Quantitative Precipitation Forecast
Issued by NWS

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000
FXUS04 KWBC 200705
QPFPFD

QUANTITATIVE PRECIPITATION FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
304 AM EDT TUE SEP 20 2016


PRELIM DAY 1 QPF DISCUSSION
VALID SEP 20/1200 UTC THRU SEP 21/1200 UTC
REFERENCE AWIPS GRAPHICS UNDER...PRECIP ACCUM - 24HR


DAY 1

SOUTHERN CALIFORNIA...SOUTHWEST INTO THE SOUTHERN ROCKIES

WHILE TROPICAL STORM PAINE IS EXPECTED TO WEAKEN...AS PER THE
LATEST NHC DISCUSSION...MUCH ABOVE AVERAGE PW VALUES WILL CONTINUE
TO BE DRAWN NORTHWARD IN THE MID LEVEL SOUTHERN FLOW BETWEEN THE
SOUTHERN PLAINS UPPER HIGH AND THE CLOSED LOW OFF THE SOUTHERN
CALIFORNIA/NORTHERN BAJA COAST.  WIDESPREAD SCATTERED SHOWER
ACTIVITY LIKELY FROM SOUTHERN CALIFORNIA INTO THE SOUTHWEST AND
SOUTHERN ROCKIES.  WITH CLOUD COVER WIDESPREAD---INSTABILITY MAY
BE LIMITED--LIMITING THE PRECIPITATION POTENTIAL.  THERE IS A LOT
OF MODEL QPF DIFFERENCES LEADING TO LOW CONFIDENCE---WITH THE IN
HOUSE PSEUDO BIAS CORRECTED MEAN USED TO MITIGATE THOSE
DIFFERENCES.  ISOLATED HEAVY PRECIP TOTAL AND RUNOFF ISSUES
POSSIBLE WHERE ANY LESSENING CLOUD COVER WILL INCREASE
INSTABILITY.

EASTERN CAROLINAS INTO THE SOUTHERN DELMARVA

AN UPPER LOW EXPECTED TO CLOSE OFF AND BECOME NEARLY STATIONARY
OVER EASTERN SC TUESDAY INTO EARLY WEDNESDAY. THIS SHOULD HELP
ANCHOR WEAK SURFACE LOW PRESSURE OFF SOUTHEAST NC AND MAINTAIN
MOIST CYCLONIC FLOW INTO EASTERN NC AND FAR SOUTHEAST VIRGINIA.
WITH THE EXPECTED SLOW MOTION OF THIS CLOSED LOW AND SUSTAINED
CYCLONIC FLOW---HEAVY PRECIP TOTALS LIKELY TO THE NORTH AND
NORTHWEST OF THIS CIRCULATION CENTER---IMPACTING AREAS FROM FAR
SOUTHEAST VIRGINIA INTO NORTHEAST NORTH CAROLINA.  AS PER THE
PMDHMD---THE GFS IS AN OUTLIER WITH THE PLACEMENT OF THE LOW ALONG
THE NC COAST AND IS FARTHER TO THE NORTHEAST WITH ITS QPF---NOT
BRINGING HEAVY TOTALS BACK INLAND AS PER THE MODEL CONSENSUS.
ISOLATED RUNOFF ISSUES MAY DEVELOP OVER NORTHEAST NC AND FAR
SOUTHEAST VIRGINIA WHERE THE MOST PERSISTENT RAIN BANDS SET UP.

UPPER MS VALLEY

LOW LEVEL SOUTHWESTERLY TO WESTERLY FLOW EXPECTED TO STRENGTHEN
TUESDAY EVENING INTO THE EARLY HOURS OF WEDNESDAY ALONG AND INTO
THE STRENGTHENING WARM FRONTAL BOUNDARY FORECAST TO STRETCH FROM
THE NORTHERN PLAINS INTO THE UPPER MS VALLEY DAY 1.  THIS WILL
SUPPORT INCREASING CONVECTION ALONG AND NORTH OF THIS FRONT--WITH
ACTIVITY STRETCHING FROM SOUTHERN MN---INTO NORTHEAST IA AND
SOUTHWEST WI.  THIS WILL BE THE FIRST DAY OF A POTENTIAL MULTI DAY
ACTIVE CONVECTION PATTERN ALONG AND NORTH OF THIS BOUNDARY.   FOR
THIS FIRST DAY---MODEL CONSENSUS IS FOR MODERATE TO LOCALLY HEAVY
PRECIP TOTALS---WITH INCREASING PRECIP POTENTIAL DURING THE DAY 2
TIME PERIOD.

PACIFIC NORTHWEST---NORTHERN ROCKIES INTO THE NORTHERN HIGH PLAINS

MODELS ARE SHOWING GOOD AGREEMENT WITH THE DEVELOPING CLOSED LOW
OVER THE PACIFIC NORTHWEST DAY 1. ONSHORE FLOW WILL BE WEAK OVER
THE PAC NW---LIMITING ANY PRECIP POTENTIAL TO LIGHT AMOUNTS IN THE
WA CASCADES AND OLYMPIC RANGE. DOWNSTREAM OF THIS AMPLIFYING
CLOSED LOW...EASTERLY LOW LEVEL FLOW WILL BE STRENGTHENING OVER
THE NORTHERN HIGH PLAINS INTO THE NORTHERN ROCKIES TO THE
NORTHEAST OF THE DEEPENING ASSOCIATED SURFACE LOW OVER THE
NORTHERN ROCKIES.  THIS WILL SUPPORT INCREASING PRECIP COVERAGE
FROM PORTIONS OF THE NORTHERN ROCKIES INTO THE NORTHERN PLAINS.
FOR THE DAY 1 PERIOD---MODEL CONSENSUS IS FOR LIGHT TO MODERATE
TOTALS---WITH GREATER PRECIP POTENTIAL DAY 2 AND BEYOND ACROSS
THESE AREAS.

ORAVEC

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

24HR QP VT 21/12Z
 0.01 536163 536155 534150 533144 530138 527134 525128 523124
      519120 516118 513116 510116 506118 502127 496127 494122
      492117 491109 491102 491093 490086 491078 492073 493065
      495050 495044 495039 495022 494018 493010 491998 491989
      492981 493973 491967 489964 485962 479969 475979 475986
      474989 472985 473972 472957 471949 469942 466932 464929
      462930 460933 460965 459979 460993 463006 469015 469019
      468021 467029 466044 466051 467057 466072 466086 466090
      463094 458095 454093 448092 449098 450105 448110 444119
      452132 449141 449146 450151 453156 456155 460151 463146
      466142 469140 476135 486140 492147 498154 500157 495158
      492161 491167 493171 497175 501179 504184 507194 506203
      505206 502207 499208 494207 478206 470210 463218 462223
      466224 473220 478219 483220 487223 490227 494236 498243
      502248 506250 517255 520251 521245 523237 525232 526223
      526216 528210 528203 528196 528189 529182 531176 536163
 0.01 501661 500650 497646 493642 489640 482643 478645 471655
      460674 451696 449704 449713 448718 445722 441728 439733
      441750 445749 448744 449738 453733 457722 459716 463711
      471703 478695 487686 490683 493678 496673 498668 501661
 0.01 480241 480234 478230 476230 472231 470233 467233 464231
      459233 453233 450233 449237 452240 458240 460239 463240
      469242 476244 480241
 0.01 473996 473994 473992 473989 472987 471989 471991 471994
      471996 472999 473996
 0.01 470009 471006 470004 469006 470009 470009
 0.01 457910 456879 452867 449865 445865 443863 440863 437866
      433868 430869 428875 428879 427883 424886 422891 419894
      414896 413900 412905 414918 418926 421930 424935 424949
      428959 433967 437970 440971 444969 447964 450954 452940
      454928 454921 456915 457910
 0.01 423687 370720 352719 341721 331724 329726 328731 328736
      328741 316751 303765 300772 299775 297777 294779 280789
      273792 264794 260795 256798 254803 254806 266818 265823
      265827 269829 271834 271840 270845 269853 270862 271868
      274872 277873 283873 285875 288873 292864 291858 294854
      301840 304832 309823 316818 319817 323814 322810 317811
      313813 311812 310810 308793 310788 312783 315774 320767
      323765 326761 332755 337762 341763 341766 341771 339775
      331792 328800 332808 331818 331820 334822 342820 349823
      353824 356822 360819 362814 365805 369797 372789 375781
      378773 384768 394750 402735 406729 411723 416715 419707
      423687
 0.01 399085 400073 396066 393057 390052 388049 385049 382050
      378050 370050 365050 363051 359051 356053 351059 348065
      343071 337075 328074 322076 314075 295072 280067 255056
      250052 243048 240046 236045 231048 230051 229055 232062
      240070 253079 263088 268091 272094 277099 282105 286110
      292117 297120 296127 290142 285146 281150 275154 270159
      268162 267167 267171 268175 272179 275185 280189 288191
      296190 303187 309184 314181 319176 325174 331175 335180
      339186 342186 346183 347180 348175 347166 346163 346158
      348153 350150 354146 359142 366141 374139 377136 378133
      380130 381125 382114 382110 381106 384098 386096 390096
      396092 399085
 0.01 302952 302947 300945 296942 292945 289952 286956 285962
      285968 287971 290971 293966 296962 299957 302952
 0.25 524166 524161 523157 521147 518140 516137 512136 505137
      500139 499146 501149 506153 509156 510160 514168 519169
      523169 524166
 0.25 479092 479082 477076 474089 472098 468105 467109 467115
      465127 468127 470123 472116 476106 478097 479092
 0.25 447940 448932 447925 444916 441906 439900 437897 435895
      432896 428897 425900 423905 422914 424921 426926 430934
      434942 436947 438951 443949 445945 447940
 0.25 388742 385738 381738 376738 373737 364735 356733 346733
      342735 339738 339745 341751 346759 348763 347769 345778
      342799 344803 349802 354797 361791 367784 370776 374769
      383753 387747 388742
 0.25 376073 376072 375071 374070 374071 374072 375073 376075
      376073
 0.25 363123 363118 362114 360112 357111 348108 343103 340102
      336102 334105 335110 338117 345120 345129 349136 353135
      356133 360128 363123
 0.25 341170 333158 333149 330142 330138 328135 326132 322131
      314132 308135 295141 293144 292149 289154 283160 282163
      281168 283172 285174 291178 295179 298179 305177 317171
      332170 341170
 0.25 297090 291085 285082 277079 271075 265071 258069 260074
      267078 272081 277086 284090 289091 293091 297090
 0.25 296819 295812 293805 289802 283800 277800 272802 273810
      275816 277820 283823 287827 289829 294824 296819
 0.50 520162 520157 519154 517151 516149 513147 509148 509150
      511153 512157 513160 515162 516164 518164 520162
 0.50 443935 443928 441921 438914 436906 432903 429904 428907
      426914 428923 430928 433934 436940 440942 443937 443935
 0.50 380750 377745 372743 362739 356738 349738 346740 344743
      345748 350760 351765 351768 349773 351782 354785 360785
      363782 370772 376762 379756 380750
 0.50 355120 354118 354117 352116 351115 349117 350118 351119
      352120 354120 355120
 0.50 326165 324156 321151 319149 313143 307142 302141 298142
      296145 295151 293156 287161 286166 289169 298172 303172
      306170 314166 323167 326165
 1.00 376756 374750 372748 366746 359744 352744 350746 350751
      353759 355768 356774 358777 364774 369769 373763 376756
 1.00 312156 311155 311154 310153 308151 307151 306151 305151
      303153 304155 306156 308157 309157 311156 312156
 1.50 372758 371752 368750 364749 360747 356748 354750 355756
      356761 358768 360770 365770 369766 370763 372758
 2.00 370759 369755 367753 365752 363751 360750 358752 357757
      358761 358765 361767 363767 365766 367764 369761 370759

$$





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