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000
FXUS04 KWBC 180658
QPFPFD

QUANTITATIVE PRECIPITATION FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
257 AM EDT SAT MAY 18 2013


PRELIM DAY 1 QPF DISCUSSION
VALID MAY 18/1200 UTC THRU MAY 19/1200 UTC
REFERENCE AWIPS GRAPHICS UNDER...PRECIP ACCUM - 24HR


DAY 1...

UPDATE...LOTS OF UNCERTAINTY REMAINS WITH THIS FCST AS SGFNT
DIFFERENCES CONTINUE TO BE NOTED BTWN MODEL QPFS FOR ALL THE
PRIMARY AREAS MENTIONED BELOW.  SOME SGFNT CHANGES WERE MADE TO
BETTER REFLECT CURRENT OBSERVATIONAL DATA PARTICULARLY OVR THE TN
AND OH VLYS.  IN ADDITION..ALTERED THE FCST OVR THE N CNTRL U.S.
TO BETTER REFLECT A GFS/UKMET BLEND..BOTH OF WHICH SEEM TO BE
DOING BETTER WITH THEIR FCSTS OF THE ONGOING ACTVTY ACROSS THE
REGION..MORE SO THAN THE ECMWF OR GEM REGIONAL.  OVR THE WRN
PORTION OF THE NATION..THERE IS BETTER AGREEMENT BTWN THE ECMWF
AND UKMET THAN WITH OTHER GUIDANCE.   KORTY

...WEST...

A VERY UNSETTLED PERIOD FOR THE WRN STATES... AS A BROAD BUT SHARP
UPPER TROUGH AXIS OVER THE INTERIOR WEST WILL BEGIN TO EJECT OUT
INTO THE PLAINS FOR SAT WHILE UPSTREAM JET DYNAMICS FROM THE PAC
STREAM INTO THE PAC NW/INTERIOR NW. ENOUGH MOISTURE CONTENT WITH
STRONG DIURNAL HEATING AND BROAD SCALE VERTICAL LIFT SHOULD RESULT
IN WIDESPREAD QPF ACROSS THE INTER-MOUNTAIN WEST... WITH THE
CURRENT ACTIVITY SLIDING ACROSS NRN UT/WRN WY/SRN MT THE NEXT 6 TO
12 HRS BEFORE WEAKENING AND RE-DEVELOPING AGAIN TMRW AFTN FROM THE
FRONT RANGE OF THE NRN ROCKIES BACK TO A DEVELOPING MID-LEVEL LOW
CENTER NEW SWRN MT. MEANWHILE... LIGHTER ONSHORE FLOW WILL
COMMENCE ACROSS THE NW AS A PROGRESSIVE PAC SHORT WAVE ARRIVES
LATER SAT FOR SHOWER ACTIVITY ACROSS THE PAC NW WITH POSSIBLE
CONVECTIVE ACTIVITY ACROSS THE INTERIOR NW. WPC GENERALLY FOLLOWED
A BLEND OF THE 12Z GUIDANCE FOR QPF AMOUNTS FOR EACH SYSTEM WITH
.50 TO 1 INCH OROGRAPHIC AMOUNTS ACROSS THE WASATCH TO THE
ABSAROKA/BIG HORN MTNS.

...PLAINS/UPPER MIDWEST...

A VERY COMPLEX FCST ACROSS THE NRN PLAINS AND UPPER MIDWEST FRI
EVENING THROUGH SAT... AS SMALL SCALE SHORT WAVE DYNAMICS
ASSOCIATED WITH THE UPPER-LEVEL TROUGH OVER THE WEST EMERGE INTO
THE PLAINS LATER THIS EVENING AND INTERACT WITH A QUASI-STATIONARY
BOUNDARY FOR ANOTHER POSSIBLE NOCTURNAL CONVECTIVE HEAVY RAIN
EVENT... SIMILAR TO OVERNIGHT LAST NIGHT. THE ACTIVITY STILL
THRIVING FROM LAST NIGHT CONTINUES TO PRODUCE SOME HEAVIER
RAINFALL AND RE-DEVELOPMENT ACROSS SERN MN INTO WI BUT MUCH OF
THIS ACTIVITY IS SLIDING INTO THE DRIER AIR MASS DOWNSTREAM AND
SHOULD BEGIN TO WEAKEN AS THE LL/850 MB PLAINS JET FOCUSES
UPSTREAM OVER THE DAKOTAS. THE NAM AND GFS SEEM TO HAVE THE BEST
HANDLING OF POSSIBLE CONVECTIVE QPF DEVELOPING ACROSS WEST CENTRAL
SD INTO WRN NE AND THEN LIFTING NORTH AND EAST UP TOWARDS
CENTRAL/SERN ND AND NRN MN. THE GFS THOUGH DOES DEVELOP A
CONVECTIVE FEEDBACK MAX BACK INTO THE COLD SECTOR BY EARLY SAT
ACROSS NERN MT/NWRN ND... WHICH APPEARS LIKE AN OUTLIER. AS THIS
COMPLEX MOSE OUT OF THE DAKOTAS RAPIDLY SAT... THE MAIN UPPER
TROUGH AXIS OVER THE WEST WILL BEGIN TO SHIFT OUT INTO THE PLAINS.
THIS SHOULD RESULT IN MORE SYNOPTIC SCALE FORCING AND MORE
WIDESPREAD HEAVY CONVECTIVE RAINFALL SAT AFTN/EVENING FROM ERN MT
AND ND/SD SOUTH THROUGH WEST CENTRAL NE/KS/OK INTO NRN TX. OVERALL
TIMING AND LOCATION OF THE SMALL SCALE FEATURES IS THE BIGGEST
QUESTION MARK BEFORE THE MAIN UPPER TROUGH AXIS ARRIVES TMRW AFTN
BUT WPC FELT CONFIDENT ENOUGH TO PINPOINT A SLIGHT RISK FOR
EXCESSIVE RAINS OVER CENTRAL SD/SERN ND FOR THE NEXT 24 HRS.

...TN/LWR OH VLYS TO MID-ATL STATES...

A MID-LEVEL/500MB LOW CENTER DETACHED MOSTLY FROM THE WESTERLIES
WILL DRIFT THE NEXT 24 HRS FROM WRN TN/KY TO THE ERN PORTION OF
THESE TWO STATES ON SAT. ONCE AGAIN... A SOLID PLUME OF 1.5 TO
1.75 INCH PWS FROM THE GULF OF MEXICO WILL POOL ON THE ERN SIDE OF
THIS SYSTEM... WHILE BEGINNING TO INGEST SOME ESERLY ATLANTIC
INFLOW. THE RESULTANT SHOULD BE LOCALIZED HEAVY RAINFALL FROM NRN
AL/MS/GA TO ERN TN/KY AND ANOTHER POSSIBLE MAX ACROSS SWRN/SRN VA.
THE GUIDANCE OVERALL HAS A DECENT HANDLING OF THE PROGRESSION OF
THIS FEATURE ALONG WITH THE MOISTURE FLUX AXIS AND WPC FOLLOWED A
BLEND OF THE OPERATIONAL ECMWF WITH THE INTERNAL PSEUDO BIAS
CORRECTED GUIDANCE AND 09Z SREF MEAN FOR QPF TOTALS. SINCE THE
SYSTEM IS NOT MOVING QUICKLY... THERE COULD BE SOME LOCALIZED
HEAVIER CONVECTIVE AMOUNTS FROM NRN AL TO ERN TN WHICH COULD
PRODUCE SOME RUNOFF ISSUES THOUGH 1 AND 3 HR FFG REMAINS
BORDERLINE.

MUSHER

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

24HR QP VT 19/12Z
 0.01 531173 540209 524265 510296 490280 484274 478275 473275
      467276 461274 453270 445267 427272 425268 422266 420261
      421258 424242 421237 419231 424219 429216 430212 429209
      426211 423210 419203 418199 419193 421190 421183 413180
      409175 404166 402162 402154 403151 406151 412152 416155
      420158 423161 427162 431164 439177 441180 444182 450183
      453180 453176 459177 459184 455189 452193 450195 449200
      449204 450207 452210 461212 466210 472208 480208 485205
      485199 481192 481188 481182 482170 481165 479162 472159
      467162 463166 457165 451164 448162 444156 441150 439145
      437138 434132 433125 430122 427123 426127 424128 419131
      412133 408134 402134 390131 384127 379123 377122 382116
      388112 391108 391103 391098 387096 382098 377099 375101
      371106 366111 366114 363118 357110 357103 355100 357095
      358089 372072 372065 375068 379067 382065 387061 392059
      396055 398049 401045 403041 402036 399028 395023 390020
      385017 380013 370011 367008 363009 359009 343003 329998
      310000 307997 306994 306988 309984 317979 318976 316973
      318970 318966 319966 326964 332961 338958 352955 356953
      358950 358946 357937 353932 353930 350919 346913 343907
      342901 334889 316873 318859 320851 319845 321834 321829
      320826 318825 315822 312821 309823 298823 289822 276821
      271819 267819 258816 253814 249810 252805 254802 260800
      270802 277803 282806 292809 303813 308817 315815 322812
      328808 339792 345788 346783 342778 340772 337765 335758
      334745 333737 339733 343729 347725 353724 361720 364719
      366721 371725 377728 382733 387741 392745 400755 402771
      402776 403781 402789 401795 400804 400808 401815 402823
      402828 404837 405845 401856 397868 392878 387879 385877
      383879 384884 388888 391892 396897 399901 402904 406903
      412905 419907 420907 422913 423921 426924 433926 437926
      439928 444928 447927 452926 455923 456915 456906 457898
      457887 460880 463876 464870 466863 465856 464845 463836
      464831 465823 465815 467808 469800 473794 480791 483792
      489793 493795 515811 532826 542834 537853 534863 532868
      531872 532876 529897 527903 527909 526925 524943 525955
      526966 525973 523982 518997 513012 511023 510030 506054
      503074 503081 505089 508099 511105 512117 513119 511123
      510129 512136 515143 517146 520148 522157 526164 531173
 0.01 525252 527238 528232 526227 525222 523217 520216 518211
      515210 513205 511203 507199 504197 499198 496201 495204
      497208 500214 505220 507225 507230 511239 513242 516246
      518249 521252 525252
 0.01 453706 453702 451698 450698 447700 445702 445703 444708
      444709 443714 446713 449711 451709 453707 453706
 0.01 427781 426777 425774 423779 424783 427781 427781
 0.01 385943 385932 384921 382917 379915 373910 369907 363901
      361900 359899 358902 361909 363919 366922 367925 369930
      371932 373942 376945 378946 382946 385943
 0.01 250988 231994 225011 232022 246020 252015 256014 262013
      268018 270020 276020 279016 279010 278007 275001 274998
      271995 266994 258991 250988
 0.25 518270 516268 513267 510266 507265 504266 503266 504267
      506269 509271 512273 515274 517276 518270
 0.25 503888 502876 500869 495858 491854 489846 487839 481836
      482840 481847 480857 478866 475872 471874 468878 465885
      463889 462894 461907 461919 459929 454943 452950 450954
      448957 439961 430961 423959 415957 403954 391958 374960
      376966 374974 374981 373985 374989 379994 385996 401001
      406006 410015 412021 415027 427036 432040 438048 441052
      439057 435064 433073 432081 431093 433101 438108 442117
      446125 449127 453126 462117 467115 476114 485116 489118
      492116 493113 494106 493100 491095 490088 488081 489075
      496058 497045 499031 502022 506013 511997 512987 513980
      512973 510967 507963 503957 503933 504921 504911 504903
      504894 503888
 0.25 480244 478241 476238 476237 473236 471236 469240 472242
      474244 477245 480244
 0.25 466222 466221 463219 460220 458219 460222 463222 466222
      466222
 0.25 463034 461030 458032 457035 457039 459041 460039 461037
      463034
 0.25 391776 389765 384755 378746 373741 361737 353737 344739
      341741 340745 341754 345757 348757 353757 357759 358764
      359770 359778 360784 358788 351795 347800 342807 340811
      340816 338820 335822 331827 326833 324844 324854 326863
      330870 344882 348886 349877 354860 356856 358854 363852
      368851 376852 381850 384842 383836 381830 390812 390804
      391796 392786 391776
 0.25 296816 295815 293814 292814 288813 285813 283813 283815
      286816 287817 290817 292818 293819 296818 296816
 0.50 507994 507986 504981 499977 496977 495971 495967 496959
      497941 498927 498918 497908 493901 490892 488888 486888
      479890 476888 471887 468893 467901 467918 466925 468935
      464940 461943 458948 456955 453961 450965 444969 437970
      428973 423975 417978 412980 408982 406982 405975 404970
      401967 398966 393967 388969 384971 380976 377981 377986
      381988 401990 406993 409998 416010 421017 429021 432024
      433027 432032 436033 438027 455016 460013 464013 469017
      472025 471041 473044 476045 482043 487040 491035 497023
      503008 506000 507994
 0.50 471094 473086 473076 471071 468069 465068 459070 454068
      451066 444065 441068 440071 441076 446084 448088 446092
      447105 449112 452114 458107 464101 469098 471094
 0.50 386786 385780 382776 378774 372774 366777 364781 364787
      361795 357800 352803 347820 344824 341828 333835 329841
      327845 327852 328858 331863 335867 338868 343865 345863
      347858 349852 352845 364840 368837 370834 371829 371822
      372818 375815 380811 382807 386798 386786
 0.50 360750 361745 359742 357742 354742 351743 348743 345743
      344747 345751 346752 347753 349753 352752 354751 357751
      360750 360750
 1.00 493933 493926 491919 489916 486915 485917 481924 477934
      473943 467951 462958 457967 453973 446979 441986 438990
      437996 442003 445004 451003 457999 459997 465995 469993
      472990 477981 481971 486962 488955 492942 493933
 1.00 380793 380790 378787 375784 373785 372785 370788 369791
      369793 368795 367799 367800 366804 369805 372803 375802
      377800 379798 379797 380793
 1.50 490934 490929 489924 485924 483927 478939 470952 463962
      458975 455979 450985 449990 456991 459988 463985 467984
      471981 475975 481963 486948 490934
 2.00 478959 479954 477950 476950 475951 473952 470955 469956
      468958 465962 464966 463969 462971 463975 467978 469975
      471973 472972 474968 475968 477963 478959

$$