Quantitative Precipitation Forecast
Issued by NWS

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000
FXUS04 KWBC 211813
QPFPFD

QUANTITATIVE PRECIPITATION FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
211 PM EDT SUN SEP 21 2014


PRELIM DAY 1 QPF DISCUSSION
VALID SEP 22/0000 UTC THRU SEP 23/0000 UTC
REFERENCE AWIPS GRAPHICS UNDER...PRECIP ACCUM - 24HR


DAY 1...


GREAT BASIN TO THE CENTRAL ROCKIES
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
AN AREA OF HIGHLY ANOMALOUS PRECIPITABLE WATER VALUES (PWS) --
3.5-4.0 STANDARD DEVIATIONS ABOVE NORMAL/NEAR THE 99TH PERCENTILE
FOR LATE SEPTEMBER PER THE RAP/SREF/GEFS GUIDANCE (1"+) -- WILL
CONTINUE TO PULL NORTHEAST NEAR AND AHEAD OF THE MID- TO
UPPER-LEVEL LOW CURRENTLY ACROSS NORTHWEST NV WHICH PROGRESSES
INTO NORTHWEST WY WITH TIME.  LOW-LEVEL INFLOW AT 700 HPA IS
FORECAST BY RECENT RAP/NAM RUNS TO BE IN THE 20-25 KT RANGE ACROSS
SOUTHERN ID, MUCH OF UT, EASTERN NV, SOUTHWEST CO, AND WESTERN WY
WHICH WOULD BE SUFFICIENT TO ORGANIZE CONVECTION ACROSS THE WEST.
SOME DRY AIR IN LOW LEVELS (OUTSIDE OF EASTERN NV WHICH HAS
MOISTENED UP DUE TO RECENT RAINS) PER REGIONAL 12Z SOUNDINGS
SHOULD ALLOW CONVECTION TO REMAIN PROGRESSIVE, THOUGH SOME CELL
TRAINING IS POSSIBLE.  EXPECTATIONS FROM DAYTIME HEATING ALONG
WITH RECENT RAP GUIDANCE INDICATES CAPE VALUES OF 1000+ J/KG IN
POCKETS ACROSS UT AND NV THIS AFTERNOON AND EVENING.  FARTHER
NORTH IN SOUTHERN ID AND WESTERN WY, BUILDING INSTABILITY COULD BE
A PROBLEM DUE TO EXTENSIVE CLOUD COVER WITHIN AN AREA OF
DIFFLUENCE TO THE NORTHEAST OF THE UPPER LOW.  AREAS OF WESTERN CO
COULD SEE SOME LOCALIZED HEAVY RAINFALL THOUGH THUNDERSTORM
ACTIVITY MAY NOT BE AS ORGANIZED.  RAINFALL RATES UP TO 1.5" AN
HOUR ARE SUPPORTED BY THE AVAILABLE MOISTURE, WITH MESOSCALE
GUIDANCE INDICATING LOCAL AMOUNTS OF 2-4" BEING POSSIBLE.  USED A
COMBINATION OF 12Z WPC CONTINUITY AND SEPTEMBER PRISM DATA FOR
PLACEMENT, AND USED THE MOST RECENT GUIDANCE TO LOWER AMOUNTS
ACROSS SOUTHWEST CO WHICH FIT IN BETTER WITH THE 00Z GEFS- AND
CLIMATOLOGY-BASED REFORECAST.


WEST TEXAS INTO NEW MEXICO AND SOUTHEASTERN ARIZONA
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
A PERSISTENT UPPER-LEVEL DIFFLUENCE BETWEEN THE CLOSED UPPER HIGH
ACROSS WRN MEXICO AND THE FASTER WESTERLIES/HEIGHT FALLS DROPPING
INTO THE MID MS VLY WILL ALLOW FOR THE DEVELOPMENT OF MORE
ORGANIZED CONVECTION, THOUGH THE LOW-LEVEL FLOW SHIFTS FROM MORE
SOUTHEASTERLY TO MORE SOUTHERLY WITH TIME.  ALSO IN THE MIX ARE
THE REMAINS OF ODILE, WHICH SHOULD OPEN UP INTO AN INVERTED TROUGH
AND DAMPEN OUT AS THE REMNANT TROUGH PROGRESSES NORTHWEST INTO NM,
WITH HEAVY RAINFALL FADING IN ITS WAKE DUE TO A DEVELOPING
SUBSIDENCE INVERSION.  PWS REMAIN BETWEEN 2 AND 3 STANDARD
DEVIATIONS ABOVE NORMAL ACROSS THE AREA FOR LATE SEPTEMBER -- IN
THE 1.75-2" RANGE -- WITH THE WESTWARD EXTENT (SECONDARY PW AXIS)
ACROSS SE ARIZONA/WESTERN NEW MEXICO AIDED BY SOME UPPER-LEVEL
MOISTURE TRANSPORT NORTHEAST OF A WEAKENING T.S. POLO.  AREAL
AVERAGE AMOUNTS RANGE BETWEEN 0.50-1" OVER MUCH OF THE AREA WHICH
FITS IN WELL WITH RECENT GUIDANCE AND IS SLIGHTLY LOWER THAN 12Z
WPC QPF CONTINUITY.  HOWEVER...PER THE AFOREMENTIONED 4KM
GUIDANCE...LOCALIZED AMOUNTS OF 2-5" INCHES ARE ADVERTISED FOR
PORTIONS OF NM, WHICH MAINTAINS A FLASH FLOOD THREAT OVER
SATURATED SOILS.


NORTHEAST
~~~~~~~~~
AN AMPLIFYING NORTHERN STREAM MID/UPPER LEVEL TROUGH WILL PUSH
GRADUALLY EASTWARD ACROSS THE NORTHEAST MONDAY. A MODEST UPTICK
WITH THE DEEP LAYER SOUTHERLY FLOW/MOISTURE TRANSPORT AND
LOW-LEVEL MOISTURE FLUX CONVERGENCE AHEAD OF THE MID/UPPER LEVEL
TROUGH WILL CONTINUE TO FAVOR NUMEROUS-WIDESPREAD COVERAGE OF
PRE-FRONTAL CONVECTION. THERMODYNAMICS DURING THIS PERIOD ARE
MODEST AT BEST HOWEVER...WITH PWS PEAKING NEAR 1.5 INCHES AND
MUCAPES AROUND 500-1000 J/KG. THIS WILL LIMIT SHORT-TERM RAINFALL
RATES AND THUS THE FLASH FLOOD THREAT...DESPITE THE SLOWER
EASTWARD PROGRESSION OF THE UPPER TROUGH AS IT AMPLIFIES.  KEPT
CLOSE TO THE 12Z WPC QPF HERE WHICH RESEMBLED THE MOST RECENT
GUIDANCE AND LINES UP FAIRLY WELL WITH THE LATEST REFORECAST DATA
USING ANALOG EVENTS.


FLORIDA/SOUTHEAST/GULF COAST
~~~~~~~~~~~~~~~~~~~~~~~~~~~~
A FRONTAL ZONE REMAINS ACROSS CENTRAL FL INTO LATE TOMORROW, WHICH
IS EXPECTED TO FOCUS PWS OF 1.75-2 INCHES AND CAUSE SHOWERS AND
THUNDERSTORMS, MAINLY DUE TO DAYTIME HEATING, THOUGH MORE LIMITED
ACTIVITY IS POSSIBLE ALONG THE BOUNDARY OVERNIGHT.  OTHER LIGHTER
ACTIVITY IS EXPECTED TO BREAK OUT ACROSS THE DEEP SOUTH AND
TOWARDS THE LOWER EASTERN SEABOARD AND GULF COASTS AS A SECONDARY
COLD FRONT MOVES IN FROM THE NORTH.  AFTERNOON SEA BREEZE ACTIVITY
SHOULD MAXIMIZE NEAR THE EAST COAST SOUTH OF THE FRONT IN THIS
PATTERN, WITH MORNING ACTIVITY MOST LIKELY IN THE KEYS AND WEST
COAST.  THE GUIDANCE IS SHOWING INCREASING SPREAD IN THIS REGION,
WITH THE 12Z REGIONAL CANADIAN MODEL (NOT SUPPORTED BY ITS
CORRESPONDING GLOBAL RUN) AND 12Z NMM SHIFTING THE MAXIMUM MORE
INTO NORTHERN FL AND MAGNIFYING AMOUNTS.  DOWNPLAYED THIS SCENARIO
FOR NOW AND KEPT CLOSER TO 12Z WPC QPF AND 00Z GEFS- AND
CLIMATOLOGY-BASED REFORECAST WHICH GENERALLY SPLIT THE DIFFERENCE
SEEN IN THE GUIDANCE, WHICH LED TO INCREASED AMOUNTS ACROSS FL AND
DECREASED AMOUNTS ACROSS THE CAROLINAS AND GULF COAST.

ROTH

GRAPHICS AVAILABLE ON THE WEB AT WWW.WPC.NCEP.NOAA.GOV

24HR QP VT 23/00Z
 0.01 406778 405776 402772 397772 395782 391787 388790 381797
      359820 353822 350817 342830 326868 319908 319941 330947
      340930 349878 351873 353864 357853 361843 371828 379832
      387831 390829 385826 383823 383819 384814 389807 392804
      397803 402803 405806 408812 409819 408824 409838 411840
      416840 417836 415830 415822 417817 423809 424803 427800
      435795 443790 448788 452785 462782 470774 478757 482750
      485741 492720 499704 503694 507683 510672 511666 511659
      511655 509647 507643 503639 498645 491655 487658 482658
      475663 472663 471661 471658 472648 473643 472640 471638
      468639 465642 460644 457647 452649 448652 441659 434667
      431670 428675 422682 411699 411704 413708 423711 430709
      433710 433713 432718 429723 427726 423727 423732 422737
      420741 415749 411758 411763 414768 416771 415775 413778
      410779 406778 524261 514242 511230 506222 492203 492199
      491198 488199 484201 479200 462195 455198 449200 433206
      429209 425210 422209 421206 420202 419196 419188 421180
      424177 423165 425161 426155 426141 428137 430135 432139
      433146 432154 430163 429166 436173 440171 445170 450171
      451177 457180 458182 461180 461173 459174 454173 453170
      454166 456162 455156 453152 453143 455138 452128 455119
      457114 461109 462105 460100 456096 455093 455089 457082
      456076 449069 446065 446057 447042 446038 443036 436032
      433026 428020 426008 424002 424996 412995 405999 402003
      397004 387006 384008 382013 382029 381038 377037 371018
      362020 356013 352004 348996 341982 337958 335956 330958
      330970 330978 331979 331984 332995 332999 330001 324999
      319997 317994 309976 308965 308964 308937 309936 318870
      341810 343805 348798 350792 354784 359776 369770 384760
      365748 363744 358744 349746 345747 343750 337757 333764
      330771 326780 323791 320800 317805 313808 311817 311830
      309835 307836 304834 300825 298814 295795 284783 271784
      247792 239809 241839 259855 290847 300848 302863 291897
      288938 288953 288966 289972 289981 290984 288986 284984
      277980 272978 271977 271973 272969 272966 269957 266954
      262951 254949 239955 236959 235963 232975 234985 234992
      236996 242003 247010 251013 256016 264022 270026 274028
      279029 284033 284038 282040 276044 270050 265051 261048
      253044 243042 232043 235052 236062 240066 244069 250075
      257081 265088 275097 282102 289104 301106 308112 317116
      322117 324115 324111 327110 330112 337113 339119 343127
      348128 351127 350125 354122 363119 356113 353110 350108
      350105 354100 358098 362096 367096 372097 376100 379102
      382106 382109 382115 376117 375122 373129 373141 374152
      377156 380160 383165 386168 390176 395185 397190 394193
      390197 383195 381195 381197 384201 391208 396213 404221
      406225 406232 413231 419229 426228 430228 435229 451225
      455226 466226 476221 481220 487223 491224 491228 488230
      484232 481239 480242 478239 475235 475239 476242 472248
      462255 454260 444269 436274 425279 421282 418287 420293
      425299 429301 434302 446299 457297 462295 468294 477292
      489290 499289 507292 513292
 0.01 528223 529215 528210 526206 524202 521198 518195 513193
      511196 510202 513207 516210 517214 520219 523223 527224
      528223
 0.25 522265 517257 510252 494251 489248 486249 483251 480254
      478261 473267 467271 460272 453275 448280 447283 450284
      457281 460279 464278 468283 470285 473286 476284 482283
      491282 497283 506285 514285 516285
 0.25 495681 494673 490672 485673 482676 475683 470685 467689
      466694 463699 457705 449712 443720 438729 438736 437739
      434744 433751 435754 437755 440752 444740 452737 462732
      468726 477719 484713 489705 493694 495681
 0.25 451110 450101 450095 448093 442089 434089 429086 425085
      423087 421090 421094 420098 418098 417090 414083 412082
      414080 420076 421073 421069 417063 409056 384050 380050
      378049 372046 369043 366037 365028 363026 359025 352023
      348018 343006 340003 339010 338014 335016 329018 317023
      312025 308028 306035 303040 302045 304048 307055 303062
      302066 303068 310077 310083 308087 307092 307097 310101
      316103 322101 328099 332100 337099 340095 344090 350086
      354082 360084 371088 375092 380094 385092 389093 390095
      392103 392108 391111 388116 388119 392120 398122 404124
      411124 416125 420132 423134 425133 433123 436121 441120
      448114 451110
 0.25 445147 446143 445140 444138 443134 442132 440134 439137
      439141 438146 439148 440152 443152 444150 445147
 0.25 412022 411021 409020 408021 409023 411023 412022
 0.25 405030 407028 405028 403027 402028 401028 401030 402030
      403031 405030 405030
 0.25 344774 342772 339775 334781 329788 326797 323806 322811
      324814 328814 330811 334802 337794 340786 344777 344774
 0.25 312856 312854 312852 311850 311849 309849 308850 308852
      308854 308856 309858 311858 312856
 0.25 295830 292811 290797 282794 275795 265794 257797 251801
      247805 244814 243817 243821 246823 251823 256822 258825
      260830 261838 262842 264846 267848 270847 275842 281838
      290838 295832 295830
 0.25 288020 285011 281005 273002 269001 266999 262992 259985
      254978 251976 251972 252968 252963 250960 246958 242959
      239963 237969 238979 240987 242996 247001 254006 260008
      265010 269013 273017 276021 279023 284022 287021 288020
 0.25 282088 279083 276079 269073 262066 255060 246054 241053
      241057 244061 247064 254071 261076 269083 277088 280089
      282088
 0.50 521269 517265 515261 511259 506261 502264 500260 496258
      489259 487261 485265 485268 487271 490273 492277 496280
      499281 507282 513282 516282
 0.50 489688 488682 483684 477690 471697 467704 461711 458715
      457718 459721 466719 474714 480708 486701 489691 489688
 0.50 447109 445104 445097 441093 438093 435094 431093 428090
      427093 429098 430103 428108 421112 416115 418119 422124
      424129 431121 434116 438113 443113 446112 447109 447109
 0.50 411115 410110 410103 410098 406095 403095 400095 399099
      399104 398109 398113 403115 406117 410115 411115
 0.50 414071 411066 405063 399065 394068 383070 380065 375062
      367062 366066 366070 368077 371082 376086 379087 383082
      388085 393088 397089 399087 401080 404075 410074 414071
 0.50 373053 370048 365043 362039 362032 349031 339026 333024
      326025 322028 319033 317038 312042 318052 318055 321061
      325065 322068 318072 317076 318079 317085 313088 313093
      312096 315097 324092 336095 341083 343077 344073 343070
      340066 341064 343063 345064 350061 356061 361059 368056
      373053
 0.50 290831 290823 288817 283817 279813 274804 271801 265801
      260804 257805 254804 252806 251810 254814 258817 261821
      263826 264831 264835 267839 271838 275836 287833 290831
 0.50 259000 258996 257991 255986 253983 250981 246979 242980
      242986 242990 244994 247998 249000 255002 259000
 0.50 245970 245968 244966 243967 242968 242970 243970 244970
      245970
 1.00 334086 334084 334082 335080 335078 335075 334075 333075
      332075 331075 329076 328077 329079 330080 332081 334082
      333084 333086 333087 334086 362052 361050 360051 361052
362052
 1.00 515277 514274 513271 513269 511268 510273 508277 505275
      503275 501277 503278 505278 508278 510278 513277 515277
 1.00 378078 378076 378074 378073 376072 375071 374071 374073
      374075 374078 376080 377079 378078
 1.00 337056 336051 333047 332042 332036 332031 328029 326031
      327036 326042 324045 320048 323052 327055 330056 336056
      337056
 1.00 282825 281824 281823 279822 279821 277820 276821 275822
      274823 273824 274825 275826 276827 278828 280827 282826
      282825
 1.00 252992 252990 251988 250986 248986 246988 247990 248990
      249992 251993 252992

$$




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