Quantitative Precipitation Forecast
Issued by NWS

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000
FXUS04 KWBC 231900
QPFPFD

QUANTITATIVE PRECIPITATION FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
259 PM EDT FRI SEP 23 2016


PRELIM DAY 1 QPF DISCUSSION
VALID SEP 24/0000 UTC THRU SEP 25/0000 UTC
REFERENCE AWIPS GRAPHICS UNDER...PRECIP ACCUM - 24HR


DAY 1

...ROCKIES AND PLAINS...

MOISTURE WRAPPING AROUND THE DEEP WESTERN U.S. UPPER LOW WILL
CONTINUE TO HIT PARTS OF UT/CO/WY/ID WITH ADDITIONAL RAIN AND
SNOW...ALTHOUGH EMPHASIS FOR WIDESPREAD AND HEAVIER RAINFALL WILL
BEGIN TO REPOSITION OUT ACROSS NORTHEAST WYOMING INTO EASTERN
MONTANA AND WESTERN NORTH DAKOTA. IT IS HERE THAT A NEW
DEFORMATION BAND WILL SET UP AS THE LARGE SCALE TROUGH SPILLS
SLOWLY OUT OF THE MOUNTAINS. RAIN WAS ALREADY FORMING ACROSS THE
DAKOTAS AND WESTERN MINNESOTA AS OF MIDDAY...IN RESPONSE TO
INCREASING UPPER DIVERGENCE AND LOW LEVEL WARM ADVECTION. EXPECT
THIS ZONE OF PRECIPITATION TO GRADUALLY LIFT NORTHWARD AS
SHORTWAVE RIDGING ASSERTS ITSELF OVER THE NORTHERN PLAINS...WITH
THE MORE SIGNIFICANT RAINFALL THEN REFORMING BACK WEST INTO
WY/MT...AND ALSO COMING OUT IN THE FORM OF PROGRESSIVE CONVECTION
EMANATING FROM THE HIGH PLAINS AS HEIGHTS BEGIN TO FALL.
INSTABILITY IS SOMEWHAT LACKING WITH NORTHWARD AND WESTWARD
EXTENT...BUT MOISTURE REMAINS PLENTIFUL...WITH STRONG MOISTURE
ANOMALIES AND ABSOLUTE PW MAGNITUDES OF GREATER THAN 1.25 INCHES
WRAPPING BACK BEHIND WHAT WILL BE AN OCCLUDED FRONT INTO EASTERN
MONTANA. THIS...ALONG WITH DURATION OF THE SLOW MOVING TROUGH AND
DEFORMATION ZONE...SHOULD SUPPORT WIDESPREAD 2-INCH RAINFALL.
THERE IS SOME WEST TO EAST VARIANCE WITH RESPECT TO THE AXIS
ACROSS EASTERN MONTANA. WPC FAVORED THE GFS MASS FIELDS...BUT
DIFLUENCE ALOFT...UPSLOPE...AND PROPAGATION OWING TO COLD POOLS IN
WEAKLY UNSTABLE CONVECTION...SHOULD PROMOTE SUBSTANTIAL
PRECIPITATION A LITTLE EAST OF THAT SEEN IN THE GFS.
THEREFORE...QPF WAS DERIVED MORE FROM THE WRF-ARW...NAM CONUS
NEST...AND PREVIOUS WPC FORECAST.

A SIMILAR MODEL APPROACH WAS TAKEN FOR THE CONVECTIVE ENVIRONMENT
OUT ACROSS THE PLAINS. WE DID INCREASE THE OVERALL VOLUME OF
QPF...ESPECIALLY ACROSS THE HIGH PLAINS OF WESTERN KS INTO CENTRAL
NE...WITH FAIRLY DEEP AND UNIFORM FORCING COMING OUT ACROSS A
MODERATELY UNSTABLE REGION. MOISTURE TRANSPORT AND TO SOME EXTENT
INSTABILITY...BECOME MAXIMIZED FROM NORTHERN OKLAHOMA INTO EASTERN
NEBRASKA LATE TONIGHT AND SATURDAY PER THE NAM...AND SOME HEAVIER
RAIN OR MORE PERSISTENT RAINFALL MAY BREAK OUT ALONG THAT SWATH.


...ELSEWHERE FLORIDA / NEW ENGLAND / PAC NW / TEXAS...

SOME SEMBLANCE OF WEAK SURFACE RIDGING DOWN THE FLORIDA PENINSULA
WILL CONTINUE TO FAVOR CONVERGENCE ALONG SEA BREEZES ON BOTH
COASTS...WITH A LITTLE MORE EMPHASIS ON CONVERGENCE INTO A TROUGH
ANALYZED NEAR THE SOUTHEAST COAST...AND OPPORTUNITY FOR CONVECTIVE
MERGERS OVER THE EVERGLADES.

LIGHT RAINFALL WILL EXIT NEW YORK AND NEW ENGLAND LATE
TONIGHT...AND IN THE PACIFIC NORTHWEST WARM ADVECTION WILL LEAD TO
LIGHT RAIN...WITH A LITTLE MORE FOCUS IN THE CASCADES...BUT THAT
ACTIVITY WILL WANE OVERNIGHT.

IN SOUTHEAST TEXAS THE HI-RES MODELS ARE SLOWLY INCREASING THEIR
QPF SIGNAL ALONG THE COAST. CERTAINLY ONSHORE FLOW WILL BEGIN TO
INCREASE IN STRENGTH AS THE LARGE SCALE FLOW RESPONDS TO HEIGHT
FALLS COMING OUT OF THE ROCKIES. REGIONAL SOUNDINGS DO SHOW LAPSE
RATES SUPPORTIVE OF SOME BETTER DEVELOPED CONVECTION DESPITE UPPER
RIDGING STILL HOLDING ON HERE. WPC TRIED TO TAKE A CONSERVATIVE
APPROACH...BUT STILL CAME UP WITH MORE THAN A HALF INCH AREAL
AVERAGE ALONG THE COAST...USING SOME INFLUENCE FROM THE NAM NEST
AND WRF-ARW...WITH A GRADIENT TOWARD LESSER AVERAGE AMOUNTS MOVING
INLAND.

BURKE

GRAPHICS AVAILABLE ON THE WEB AT
WWW.WPC.NCEP.NOAA.GOV/QPF/QPF2.SHTML

24HR QP VT 25/00Z
 0.01 552034 550021 551014 550009 542990 538979 533970 526953
      518936 509921 499911 493906 488906 485904 454888 450886
      445886 440886 437884 426871 423867 421867 419870 419876
      421882 422888 425898 433916 436923 440929 440931 438932
      433933 422934 411935 403937 373953 366957 359960 351964
      346966 341966 332966 327965 325962 319957 314952 311942
      308938 304936 293935 289934 284933 276931 273931 271933
      268935 265940 264952 265962 264970 265974 264977 265980
      270981 280983 288981 292980 294982 295985 293987 291989
      288994 287998 289003 291006 301005 308001 310998 312001
      310009 308013 304015 300017 296016 283014 272014 267014
      263012 258005 253000 249999 246999 243002 243007 246012
      261023 265030 270036 255041 246046 241051 240060 243067
      247076 254081 259086 265089 279097 288094 289087 288082
      302075 300065 306060 317049 324046 332043 340040 349037
      355034 363033 379030 388033 398037 402046 404049 408051
      412053 411056 406057 401056 397057 395059 392062 388064
      388075 391085 393094 393107 387113 383119 384125 393127
      399134 406140 418143 421145 423143 431138 434136 437136
      440139 444142 450142 458143 463144 462148 459147 457149
      457152 458155 463154 466157 468154 474157 470148 469144
      472141 480138 483133 481130 473127 473120 476117 479107
      478102 479099 485092 493087 506083 514080 521076 533066
      543057 546055 547052 548042 552034
 0.01 532203 531194 529188 527182 527173 524168 521167 519168
      508163 505162 502160 499162 498165 497170 497177 499185
      502189 511197 515202 518207 525214 529210 532203
 0.01 522267 522253 520248 517245 507229 504227 502221 501215
      498212 495209 491208 483206 474209 467212 459214 451214
      442215 434217 420223 419228 422231 429233 431234 430237
      427240 429245 435246 440247 444245 447242 447239 445235
      438233 439229 443229 452229 468227 475222 482220 496223
      500232 501237 499239 500243 500246 499249 493254 491267
      490274 491279 497286 505291 508291 509289 512286 518277
 0.01 522160 523153 521149 517143 510139 504136 500134 498132
      495130 493130 492136 493140 498145 504149 507152 511153
      515159 519160 522160
 0.01 461180 459180 456179 454181 452183 448182 446184 443183
      442186 444186 448187 451190 452191 454189 456187 457184
      459182 461180
 0.01 457008 456007 455006 453006 452005 451004 450005 450007
      451009 453009 454009 456009 457008
 0.01 431668 429661 427660 425662 420671 418677 415682 413692
      410697 409703 407714 406729 407743 408750 410756 415767
      416779 418783 422782 425777 425769 426763 425755 422735
      427732 429728 431721 431716 433703 433689 431668
 0.01 384795 384793 384790 383788 382786 380786 378786 378787
      376789 376792 377794 379796 381798 383798 384795 384795
 0.01 379056 376051 369046 365047 362051 359051 356055 354055
      348061 348065 350066 354067 357065 360065 364063 368059
      371057 373057 375057 379056
 0.01 355730 353724 348724 343726 340731 337734 336739 334751
      328759 322768 317776 314785 312792 312796 312799 310800
      306803 299810 291807 297799 298794 295789 285786 274787
      264792 252795 249796 249799 248803 247808 249812 253815
      256819 260823 264824 269826 272828 276830 282830 287828
      289829 290832 291835 293837 298838 300842 299848 296851
      296855 300861 304861 307850 311839 315832 322823 329816
      336808 338806 340801 343796 345791 347779 354759 356744
      355730
 0.01 245819 245813 243808 239807 237810 235814 236820 236826
      237832 240834 242831 243827 244821 245819
 0.25 539035 541028 541021 540011 537003 533996 526984 518973
      515967 512957 510949 506943 502938 499938 497939 494939
      491937 487937 484937 480935 476935 477943 480950 483958
      481965 474976 473981 474985 476994 476006 475010 472012
      469018 467021 463021 451024 443025 435024 426024 419024
      414028 412030 411033 412037 415038 422040 431042 434048
      433057 431064 431071 428077 425084 422086 421089 422092
      424095 420099 417097 415094 413092 410091 408093 408098
      404106 402112 400115 402118 405121 408121 415120 429121
      436119 441118 447116 452113 458110 461101 465095 469091
      473086 478082 488077 500071 507068 511065 516061 522059
      531053 534048 537043 539035
 0.25 455966 456962 455958 453953 450949 446947 434945 423945
      382957 372962 364967 356972 350978 345982 340984 336987
      334992 333998 331002 324009 320014 321016 323016 329023
      333023 335018 336017 339016 339019 339023 341024 346023
      354017 358015 360011 360007 362003 366998 370996 375994
      377998 374008 371014 368016 364021 364025 365026 375023
      383019 385011 386002 388997 395997 399998 403002 407003
      410001 412996 411989 412985 413984 417981 424980 429983
      433983 438981 441978 445974 450973 455966
 0.25 418109 418107 419104 419102 418100 416100 416102 415103
      414104 413106 413108 413111 414111 416111 417110 418109
 0.25 417078 417074 417070 415066 414065 410064 407065 405065
      403067 401072 401074 401076 403079 406080 409080 411080
      415079 417078
 0.25 350747 349740 346739 342743 341747 340751 339758 339762
      339765 341765 344765 346763 348759 349755 350749 350747
 0.25 311811 312809 311808 309809 308810 306811 305812 306814
      308814 310813 311811 311811
 0.25 308028 309026 309024 309023 308024 307025 306026 305028
      303030 302032 303033 304033 306033 307032 308030 308028
      308028
 0.25 303958 304954 303951 301947 297943 292941 283939 278939
      274942 272947 273952 270956 270960 274964 275970 277974
      281977 286976 289972 294963 299961 301960 303958 303958
 0.25 292023 290021 289021 287021 285021 283021 281021 279021
      278022 277022 277024 279024 280024 281024 283023 285024
      286026 287026 288026 290025 290024 292023
 0.25 287814 285810 282809 277805 272799 270797 266797 259799
      254804 254808 257809 261817 266819 273817 281819 285817
      287814
 0.25 284070 284067 282066 277063 273061 272056 269052 263051
      254055 252055 250058 253063 255067 254071 255076 257080
      266086 271088 272083 272079 276077 281075 284071 284070
 0.50 535027 534019 533012 532005 529000 524993 517987 512975
      507966 503963 500962 498964 492970 489975 485979 484986
      484990 487003 489007 488014 485019 482022 472025 462027
      454028 433030 421030 419031 419034 422036 433038 437042
      439048 437056 435062 435076 436083 435091 432095 430101
      427104 425109 426112 429113 435113 440113 444111 453106
      462087 469080 477076 485072 492067 501063 509058 516052
      523047 527043 531038 534032 535027
 0.50 497952 496949 494947 495949 496950 497952 497952
 0.50 432964 431959 430958 425956 418954 412955 405956 400958
      396961 394962 391962 386959 380961 371966 362972 355978
      348987 340993 340998 340000 346000 349000 350002 349006
      351013 351009 353007 359998 367990 375984 384978 391971
      393968 396968 403969 414967 426967 432964
 0.50 412071 412070 410068 408068 408070 408071 410073 412072
      412071
 0.50 345752 345752
 0.50 299952 294947 290945 285943 280945 279952 278956 280958
      279964 278968 279970 281973 283972 286966 290962 292958
      296954 299952
 0.50 275809 275807 274807 273805 272804 271804 270803 269802
      268801 266801 265801 263802 263804 263805 265805 267806
      269807 270808 271808 273809 274809 275810 275809
 0.50 271071 272067 271064 269062 269058 268056 265054 261055
      259057 257059 256061 257063 258066 260068 263070 265072
      267073 269072 271071
 0.50 409108 409106 407107 409109 409108
 1.00 525018 525009 521004 516004 513006 505017 499026 490033
      485035 479036 466036 455034 450034 447036 446040 445049
      442055 440062 441068 443074 446079 450083 453084 455083
      463077 482066 492059 500054 510047 514044 517039 523028
      525018
 1.00 443103 443101 443100 441099 440100 439101 437102 437103
      436105 436107 437108 437107 439106 440106 442106 442105
      443103
 1.00 377974 375971 371972 368975 365978 362981 359985 357988
      357992 360990 362987 365983 368980 371977 375976 377974
 1.00 265064 265062 265060 264060 262060 261061 262063 263064
      264064 265064
 1.50 515025 515020 514018 511021 507024 506027 500034 494038
      485042 478045 473045 468044 458044 455046 452050 447056
      444060 443065 445069 448072 455076 460071 469069 475064
      479062 482059 488054 501044 508039 510035 512031 515025
 2.00 472056 469053 465051 460052 458056 456060 452061 449065
      450067 453069 456066 459063 462061 466059 469057 472056

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