Quantitative Precipitation Forecast
Issued by NWS

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000
FXUS04 KWBC 031836
QPFPFD

QUANTITATIVE PRECIPITATION FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
235 PM EDT THU SEP 03 2015


PRELIM DAY 1 QPF DISCUSSION
VALID SEP 04/0000 UTC THRU SEP 05/0000 UTC
REFERENCE AWIPS GRAPHICS UNDER...PRECIP ACCUM - 24HR


DAY 1...

...NORTHERN ROCKIES AND NORTHERN PLAINS....

THE UPPER AIR PATTERN WILL CONTINUE TO AMPLIFY WHILE SHOWING
LITTLE DOWNSTREAM PROGRESSION THROUGH FRIDAY. A TROUGH ALONG THE
WEST COST DIGS TO 3 STANDARD DEVIATIONS BELOW CLIMATOLOGICAL 500
MB HEIGHTS...WITH GRADUAL GRADIENTS AND A GENTLY SLOPING FRONTAL
ZONE EXTENDING EAST TOWARD RIDGING IN THE MIDWEST. LIGHT TO
MODERATE PRECIPITATION WILL BE ORGANIZED ALONG A MID LEVEL FRONTAL
ZONE IN THE NORTHERN ROCKIES...ESPECIALLY IDAHO / MONTANA...WITH
UPPER FLOW BECOMING INCREASINGLY DIFLUENT BY FRIDAY AFTERNOON AS
THE UPPER LOW DIGS INTO OREGON. THE LEADING FRONT AT THE SURFACE
WILL PUSH OUT INTO THE DAKOTAS...AND THE LARGE SCALE FLOW WILL
PICK UP A SMALLER SHORTWAVE LIFTING OUT OF THE FOUR CORNERS
REGION. THIS SHORTWAVE WILL ENCOUNTER RELATIVELY HOT AND DRY
CONDITIONS ALONG THE EASTERN SLOPES OF THE ROCKIES THIS
AFTERNOON...BUT WIDELY SCATTERED THUNDERSTORMS ARE LIKELY ALONG
THE TRACK UP THROUGH NORTHEAST CO INTO NE/SD OVERNIGHT. THE WAVE
WILL ENCOUNTER GREATER MOISTURE AND INSTABILITY POOLED ALONG THE
SURFACE FRONT IN ND/MN FRIDAY AND FRIDAY EVENING...WITH A LIKELY
ORGANIZED THUNDERSTORM EVENT ENSUING. WE BACKED UP THE TIMING OF
THE QPF IN ND SOMEWHAT BASED ON THE MASS FIELDS FROM THE GFS...BUT
ALSO SUPPORTED BY QPF FROM THE 12Z NAM CONEST.


...GREAT LAKES / OHIO VALLEY / MID ATLANTIC...

A SLOW MOVING UPPER LOW WAS SURROUNDED BY RELATIVELY STEEP LAPSE
RATES AND MOISTURE THAT WAS SUPPORTIVE OF PRECIPITATION...WITH PW
VALUES AROUND 1.50 INCHES. COVERAGE OF CONVECTION HAD BEEN
GENERALLY LIMITED...HOWEVER...AS THE COMPACT LOW WAS PRODUCING
LIFT MAINLY NEAR ITS CENTER...ACROSS LOWER MICHIGAN. SCATTERED
AFTERNOON/EVENING THUNDERSTORMS ARE ALSO EXPECTED AT A GREATER
RADIUS TO THE SOUTHWEST THROUGH SOUTHEAST OF THE LOW...ALONG A
WEAKLY DEFINED FRONTAL ZONE AND WITHIN THE DIFLUENT MID LEVEL FLOW
AHEAD OF THE LOW. OVERNIGHT...SOME CONFLUENCE WILL BE MAINTAINED
ON THE BACK SIDE OF THE SYSTEM OVER IL/IN...AND POSSIBLY EXTENDING
INTO PARTS OF IA/WI...AND THIS WILL LIKELY YIELD ADDITIONAL
THUNDERSTORM ACTIVITY...ALTHOUGH MODEL FORECASTS ARE QUITE
LIMITING IN AREAL COVERAGE. WPC ATTEMPTED TO INCORPORATE TRENDS IN
THE 12Z GUIDANCE...BUT OVERALL MADE LITTLE CHANGE...WITH AREAL
AVERAGE 0.50 INCH QPF CONFINED NOW TO THE AREAS AWAY FROM THE MID
LEVEL VORTICITY CENTER...WHERE GREATER INSTABILITY WILL BE
AVAILABLE FROM IL TO OH.


...SOUTHWEST U.S...

THE MONSOON CONTINUES...WITH PRECIPITABLE WATER VALUES STILL
RUNNING JUST SLIGHTLY ABOVE AVERAGE...INCLUDING A CONNECTION TO
HIGH ALTITUDE MOISTURE STREAMING NORTH FROM TROPICAL STORM KEVIN.
THE MESOSCALE MODEL SIGNAL FOR HEAVY RAINFALL IS STRONGER TODAY
THAN IT WAS ON WEDNESDAY...ESPECIALLY OVER SOUTHERN AZ...WHERE
EVEN THE SSEO MEAN...AN AVERAGE OF SEVERAL MODELS...PRODUCES
GENEROUS COVERAGE OF 1 TO 2 INCH RAINFALL NEAR AND SOUTH OF I-10
AND I-8. A LIMITING FACTOR...HOWEVER...WILL BE WEAK WINDS BELOW
600 MB...SO STORMS MAY BECOME OUTFLOW DOMINANT RATHER QUICKLY.
ISOLATED FLASH FLOODING WILL BE POSSIBLE IN SOUTHERN AZ TO WESTERN
NM...PRIMARILY DURING THE EARLY STAGES OF CELL FORMATION PRIOR TO
OUTFLOW DOMINANCE...AND/OR DURING CELL MERGERS. FARTHER
NORTH...THE SHORTWAVE THAT HAD FORMED OVER THE FOUR CORNERS LAST
NIGHT WILL PASS THROUGH CENTRAL COLORADO...AND MAY RESULT IN A
SLIGHT INCREASE TO AREAL COVERAGE OF 0.25 INCH OR GREATER
PRECIPITATION BEFORE IT LIFTS OUT INTO THE PLAINS OVERNIGHT.


...LOUISIANA AND FLORIDA...

THE REMNANTS OF ERIKA WERE STILL EVIDENT IN VISIBLE SATELLITE
IMAGERY...EMERGING BACK INTO THE ATLANTIC OFF THE GEORGIA COAST.
THIS FEATURE WILL MOVE OUT TO SEA...BUT A LARGER SCALE TROUGH AXIS
IS FORECAST TO EXTEND BACK OVER FLORIDA WHILE DRIFTING SOUTHWARD.
LIGHT WEST TO NORTHWEST FLOW NEAR THE TROUGH AXIS WILL SUPPORT
SOME TENDENCY FOR PRECIPITATION TO FAVOR THE CENTRAL AND EASTERN
PORTIONS OF THE PENINSULA THROUGH FRIDAY. THE GFS TENDS TO HANDLE
FLORIDA WELL...AND WE BLENDED TOWARD BOTH THE 12Z GFS AND WRF-ARW.
AT THE FAR WESTERN EXTENT OF THE DEFINABLE TROUGH AXIS SITS
LOUISIANA...WHERE RICH MOISTURE REMAINED POOLED ALONG THE
COAST...AND A SLIGHT ONSHORE FLOW COMPONENT TO THE LOW LEVEL FLOW
WILL CONTINUE TO SUPPORT A SHOWERY REGIME WITH OCCASIONALLY HEAVY
DOWNPOURS...AND AREAL AVERAGE PRECIPITATION APPROACHING ONE INCH
SOUTH OF NEW ORLEANS.

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

BURKE

24HR QP VT 05/00Z
 0.01 556958 555942 555927 550927 546924 538922 527935 521940
      518938 513938 509936 505936 499936 495938 480947 475949
      469949 464949 461955 454971 449982 442986 436987 432989
      424993 412993 406998 401002 395009 389014 383023 382027
      381034 382046 369044 359048 352051 347052 341052 337053
      331053 328055 329058 341059 344061 344065 340068 333071
      324074 316077 309079 305080 299079 291076 282073 277071
      274067 272062 268059 264057 259055 255056 253061 252067
      250071 241074 240079 242083 248090 255095 262101 268106
      274111 277113 282114 292115 297114 300118 304125 307128
      313131 323133 327133 331131 337124 346125 351123 354120
      358110 359104 363100 367101 370100 379101 385095 392091
      398085 410071 417067 418060 416055 414050 411047 403043
      398036 399031 402026 410023 416022 419021 430023 433026
      436030 442027 446022 451020 457020 465020 467021 467024
      467032 465038 463043 459055 456059 456064 456071 457076
      461087 462094 461097 458097 450094 446092 442091 439094
      437100 439105 436109 435114 436119 439119 440125 439132
      436136 427149 419154 414160 412164 413171 414172 420169
      426165 432159 446167 445171 442170 438171 434169 431169
      427170 423176 418184 409201 404207 402211 401216 405224
      410230 412235 416237 420240 425242 427242 429241 432237
      433233 436232 445231 456229 464227 470223 475222 480223
      478228 474229 468235 465236 466238 471241 474245 478246
      480248 480252 489273 494283 499285 501286 503285 506282
      507277 505266 504261 501257 498249 494244 492240 487233
      484232 482228 484225 486225 491225 493226 493230 497239
      501246 505253 509263 511268 516270 522263 526250 528230
      529222 530219 532216 533210 535206 537201 538193 539186
      538180 541168 541160 540154
 0.01 540154 537144 533133 531127 528124 523122 520117 514111
      512106 511100 509093 510086 511069 509063 506060 502057
      498056 495055 494053 496048 498042 501039 514025 526011
      537997 543989 548979 552970 555966 556958
 0.01 493202 494195 493191 491183 492171 496166 496162 494159
      487155 481156 474158 468160 461161 458164 457169 461176
      461180 459182 453188 451192 451197 454205 459210 465210
      471208 475208 478207 483203 486202 490202 493202
 0.01 464256 465251 464246 461243 457243 452242 448243 441245
      437245 434248 427252 429256 432259 440264 445266 450267
      456264 459262 462258 464256
 0.01 454083 454081 453078 450075 448073 447070 445070 441069
      441072 443074 444077 446077 448080 449083 451085 452085
      454083
 0.01 455835 446802 441798 434797 422798 413799 412797 412794
      414791 415782 413779 413777 414774 420764 423758 421754
      415748 413746 414742 421729 424722 427716 428711 428707
      424706 419705 417701 414700 411702 409704 405710 392734
      391741 393746 393750 386754 380757 377759 373760 366762
      358763 354758 350753 346748 337740 326731 322725 318722
      312718 307718 302723 300730 291739 285749 282756 280762
      279771 278776 275778 263783 260788 260795 260797 258798
      254798 250804 251811 255816 257819 260819 266820 271823
      269830 269837 272843 276849 281854 286857 291858 295853
      294843 293840 294837 297835 299837 301846 300850 300854
      302859 306859 306856 306847 308841 314831 319826 324822
      328818 332811 340799 350790 354789 357791 359796 358800
      356807 353812 346822 342828 339835 336841 334840 334835
      333828 329826 325827 322831 322835 324838 325843 326846
      327853 330862 333869 339880 344883 350884 353883 354880
      352872 348867 344862 342859 342856 346855 348853 357844
      362843 364841 368840 370842 379853 387863 391866 395871
      398878 402885 409898 412904 417910 424919 429923 433924
      435926 443926 446919 445904 439890 432876 429866 429862
      431859 439859 444856 449844 455835
 0.01 407110 408105 408100 406100 404102 404104 402106 400108
      396110 393110 391112 392114 394114 398113 400111 403111
      405112 407110
 0.01 317926 314914 314905 312899 308886 307878 305873 299870
      294869 288871 284871 278879 274885 272890 271904 271912
      273917 280926 281929 284929 286928 289929 290937 288943
      285948 282954 279959 277966 277972 281975 286973 290969
      294964 296960 303952 307947 309941 314934 317926
 0.01 281983 281980 277980 273980 270978 268978 266976 263975
      261976 262978 264980 266982 267984 269986 271987 273986
      275984 279983 281983
 0.01 267019 265015 258012 258007 262004 264999 264995 262992
      254986 250976 241972 235975 233979 232995 234001 236006
      241009 246012 250015 256017 261019 267019
 0.25 546957 546951 545947 541943 535945 530949 520955 516955
      511960 504961 498961 490962 484964 474971 470974 465979
      456988 452993 448000 450003 456003 470001 477002 482004
      490016 494021 497022 499021 509013 519005 527994 534983
      541971 544964 546957
 0.25 534174 535168 534163 532154 528137 525134 522133 516130
      510125 505120 502114 502103 501092 499085 496082 492084
      488088 484094 479099 468105 463109 459115 451127 444140
      440149 445152 451151 457148 468142 473140 480137 491137
      497142 501148 505155 510159 515165 520170 523175 527179
      532177 534174
 0.25 445005 444004 443002 441001 440002 440004 441006 442007
      443007 444005 445005
 0.25 436828 435823 433821 426816 409821 402824 396829 394833
      393838 394845 394851 402866 410882 415889 420895 425894
      426890 423880 419872 416863 415850 415844 416839 421834
      426833 431832 435830 436828
 0.25 433004 433002 432001 431000 429001 428001 428004 428006
      429007 430008 432006 432005 433004
 0.25 401060 402058 400056 398057 397057 396057 395058 393059
      391061 390061 389062 388063 388066 389068 390068 391068
      392068 394066 396065 397064 398063 399062 400060 401060
 0.25 393796 394791 394787 392784 389783 385784 380788 377792
      372796 368800 366802 366807 370808 376807 382807 387804
      390801 393796
 0.25 381081 382076 382072 382069 379067 377065 375064 371064
      370066 371069 373071 374075 374078 375081 377082 379082
      381081
 0.25 365816 364814 362814 361816 360816 359817 358819 357819
      357821 357823 358824 360824 361823 361822 363820 365818
      365816
 0.25 346118 342113 341110 342104 344097 344089 346082 344079
      339080 335083 332085 331088 329091 327092 320090 315093
      311097 307103 308111 311116 318120 320119 319116 320112
      322111 329109 332110 334112 340115 345119 346118
 0.25 315770 313764 310759 310754 310750 309745 305742 302741
      298742 295747 294752 293759 294765 293770 290776 283784
      281790 283796 285798 288798 296798 299798 302796 306792
      312781 314777 315770
 0.25 303909 303903 302898 299889 298884 294880 285880 281887
      277896 278902 279906 284914 290920 293922 296922 299920
      301916 303909
 0.25 297821 295815 293813 287808 283805 280804 269805 259804
      257803 254805 256810 260813 263815 272816 279820 287823
      291825 294824 297821
 0.25 288087 290083 288081 283079 272077 266076 261078 261081
      265084 273091 265093 265095 266097 270100 274102 277104
      281103 284100 282095 277092 278091 283090 288088 288087
 0.50 529172 530166 529162 527151 523144 517141 510136 507137
      507142 509151 513158 518162 521165 523168 524172 526175
      529172
 0.50 538960 534958 530959 522962 515965 509972 496967 489970
      482975 476981 474985 472991 475995 480996 485997 488000
      493006 500011 504011 508009 515004 520999 525991 534973
      538960
 0.50 496118 497108 497103 495100 492099 487102 478108 469114
      466119 461124 458127 455132 454137 455140 460140 469135
      474132 479131 484131 490127 493122 496118
 0.50 422888 422886 422885 421884 420882 419881 418879 417879
      416878 414878 414879 414880 415882 416884 416885 418886
      418887 420888 421888 422889 422888
 0.50 419827 416826 413826 406831 401836 398838 398844 398850
      400855 405863 407866 408861 405850 403839 410833 417828
      419827
 0.50 340093 339091 339089 337088 336088 336091 335093 335095
      334095 334097 336098 337097 338097 340095 340093
 0.50 327102 327100 324098 322097 320097 318099 316101 314103
      312107 312111 315112 316110 318108 321106 323106 325104
      327102
 0.50 308778 309773 309769 307767 303766 301768 300770 298773
      297777 296779 295782 295786 296788 300788 302787 304785
      306782 307780 308778
 0.50 299907 300901 295899 293895 291892 287893 284897 282902
      284906 287910 290913 293914 295911 299908 299907
 0.50 289818 288815 286813 284810 282809 280808 276809 275810
      275814 277815 279816 281817 284819 287820 289818
 0.50 264811 264810 263809 262807 261807 260806 258805 257805
      256807 257809 258810 260811 262810 263811 264811 264811
 1.00 522981 522978 520977 515977 509982 502986 495982 488980
      482984 484987 489988 497993 499995 500000 505002 508001
      515996 520987 522981

$$




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