000
FXUS04 KWBC 120951
QPFPFD

QUANTITATIVE PRECIPITATION FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
550 AM EDT SUN MAY 12 2013


FINAL DAY 1...DAY 2 AND DAY 3 QPF DISCUSSION
VALID MAY 12/1200 UTC THRU MAY 15/1200 UTC
REFERENCE AWIPS GRAPHICS UNDER...PRECIP ACCUM - 24HR


UPDATE

NO SIGNIFICANT CHANGES MADE TO THE PRELIM DAY 1 QPF FOR THE FINAL
ISSUANCE.

DAY 1

FAR EASTERN NEW ENGLAND

THE LEAD SURFACE FRONTAL BOUNDARY STRETCHING FROM THE MID ATLANTIC
INTO NEW ENGLAND EARLY THIS MORNING IS EXPECTED TO PUSH OFFSHORE
OF THE MID ATLANTIC/NEW ENGLAND COAST AFTER 1200 UTC.  AN AREA OF
LOW PRESSURE DEVELOPING ALONG THE FRONT WILL PUSH
NORTHWARD---ACCENTUATING LARGE SCALE LIFT SUNDAY OVER FAR EASTERN
NEW ENGLAND FROM NEAR CAPE COD & THE ISLAND INTO EASTERN MAINE.
MODEL CONSENSUS IS FOR LIGHT TO MODERATE PRECIPITATION AMOUNTS IN
THE .10-.25" RANGE OVER FAR EASTERN PORTIONS OF NEW ENGLAND.

LEE OF THE GREAT LAKES

IN THE WAKE OF THE INITIAL FRONT MOVING OFFSHORE---A SECONDARY
STRONGER FRONT ASSOCIATED WITH THE AMPLIFYING GREAT LAKES/SOUTHERN
CANADA CLOSED LOW WILL PUSH EASTWARD ACROSS THE EASTERN U.S.
CYCLONIC FLOW IN THE WAKE OF THIS SECOND FRONT WILL SUPPORT LATE
SEASON LAKE EFFECT SNOWS OFF THE UPPER LAKES EARLY THIS MORNING
BEFORE WEAKENING BY EARLY AFTERNOON.  INCREASINGLY WESTERLY LOW
LEVEL FLOW ALONG THE LONG AXIS OF LAKE ONTARIO WILL DEVELOP BY
SUNDAY EVENING AND CONTINUE INTO THE EARLY HOURS OF
MONDAY---SUPPORTING LAKE EFFECT SNOW CHANCES IN THE TUG HILL AREA
OF NORTHERN NY.

NORTHEASTERN MEXICO INTO FAR SOUTH TX

THERE IS NOT EXPECTED TO BE ANY SIGNIFICANT CHANGES TO THE RECENT
PATTERN ACROSS NORTHERN MEXICO INTO SOUTH TX.  MODELS AGREE THAT
THE MEAN TROF WILL PERSIST OVER NORTHERN MEXICO WITH SHORTWAVE
ENERGY EJECTING EAST NORTHEASTWARD FROM THIS TROF SUPPORTING
ADDITIONAL CONVECTION OVER NORTHEASTERN MEXICO INTO FAR SOUTHERN
TX.  SIMILAR TO PREVIOUS FORECASTS---CONFIDENCE IS LOW WITH
RESPECT TO QPF DETAILS GIVEN THE LARGE MODEL SPREAD.  LIGHT TO
MODERATE AREAL AVERAGE PRECIPITATION AMOUNTS DEPICTED GIVEN THE
UNCERTAINTIES---WITH THE POTENTIAL FOR LOCALLY HEAVY TOTALS
AFFECTING NORTHEASTERN MEXICO INTO FAR SOUTHERN TX.

PACIFIC NORTHWEST

THE SURFACE FRONTAL BOUNDARY OFF THE PACIFIC NORTHWEST COAST EARLY
THIS MORNING WILL BE PUSHING INLAND THROUGH THE PACIFIC
NORTHWEST/NORTHERN GREAT BASIN REGION SUNDAY AND INTO THE NORTHERN
ROCKIES BY SUNDAY NIGHT/EARLY MONDAY MORNING.  AN AXIS OF ABOVE
AVERAGE PW VALUES ALONG THIS FRONTAL BOUNDARY WILL SUPPORT
INCREASING PRECIPITATION CHANCES FOR THE COASTAL PACIFIC NORTHWEST
SUNDAY.  ADDITIONAL SHORTWAVE ENERGY MOVING TOWARD THE PACIFIC
NORTHWEST COAST SUNDAY NIGHT INTO EARLY MONDAY MORNING MAY ENHANCE
UVVS AGAIN ALONG THE OREGON AND WA COAST TOWARD THE END OF THE DAY
1 PERIOD WITH ADDITIONAL PRECIPITATION CHANCES.


DAYS 2 AND 3...

...PACIFIC NORTHWEST...

THE POLAR JET STREAM WILL REMAIN OVER THE PACIFIC NORTHWEST
THROUGH EARLY NEXT WEEK...HELPING TO MAINTAIN A PREDOMINANTLY WET
PATTERN FOR THE AREA.  CURRENT GUIDANCE SHOWS GOOD AGREEMENT IN
ALLOWING FOR A SURGE OF ASCENT AND MOIST ONSHORE FLOW TO DEVELOP
MONDAY AND MONDAY NIGHT IN RESPONSE TO THE PASSAGE OF QUICK-MOVING
BUT RELATIVELY STRONG SHORTWAVE TROUGH.  WEAKER BUT STILL MOIST
ONSHORE FLOW SHOULD THEN PREVAIL THROUGH TUESDAY IN ADVANCE OF
ANOTHER YET WEAKER SHORTWAVE TROUGH ARRIVING LATE WEDNESDAY.
GIVEN GOOD OVERALL MODEL AGREEMENT...USED A MIXTURE OF HIGH-RES
GUIDANCE AND COURSER-GRIDDED GUIDANCE TO DERIVE THE
QPF...PARTICULARLY OVER THE COASTAL RANGES AND CASCADES...WHERE
THE HIGHEST TOTALS ARE ANTICIPATED.

...UPPER MIDWEST/UPPER GREAT LAKES...

A VIGOROUS SHORTWAVE TROUGH WILL CROSS SOUTH CENTRAL CANADA
TUESDAY AND TUESDAY NIGHT...RESULTING IN AN ELONGATED BAND OF
ISENTROPIC UPGLIDE FORMING AHEAD OF AN ACCOMPANYING WARM
FRONT...WHILE STRONG BOUNDARY LAYER CONVERGENCE FORMS
SOUTHWESTWARD TOWARD THE PLAINS ALONG A COLD FRONT.  THE WARM
CONVEYOR BELT REGION NORTH OF THE WARM FRONT IS THE MOST LIKELY
AREA FOR PRECIPITATION TO DEVELOP AS THE WARM SECTOR WILL LIKELY
BE ACCOMPANIED BY STRONG CONVECTIVE INHIBITION.  MODEL FORECASTS
OF BOUNDARY LAYER DEWPOINTS...AND IN RESPONSE...MOST UNSTABLE OR
SURFACE-BASED CAPES...
PARTICULARLY FROM THE NAM/GFS APPEAR SUSPICIOUSLY GENEROUS OR
HIGH...WHICH COULD BE IN RESPONSE TO AGGRESSIVE EVAPOTRANSPIRATION
18-00Z WITH DEVELOPING GREEN VEGETATION.  IN ANY EVENT...THE
SLIGHTLY DRIER ECMWF APPEARS MORE REALISTIC GIVEN THE WEAK
CONNECTION TO THE DEEPER MOISTURE ORIGINATING FROM THE GULF OF
MEXICO.

...CENTRAL AND SOUTHERN ROCKIES...

DIFFERENTIAL HEATING AND MORE PREDOMINANT REGIONS OF UPSLOPE FLOW
SHOULD BE SUFFICIENT TO INITIATE WIDELY SCATTERED SHOWERS AND
THUNDERSTORMS OVER THE HIGHER TERRAIN TUESDAY AND WEDNESDAY
AFTERNOON.  HOWEVER...GENERALLY WEAK TROPOSPHERIC FLOW AND LIMITED
QUANTITIES OF MOISTURE/INSTABILITY PRECLUDE HIGH QPF TOTALS.
RELIED MOSTLY UPON THE HIGHER RESOLVING FOR SYSTEM DETAILS.

...SOUTHERN PLAINS AND TEXAS...

THE UPPER LOW OVER MEXICO IS EXPECTED TO SLOWLY LIFT NORTHWARD
THROUGH EARLY NEXT WEEK...WITH THE PREVAILING SOUTHERLY FLOW AHEAD
OF THE LOW AND EMBEDDED PERIODS OF MESOSCALE ASCENT SLOWLY
MOISTENING THE LOWER ATMOSPHERE WHILE ALSO LOWERING CONVECTIVE
INHIBITION.  SCATTERED CONVECTION MAY ORIGINATE ALONG A SLOWLY
FORMING DRYLINE OVER SOUTHWEST TEXAS LATE MONDAY AND ALSO MONDAY
NIGHT WITHIN THE DEVELOPING THETA-E GRADIENT AHEAD OF THE
DRYLINE...WITH THE SAME REGIME REPEATING ITSELF ON
TUESDAY...ALBEIT SLIGHTLY FARTHER NORTHEASTWARD.  THE SLOWER ECMWF
SOLUTION FOR PROGRESSION OF THE UPPER LOW WAS PREFERRED OVER THE
FASTER NAM/GFS.

JAMES

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

24HR QP VT 13/12Z
 0.01 500635 497628 494624 485614 474604 464603 445614 439619
      434622 421630 418631 412635 402646 399652 395659 384668
      380672 377676 372681 370685 364696 367702 365707 351724
      344732 336743 331751 330756 329762 329767 332776 340779
      356766 362762 366758 372752 375748 386741 392738 396738
      402737 409734 418726 428716 430711 436707 450704 452702
      455703 459704 464701 468701 480692 487687 491684 494683
      500680 503675 506667 507661 506656 501641 500635
 0.01 522770 520765 515758 511757 509750 507739 505735 503733
      498730 495732 493738 491742 487738 482734 476734 470736
      465739 461748 458755 459761 457767 455769 453773 450776
      446778 443778 440770 444758 446752 446745 444740 442739
      438738 435740 432745 431749 431752 429756 428763 426774
      413785 414791 413797 411801 409803 409808 408813 410819
      413818 414814 417812 421811 430814 435812 440814 443818
      444822 446830 446837 445840 443844 440846 434848 432850
      433854 434858 438861 448865 452869 455873 457880 462890
      465893 468888 470887 470884 469875 464853 465848 468846
      474843 485840 488838 492834 499829 503821 507809 510806
      515802 519798 521793 522786 522779 522770
 0.01 536211 538203 538193 534181 526170 522166 517162 512155
      509151 504149 497147 493140 489137 486134 481133 480136
      488143 490149 490160 487164 484164 483169 485173 484181
      485189 487193 490194 492198 493203 487203 483205 465211
      461213 455212 446216 441218 438221 434224 433228 434231
      446232 448233 446236 443238 441242 443246 450248 453246
      459247 464247 470254 484270 503289 508290 512287 518278
      520274 521269 522262 522256 521250 519244 515233 510222
      508215 508211 510209 514210 516214 520217 523219 525222
      529223 536211
 0.01 511984 505971 501967 495964 491964 483965 469968 463970
      458974 455978 455989 462997 474003 483008 487008 489010
      495011 499008 505003 508997 509994 510989 511984
 0.01 455231 453229 450229 449229 449233 452233 455231
 0.01 463136 464114 463110 455108 453105 453101 450096 444096
      438099 430091 424084 423088 425089 429096 432100 438104
      443113 445117 445122 446129 449131 451134 457135 463136
 0.01 404057 401053 392053 389052 386050 378050 361050 358051
      356053 355054 358058 363059 364061 361061 358065 358067
      364068 369067 372072 375075 378072 375067 375065 370058
      377057 381061 384061 386059 390058 395058 404057
 0.01 349117 346112 341106 341096 341085 336082 333078 330078
      329082 330085 331088 330092 329095 329105 334109 337113
      341114 345116 349117
 0.01 300818 298811 295807 291803 286800 277796 273794 267793
      255800 253804 252808 259812 269817 278819 288821 292823
      295827 298823 300818
 0.01 231979 232987 231996 231003 234011 236016 237020 237025
      237030 239034 241037 244038 248038 249041 250045 252048
      253053 254055 256060 258063 258066 260068 264072 277078
      282082 291082 297080 300077 302072 302068 302065 300062
      299057 297053 296043 291031 290021 288018 287012 287003
      284997 282975 279967 276963 272961 271957 266951 242954
      239954 236958 233964 231970
 0.25 492659 490653 488648 485645 482639 479634 475631 468627
      463624 459622 455622 451624 446629 437636 429642 421649
      416658 409667 405675 399683 388699 377712 364726 357732
      352738 350742 352747 356747 361744 377732 393720 409708
      416702 423697 431691 437686 440686 443688 448692 449695
      456696 465690 482678 490670 492662 492659
 0.25 511777 509767 504762 494760 484760 481762 478766 475771
      473777 473786 476795 476799 475803 473809 469815 468822
      469827 471831 475832 483828 493820 500807 504801 509794
      511788 511777 511777
 0.25 516267 518260 517254 514241 512235 510231 504220 499210
      495208 491208 487210 483212 480216 484221 490229 496240
      501247 502251 502255 499256 493246 491241 488239 484241
      482241 480236 477232 473234 471236 470239 471243 473245
      482252 489260 494268 501278 504279 507278 509274 514270
      516267
 0.25 528194 529189 527184 527182 524180 521178 518179 515180
      513180 513185 515187 517191 520196 522198 525198 528194
 0.25 440752 439748 438745 435747 433751 433752 433756 433760
      437762 439758 439757 440752 440752
 0.25 466222 469218 467217 466217 463220 461220 463222 466222
      466222
 0.25 282041 281034 277028 273023 268022 266029 263035 263041
      265047 269052 274056 278054 280050 282044 282041
 0.25 274986 274978 271974 268969 266967 263967 260968 258966
      253967 249968 245969 243972 239981 238985 238993 240004
      243010 248012 255018 260019 265017 266010 266007 268005
      271001 273995 274986
 0.50 476658 469644 463640 459638 454637 448639 435647 430653
      427659 426665 422671 420678 420681 425682 433680 443677
      453681 458681 465677 471672 476663 476658
 0.50 506780 505774 503770 496769 489768 485769 482774 481778
      481784 481795 479801 477811 477817 484819 488818 492814
      496806 500798 504791 506781 506780
 0.50 515257 513247 511239 510235 506230 503224 500215 498213
      494210 488213 486216 485219 487222 492229 495235 499242
      504249 506258 510265 514260 515257
 0.50 501270 502266 501265 499262 497259 496258 494254 494253
      492250 489247 490252 491254 492257 493259 495263 497268
      498269 500271 501270
 0.50 479239 478238 476235 474237 475239 478240 479239
 0.50 262999 262993 261987 259984 254984 249986 246988 245992
      247998 248001 250004 253006 257006 260002 262999
 1.00 510255 510248 508242 505238 503233 501228 499222 496217
      492216 488220 492225 494231 497235 499238 502240 504243
      506249 508254 510255

24HR QP VT 14/12Z
 0.01 563957 563951 562946 560936 551925 547923 542919 538917
      535915 534910 539905 539900 537896 533893 531891 528891
      518886 509884 499880 487879 483880 481878 477879 473878
      472877 473875 479871 486870 491870 497871 503871 507873
      510873 513875 519876 525870 525866 524859 519856 515853
      511850 506848 496846 491844 486844 479846 472848 468847
      461850 455852 452856 446859 441864 439867 439870 441880
      442884 440888 438893 438900 442905 446907 452906 457908
      464907 470905 475909 477911 475913 474916 471921 470927
      471935 472951 480959 482959 485961 489962 513966 519966
      522968 529970 534972 537976 540976 543979 548979 551978
      554976 557971 560966 563957
 0.01 496707 494696 491690 487689 481689 476692 470696 465701
      462702 459704 453709 450714 440725 438735 434739 430745
      433759 435762 440762 451761 460766 464769 468773 476779
      484784 489782 493779 497763 498751 496740 495734 493726
      489722 491718 494719 495715 496707
 0.01 536211 538195 538186 537179 537163 536159 536148 536131
      536120 536104 537087 536071 536061 535053 533048 533040
      529026 528019 526014 525009 522004 518993 514988 510985
      507982 503979 498978 491977 485978 481980 476999 474003
      474009 477020 480030 483044 484052 483059 480070 476076
      474083 470085 466091 462093 459096 456099 453097 448096
      444092 441091 438088 436091 433092 428089 425090 425093
      427096 429099 429102 426107 420107 426115 429116 433113
      454114 460111 464110 468107 474106 475112 475116 474120
      468125 464128 459129 446141 438140 436144 434149 432152
      434154 437162 440171 440179 439187 432211 428217 423223
      419231 418237 418242 420245 424248 435252 452262 461266
      468272 477277 483283 492288 497291 504292 506291 508285
      511278 514273 519263 520258 521244 523235 525232 529227
      532221 536211
 0.01 507095 507091 505088 504091 504095 505100 507095
 0.01 447076 445072 444072 447076 447076
 0.01 369708 365696 360687 348682 340684 331689 323694 315700
      288724 277736 273740 269744 268748 266750 262755 260760
      256768 255770 256774 254777 252781 250788 250796 252805
      257815 263816 267814 270807 270803 271798 276796 280794
      289790 294785 300780 305773 310768 315761 324755 334751
      342745 347740 356733 359731 362726 366723 367719 368713
      369708
 0.01 398796 397796 394794 391796 388797 386798 384803 381804
      379805 376807 377810 381812 382808 385807 388805 390801
      392800 395798 398797 398796
 0.01 414072 414060 412057 410056 403053 395053 389056 387058
      385057 375049 366049 358051 355054 358059 362060 364062
      367068 370071 372075 375081 377084 379082 384077 388077
      392079 395077 398079 401079 402078 407077 410077 412075
      414072
 0.01 409106 409102 406102 406106 406110 406114 409110 409106
 0.01 230002 231012 234019 241031 255051 275069 281073 288076
      293078 297075 300072 301067 303063 302052 300046 299043
      296040 293038 291034 294028 295024 293019 291017 282016
      275013 274011 275008 279002 280995 279986 276979 272972
      268967 263964 257963 248952 243951 237954 234958 233963
      231971
 0.25 526193 525189 522182 516173 509166 502163 491158 487156
      483152 468143 466142 463143 459146 456150 455155 456159
      459164 455172 450180 447187 449193 452193 455189 459187
      462182 466174 469169 474170 478172 481177 485186 486191
      484196 476202 469206 462210 446216 439219 435221 433225
      435227 440231 441235 443240 447243 467252 475257 483263
      490271 496278 499279 504276 509265 511261 514253 514241
      513227 512218 513214 515211 521205 524201 526193 526193
 0.25 524111 525106 525101 525096 525092 525087 523083 523082
      520078 518082 517084 517087 516091 517096 517101 517102
      517105 518110 519114 522115 524111
 0.25 337702 332703 328706 322711 310726 302738 296751 287765
      282772 279777 279780 280781 285780 291774 301763 311749
      321736 326729 329722 330718 332714 336706 337702
 0.25 281053 282050 282047 280044 280043 278041 277040 274038
      271036 268035 266036 265038 265041 266044 266045 268047
      269048 270050 272051 274053 277054 280054 281053
 0.25 260020 261014 259008 256000 254997 252992 249983 246980
      242978 237984 235988 235993 237004 242010 248015 251018
      254021 257022 260020
 0.50 505267 505255 510246 509236 508232 504223 502219 498214
      491209 486208 482209 473210 466212 459215 452219 444220
      440222 444225 451225 456225 461227 462230 461235 460240
      462242 471246 481253 487259 493267 500272 503270 505267
 0.50 512185 512180 509179 507176 504175 501173 500173 498171
      495169 493168 490170 492174 493176 495177 497180 498181
      500183 503186 506186 509186 512185 512185
 0.50 503252 500251 499246 496241 494237 491233 489229 483227
      481231 484236 485237 488238 490239 493243 495247 498248
      500251 503252
 0.50 464157 465153 465152 463153 463157 464157 464157
 1.00 505244 506239 505237 504234 503231 502228 501227 498224
      496222 493219 490217 487219 490222 492225 493226 495228
      496231 497234 498236 499239 502242 504243 504244 505244
 1.00 500260 499259 497255 494251 493248 492247 489247 490252
      491254 492258 493259 495262 498264 500260
 1.00 473219 472218 470216 466217 466218 469220 472220 473219


24HR QP VT 15/12Z
 0.01 550899 548891 545880 542874 540864 537856 532848 524840
      520834 515829 507822 497815 489810 480804 475803 470800
      451789 440784 431779 413775 407774 405780 398788 396793
      394794 392799 400804 418816 422819 426824 429830 431838
      433848 437852 440861 439868 436874 433882 429892 418916
      412927 410932 409938 413941 415944 414948 411952 411959
      413967 416972 417974 422970 429960 433960 435957 441954
      443951 446949 454941 458936 462935 464936 467942 469946
      469951 471956 475962 481976 487990 489995 492004 493012
      493019 490037 496050 499055 500062 501068 500073 498081
      496086 494097 492104 490115 488122 484128 471145 473152
      472163 475168 480169 484174 488176 490180 491189 493194
      501189 504188 507190 510195 513200 512205 512209 514210
      528213 532209 535206 537202 538194 536188 531174 528169
      524160 523153 521143 520139 520133 522125 524115 527110
      529102 531092 533084 534072 536055 536041 536029 536018
      537010 535001 535992 543981 546976 547963 547955 549946
      550920 550913 549904 550899
 0.01 520269 521260 520254 521245 519239 517234 516227 513222
      509217 503210 497207 492205 486203 480204 474208 470210
      467213 466218 472221 478221 478225 477227 474229 471229
      468231 461233 458236 458241 461246 462248 465249 476254
      481257 484261 487265 490270 495281 498285 500287 503286
      510281 514277 517272 520269
 0.01 418053 417047 415041 411036 409029 406022 402015 398014
      394018 391024 389031 386035 380039 376041 372039 368041
      363045 359050 352051 338051 330055 329059 331061 334065
      338076 340080 340084 341092 347096 351091 353086 359075
      363071 366070 369072 378076 379069 380066 384065 388063
      395062 410062 413061 416057 418053
 0.01 372964 373960 371957 368957 361959 358960 347964 341965
      338965 335964 326964 319964 316963 306965 302969 299972
      297982 297987 294988 292987 289977 286972 283969 268962
      262961 257962 251963 246965 241970 237978 238988 242996
      255008 258011 262012 267017 276020 280022 283024 284027
      287031 290031 295031 298031 301033 310034 322033 332031
      335028 340024 341020 340014 333007 330004 325002 322001
      319999 321997 333995 339994 342992 348989 351987 357985
      359981 362980 364977 367972 372964
 0.25 542932 542923 541915 538903 535886 531876 526866 519858
      514853 508848 500844 495846 492851 492859 495866 497870
      499875 498899 501911 504925 505941 505953 502978 501985
      502992 503009 504017 505022 508031 512042 514055 514065
      512082 510093 510097 512099 515095 519083 522072 527015
      528003 531989 536965 538958 541948 542932
 0.25 523192 522187 521185 518182 517181 515179 512178 510180
      512181 514185 515186 517188 519191 520192 523192 523192
 0.25 514257 514249 513245 509236 505230 502227 498227 497235
      499243 499247 495246 490242 486246 488253 493262 497269
      499271 503274 506270 507263 508259 511258 514257
 0.25 475831 473828 470824 466822 459816 454813 448812 447816
      449821 451823 452826 448829 450834 454839 461841 468838
      474836 475831
 0.50 537939 537930 537921 533909 528898 522894 515899 512908
      511924 512937 512945 511951 510965 508977 507982 507989
      509997 509005 510012 511017 516025 520020 522007 524996
      528983 530970 533960 535949 537939
 0.50 498260 497256 496254 494252 491252 491253 493256 494258
      496261 498260
 1.00 528942 528937 528936 527937 528942 528942
 1.00 525962 524958 521963 524963 525962
 1.00 518992 520987 517987 517992 518993 518992

$$