Quantitative Precipitation Forecast
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000
FXUS04 KWBC 280610
QPFPFD

QUANTITATIVE PRECIPITATION FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
209 AM EDT SUN AUG 28 2016


PRELIM DAY 1 QPF DISCUSSION
VALID AUG 28/1200 UTC THRU AUG 29/1200 UTC
REFERENCE AWIPS GRAPHICS UNDER...PRECIP ACCUM - 24HR


DAY 1...

SOUTHWEST INTO THE CENTRAL AND SOUTHERN PLAINS
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
A SHORTWAVE SHOULD TRACK SLOWLY EASTWARD TOWARD THE AZ/NM BORDER
REGION THIS EVENING WITH MODELS IN GOOD AGREEMENT TIMING-WISE.
BROADER DIURNAL THUNDERSTORM COVERAGE IS EXPECTED ACROSS THE
SOUTHERN ROCKIES AND FROM WESTERN TX INTO SOUTHWEST KS WHERE THERE
MESOSCALE GUIDANCE AGREEMENT FOR LOCAL AMOUNTS IN THE 3-6" RANGE.
A CONSERVATIVE APPROACH WAS FOLLOWED FOR THE QPF, USING 00Z WPC
QPF CONTINUITY AND THE MOST RECENT GUIDANCE AS A GUIDE.  A SLIGHT
RISK OF EXCESSIVE RAINFALL IS PLANNED FOR PORTIONS OF SOUTHERN NM
AND WESTERN TX WHERE THE HIGHEST PRECIPITATION AND THE LOWEST
FLASH FLOOD GUIDANCE VALUES ARE EXPECTED TO OVERLAP.


MINNESOTA/WISCONSIN
~~~~~~~~~~~~~~~~~~~
A WARM FRONT ADVANCES INTO CENTRAL MN AHEAD OF A SHORTWAVE MOVING
NEAR THE CENTRAL US/CANADIAN BORDER.  PRECIPITABLE WATER VALUES
RISE ABOVE 1.5" AS LOW-LEVEL INFLOW BECOMES INCREASINGLY CYCLONIC
AFTER 12Z, WITH WINDS EVENTUALLY RISING TO 40+ KTS AT 850 HPA.  A
CAP APPEARS TO BE BUILDING, USING THE 9C ISOTHERM AT 700 HPA AS A
GUIDE.  THE INGREDIENTS APPEAR TO EXIST FOR AN ORGANIZED
CONVECTIVE COMPLEX, PERHAPS ONE OF THE QUASI-LINEAR VARIETY WITH
AN ASSOCIATED COLD POOL FORMING DURING THE AFTERNOON AND EVENING
HOURS ACROSS WEST-CENTRAL MN.  BUT WHERE DOES IT GO FROM THERE?
INTERESTING TRENDS ARE SEEN, WITH SOME OF THE MESOSCALE GUIDANCE
TRENDING NORTHWARD WHILE THE GFS/NAM GUIDANCE TREND SOUTH.  THE
BREADTH OF THE INSTABILITY FORECAST BY THE 21Z SREF MEAN IS
IMPRESSIVE NEAR AND SOUTH OF THE WARM FRONT.  WHILE NORMALLY A
COMBINATION OF FORWARD PROPAGATING CONVECTIVE VECTORS (WHICH POINT
EASTWARD) AND 1000-500 HPA THICKNESS PATTERN (WHICH POINT SOUTH TO
SOUTH-SOUTHEAST) WOULD BE USED FOR FORWARD PROPAGATION, THE DEGREE
OF INSTABILITY INDICATES THAT MERELY FOLLOWING THE FORWARD
PROPAGATING VECTORS SHOULD SUFFICE.  THIS IDEA CAN BE REVISITED IN
LATER FORECASTS.  WPC MOVES THE COMPLEX EASTWARD WITH TIME ACROSS
MN.  THE SOLUTION CHOSEN RESEMBLES A COMPROMISE OF THE 00Z GFS/00Z
NAM OR THE 12Z/00Z WRF NSSL RUNS.  THE 00Z CANADIAN REGIONAL AND
12Z ECMWF APPEAR TO BE LOWER PROBABILITY SCENARIOS FOR THIS
COMPLEX`S EVOLUTION.  COORDINATION WITH THE MPX/CHANHASSEN MN
OFFICE NUDGED THE QPF SOLUTION NORTHWARD FROM WHAT WAS ORIGINALLY
PROPOSED.  THE SHIFT MADE TO THE 00Z WPC QPF WAS SOUTHWARD IN THIS
AREA.  BOTH MARGINAL RISK AND SLIGHT RISK AREAS ARE PLANNED BASED
ON THE 06Z WPC QPF PATTERN.


LOWER MS VALLEY & WESTERN GULF COAST
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
A SURFACE TROUGH/850 HPA CIRCULATION INTERACT WITH PRECIPITABLE
WATER VALUES OF 2-2.25" TO LEAD TO HEAVY RAINS ACROSS PORTIONS OF
LA AND THE LOWER TO MIDDLE TX COAST.  THE MAIN CHALLENGE HERE
CONTINUES TO BE WITH HOW FAR NORTH THE HEAVIER CONVECTIVE BANDS
WILL DEVELOP, WHICH MOVED FAIRLY FAR INLAND ACROSS LA ON SATURDAY.
DIFFERENTIAL HEATING ALONG THE SYSTEM`S NORTHERN FRINGE WILL
LIKELY SUPPORT SOME HEAVIER RAIN BANDS INLAND ACRS PARTS OF THE TX
COAST INTO LA DURING DAYTIME HEATING (ROUGHLY 15Z-03Z).  CLOSER TO
THE LOW-LEVEL CIRCULATION, ONSHORE FLOW SHOULD FOCUS HEAVY RAIN
NEAR THE COAST, PARTICULARLY IN THE 06Z-15Z TIME FRAME.  FOR THE
MOST PART..BLENDED 00Z WPC CONTINUITY WITH IDEAS INTRODUCED BY THE
SATURDAY CONVECTIVE PATTERN ACROSS LA.  HOURLY RAIN RATES COULD
REACH 3" WHERE CELLS MERGE OR WITHIN SHORT TRAINING BANDS.  THE
MESOSCALE GUIDANCE SHOWS POCKETS OF 3-6" OF RAIN NEAR THE LA AND
UPPER TX COAST.  THE PLAN IS FOR A LARGER SLIGHT RISK TODAY WHEN
COMPARED TO SATURDAY AS SATURDAY`S RAINFALL LED TO SOME REDUCTION
IN THE FLASH FLOOD GUIDANCE/SOIL SATURATION ACROSS SOUTHERN LA.


FLORIDA
~~~~~~~
AN AXIS OF ABOVE NORMAL MOISTURE NEAR THE SOUTHERN PERIPHERY OF
SUBTROPICAL RIDGE IN THE VICINITY OF AN OCCASIONALLY CONVECTIVE
LOW PRESSURE AREA MOVING THROUGH THE FL STRAITS WILL TO LEAD TO
THUNDERSTORMS ACROSS PORTIONS OF THE SOUTHERN PENINSULA.  THE
DEGREE OF HEAVY RAINFALL IN FL DEPENDS ON IF THE SURFACE LOW GETS
BETTER ORGANIZED UNDER A REGIME OF WEAKENING VERTICAL WIND SHEAR
AS AN UPPER LOW WITH ITS NORTH BEGINS TO RECURVE...SEE TROPICAL
WEATHER OUTLOOKS FROM THE NHC ON ITS POTENTIAL FOR TROPICAL
CYCLONE DEVELOPMENT.  SOME LIGHT NORTH TO NORTHEAST VERTICAL WIND
SHEAR IS EXPECTED THUS RAIN PATTERN OVER FL (OUTSIDE THE KEYS)
SHOULD CONTINUE TO BE DOMINATED BY ENHANCED EASTERLY FLOW WITHIN A
VERY MOIST AIRMASS -- CLOSER TO THE COAST IN THE 06Z-15Z PERIOD
AND DUE TO SEA BREEZE CIRCULATIONS BETWEEN 15Z-03Z.  SLIGHTLY
INCREASED AMOUNTS ACROSS SOUTHERN FL AND THE KEYS FROM 00Z WPC
CONTINUITY BASED ON THE MOST RECENT GUIDANCE.


CAROLINAS
~~~~~~~~~
AN AXIS OF HIGH MOISTURE AROUND SOUTH SIDE OF A WARM CORE RIDGE
WILL PROVIDE HEALTHY ENVIRONMENT FOR SEA BREEZE ACTIVITY TO
DEVELOP OVER PORTIONS OF THE EASTERN CAROLINAS DURING THE
AFTERNOON AND EVENING HOURS.  MODELS SHOWED DECENT AGREEMENT HERE
SO DID NOT VARY TOO MUCH FROM CONSENSUS OR FROM THE 00Z WPC QPF
CONTINUITY.


EASTERN TN AND EASTERN KY
~~~~~~~~~~~~~~~~~~~~~~~~~
PULSE THUNDERSTORMS ARE EXPECTED WITHIN A LIGHT BUT MOIST FLOW
REGIME, WITH OUTFLOW BOUNDARIES POTENTIALLY DOMINATING CELL
MOVEMENT.  USED A COMPROMISE OF THE 12Z ECMWF AND 00Z GFS FOR THE
PRECIPITATION PATTERN IN THIS AREA, WHICH ENDED UP A BIT WETTER
THAN THE 00Z WPC QPF CONTINUITY.


NORTHEAST
~~~~~~~~~
A WEAKENING SHORTWAVE AND ASSOCIATED FRONTAL ZONE ARE EXPECTED TO
BE ACCOMPANIED BY A BAND OF SHOWERS AND THUNDERSTORMS ACROSS THE
NORTHEAST DURING DAYTIME HEATING ON SUNDAY.  PRECIPITABLE WATER
VALUES OF 1.5-2" ARE EXPECTED NEAR THIS BOUNDARY/FRONT ALOFT.
WHILE AREAL AVERAGE AMOUNTS SHOULD BE GENERALLY LIGHT TO MODERATE,
POCKETS OF HEAVY RAINFALL SHOULD BE POSSIBLE NEAR AND WITHIN THE
CONVERGENT CYCLONIC FLOW NEAR THE SURFACE FEATURE.  LOCAL AMOUNTS
IN THE 2-4" RANGE SHOULD BE POSSIBLE, GIVEN ENOUGH INSTABILITY
BUILDS ACROSS THE PERIOD, WHICH IS A QUESTION MARK THE FARTHER
EAST YOU GO IN NEW ENGLAND.

ROTH

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

24HR QP VT 29/12Z
 0.01 555031 554020 552015 550006 545001 540997 534997 528999
      523001 518006 513009 508014 508019 510022 514023 517022
      519021 530017 540025 549033 552036 554037 555031
 0.01 538205 539196 539191 538188 534177 529168 525160 521155
      517153 508146 500148 499152 500157 502161 502166 500168
      497172 496179 501186 506189 509193 510200 511207 510212
      509214 507216 504216 498210 493209 489210 484209 480211
      479213 479216 481218 484222 489225 490228 489231 488234
      486234 483230 480227 475229 471232 470234 469240 471249
      470264 469272 467278 461290 459295 460300 465307 468319
      470321 473320 477317 483313 491310 495309 499306 506299
      509297 512291 516283 518275 521269 522261 523254 523247
      525241 529229 532222 535215 538205
 0.01 535971 535963 535955 535949 533944 531940 531936 534932
      535928 534921 533915 531912 528910 520910 517908 513908
      509908 505906 498900 493894 488889 483882 481879 478877
      467868 459866 455864 450864 444869 440875 437884 435895
      434905 434914 436926 438940 439950 441959 445966 450974
      455981 460986 463987 467986 470983 476983 482985 489988
      496991 507992 520987 525984 530979 535971
 0.01 523757 522739 521725 520716 518707 516703 512699 506692
      503688 500682 494670 491666 489659 488652 486648 484643
      482640 478635 472631 469628 465628 461627 455630 448635
      442642 437651 434660 429671 426681 424693 423707 424718
      420729 414746 409763 407772 404781 402786 399789 396792
      391794 387794 383797 379798 376801 367805 359812 351818
      347821 344826 339836 339840 337844 340852 343860 347865
      354868 356867 360868 368872 375878 378881 379889 377915
      376920 373925 367932 364936 361938 355941 353942 350941
      344939 339937 335935 332930 324916 319908 316899 305863
      303850 301839 299834 298827 300824 304826 313829 315829
      318823 321818 325814 334818 340813 344807 354795 358788
      359782 361776 364768 363756 360747 361743 359740 351735
      348733 341734 330733 326731 324732 322734 319739 319743
      321747 323754 326773 325782 321782 316781 310779 306780
      304778 299779 295777 291774 285768 279763 272760 267758
      263755 251756 247755 242752 232752 226751 220752 220758
      219763 218766 218772 218782 216788 215797 217807 218819
      226839 237850 242861 246869 251876 256886 259897 263910
      264920 261929 257945 255956 255962 256965 257970 260974
      266980 269979 275980 282983 286985 292985 300981 309977
      318971 322968 327966 334972 339978 343981 346985 346989
      344991 337998 324004 320005 314004 311005 307009 294018
      292023 288026 285030 280031 267030 261030 256031 250034
      244034 240036 237040 234043 234047 237053 238061 241068
      255077 269087 273090 279091 285092 287093
 0.01 287093 299095 303097 309099 315100 319102 329096 334099
      337101 342107 350123 354120 351115 349110 345102 344094
      347088 350088 352092 357099 365112 369112 368108 366103
      362101 359097 357094 358090 361086 360080 359076 363074
      366074 368077 373085 376094 378097 380093 382086 386089
      391089 388085 385081 386078 391082 398078 401076 403071
      405066 406061 403035 401029 401020 408013 413008 416999
      417992 419989 423980 423972 422967 421966 417965 413966
      398981 392986 384989 381991 377990 382981 391965 395959
      400957 406957 409957 410955 414948 417943 418939 421917
      420911 420906 418893 418888 418882 423869 432854 442839
      461832 464832 467834 471836 475839 478842 484847 490853
      494861 499868 505867 509869 510866 512859 514845 516840
      516830 517824 516818 516810 517804 516789 518777 523757
 0.01 480100 481090 478081 475078 473078 471082 471088 470095
      468100 465104 462114 463118 465120 469120 472118 476112
      479104 480100
 0.01 455115 456106 457096 455090 454088 452090 449089 447091
      441093 438093 438095 439100 443101 446104 449107 452114
      454117 455115
 0.01 408117 409101 408096 405092 403093 401097 399101 395105
      391107 382109 377110 374114 375120 375127 373132 376130
      382124 393122 399122 404121 408117
 0.01 374191 375189 375186 373184 372183 370183 368182 366182
      365182 363183 362184 364186 366187 367187 369188 371188
      372190 372191 374191 374191
 0.25 518268 519262 519256 516249 509235 504228 501226 498227
      497231 496235 498245 495246 492244 488241 481259 477269
      476278 476284 477287 481288 496292 503291 507287 512280
      516275 518268
 0.25 528191 527188 527186 526185 526184 524182 524181 523180
      521179 520178 518178 517180 517182 517185 518188 519188
      520190 521191 521192 523194 524195 526195 527193 528191
      528191
 0.25 511744 511739 509735 507728 504723 500721 496722 488721
      483723 480727 477729 475727 475724 479719 481711 484700
      485686 484677 482670 478665 474659 466655 463653 463645
      459643 453646 449652 446658 442668 442674 445678 450679
      452681 451684 451687 445700 442710 438721 435727 434735
      431741 427747 423756 419768 415779 415783 417783 421785
      424783 427779 434771 440760 450751 452746 456742 465740
      470742 473748 480759 484763 486770 489783 491790 496794
      500792 502790 504785 506773 508758 511744
 0.25 508973 508968 507965 503961 497954 493941 486934 472921
      458907 454904 449903 446906 445911 443920 443927 445940
      448952 453962 456966 460970 464972 469973 479970 486962
      490960 494961 495963 493972 495978 501979 505977 508973
 0.25 413816 412811 409814 407817 405822 403827 402832 402839
      404845 406845 409840 410836 410831 411824 412819 413816
 0.25 406998 401996 396998 392999 389000 385002 381005 379008
      381012 386011 390009 394007 397005 401002 404000 406998
 0.25 402919 403910 401903 397899 394904 392909 391916 390924
      389931 391936 396933 399929 401922 402919
 0.25 382117 381116 380117 381119 382117 393068 394066 394064
393062
      391061 389062 388063 387064 387065 386068 387069 388070
      389071 390072 392071 392069
      393068
 0.25 379843 379835 377830 374826 372819 370814 364816 357821
      350829 346833 344836 345844 347849 353856 362859 369859
      373857 378848 379843
 0.25 371052 368050 363051 350051 349048 351041 353031 357020
      365013 368009 368005 364003 360002 352007 343013 334018
      327022 319027 308030 302032 299034 297039 299044 305052
      310057 314060 317063 319064 319067 315067 311066 302060
      295052 288045 280042 267040 259040 254042 252045 252053
      254061 262067 273072 294077 305080 311081 316080 319077
      322077 324079 330084 333085 336084 337077 344067 351064
      354060 359059 366056 370054 371052
 0.25 356770 356766 354761 351756 343748 335742 330739 325740
      329755 330763 333767 337771 336778 335785 334791 340794
      344791 348786 350781 356770
 0.25 318941 318936 317932 314926 309911 305882 303874 299867
      296862 291857 282851 272847 267842 264836 264833 265831
      268828 273828 276828 280825 278821 275817 272812 272807
      275805 284805 290806 293805 295803 295800 290789 288784
      284779 279776 272773 267771 259769 254768 249767 242765
      239765 235767 230770 225775 223781 221789 222803 224817
      229831 233838 237843 254854 259859 262866 266882 270896
      273908 274915 275925 275935 275942 271953 269959 268966
      270972 276975 283974 290972 297970 301968 309960 312955
      315949 318941
 0.50 344041 346037 346033 345026 344024 341023 338024 329029
      321034 315036 310036 305036 302038 305044 309047 319050
      325058 330060 334058 338049 344041 357014 356012 354013
356014 357014 359011 358011 357011 358012 359011
 0.50 517267 516259 514253 507244 503242 504249 504252 503256
      498255 493253 490252 488254 486260 483268 481276 481280
      482282 492284 499288 503286 510276 514272 517267
 0.50 501747 501744 501742 500739 498738 497738 495740 494743
      494746 494747 495748 496749 498750 499752 498754 497755
      498756 500756 500755 500752 500749 501748 501747
 0.50 475692 474687 473682 473679 470676 469675 467674 465675
      466678 467682 469684 470686 471691 473695 475692
 0.50 471706 470698 467699 461706 456712 453715 453711 452708
      449709 446714 444718 442723 441728 444732 448731 455730
      459729 462725 466717 470708 471706
 0.50 476952 477947 477942 474937 469928 462921 455915 452914
      450916 448920 447930 448937 452949 456959 460964 464967
      469967 472964 475960 476953 476952
 0.50 433756 434754 433753 431754 430755 428757 427759 426760
      425762 425763 425765 425767 426769 428767 429766 431764
      432761 433759 433756 433756
 0.50 370846 371844 371842 371840 370839 368840 366839 365838
      364838 362838 361841 361843 362845 363846 364847 365848
      367849 368848 370847 370846
 0.50 350773 349771 348772 346775 345778 344781 343783 342786
      342789 344787 345785 347782 348779 349776 350773
 0.50 334080 334077 332077 334079 334080 334080
 0.50 310941 310934 308928 305918 304912 303904 302891 302883
      300878 294871 290868 285865 279865 275867 272873 272877
      274890 280912 281926 282939 281946 279952 276962 277969
      279971 282970 290967 295965 299961 304954 308946 310941
 0.50 292067 292062 290060 285053 280049 273047 263046 258047
      257049 257054 259057 262062 269066 277067 285068 292067
 0.50 281790 281783 279779 277778 275779 271778 267776 262776
      253775 248773 241773 233778 227785 225793 224800 225807
      227819 231829 235836 239839 244840 250839 252836 255832
      256826 260824 265823 271823 274821 266817 263814 262809
      264806 267804 275797 280791 281790
 1.00 503273 503270 502267 499263 497261 494260 492261 491266
      490270 490274 493277 497276 498276 501275 503273
 1.00 468954 468947 468940 467935 464930 462927 457925 455925
      453930 453937 455942 456947 459952 461954 465957 467955
      468954
 1.00 301937 301932 299926 299918 297908 296897 296891 294885
      291879 286873 281876 280885 280894 283904 285912 288922
      290929 291935 289939 287947 283955 282959 283962 290959
      294954 298945 301938 301937
 1.00 262799 259793 256790 248786 241785 236787 231790 229794
      228800 228805 230816 234828 237832 242833 247829 248825
      252816 256806 262799
 1.50 463942 463940 463937 462936 461935 460933 459934 458935
      458937 459938 459940 460942 462943 463942
 1.50 290893 290891 290889 289888 288887 287886 285887 285889
      285890 286891 287893 287894 289894 290893
 1.50 255799 251793 245790 240789 236790 233793 231796 231804
      231814 234822 238828 243828 244825 246819 249812 252804
      255799
 2.00 251800 249796 247794 244793 239792 236793 233797 232804
      232810 233816 236822 238825 241824 243819 246813 247808
      249802 251800
 3.00 245801 244799 242797 238797 237798 236802 236805 235808
      235812 237815 238816 240815 241811 242809 243806 244803
      245801
$$





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