Quantitative Precipitation Forecast
Issued by NWS

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000
FXUS04 KWBC 020942
QPFPFD

QUANTITATIVE PRECIPITATION FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
542 AM EDT TUE SEP 02 2014


FINAL DAY 1...DAY 2 AND DAY 3 QPF DISCUSSION
VALID SEP 02/1200 UTC THRU SEP 05/1200 UTC
REFERENCE AWIPS GRAPHICS UNDER...PRECIP ACCUM - 24HR


DAY 1...

PACIFIC NORTHWEST...

MODELS ARE WELL-CLUSTERED WITH THE TRACK AND STRENGTH OF THE
SHORTWAVE TROUGH AMPLIFYING ACROSS THE PACIFIC NORTHWEST WITH THE
HI-RES GUIDANCE WEIGHED MORE THAN USUAL TO CAPTURE ITS RESOLUTION
PRODUCING BASIN AVERAGE TOTALS GENERALLY LESS THAN 0.5 INCHES FOR
THE WASHINGTON CASCADES.

SOUTHERN PLAINS TOWARD THE OH VALLEY/NORTHEAST/NEW ENGLAND...

DEEP MOISTURE FLUX AND FRONTOGENESIS ASSOCIATED WITH THE INFLUENCE
FROM THE APPROACHING SHORTWAVE TROUGHS OVER THE PLAINS AT 00Z WILL
CONTINUE TO PROVIDE THE NECESSARY ASCENT TO RELEASE WIDESPREAD
CONVECTION ALONG THE ASSOCIATED SYNOPTIC COLD FRONT THAT IS
FORECAST TO MOVE STEADILY INTO NEW ENGLAND.  USED A COMBINATION OF
THE 00Z NAM/GFS/12Z ECMWF ALONG WITH SOME HI-RES GUIDANCE TO
GENERATE THE VARIOUS QPF AS THE SOLUTION ENVELOPE REMAINED
SUFFICIENTLY WIDE TO CONSIDER MULTIPLE SOLUTIONS GIVEN SOME
UNCERTAINTIES IN MESOSCALE EVOLUTION.  A SMALLER BUT STILL
SIGNIFICANT AREA OF ADDITIONAL RAINFALL WILL ACCOMPANY THE
EVOLVING MCS OVER KANSAS/MISSOURI...
WHICH IS EXPECTED TO DIMINISH BY AFTERNOON THEN RESUME TONIGHT AS
THE LOW LEVEL JET DEVELOPS NORTH OF THE RESIDUAL OUTFLOW AND
SLOWING SYNOPTIC FRONT.

CAROLINAS...

DIFFERENTIAL HEATING CIRCULATIONS MAY BE SUFFICIENT TO GENERATE
ENOUGH LIFT TO INITIATE SCATTERED CONVECTION ACROSS THE PIEDMONT
AND COASTAL PLAINS IN THE WEAKLY CAPPED AND MODERATELY/HIGHLY
UNSTABLE ENVIRONMENT.  USED A COMBINATION OF THE NAM AND OTHER
HI-RES GUIDANCE PREDOMINANTLY AS THE SCALE OF THE CONVECTION WILL
LIKELY BE TOO SMALL FOR THE GFS TO RESOLVE ADEQUATELY.

WESTERN GULF COAST...

ONSHORE FLOW AND SEE BREEZES ARE EXPECTED TO GENERATE SCATTERED
CONVECTION WITHIN THE EMBEDDED DEEP MOISTURE PLUME CONTINUING
ALONG THE TEXAS COAST...WITH A MIXTURE OF THE HI-RES GUIDANCE AND
GLOBAL SOLUTIONS PREFERRED TO GENERATE THE QPF.


DAYS 2-3...

...SOUTHEAST INTO THE CAROLINAS...

AS A RELATIVELY FLAT UPPER TROUGH LIFTS NORTHEASTWARD INTO THE
CANADIAN PROVINCES...ITS ASSOCIATED COLD FRONT WILL MOVE SOUTH AND
EASTWARD ACROSS THE NORTHEAST AND WILL MAKE IT ONLY AS FAR SOUTH
AS NORTH CAROLINA...WHERE IT WILL BECOME STATIONARY ON WEDNESDAY
AND THURSDAY BEFORE DISSIPATING THURSDAY NIGHT.  LOW LEVEL
CONVERGENCE/VERY MOIST AIR SOUTH OF THE FRONT AND POSSIBLY WEAK
IMPULSES ALONG THE NORTHERN PERIPHERY OF A PROMINENT UPPER RIDGE
OVER THE SOUTHEAST WILL LIKELY LEAD TO SCATTERED SHOWERS AND
THUNDERSTORMS ACROSS THE SOUTHEAST WITH MORE ORGANIZATION LIKELY
NEAR THE STATIONARY FRONT ON WEDNESDAY INTO THURSDAY.  SOME OF THE
MOISTURE FROM TROPICAL DEPRESSION 5...WHICH COULD BECOME A
TROPICAL STORM BEFORE LANDFALL IN EASTERN MEXICO...COULD
ACCELERATE NORTH NORTHWESTWARD IN THE ENHANCED SOUTHEASTERLY FLOW
IN THE WESTERN GULF AND BECOME INVOLVED IN THE ANTICYCLONIC
CIRCULATION OVER THE SOUTHEAST. THE 12Z UKMET/21Z SREFMEAN ARE THE
DRIEST OF THE MODEL FORECASTS...WHILE THE 00Z CANADIAN IS THE
WETTEST.  THE CHOICE OF THE 00Z GFS/NAM AND 12Z ECMWF AND THE MOST
RECENT ECMWF AND GEFS MEANS WERE BLENDED TO CONSTRUCT THE FORECAST.

...NORTHERN ROCKIES/NORTHERN PLAINS/UPPER MISSISSIPPI VALLEY/UPPER
MIDWEST...

A SIGNIFICANT SHORTWAVE TROUGH WILL DIVE INTO THE PACIFIC
NORTHWEST ON TUESDAY INTO WEDNESDAY AND THEN LIFT EAST
NORTHEASTWARD INTO SOUTH CENTRAL CANADA BY EARLY FRIDAY DRAGGING A
STRONG COLD FRONT EASTWARD ACROSS THE NORTHERN AND CENTRAL ROCKIES
INTO THE NORTHERN PLAINS AND UPPER MISSISSIPPI VALLEY STATES.
WHILE MUCH OF THE HEAVIEST QPF WILL LIE NORTH OF THE CANADIAN
BORDER...PACIFIC MOISTURE WILL FALL ACROSS THE NORTHERN ROCKIES
PARTICULARLY IN NORTHERN IDAHO AND MONTANA.

MEANWHILE...AS THE SYSTEM MOVES EASTWARD ON WEDNESDAY THROUGH
EARLY FRIDAY...IT WILL TAP INTO MOISTURE STREAMING NORTHWARD
AROUND THE WESTERN EDGE OF THE LARGE UPPER ANTICYCLONE COVERING
MUCH OF THE CENTRAL AND EASTERN US.  A SOUTH TO SOUTHWESTERLY LOW
LEVEL JET WITHIN THE CONFLUENT ENTRANCE REGION OF AN UPPER JET
STREAK PACKING 850 MB WIND SPEEDS OF 35 TO 50 KNOTS WILL POSSIBLY
LEAD TO THE DEVELOPMENT OF HEAVY THUNDERSTORMS/MESOSCALE
CONVECTIVE SYSTEMS ACROSS THE MIDDLE TO UPPER MISSISSIPPI VALLEY
AND PARTS OF THE MIDWEST ON WEDNESDAY INTO THURSDAY EVENING. AREAL
AVERAGED RAINFALL OF .50 TO GREATER THAN 1 INCHES QPF IS EXPECTED
ACROSS THIS REGION AND WITH FLASH FLOOD GUIDANCE VALUES LESS THAN
2 INCHES...A SLIGHT RISK OF EXCESSIVE RAINFALL IS DEPICTED ACROSS
A SMALL PORTION OF MINNESOTA AND WISCONSIN FOR DAY 2/WEDS
AFTERNOON THROUGH THURSDAY MORNING.

...SOUTHERN TEXAS...

TROPICAL DEPRESSION 5 IS EXPECTED TO DRIFT NORTHWESTWARD TOWARD
THE MEXICAN COAST BY WEDNESDAY MORNING. SEE NHC GUIDANCE FOR
FURTHER DETAILS CONCERNING ITS FORECAST TRACK AND POSSIBLE
DEVELOPMENT INTO A TROPICAL STORM.  WHILE THE BULK OF LOW LEVEL
MOISTURE IS EXPECTED TO MOVE TOWARD THE NORTHERN MEXICO
COAST...SHOWERS AND THUNDERSTORMS SHOULD BE ON THE INCREASE ACROSS
THE LOWER RIO GRANDE INTO SOUTH TEXAS ON WEDNESDAY INTO THURSDAY
WITH QPF AMOUNTS EXPECTED TO EXCEED 1 INCH AND POSSIBLY QUITE A
BIT MORE.

...CENTRAL ROCKIES/CENTRAL PLAINS/MID MISSISSIPPI VALLEY...

WHILE THE MAIN UPPER TROUGH HAS LIFTED NORTHEASTWARD INTO SOUTH
CENTRAL CANADA ON WEDNESDAY INTO THURSDAY...A PORTION OF THE
TROUGH HAS REMAINED OVER THE SOUTHWEST WITH AN UPPER JET IN
EVIDENCE OVER THE SOUTHWEST BY FRIDAY MORNING. THAT COMBINATION
INDICATES A DOUBLE JET PATTERN WITH THE EASTERN ROCKIES AND
CENTRAL PLAINS LYING BETWEEN THE EXIT REGION OF THAT JET AND THE
BROAD ENTRANCE REGION OF THE JET OVER THE NORTHERN PLAINS.  AS A
RESULT...PRECIPITATION BEGINS TO EXPAND ON DAY 3 OVER THE
SOUTHWEST INTO THE SOUTH CENTRAL ROCKIES WITH UPSLOPE FLOW
DEVELOPING IN EASTERN COLORADO BY THURSDAY EVENING.  BY FRIDAY
MORNING...AN AREA OF QPF HAS EXPANDED NORTHEASTWARD ALONG AND
BEHIND THE FRONTAL BOUNDARY SEPARATING THE COOLER AIR EXPANDING
ACROSS THE PLAINS STATES AND EASTERN ROCKIES. RAIN LOOKS TO BE
DEVELOPING FROM EASTERN COLORADO NORTHEASTWARD ACROSS THE CENTRAL
PLAINS INTO THE MID MISSISSIPPI VALLEY WITH ALL MODELS IN SOME
FORM OF AGREEMENT...THOUGH AMOUNTS AND LOCATION ARE ANOTHER STORY.

JAMES/KOCIN

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

24HR QP VT 03/12Z
 0.01 537194 537181 538173 538167 537161 536154 535137 535131
      534125 530116 529110 529103 529096 529087 528075 526063
      521051 518040 517033 519031 520033 527037 531035 533031
      534016 534002 533995 533987 533970 533963 532958 532953
      531940 529935 526931 517931 512931 509928 502907 498896
      495891 491889 488886 484887 480887 476890 473894 473900
      473907 472912 472917 474922 477934 477949 482961 495003
      498011 503018 504023 504029 503038 503054 502068 498081
      497095 496110 494116 492121 490126 487128 482130 481134
      480142 479147 477149 472153 466159 469164 471167 475171
      475177 477187 478192 477198 471205 464212 460213 456213
      451215 448217 445218 446222 455226 457226 460229 457233
      454234 451237 454238 458237 461236 462240 463244 465248
      469251 474253 482260 490264 494266 497270 499274 502278
      505278 509277 512274 515267 517262 519254 521249 522241
      526212 528203 533203 537194
 0.01 231991 232998 236004 242008 249012 256012 261011 266011
      272012 276013 280015 283018 286020 289018 289010 286003
      282999 275995 274992 276991 279990 292983 302976 308973
      314968 324956 331950 334948 335946 338947 347948 351956
      355963 357971 360979 362983 366985 376990 384991 390996
      394995 396992 399990 400986 402977 402970 401966 395945
      387931 383923 380916 379911 380907 385902 394890 407861
      416847 421839 426831 434819 442805 445799 449790 455774
      457767 459763 462760 471748 474745 476740 482734 493720
      492715 492711 493708 497700 503683 506675 507668 505655
      503644 498628 493621 487618 479621 471626 464632 456639
      452645 447650 443655 437662 419688 415693 412700 411704
      414708 420707 424707 423711 418716 415721 411725 404731
      398736 392741 382749 375755 373754 373751 374747 375731
      373729 369729 367731 363733 352744 348750 346758 345762
      343763 339764 329770 304784 287791 284793 280793 278790
      275789 270787 260787 256788 252790 247794 243801 245805
      243809 244811 246816 249820 253822 260825 267829 274830
      280834 286839 288843 290844 292846 294850 296857 298864
      299875 298880 294882 289886 289896 290905 291918 291926
      290931 273935 268935 265937 261939 255941 250941 245941
      243943 237947 234953 233962 230969
 0.01 448889 447884 446879 442875 438875 434883 432886 430892
      430897 429902 426914 427921 428928 429933 433933 438928
      442918 445906 445901 446896 448889
 0.01 447981 448977 447974 447968 445964 442961 437961 434964
      431968 429971 429978 431983 433985 436988 441988 443985
      447981 447981
 0.01 379782 377780 376781 374782 373783 372784 371785 369786
      369787 368788 369790 371789 373789 375789 376787 378785
      378784 379782
 0.25 531173 527153 524136 520116 515100 511097 508099 506104
      505110 504119 500129 497136 492141 490162 488171 493178
      501186 502196 500200 497203 490201 489200 486202 475210
      470214 468217 468220 481224 485226 487229 493235 497240
      499243 504246 508247 510242 511231 512206 513201 516198
      520194 526181 531173
 0.25 492682 491673 487670 480670 474667 465664 461659 459657
      456659 441679 437684 435690 435698 434706 433712 431718
      426724 422730 418741 412751 408756 406763 402777 395788
      388795 384799 380804 377811 375817 371828 371832 373835
      375835 378835 379838 379845 377853 374860 373866 372876
      376880 379881 383880 390872 398861 411841 417831 423819
      429807 432801 433795 434788 436781 442769 447756 453745
      459736 464732 469726 472720 475713 475706 478701 488693
      491688 492682
 0.25 396979 395970 394966 391963 386960 380956 375954 373957
      373963 375970 378977 382983 385986 389988 393987 395984
      396979
 0.25 365896 365889 365881 364874 361870 355869 352875 350880
      349888 351892 353893 355899 357905 360907 364906 365898
      365896
 0.25 365969 365964 364959 363949 363938 363933 362929 359922
      357918 354919 350925 350936 354943 356952 358961 361969
      363971 365969
 0.25 349800 349795 347793 343793 340795 335799 331804 323814
      318817 312820 305823 300827 299830 300835 303840 308845
      312845 316844 322841 326837 330831 333825 335819 340814
      344809 347804 349800
 0.25 311952 312945 312941 311936 307934 304937 298945 290952
      277965 273967 268965 257962 253962 246961 242963 239966
      236970 234976 233983 235989 237992 242995 251998 256998
      260996 260990 262987 265984 270981 279976 287972 294965
      302959 306957 310954 311952
 0.25 309924 309922 308920 307918 306916 305914 304912 302909
      302912 301914 301916 300918 301920 301922 301924 301925
      303926 305926 306926 308925 309924
 0.25 268800 267798 266796 264795 262795 260796 259796 258797
      257798 257799 257800 259801 261802 262803 263803 264802
      265801 266801 268800
 0.50 528167 526159 524152 520141 516126 514118 512117 510118
      507124 504131 498142 497146 497151 498159 498167 499170
      502172 502175 505179 509181 512183 515181 515174 515170
      518168 524170 527169 528167
 0.50 502233 503224 501217 499214 496213 489212 482211 478213
      473216 476218 482222 488224 494227 498231 500233 502233
 0.50 457714 456708 452707 450706 449701 449698 445698 441701
      438709 437715 435720 429729 426740 425744 422749 416755
      413758 411761 411764 409775 405785 395801 396807 400807
      405806 407808 396824 392832 388842 381862 382868 385871
      389868 391865 402848 411831 415822 417817 418810 414800
      417800 416797 426780 436763 440755 443744 445737 447733
      453725 456720 457714
 0.50 391981 392977 392972 390970 388968 386966 384965 380964
      378965 379969 380972 381974 382977 384980 385981 389983
      391981
 0.50 362896 362894 361894 361892 360890 360887 360885 360883
      359881 358879 357877 357879 356881 356883 356885 356887
      356888 357890 358892 360894 360896 360897 362898 362896
 0.50 361954 361949 361945 361941 360938 357937 356934 355931
      353932 354935 355938 356941 357945 357948 358952 359954
      361954
 0.50 252972 248970 243971 240973 238977 237981 238985 240990
      243992 246992 248989 246986 248983 250978 251974 252972
 1.00 515150 514149 513147 513146 512144 512143 510142 509144
      510146 511148 512149 513150 514151 515150

24HR QP VT 04/12Z
 0.01 531178 529177 529171 530159 526140 528110 533065 531021
      531978 520950 505922 509899 515866 514834 506821 492815
      479814 465825 451837 432849 416858 401864 390865 383861
      378849 377831 384818 395798 392794 381802 376801 375789
      375766 371748 369737 370727 366719 357718 347725 336741
      333747 334749 332755 329761 314783 310786 302788 292786
      268775 262774 256775 251777 246782 238793 238794 236800
      233810 235819 236827 240835 251844 267855 280867 290893
      291916 291920 292924 286935 277942 269944 266945 257946
      248947 243949 237953 233957 231965 230979 231985 231004
      229037 232059 243078 260088 275099 290112 302123 314123
      317111 311097 300088 288080 265061 264043 273037 285032
      298014 309000 309985 305974 299952 301927 301926 303922
 0.01 303922 305920 309918 316916 327914 338916 357925 375935
      385956 395960 406951 416947 428956 432970 441976 452984
      457003 464036 473054 480064 476076 463086 444071 441078
      446085 449097 443106 442113 452121 464122 463134 461146
      467167 478189 488190 502188 513176 524178 528178 528180
      531178
 0.01 496223 495220 492217 486212 483210 479209 474212 468216
      461218 459219 458223 467226 472223 478219 484223 488225
      491224 496223
 0.01 491664 488655 483644 478632 474623 470622 467624 459630
      452636 445643 439649 431656 423663 417669 415672 416678
      419681 423683 431685 447689 455693 457702 449713 437728
      439736 448730 457719 465720 473732 476737 482743 489747
      491744 490738 482715 478705 476700 477693 479682 481678
      484674 489669 491664
 0.01 383022 383012 381004 376003 371005 364009 360013 355017
      350022 344033 340037 335040 332048 334049 338050 343047
      351046 351044 355043 364043 369041 375037 381026 383022
 0.25 518148 518136 517121 515108 518096 521087 524072 524063
      524055 523042 523029 524012 524993 523981 518973 511966
      507964 503965 499967 494967 485965 479965 477967 477970
      477984 477989 474992 471996 469000 469009 469016 471028
      476036 481043 485047 487051 490062 491068 491076 492088
      489102 488111 486116 483125 480136 480144 481150 482162
      487171 494176 496176 501174 510157 515152 518148
 0.25 467649 464647 459648 455650 453654 450658 448663 447668
      448671 451671 455668 458664 461661 463658 465654 467649
 0.25 487902 487894 487888 483877 481867 479862 475858 469856
      464856 460857 449871 445874 444877 440887 439892 437897
      429902 426902 424900 417895 406895 397897 378898 374899
      370901 367905 367909 371916 377923 384929 391932 398933
      401930 403925 417935 433935 440942 442952 443959 444962
      448966 452967 456967 460965 467961 474957 477953 479949
      484925 486913 487902
 0.25 368773 368767 366763 363752 361742 358739 354738 351745
      347753 345761 344772 343780 340788 336796 334804 336814
      337816 340815 342813 347812 351814 353818 353824 356824
      358820 362812 364804 365793 368773 368773
 0.25 361861 361856 360851 356847 349845 343847 338852 333856
      323864 317875 314881 313886 314890 317895 320897 324897
      330895 334893 342884 350875 356870 359865 361861
 0.25 318848 321842 319835 314833 310834 308837 308840 309844
      310847 312848 316849 318848
 0.25 300851 300849 298847 296848 296849 296851 298852 300851
      300851
 0.25 285800 283795 278792 269790 260791 254793 250796 243803
      242808 241813 243818 246821 253822 257820 262817 266813
      270805 281802 285800
 0.25 290014 291008 289003 286995 281987 284976 285973 285968
      283962 281959 278957 272956 263955 254956 245958 238963
      235968 234971 235983 236993 238003 242010 248015 253017
      258018 267019 274021 283020 287017 290014
 0.25 267083 265077 262072 258069 253065 249062 244059 242060
      242063 245068 249072 252077 256079 261083 266084 267083
 0.50 518083 520070 520055 520038 521025 522997 522989 520983
      517978 513975 510975 507976 504980 500986 499993 497997
      495000 492001 486995 483994 479994 476997 473001 472006
      473011 475021 476026 478030 484035 490040 493043 495048
      496058 497072 496094 493107 490116 488126 487133 488138
      490142 490148 490161 492165 494166 500162 505155 509146
      511136 512129 512123 511112 512097 518083
 0.50 476925 477902 476896 475891 471880 468872 465869 461871
      456877 451882 449885 448892 446904 443910 439918 439924
      440929 443937 446948 446955 447959 449963 454963 460959
      466954 471947 474938 476926 476925
 0.50 376909 376914 383922 393925 399921 401913 398911 395916
      389919 385917 380909 376909
 0.50 364775 365769 363765 361760 359754 356752 354755 352760
      352764 351775 349787 350798 351802 354804 358803 359798
      362788 364778 364775
 0.50 286012 283005 280001 277999 274997 272994 274984 277976
      278971 277968 275964 272962 265960 255960 247962 240965
      238968 237971 237981 238991 240999 244006 250010 258012
      266015 271017 276017 282015 286012
 0.50 262807 261806 260806 258806 256806 255808 256810 258809
      260808 262807 262807
 0.50 251808 252806 251804 250803 248803 247804 246805 245807
      245808 245809 245811 245813 245815 246816 247815 247814
      248812 249810 251808 251808
 1.00 517017 517001 515995 512992 509997 508003 503016 499029
      502043 502050 502060 503066 505073 508073 511069 513062
      514053 515036 517020 517017
 1.00 460953 465947 469936 469921 467904 464893 459889 456896
      456908 458916 458922 454922 451920 449923 448926 450935
      451943 451954 454956 458955 460953
 1.00 360774 359772 358771 357771 356772 356775 357777 357778
      359776 360774
 1.00 269972 269969 268966 263965 256964 250965 242970 240974
      240981 242993 243998 246002 250005 254007 261007 266007
      266000 264995 261984 261980 264976 269972
 1.50 514019 515012 514006 513006 511009 510014 508019 506023
      504029 504037 505042 506045 508045 510041 511035 512028
      514022 514019
 1.50 260002 261997 260994 257987 253982 251979 252975 254973
      254969 246970 244972 243978 243988 244996 249002 256004
      260002
 2.00 258998 258994 256990 253986 250984 249980 248977 246977
      245982 245988 246994 247998 250000 255001 258998 258998


24HR QP VT 05/12Z



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