Quantitative Precipitation Forecast
Issued by NWS

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000
FXUS04 KWBC 141901
QPFPFD

QUANTITATIVE PRECIPITATION FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
300 PM EDT TUE APR 14 2015


PRELIM DAY 1 QPF DISCUSSION
VALID APR 15/0000 UTC THRU APR 16/0000 UTC
REFERENCE AWIPS GRAPHICS UNDER...PRECIP ACCUM - 24HR


DAY 1

...NORTHERN AND CENTRAL ROCKIES AND ADJACENT HIGH PLAINS...

A VIGOROUS TROUGH IS FORECAST TO DIG TONIGHT AND
WEDNESDAY...POSSIBLY CLOSING A 500 MB LOW CENTER OVER UT/CO BY
16/00Z. THE STORM IS NOT PARTICULARLY MOISTURE-LADEN...WITH PW
VALUES AVERAGING 0.25 TO 0.50 INCHES THROUGH DAY 1. FORCING WILL
BE IMPRESSIVE...HOWEVER...ALIGNED NORTH TO SOUTH...AND OWING TO
STRONG HEIGHT FALLS OVER THE GREAT BASIN AND CENTRAL ROCKIES...AND
STRONGLY DIFLUENT UPPER FLOW IN TANDEM WITH A LOW LEVEL FRONTAL
ZONE OVER THE NORTHERN ROCKIES AND ADJACENT HIGH PLAINS. THE PATH
OF THE DEVELOPING MID LEVEL LOW FROM SOUTH OF BOISE TO NEAR GRAND
JUNCTION PLACES MUCH OF WYOMING IN THE REGION OF GREATEST ASCENT
AND MODEL QPF. TRENDS IN QPF HAVE BEEN RATHER FLAT...SO WE
MAINTAINED GOOD CONTINUITY...BUT DID BLEND TOWARD THE 00Z ECMWF
AND 12Z UKMET GIVEN THEIR MORE GENEROUS PLACEMENT OF 0.25
INCH-PLUS AMOUNTS ACROSS WYOMING AND GETTING INTO NORTHERN
COLORADO BY THE END OF DAY 1. LOWERING HEIGHTS WITH THIS
AMPLIFYING UPPER TROF WILL SUPPORT LATE SEASON HEAVY SNOWS THROUGH
THE NORTHERN ROCKIES. SEE THE QPFHSD FOR FURTHER WINTER WEATHER
DETAILS.


...CENTRAL APPALACHIANS / MID ATLANTIC / NORTH CAROLINA...

A FRONTAL ZONE WILL SINK THROUGH THE MID ATLANTIC STATES TOWARD
NORTH CAROLINA BY EVENING. WIDESPREAD...MAINLY STRATIFORM
PRECIPITATION WILL PERSIST NEAR AND NORTH OF THE FRONT WITHIN A
ZONE OF FRONTOGENESIS. MODELS HANDLE THIS MODERATELY FORCED
PRECIPITATION SIMILARLY...ALTHOUGH WE PREFERRED THE PACE AT WHICH
THE 00Z ECMWF AND 12Z NAM PUSH THE BACK EDGE OFFSHORE LATER
TONIGHT IN VA/MD. THE SREF APPEARED TOO SLOW AND THE GFS/UKMET
SLIGHTLY FAST. PRECIPITATION SHOULD BECOME INCREASINGLY CONVECTIVE
WITH SOUTHWARD EXTENT...BEGINNING ALONG THE COAST OF NC AND IN
CENTRAL VA...WITH CONVECTION MEETING UP ALONG THE VA/NC BORDER
TOWARD 00Z PER HRRR FORECASTS. AT LEAST THIS IS THE THINKING THAT
WAS USED TO CRAFT QPF THROUGH 06Z. PRECIPITABLE WATER VALUES WERE
IMPRESSIVE...WITH 1.8 INCHES MEASURED IN THE MORNING RAOBS AT
CHS/MHX...AND ADVECTING INTO VA/NC. THE TIME AND SPACE WINDOW FOR
ORGANIZED HEAVY RAINFALL MAY BE SMALL...BUT RELATIVELY FOCUSED.


...CENTRAL GULF COAST INTO THE SOUTHEAST...

AT 18Z AN ORGANIZED MCS WAS TRACKING EAST ALONG THE CENTRAL GULF
COAST. AMPLE HEATING / INSTABILITY AND MODEST INFLOW SHOULD
SUSTAIN THIS SYSTEM THROUGH EARLY EVENING...SO WE WERE GENEROUS
WITH EASTWARD EXTENT OF QPF THROUGH 00Z. ELSEWHERE IT WAS
DIFFICULT TO EXTRACT CONSISTENT SIGNALS FROM THE MODEL QPFS
THROUGH WEDNESDAY IN THE SOUTHEAST U.S. THE AIR OVER SOUTHERN
LOUISIANA HAD BEEN OVERTURNED...AND APPEARED SPENT FOR THE TIME
BEING. OUTFLOWS AND A SURFACE BOUNDARY MAY YIELD SOME ORGANIZED
CONVECTION FARTHER NORTH FROM NE TX INTO NORTHERN MS/AL THROUGH
EVENING. A SHORTWAVE WHICH HELPED INITIATE THE GULF COAST ACTIVITY
WILL ALSO LIFT UP TOWARD NORTHERN AL AND ACROSS INTO SC THROUGH
WEDNESDAY MORNING...PROVIDING AN ORGANIZING INFLUENCE. MODEL QPFS
WERE SOMEWHAT SCATTERED ON A 6-HOUR TIME SCALE...HOWEVER...SO WE
ATTEMPTED TO MAINTAIN CONTINUITY AND DID NOT HAVE CONFIDENCE TO
INTRODUCE PARTICULARLY HEAVY AMOUNTS EXCEPT WITH THE ORGANIZED MCS
EARLY IN THE PERIOD. GENERALLY WPC QPF REFLECTS A MIX OF THE 00Z
ECMWF WITH 12Z GFS...AND WAS SIMILAR TO OUR IN-HOUSE ENSEMBLE
WHILE BEING MORE CONSERVATIVE ON AMOUNTS.

...OK/AR/MO...

AN UPPER LOW HAD LINGERED OVER OKLAHOMA...WELL BEHIND THE BETTER
DEFINED CORRIDOR OF WESTERLY FLOW. THIS FEATURE WILL LIFT
NORTHEAST AND GRADUALLY WEAKEN AS IT IS REPLACED BY THE STRONG
UPSTREAM SYSTEM IN THE ROCKIES...DIGGING INTO THE BASE OF THE
LONGWAVE WESTERN/CENTRAL U.S. TROUGH. THERE WAS ENOUGH MID LEVEL
MOISTURE NEAR THE CIRCULATION IN OKLAHOMA TO HAVE PRODUCED LOCAL
QUARTER TO HALF INCH AMOUNTS...BUT MORE GENERALLY TENTH INCH AREAL
AVERAGE AMOUNTS SINCE MIDNIGHT TUESDAY. MODELS GENERALLY CARRY
TENTH INCH PER 6-HOURS AMOUNTS ALONG THE TRACK OF THE WEAKENING
CIRCULATION INTO CENTRAL MO BY TONIGHT. A SECOND AREA OF SIMILARLY
LIGHT PRECIPITATION IS EXPECTED FARTHER SOUTH IN
ARKANSAS...PERHAPS INITATING IN THE ARKLATEX REGION...SUPPORTED BY
WEAK WARM ADVECTION. WPC QPF GENERALLY FOLLOWED A BLEND OF THE GFS
AND ECMWF...WHICH WAS SIMILAR ALSO TO THE GEM REGIONAL.

BURKE

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

24HR QP VT 16/00Z
 0.01 496300 513295 525272 525255 520249 515243 512234 506229
      499214 496210 495211 492212 490212 488210 485208 480207
      476206 470210 463211 435217 428219 423222 430226 437228
      451226 455225 459225 462225 465222 472220 476220 478219
      483219 486221 489222 490224 492230 495238 497241 495244
      490238 487236 484237 479242 479246 481250 481260 477271
      477274 477279 480286 485292 492298 496300
 0.01 511155 512149 511146 507141 504136 502129 500121 498115
      495110 490108 489116 490124 491127 489129 486130 483129
      476129 474133 473138 475139 480138 485143 489147 497156
      502159 507159 511155
 0.01 502080 500070 498066 494065 487062 480061 477059 475056
      477054 482049 494038 494034 493029 492025 487025 480024
      473026 437019 434018 431020 425025 411028 407030 402030
      395034 383042 370050 358055 357058 361058 369055 375055
      379058 380062 378064 375063 371062 367061 366063 369069
      371071 372077 372082 374086 377087 381087 384093 391091
      393098 397091 399089 401091 402096 402102 377119 373127
      374131 376133 384137 387137 390136 405133 412130 416129
      419131 422135 424136 431134 437131 439133 438138 438146
      440149 442151 445150 445140 450136 452135 454137 457139
      457143 456146 454149 453156 455156 458153 473159 474156
      472151 470149 468145 463139 463132 464127 468119 472115
      479111 481109 484105 489096 494092 499087 502080
 0.01 461180 461177 458176 456174 455171 451170 449173 449175
      450178 448182 447184 449187 451189 453188 455186 458185
      459183 461180
 0.01 400739 399731 397725 396717 397709 396702 393699 390696
      385694 383691 384688 385683 381668 377667 371668 367669
      364674 345710 341722 337732 333741 330748 327753 326758
      322762 318765 314769 309776 305786 305799 299801 294800
      286801 281802 271807 260805 253805 252806 252810 257818
      265823 284830 288831 292834 290841 287845 281853 276863
      272872 268880 262890 258901 257907 256913 255919 255923
      259929 263929 266925 270927 271929 272934 275938 278941
      283942 293936 297933 299928 301924 303921 306920 312920
      315918 320915 320923 317935 317941 320946 325952 332958
      338958 339956 340951 341948 344948 350952 354952 358949
      361944 364941 370939 373945 381948 386957 389961 393963
      398961 402957 409933 407919 402908 397900 391892 377873
      375868 373865 373861 373853 374846 374840 375834 378828
      381823 384813 385809 385804 382799 384795 389785 392780
      395773 397761 399749 399743 400739
 0.01 362067 361065 360065 359064 358065 359065 360067 362067
      362067
 0.01 307030 305025 301021 296018 291015 283015 277015 275017
      275022 276024 279026 284028 287033 293034 295032 299032
      305032 307030
 0.01 290077 291073 292069 291066 290064 288061 286060 284060
      281061 280063 280067 280070 281074 281076 283079 287079
      289079 290077
 0.01 272993 273983 272972 270965 266959 262954 258953 255955
      250958 245964 246969 244973 241979 237985 236988 235993
      236998 241004 243010 248016 254019 257018 260015 259009
      261000 262995 266995 270995 272993
 0.01 265052 266050 265048 265047 264045 264043 264041 262040
      260040 260041 259043 259045 259047 260047 261049 261051
      261052 263053 263054 265052 265052
 0.25 498291 509293 522275 524261 521259 518256 514253 511249
      509246 505245 504255 501257 497255 491248 489251 488254
      489262 488275 489279 492284 498291
 0.25 472096 472093 469090 464091 459092 452093 444084 442081
      444082 449086 453086 457088 462087 468083 470081 470076
      466072 463066 460058 457052 447045 444046 442048 440050
      436050 429048 424050 417052 411052 407054 406058 407066
      410071 415077 418078 420081 420085 422091 427096 433102
      437103 444100 445103 444108 447116 449118 453117 456113
      459105 463104 468106 472096
 0.25 442041 441039 441040 441042 442041
 0.25 420116 417113 412111 412106 411099 410095 407093 405097
      405105 403109 400111 391113 385119 382124 384125 388124
      390123 391121 394118 396117 399119 409121 417118 420116
 0.25 390718 389711 387707 381707 376707 371707 372703 373698
      373691 372686 370685 367689 364699 359709 354717 349725
      344734 341743 339747 339752 346752 352749 360743 363742
      364750 363756 360758 355767 351777 349781 346784 342782
      339779 336777 331776 327779 324782 323783 322790 322797
      321802 319806 313809 301808 290809 286809 282811 278819
      289821 309826 311832 311835 310839 302844 296849 291856
      286863 280872 276882 273892 273897 273904 275908 279911
      287909 295905 309892 312890 317888 324889 327892 342904
      344908 349910 356908 374920 380925 384929 386933 388936
      393936 396932 398928 395918 390911 387907 383904 379903
      374902 369900 365896 359890 349887 348880 350875 352865
      356857 360848 364837 366827 366819 364811 362807 361801
      363797 364790 367782 372774 379768 382764 385759 388748
      390737 390718
 0.25 268817 271818 274817 272816 269815 268817
 0.25 253006 254002 253998 252996 251993 249991 248990 246990
      243992 242994 243996 244998 245002 247004 248006 251007
      253006
 0.50 520271 520266 519263 513257 509255 508259 508262 507267
      501262 497263 495264 495275 497283 503288 507288 510287
      514282 519274 520271
 0.50 458076 457072 453071 450068 445066 435064 431067 429070
      426074 424079 424086 426091 429094 433095 432092 430087
      431078 432075 434075 439074 444077 448080 451082 454081
      458076
 0.50 411117 410115 410114 410112 410110 410108 410105 409103
      407105 407107 406109 405112 404114 404116 406117 408118
      410118 411117
 0.50 386742 385734 384729 383720 381719 379721 377727 374733
      371738 372743 371749 372754 373758 378757 382753 385747
      386742
 0.50 367721 364715 361716 356721 353726 352731 349738 350742
      353739 358735 361731 365726 367721
 0.50 365771 365768 363765 360768 358772 356777 355781 354786
      352791 353797 357797 359794 360789 361783 363778 364773
      365771
 0.50 358828 357818 356813 354810 351802 346796 341789 339786
      336786 335787 336791 337798 337800 334800 328798 323803
      321812 317817 316823 317829 316837 315841 313843 305846
      300848 298851 294856 286869 282876 279882 277891 277896
      278902 280905 285904 290901 301891 311880 317877 320877
      323879 328879 332881 336887 339886 341884 343875 346866
      349859 353853 355843 358828
 0.50 350820 348816 345816 341817 338817 336821 333824 331827
      331831 335833 339832 342829 345825 349823 350820
 0.50 304816 302815 299813 297812 293812 291812 288811 284812
      284813 286815 288817 291818 294819 297819 300819 301819
      304816
 1.00 347842 346840 348838 346836 345838 344839 344840 345842
      345843 346842 347842
 1.00 333863 333861 333859 331857 331856 329856 328857 327857
      326859 326860 325861 325864 325866 326868 326870 327870
      328868 329868 330867 331865 332865 333863
 1.00 312869 310865 308863 307857 306854 304854 299861 296870
      292876 285883 282891 283893 285893 289890 294889 297887
      300882 305877 312871 312869

$$





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