Quantitative Precipitation Forecast
Issued by NWS

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000
FXUS04 KWBC 012241
QPFPFD

QUANTITATIVE PRECIPITATION FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
639 PM EDT FRI MAY 01 2015


FINAL DAY 1...DAY 2 AND DAY 3 QPF DISCUSSION
VALID MAY 02/0000 UTC THRU MAY 05/0000 UTC
REFERENCE AWIPS GRAPHICS UNDER...PRECIP ACCUM - 24HR


MADE ONLY VERY MINOR CHANGES TO THE PRELIM DAY 1 QPF..BASED MOSTLY
ON RECENT RADAR IMAGERY/TRENDS.

DAY 1...

MID ATLANTIC

THE POSITIVELY TILTED UPPER TROF MOVING SOUTHEASTWARD THROUGH THE
SOUTHERN MID ATLANTIC THIS AFTERNOON WILL SWING OFFSHORE OF
EASTERN NC EARLY DAY 1---PROGRESSING STEADILY EASTWARD INTO THE
WESTERN ATLANTIC OVERNIGHT.  ORGANIZED SHOWER ACTIVITY WILL
DIMINISH EARLY DAY 1 AS THE UPPER LOW AND ASSOCIATED SURFACE
CENTER PULL AWAY FROM THE COAST.  WIDELY SCATTERED SHOWERS MAY POP
UP SATURDAY AFTERNOON THROUGH THE MID ATLANTIC UNDERNEATH CYCLONIC
FLOW ALOFT---BUT ACTIVITY SHOULD BE SCATTERED WITH LIGHT AREAL
AVERAGE AMOUNTS.

LEE OF THE CENTRAL ROCKIES INTO THE CENTRAL PLAINS

THE LOW LEVEL SOUTHERLY FLOW EXPECTED TO STRENGTHEN EARLY DAY 1
FROM THE LEE OF THE CENTRAL ROCKIES INTO THE CENTRAL PLAINS AS
SHORTWAVE ENERGY PUSHES EASTWARD FROM CO INTO THE CENTRAL PLAINS.
MODEL CONSENSUS IS FOR POTENTIAL OF TWO AREAS OF CONVECTION TO
FORM.  ONE INITIALLY OVER EASTERN CO EARLY DAY 1---SINKING
SOUTHEASTWARD INTO WESTERN KS---WITH A SECOND AREA FARTHER
EASTWARD IN THE VICINITY OF SOUTHEAST NE/NORTHEAST KS INTO NW
MO/SE IA.  IN BOTH AREAS---PRECIPITATION AMOUNTS EXPECTED TO
REMAIN IN THE LIGHT TO LOCALLY MODERATE RANGE GIVEN MODEST PW
VALUES.

ELSEWHERE---MOSTLY LIGHT PRECIP TOTALS EXPECTED AHEAD OF A FAST
MOVING FRONT MOVING ACROSS THE NORTHERN PLAINS AND OVER THE GREAT
BASIN INTO THE SOUTHWEST WHERE SCATTERED DIURNAL ACTIVITY IS
POSSIBLE.



DAYS 2/3...


...GREAT BASIN/ROCKIES...

GENERAL PATTERN FAVORS DIURNALLY DRIVEN SHOWERS AND THUNDERSTORMS
ACROSS THE AREA BOTH SUNDAY AND MONDAY AFTERNOON...FOCUSED ALONG
THE HIGHER TERRAIN. SOUTHERLY FLOW AHEAD OF THE TROUGH APPROACHING
THE WEST COAST...AND ON THE BACKSIDE OF THE HIGH OVER THE
SOUTHEAST PORTION OF THE COUNTRY...WILL INCREASE PRECIPITABLE
WATER VALES ACROSS THE REGION. BY MONDAY LOOKING AT VALUES 2 TO 3
STANDARD DEVIATIONS ABOVE NORMAL FROM THE NEW MEXICO TEXAS BORDER
NORTH INTO EASTERN COLORADO. LACK OF STRONG FORCING SHOULD LIMIT
OVERALL QPF AMOUNTS...WITH AMOUNTS GENERALLY A HALF INCH OR LESS
THROUGH MONDAY. ALTHOUGH LOCALLY HIGHER AMOUNTS ARE LIKELY ALONG
THE HIGHER TERRAIN. THE MODELS ARE IN FAIR AGREEMENT WITH OVERALL
FEATURES...THUS GENERALLY USED A MODEL COMPROMISE FOR QPF AMOUNTS.

...CENTRAL AND NORTHERN PLAINS TO THE MID AND UPPER MISSISSIPPI
VALLEY/GREAT LAKES...

A COLD FRONT WILL MOVE SOUTHEAST ACROSS THE PLAINS INTO THE
MISSISSIPPI VALLEY AND GREAT LAKES REGION SUNDAY INTO MONDAY.
PRECIPITABLE WATER VALUES INCREASE ALONG AND AHEAD OF THE
FRONT...GENERALLY ABOUT 1 TO 2 STANDARD DEVIATIONS ABOVE NORMAL.
COMBINE THIS WITH FORCING FROM THE WAVE AND FRONTAL BOUNDARY...AND
EXPECT SHOWERS AND THUNDERSTORMS TO INCREASE IN COVERAGE ALONG THE
FRONT BY SUNDAY AFTERNOON.  SYSTEM IS PRETTY PROGRESSIVE...WHICH
SHOULD HELP KEEP QPF AMOUNTS FROM GETTING TOO HIGH. GIVEN THE GOOD
MODEL AGREEMENT...WPC STAYED CLOSE TO A BLEND OF THE GFS AND ECMWF
FOR DAY 2 QPF...WITH SOME ADJUSTMENTS BASED ON THE GFS AND ECMWF
ENSEMBLE PROBABILITIES. THIS RESULTED IN AN AREA OF BETWEEN 0.5
AND 0.75 INCHES ACROSS WESTERN WISCONSIN WEST INTO SOUTHERN
MINNESOTA.

BY DAY 3...MONDAY...THE FRONT STALLS OUT ACROSS THE CENTRAL
PLAINS. ONGOING CONVECTION SUNDAY NIGHT WILL MAINLY BE FOCUSED
FROM SOUTHERN WISCONSIN INTO EASTERN IOWA...AND SHOULD BE ON A
DECREASING TREND BY LATER IN THE NIGHT. HOWEVER BY MONDAY
AFTERNOON WOULD EXPECT COVERAGE TO INCREASE ALONG THE BOUNDARY.
THE NAM SEEMED A BIT EXCESSIVE WITH ITS QPF AMOUNTS...AND THE GFS
APPEARED TO BE SUFFERING FROM CONVECTIVE FEEDBACK...RESULTING IN A
QPF AXIS TOO FAR NORTH. THUS WPC PREFERRED A BLEND OF THE ECMWF
AND THE UKMET AS A STARTING POINT WITH REGARDS TO QPF...AGAIN WITH
SOME ADJUSTMENT FROM THE ECMWF ENSEMBLES...WHICH IN GENERAL WERE
IN AGREEMENT WITH THE DETERMINISTIC. THIS RESULTS IN A CORRIDOR OF
AMOUNTS OVER 1 INCH FROM EASTERN IOWA WEST TOWARDS THE NEBRASKA
AND KANSAS BORDER. PRECIPITABLE WATER VALUES AND INSTABILITY ARE A
BIT TOO LOW FOR WHAT WE WOULD LIKE TO SEE FOR EXCESSIVE
RAINFALL...BUT GIVEN THE STATIONARY BOUNDARY AND INCREASING
MOISTURE VALUES...SEEMS PROBABLE THAT ISOLATED HIGHER AMOUNTS ARE
POSSIBLE. ALSO VARIOUS ENSEMBLES DO SHOW SOME LOW PROBABILITIES OF
2 OR MORE INCHES OF QPF NEAR THE KANSAS AND NEBRASKA BORDER...SO
SOMETHING TO KEEP AN EYE ON.


ORAVEC/TERRY/CHENARD


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

24HR QP VT 03/00Z
 0.01 536207 538196 536188 530174 522162 514152 511151 508148
      504150 505159 503163 502168 503186 511197 516201 521207
      525212 527215 530216 534213 536207
 0.01 506955 506948 506942 497941 486952 476964 467976 463984
      460993 458998 457004 456008 456015 456018 459015 463008
      467001 472994 478988 484982 494972 500967 504960 506955
 0.01 426751 422745 420742 418743 411744 409746 408749 405757
      406760 405764 394773 388777 383779 381781 374783 370785
      368788 370791 373792 380791 389788 396784 400780 404773
      415763 420759 423756 425753 426751
 0.01 427125 428118 427112 425108 422105 418102 417096 418083
      418076 417070 417063 415057 412053 408051 403050 399048
      399045 403043 410040 415040 417039 418036 417031 414027
      408019 410014 412007 412992 414989 414982 414975 412972
      413968 417966 423966 425963 425956 423952 421947 417945
      413941 410937 409931 410926 410919 407919 403928 402933
      400933 396931 394934 392938 391945 391951 389956 388964
      386970 385976 387979 392980 394982 398984 402983 401993
      399006 398012 395015 390021 387021 387018 388013 385010
      382005 378995 375994 372997 369005 368011 368019 370028
      368039 366042 360042 355043 354049 357060 359065 361067
      365068 370070 372075 375079 377080 381078 383077 386078
      390080 393080 395083 399081 402079 407078 410081 410084
      409086 406095 409105 414113 417115 418119 419122 418125
      416130 408135 404136 401140 398152 380186 376183 370182
      370187 373190 380196 382197 387196 388194 385190 389183
      399169 405159 409153 415154 419152 421146 422138 427125
 0.01 393766 390764 387766 378766 367766 363766 360768 355769
      351772 347774 346777 350780 354780 361775 363775 364778
      368778 379777 387773 391770 393766
 0.01 377746 376736 375733 375728 374722 371715 367712 362713
      360715 355719 351724 339730 335735 331741 330747 332754
      337757 343757 346755 348757 351760 354761 356762 360761
      366759 372756 376751 377746
 0.01 344087 345083 343078 340076 334075 331077 330081 331086
      333090 334095 336098 342098 342094 342090 344087 344087
 0.01 320097 321091 319086 310083 303078 297073 291068 288066
      282066 280067 280074 285079 293083 301087 307092 316097
      320097
 0.01 265800 264798 261797 253799 250803 247807 244813 243815
      244819 248818 251817 253818 259820 261819 261815 259809
      260806 262805 265800
 0.25 392038 392036 391035 390034 389032 388031 387031 386030
      384031 383033 383035 384037 384038 385039 387040 389040
      391040 392038
 0.25 361740 360740 358738 356739 355739 353740 351742 351744
      352745 353746 354746 356746 357746 358745 359744 360743
      360741 361740

24HR QP VT 04/00Z
 0.01 509146 507141 505137 501136 499140 495142 493137 491134
      489131 487136 489140 492143 497144 501147 504149 508147
      509146
 0.01 510924 510910 509904 507898 505895 502893 500895 499900
      498905 495906 492903 494896 498887 500883 500878 501875
      500867 501861 499857 494857 490860 485858 479859 469862
      460866 451870 442875 438878 436882 433885 429887 424888
      420886 414882 410882 406884 401885 399887 391892 387897
      391906 390912 389917 381922 371922 367925 364930 365932
      369932 376932 382931 386930 390928 393924 396924 397930
      397937 395942 387955 391959 396959 399961 402959 408955
      413954 414958 410968 405978 395991 393993 390995 384994
      378995 373998 364003 358009 352015 344019 340019 335021
      326020 321018 318020 316023 314025 312025 301024 295021
      290019 286020 279021 273020 270018 267015 262008 255001
      248996 237991 233993 234997 236000 240002 247007 251014
      252016 256018 264024 270028 280030 284036 286039 289041
      300039 303041 306045 311047 316044 319039 321034 323031
      326029 332029 335028 338028 342027 347024 350022 354023
      357028 356035 356047 356053 357057 357064 358068 355072
      351074 347074 344077 341080 339084 343092 338093 334095
      333098 336099 342098 347095 347091 353091 361087 363085
      365081 362072 361069 364069 366070 371073 373077 370079
      371082 375083 377087 378096 381096 384093 390086 396082
      393095 389104 386108 382110 377112 373115 368117 366122
      368126 369130 367132 363134 365137 369136 372132 376135
      379134 385128 391123 393121 398122 401122 404125 404132
      402135 399134 397136 392141 388152 383163 382171 383182
      384184 386185 389178 391173 394169 398166 401161 404156
      406155 409155 411153 410149 411145 413145 415150 415156
      418154 420154 422150 426125 430115 436110 441120 442122
      441126 438131 436144 436150 437156 439156 439153 439147
      440143 442142 446140 450139 454135 455127 461124 462121
      459118 456114 456110 459109 462106 464103 466102 469105
      472101 473094 473091 471090 468087 465090 461091 457088
      458075 457061 457058 457053 460050 461042 462037 463021
      463015 460010 458015 457021 455030 453036 452031 450029
      444034
 0.01 444034 443031 440031 438032 437036 434044 431046 427045
      422046 416044 409041 403039 398034 396034 395029 397026
      397020 397016 395011 394009 396005 399001 407003 415004
      418006 422999 427993 430987 433983 436977 441971 443973
      443978 446983 448991 452997 456001 462999 465994 467990
      469987 474982 481974 491963 499955 507942 509934 510924
 0.01 468694 465690 462678 459671 456665 453666 452669 450677
      446690 437702 436704 433706 430711 427717 430724 434728
      437731 439731 446730 449727 451724 452718 456711 463699
      468694
 0.01 453740 452737 449737 447736 443736 442735 440736 437738
      437741 438743 441745 443745 446745 449744 451741 453740
 0.01 448085 445078 443075 439074 436078 433077 432073 435066
      443067 445062 445056 445050 443047 437048 431054 426072
      421076 417083 416093 418097 420097 422092 422087 427079
      430082 434084 437082 441083 443085 446087 448085
 0.01 418133 419128 419123 418119 415118 411119 410122 410126
      410131 410133 410138 413141 416139 417135 418133
 0.01 387198 386194 383191 380187 377185 372181 370181 367185
      367187 369189 372192 375195 379198 382200 386199 387198
 0.01 363820 363816 359818 356821 352824 350826 348831 348833
      350838 354837 357834 358830 360824 363820 363820
 0.01 279985 277980 274978 270976 266974 264974 259975 255976
      257980 261982 264983 268981 272983 275985 279985
 0.01 269800 266797 262795 259797 255800 249806 244802 242804
      242811 243823 246826 251824 253821 255819 254816 251814
      251809 256803 266801 269800
 0.25 472927 471922 469918 467913 465906 464901 465893 466887
      466881 461878 452884 446889 441899 436908 433912 433919
      428945 428956 428958 431960 437960 440959 443960 449961
      452964 455976 458975 459971 459967 461962 464955 465949
      472927 472927
 0.50 458908 459899 455895 450897 446903 441914 435926 432940
      433947 435949 438950 442949 446954 451955 455950 454947
      449943 448936 450929 453924 457918 458908


24HR QP VT 05/00Z
 0.01 489341 489338 490336 492334 493332 494329 495328 496325
      497323 497322 498321 499319 500317 501314 503312 504310
      504308 505307 520271 522255
      524249 526241 528237 528231 526236 522237 519239 516240
      514238 509227 502227 494228 496237 499242 501247 503251
      500254 494252 491249 486247 481244 477243 473244 465246
      463250 462258 461271 453277 441288 435297 433310 433317
 0.01 538732 532715 523695 519686 515674 509663 503657 497664
      489672 482681 479686 476691 466707 462715 457721 420787
      411802 406810 402820 398832 393841 390851 389856 389861
      390864 390870 391883 392897 393907 391920 390925 387929
      381937 376946 371957 370963 369969 368974 366982 362991
      357997 351002 344008 341010 336012 333014 328014 325011
      324009 325006 326996 323988 319985 315981 306977 301976
      297975 289978 283974 279972 276967 274964 269963 265964
      261966 255966 252968 251970 250975 249983 249994 249998
      251002 257005 265008 269015 274022 280029 284033 288037
      294043 296047 299050 303053 308055 313057 319057 330058
      337059 341062 357071 370082 376086 381092 384093 387091
      390089 394086 397087 400087 403090 405091 406095 395107
      392109 388111 383111 379114 377121 374126 374130 376130
      380128 393121 395120 396123 394129 392142 389148 391151
      389155 388162 385165 384170 384174 383181 381186 374185
      368185 366185 368188 376196 382200 386202 391202 391197
      389193 390180 393177 394167 395160 396155 412161 415163
      418162 417152 412145 406140 401138 399134 400130 406124
      415119 416113 420111 422110 424112 426110 427103 425098
      422098 422100 419105 414108 412102 413095 409092 406090
      405087 405084 413082 420080 427077 430076 433077 433080
      433085 437086 437090 435090 432089 430087 451096 453098
      454094 453092 448091 448088 451088 454085 454080 453070
      455061 458057 460053 460044 453022 449015 444010 442010
      439013 435016 432011 427003 426999 425992 425973 426965
      428962 433953 435949 437942 448921 455906 458902 462898
      467893 468889 467883 474878
 0.01 474878 477875 479871 484862 489853 492851 493854 494860
      496874 497878 498880 503882 506884 510881 510873 510864
      509857 508848 506842 506834 504829 503823 498812 496807
      495799 491787 498780 503772 516756 522749 528743 538732
 0.01 361130 359124 356120 351112 348107 345103 342094 337094
      333097 328105 328109 333112 339114 342114 342118 344130
      347134 352136 356134 360131 361130
 0.01 365818 364814 362814 359816 356818 354817 350822 349826
      346833 345840 347844 348844 352846 356841 359835 361830
      363823 365818
 0.01 344175 344173 344171 343169 343168 341166 339165 338165
      336163 334164 334165 334167 336167 337168 339168 340170
      341171 342173 342175 344176 344175
 0.01 325786 325781 323784 320784 311790 303795 296801 287808
      286811 286814 288816 291819 296820 302820 306816 313809
      318800 323793 325786
 0.01 243734 234740 222746 212753 209758 207766 208779 211794
      211800 211808 214824 217837 219845 222850 224865 226869
      226874 228876 228880 232891 237903 242914 246919 252922
      273931 286935 293935 296937 299937 301939 304939 309938
      312933 314925 316918 319911 321907 320900 315897 315890
      313888 309887 306886 302885 288882 281874 274866 265858
      261854 256850 253845 251838 250831 251825 252818 255812
      263801 266790 268778 270763 272750 274735 274727 271720
 0.25 514279 513275 511271 505266 497265 491268 488275 490283
      491292 493295 497297 504297 508293 512284 514279
 0.25 518729 516722 512718 509715 505709 505697 505694 503693
      497696 489702 486707 482713 475720 469730 463740 461746
      459753 461766 463775 462780 460785 460788 462790 464796
      471795 475791 478786 483774 497758 505749 512740 515735
      518729
 0.25 475840 475835 474832 470826 464823 461814 459809 457808
      455809 452811 450815 448824 446831 449832 449836 445843
      439849 435853 430853 425853 424850 422844 419839 416837
      415833 414827 411830 409833 405871 402878 402886 400908
      398925 397938 395947 393953 389958 385964 384977 380995
      379004 384008 391019 400030 410036 411045 418049 422050
      424048 429049 433047 438048 441046 444045 445042 442038
      438035 434030 429028 424025 421024 418024 414025 412022
      410012 409002 412994 415986 417977 417968 418960 423941
      430928 438915 445904 452889 455882 457879 457873 460865
      463856 465853 470849 474845 475840
 0.25 452799 449797 445802 441806 438812 435818 433823 431828
      431832 433830 436825 440820 443815 447809 450804 452799
 0.25 429042 430040 429038 427039 426040 424041 423041 422043
      422044 424046 425045 427044 428044 429043 429042
 0.25 421060 421057 418056 414055 411055 407054 404054 400054
      399057 401060 403062 406063 409064 412064 415064 417062
      419062 421060
 0.25 383054 383051 381049 379048 378047 376046 374045 372045
      372046 371048 371050 372053 374053 376053 377054 379055
      380056 381056 382056 383055 383054
 0.25 356036 354032 352030 347028 343028 336028 332027 327028
      325030 321037 321042 324045 331048 338045 343041 349038
      356036
 0.25 260743 261740 259737 253736 243741 223754 220757 219764
      218778 218792 221805 222812 224819 227824 229831 233843
      240851 242852 243849 242842 241836 241827 242815 243809
      246807 246803 248798 247793 250780 256756 260743
 0.25 268902 269898 268894 266892 263891 261890 258890 256891
      254893 254897 255899 257903 258904 260905 264906 266905
      268902
 0.50 509283 510281 510280 508280 506280 505279 503279 501278
      500279 501282 501283 502285 502286 503287 504289 505290
      506290 508288 508285 509283 509283
 0.50 446867 445863 443863 436866 430869 425867 423869 414882
      411885 409896 410903 411898 414896 417895 420898 424898
      424903 420909 415915 409910 407913 404917 402926 401936
      400947 397956 395963 391972 388980 388993 390000 393003
      398004 403998 407991 410983 411979 412973 413963 415952
      416943 420935 425930 429923 433916 436908 439899 442889
      442881 441877 446867
 0.50 243769 242762 239757 235756 228758 225761 224767 224779
      223784 221788 221794 223799 225804 228807 232805 235800
      238791 241781 243770 243769
 1.00 423924 423921 423919 422919 421920 419921 418924 419926
      420926 421926 422924 423924
 1.00 407977 407973 407970 406966 405962 403960 402962 400965
      399968 398971 397975 397979 398983 400985 403986 405984
      406980 407977

$$




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