0.25 536209 537204 537199 536191 533187 529182 523180 520180
      518183 520189 521197 523205 526210 530213 534212 536209
 0.25 524262 522253 519247 513237 510232 505228 501225 496223
      493225 491227 492235 493238 492241 487241 485243 483247
      484255 485263 486269 488277 491282 495286 501290 506292
      510291 516283
 0.25 505665 505656 504648 501640 499635 496632 492632 485639
      480648 477659 474669 472680 469691 465701 460709 455718
      453723 453728 463726 472723 480716 486709 492701 497692
      501682 504673 505665
 0.25 443740 439740 435742 431745 428748 426752 424756 425761
      428759 431754 435752 438750 441746 442742 443740
 0.25 435729 434729 432728 431728 430728 428728 428729 429731
      431732 432731 434730 435729
 0.25 441817 440817 439818 441819 441817
 0.25 404748 405745 404743 401746 399749 398751 396753 394756
      393759 395763 398761 399758 401755 402753 403750 404748
 0.25 386765 385757 382757 379754 374753 370750 364753 358761
      353770 349780 348786 350791 359790 363789 367786 376780
      379776 382772 386765
 0.25 385806 385801 381802 378806 369815 361825 353835 345844
      341848 335851 330839 327845 325851 317862 310871 305874
      297875 291879 287882 282886 276889 270899 258921 252933
      245942 236950 233955 234962 235971 237973 241973 248972
      253969 262961 269952 273945 275939 276933 276924 276914
      276905 278899 282899 286898 286904 288906 292907 302904
      316885 320879 323873 327870 330869 331873 332876 334876
      340873 344868 348863 354852 361841 368830 375819 381812
      385806
 0.25 357725 355725 353727 350729 348731 347733 345736 344739
      346741 348744 350742 351740 353737 354734 355731 357728
      357725
 0.25 337810 337799 335796 332795 322804 310812 307815 309818
      314823 315826 313829 310836 299846 298849 298853 300855
      304855 307850 310843 315837 319832 325827 331823 334817
      337810
 0.25 261004 259000 257997 255995 257993 259990 257988 253988
      248989 246992 246996 247000 251003 254005 260005 261004
 0.50 535204 535201 534196 533193 531191 528191 526192 526195
      525199 526204 528207 529208 532209 534206 535204
 0.50 520271 521266 522260 519252 516246 512240 508235 502230
      496228 493231 496238 496245 489244 486245 485248 485257
      487264 489273 492279 496285 502288 507289 512284 516279
      519272 520271
 0.50 500653 498646 496641 491639 488644 483654 480665 479678
      477691 477700 478704 479707 482706 485702 491693 496683
      497677 498670 500656 500653
 0.50 369761 368758 366760 363762 361765 360767 359770 357772
      356775 355777 357779 361776 362774 364772 365770 367767
      368764 369761
 0.50 359839 360834 358834 356837 354839 352841 350843 348845
      347848 345851 345853 347854 349852 351850 353848 355846
      357843 358841 359839
 0.50 331802 331801 329801 327803 325804 324805 324806 322808
      322810 324812 326812 327812 328811 329809 330807 331805
      331804 331802
 0.50 318873 316870 314873 310877 306879 301879 296885 293891
      292894 294897 295902 297903 300903 300899 301896 303896
      307895 311889 313887 314883 317875 318873
 0.50 270939 269925 268919 265919 263921 257930 251939 244947
      240951 237955 236960 236963 239969 244970 250968 259962
      265954 268948 270941 270939
 1.00 516273 519264 518257 513246 506238 502235 500235 498237
      501248 501252 498252 493248 490247 487250 488258 491271
      496280 500284 505285 509282 512279 516273
 1.00 263947 263939 262937 259937 255941 252945 248949 245954
      241957 240959 241964 244966 250964 254962 259958 261954
      263947
 1.50 515269 516265 516261 515256 512250 510246 502238 502243
      504249 504255 500256 496253 491250 488252 488254 489260
      493272 496276 499281 505282 508278 515270 515269
 1.50 258954 258949 257947 254947 252949 250951 248953 246955
      245958 244960 244963 248962 250961 253960 255958 257956
      258954
 2.00 514266 514261 513257 509250 507252 507256 505259 503260
      497255 490252 490255 491260 493268 497275 499278 503279
      507274 509269 512267 514266
 3.00 503273 503269 502266 500263 498260 496258 493257 493259
      494264 495267 496269 497272 499274 502275 503273
 4.00 499266 499265 497263 496262 495262 495263 496265 497266
      498268 499266

$$





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