Quantitative Precipitation Forecast
Issued by NWS

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000
FXUS04 KWBC 281858
QPFPFD

QUANTITATIVE PRECIPITATION FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
258 PM EDT WED SEP 28 2016


PRELIM DAY 1 QPF DISCUSSION
VALID SEP 29/0000 UTC THRU SEP 30/0000 UTC
REFERENCE AWIPS GRAPHICS UNDER...PRECIP ACCUM - 24HR


DAY 1

MID ATLANTIC INTO THE UPSLOPE AREA OF THE CENTRAL APPALACHIANS

MODELS REMAIN CONSISTENT WITH THE EVOLUTION OF STRONG CLOSED LOW
INITIALLY OVER THE MID WEST---SINKING SLOWLY SOUTHWARD INTO THE OH
VALLEY.  PRECIPITATION COVERAGE AND INTENSITY WILL BE INCREASING
ON THE EASTERN SIDE OF THIS CLOSED LOW ACROSS THE MID ATLANTIC AND
INTO THE UPSLOPE REGIONS OF THE CENTRAL APPALACHIANS THIS PERIOD.
THERE IS A STRONG MODEL SIGNAL FOR HEAVY TO EXCESSIVE RAINFALL
AMOUNTS DEVELOPING OVERNIGHT THROUGH THE MID ATLANTIC WHERE
TRAINING OF HEAVY PRECIPITATION IS POSSIBLE.  THERE IS OVERALL
GOOD AGREEMENT ON THE HEAVY TO EXCESSIVE RAINFALL
POTENTIAL---ALTHOUGH THERE ARE SOME DIFFERENCES WITH THE MAX AXES.
 THE NAM HAS BEEN THE MORE WESTERN OUTLIER OVER THE PAST FEW RUNS
WITH THE AXIS FOR THIS PERIOD---WHILE SOME OF THE HIGHER
RESOLUTION RUNS---INCLUDING THE GEM---ARW AND MANY OF THE HRRR AND
HRRR EXPERIMENTAL HAVE BEEN FARTHER EAST.  THE HRRR AND HRRR
EXPERIMENTAL HAVE BEEN MORE CONSISTENT--WHILE THE HI RES ARW AND
NMMB HAVE SHOWN MORE VARIABILITY.  THE HRRR AND HRRR EXPERIMENTAL
SHOW VERY HEAVY TOTALS IN THE DC-BALTIMORE METRO AREA---WITH
VALUES OVER 10".  THE HRRR TIME LAGGED ENSEMBLES ALSO SHOW VERY
HIGH PROBABILITIES OF 2...3 AND 6 INCH AMOUNTS IN THE 6 HOUR
PERIODS ENDING 0300 AND 0900 UTC THURSDAY.  HRRR TLE PROBABILITIES
ARE AS HIGH AS 70 TO 90% FOR 2 INCH AMOUNTS...50 TO 70% FOR 3 INCH
AMOUNTS AND 20 TO 30% FOR 6 INCH AMOUNTS IN THE AFOREMENTIONED 6
HOUR PERIODS FROM NORTH CENTRAL VA INTO CENTRAL MD.  WHILE
CONFIDENCE IS LOW ON THE HRRR EXPERIMENTAL`S VERY HIGH
TOTALS---THE POTENTIAL FOR THE PRECIP AREA TO PIVOT OVER THIS AREA
EARLY MORNING HOURS THU TO AROUND SUNRISE THU AS THE LOW LEVEL
FLOW BACKS TO A MORE EAST SOUTHEASTERLY DIRECTION---DOES WARRANT
POTENTIAL FOR VERY  HEAVY TO EXCESSIVE AMOUNTS.  NO CHANGES MADE
TO THE PREVIOUS EXCESSIVE RAINFALL POTENTIAL OUTLOOK ACROSS THIS
AREA AS THE MODERATE RISK AREA SEEMS TO FIT WELL WITH THE HIGHER
HRRR TLE PROBABILITIES.  AREAL AVERAGE 2-4" AMOUNTS DEPICTED DAY 1
ACROSS THE MID ATLANTIC---WITH POTENTIAL FOR ISOLATED TOTALS OF
5-10" WHERE THE RAIN BANDS TRAIN OR PIVOT EARLY THURSDAY.  THE
EMPHASIS FOR THE HEAVIEST PRECIPITATION SHOULD BEGIN TO SHIFT BACK
MORE TO THE WEST SOUTHWEST DURING THURSDAY INTO THE UPSLOPE AREA
OF THE CENTRAL APPALACHIANS FROM NORTHWEST VA INTO NORTHEAST WV AS
THE LOW LEVEL FLOW BACKS TO A MORE EAST SOUTHEASTERLY DIRECTION.
DAY 1 QPF DID BEGIN TO SHOW THIS TRANSITION BEING SLIGHTLY WETTER
THAN THE PREVIOUS RUN OVER  NORTHEAST WV AND NW VA FROM THE
PREVIOUS FORECAST---WITH THIS TREND MORE EMPHATIC DURING THE DAY 2
TIME PERIOD.

LOWER LAKES INTO THE OH VALLEY

SHOWERY CONDITIONS LIKELY TO CONTINUE IN THE VICINITY OF THE SLOW
MOVING CLOSED LOW DROPPING INTO THE OH VALLEY DAY 1.  THE MOST
ANOMALOUS PW VALUES WILL BE EAST OF THE APPALACHIANS OVER THE MID
ATLANTIC REGION---WITH PW VALUES CLOSER TO OR SLIGHTLY ABOVE
SEASONAL MEANS IN THE VICINITY OF THIS CIRCULATION.  THIS WILL
SUPPORT MUCH LESS PRECIP AMOUNTS DAY 1 OVER THE LOWER LAKES INTO
THE OH VALLEY THAN POINTS FARTHER EAST.  BEST CHANCE OF HEAVY
TOTALS WILL BE JUST NORTH OF THE MID TO UPPER LEVEL CENTER FROM
NORTHERN IN---NORTHERN OH--SOUTHEAST L.P. OF MI WHERE THE COMMA
HEAD/DEFORMATION PRECIP BAND HAS THE BEST CHANCE OF SETTING UP.
HERE .50-1"+ AREAL AVERAGE AMOUNTS DEPICTED---WITH LESS TOTALS
SOUTHWARD INTO THE OH VALLEY--BUT HEAVIER IN THE UPSLOPE SECTIONS
ON THE WESTERN SIDE OF THE CENTRAL APPALACHIANS.

SOUTHWEST INTO THE GREAT BASIN

THE CLOSED LOW INITIALLY OVER SOUTHERN CALIFORNIA WILL CONTINUE TO
PUSH NORTHEASTWARD INTO THE GREAT BASIN ON THE SOUTHEASTERN SIDE
OF THE AMPLIFYING MID TO UPPER LEVEL TROF OFF THE PACIFIC
NORTHWEST COAST.  SCATTERED SHOWERS WILL CONTINUE IN THE AXIS OF
ABOVE AVERAGE PW VALUES STREAMING NORTHEASTWARD WITH THIS CLOSED
LOW FROM THE SOUTHWEST INTO THE GREAT BASIN.  CONFIDENCE LOW WITH
DETAILS---WITH AREAL AVERAGE LIGHT TO MODERATE AMOUNTS DEPICTED
WITH ISOLATED HEAVY TOTALS POSSIBLE.

ORAVEC

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

24HR QP VT 30/00Z
 0.01 496328 493325 489322 486319 481317 472318 464315 463311
      462306 467298 473293 481290 485291 488289 494285 503288
      508290 513290
 0.01 544041 544034 543031 542023 539008 536002 531998 528994
      526997 521004 519009 517017 516025 512042 512056 512068
      510075 509084 511089 512092 512096 510101 508109 504119
      501128 501137 504135 506130 513117 518106 522099 525094
      530085 539054 544041
 0.01 506158 506153 504151 501149 498147 494147 492143 490137
      481130 477131 474136 475140 478144 476147 471147 467143
      466137 463132 459130 457127 457122 457116 459111 460103
      456097 453094 446093 445091 442090 438090 436092 435094
      432092 427088 423099 419101 413100 412098 412095 412087
      410086 409081 409078 410075 413073 413071 413067 416064
      412063 408059 404058 402059 398059 391063 388070 386071
      383070 380066 377066 374065 366063 360067 354069 347070
      342070 337071 331071 326071 320069 315069 311072 304071
      300068 297063 294060 287055 281053 272051 264052 261057
      259069 259078 261082 264087 268089 272088 275090 278092
      284091 288092 292096 297096 301097 303100 305105 309111
      317116 326111 329112 332113 332117 328126 323135 318140
      313141 311142 310138 311133 313129 314122 312120 308119
      302129 299133 296136 292139 289144 288150 289154 292158
      296160 301163 305162 318160 323156 326150 329145 334143
      340135 343134 345135 349137 354135 360137 363138 364141
      367146 369149 376150 379151 382150 386150 390152 391157
      389159 383163 382170 387169 391172 393168 398159 401158
      404158 407155 417161 423157 428153 430152 432154 434157
      435160 438161 446163 447165 451166 454163 458158 462156
      480160 495159 503162 506158
 0.01 442791 441773 440763 439755 438751 438746 435741 432740
      427733 419733 410734 404736 401734 399728 395723 391719
      386718 378717 370720 364724 357729 340737 334739 328741
      319747 312751 305757 299763 293768 287774 284776 279777
      273778 271780 267780 261781 257777 253777 249779 247782
      243784 249787 253789 258788 257791 254790 254794 256797
      255802 252808 253822 253827 252832 249841 247849 248852
      250855 259858 262859 264862 265869 269873 275874 281873
      284872 286876 290885 291887 294883 299879 310865 320847
      323842 324839 329831 339819 344813 347811 349813 352815
      359824 356830 353834 349842 345851 344853 344860 350859
      352870 359870 387893 390895 394895 402890 406889 409887
      415882 419882 424880 429877 431872 431863 434853 435842
      436836 438833 438807 442791
 0.01 422136 421129 417129 415130 412128 409125 407126 402126
      400123 397120 394121 391123 388123 384125 384128 387134
      388139 391141 394139 399140 407142 412142 414141 420137
      422136
 0.01 383195 381192 378189 375186 370184 364183 359183 359186
      364188 367189 372192 375195 381196 383195
 0.01 373175 374166 374163 371161 368158 363154 359158 356162
      354168 353173 351175 350179 352180 358179 363178 369177
      373175
 0.01 345182 345177 344171 343168 341166 336167 330165 327168
      332170 335172 339171 341175 341180 344183 345182
 0.01 268783 266783 265783 263783 261783 260784 260787 261788
      263786 265785 267785 268783
 0.01 231994 233005 236010 240014 242013 245010 247008 251009
      252016 254014 262004 262000 261998 257996 254993 254988
      257983 266977 269975 270970 271965 271949 267919 267914
      268909 267904 265890 262895 262903 262919 260927 258927
      257924 255921 253920 248919 242922 239927 237932 236940
      236948 234954 231963
 0.25 434778 434765 431756 428750 423747 413746 406746 400744
      387739 382740 376739 370741 365745 362750 361756 357763
      352767 345769 338770 332771 327773 322777 318781 310784
      301786 288786 281787 275790 278799 283803 285806 287810
      291814 294815 296813 302811 309810 315809 320805 336801
      349801 369811 384813 384815 380819 376824 374830 372836
      370842 369845 370848 372847 377842 387836 393833 400833
      403838 403843 402848 400855 398859 399865 402869 408871
      415871 418871 421870 426860 431842 431836 432825 431807
      433792 434778
 0.25 380081 381078 381076 379075 378074 376074 375075 374078
      374080 375081 377082 379082 380081
 0.25 371095 371090 370088 366085 356080 348077 342078 330081
      326086 327093 330099 334103 340113 345116 350117 355104
      360102 365104 371095
 0.25 295830 294826 292822 287821 281822 270822 266822 265824
      263828 259838 258843 260848 269852 275859 279861 282860
      286858 290854 292850 293843 293837 295830
 0.25 293079 293074 289072 284070 280069 277066 273065 269064
      268070 269075 272077 277079 281080 285080 288081 292080
      293079
 0.25 231986 239987 244986 248984 253978 259973 262969 263966
      262958 260953 255952 250947 245948 243950 239958 235966
      232975 232976
 0.50 430769 428763 425758 423755 419753 410754 407754 403752
      393749 390748 385749 378753 373758 366766 360772 355773
      351773 344775 338777 334780 334784 338785 344788 350793
      354797 359797 365802 375801 378800 381802 390806 393808
      395812 394816 392819 385825 382828 381831 384831 390829
      397826 403826 406829 411838 409847 408859 411856 416857
      421855 424853 426848 428838 427826 425812 424803 426791
      428784 429774 430769
 0.50 342100 343098 343096 343094 342091 340090 339089 338089
      337089 335090 335093 335095 336097 337097 338099 339100
      340100 341101 342100
 0.50 310801 311797 310794 308793 303791 298791 293791 289791
      284791 283796 286799 290800 294801 298802 303803 309802
      310801
 0.50 288833 287830 285829 282828 280827 276826 272827 270828
      270833 271835 274836 275836 279835 282834 286834 288833
 0.50 283848 284846 283844 281844 279844 278844 277844 276844
      274845 273847 273849 274851 274852 275853 276854 278854
      280853 280852 281850 282850 283848 283848
 0.50 231982 237984 242982 246978 251976 255972 257968 257964
      252961 248960 245962 241966 238969 236975 233979 231981
 1.00 422773 420766 418764 412760 404757 398756 389754 382757
      371770 361781 357784 356788 358792 361794 364796 368797
      377795 386795 393798 401802 404803 408802 412793 415788
      420780 422773
 1.00 423834 422829 422827 420824 418821 416820 414818 411817
      409819 410822 413823 415824 417826 418830 419833 422834
      423834
 1.50 416779 416772 414769 409766 398759 392757 388758 378767
      370777 362787 363790 366791 371792 378791 384792 397795
      403795 407791 415781 416779
 2.00 411779 412774 410772 407769 400762 395759 391759 387761
      383765 377772 370781 369784 371786 374787 381788 385790
      395792 401792 405789 411780 411779
 3.00 405778 402772 398768 394765 390765 387766 382770 379774
      377777 377780 382782 387784 393785 398784 402781 405778
 4.00 393775 393773 393772 392771 391770 389770 387771 386772
      386774 388776 390778 391778 392778 393776 393775

$$





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