Quantitative Precipitation Forecast
Issued by NWS

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000
FXUS04 KWBC 270827
QPFPFD

QUANTITATIVE PRECIPITATION FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
326 AM EST TUE JAN 27 2015


PRELIM DAY 1...DAY 2 AND DAY 3 QPF DISCUSSION
VALID JAN 27/1200 UTC THRU JAN 30/1200 UTC
REFERENCE AWIPS GRAPHICS UNDER...PRECIP ACCUM - 24HR

DAY 1...

...NORTHEASTERN U.S. BLIZZARD...

THE RAPIDLY OCCLUDING LOW PRESSURE SYSTEM SOUTH OF LONG ISLAND IS
FCST TO CONTINUE TO LIFT NEWD TO A POSITION OFF THE ERN TIP OF
MASSACHUSETTS TUES EVENING THEN CONTINUING TOWARD THE WRN TIP OF
NOVA SCOTIA BY WED MRNG.  SATL IMAGERY CONTINUES TO SHOW DRY SLOT
WRAPPING CYCLONIC AROUND ERN SIDE OF DVLPG LOW AND AS A
RESULT..EXPECT THE MOST EFFICIENT/HEAVIER SNOW FALL AMOUNTS TO
OCCUR DURING THE FIRST HALF OF THE DAY ONE PD AS MID LEVEL DRYING
GRADUALLY GET ENTRAINED INTO THE SYSTEM.  MOST OF THE 00Z MODEL
GUIDANCE CONTINUES TO BE SLIGHTLY FASTER THAN THE 12Z EC OPERATION
RUN AND ARE ALL EAST OF THE EC WITH THE HEAVIER QPF AMOUNTS.  FEEL
THIS TREND IS REASONABLE AS THE EC HAS BEEN CONSISTENTLY TOO FAR
WEST OF THE SUITE OF MODEL GUIDANCE FOR SEVERAL MODEL RUNS.  ITS
OWN ENSEMBLE MEAN SUPPORTS AN EWD/NEWD SHIFT TO HEAVIER QPF
AMOUNTS.  STGLY DIFFLUENT UPR FLOW PATRN EARLY IN THE PD AS A
RESULT OF NEG TILT ORIENTATION OF THE UPR TROF ALONG WITH STG
85H/7H THETAE ADV..SHOULD CONTINUE TO ENSURE STG UVVS IN COMMA
HEAD BAND THRU EARLY TUES AFTN BEFORE SLOW WEAKENING OCCURS.  FOR
QPF AMOUNTS A BLEND OF THE NAM/EC MEAN SEEMED THE BEST COURSE OF
ACTION AS THE GFS APPEARED A LITTLE QUICK TO SHIFT STG HEAVY PCPN
BAND ON THE WEST SIDE OF THE LOW TO THE NE...WHILE THE OPERATIONAL
EC AGAIN APPEARED TO FORCE HEAVIER AMOUNTS TOO FAR WEST.  AS A
RESULT...PLACED HEAVIER AMOUNTS OF 1 TO 1.25 INCH AREAL AVG LIQUID
EQUIVS FROM EXTREME NE MA ACRS SRN AND ERN MAINE. SOME BANDED TYPE
FEATURES LIKELY WITHIN THIS HEAVIER QPF AXIS..BUT CONFIDENCE IN
RESOLVING THE SMALLER MESOSCALE BANDS WAS LOW.  PLEASE REFER TO
THE HEAVY SNOW DISCUSSION...QPFHSD...FOR WINTER WEATHER DETAILS.


...SOUTHWEST/GT BASIN...

A RATHER ORGANIZED NEG TILTED UPR TROF IS FCST TO RAPIDLY WEAKEN
AS IT LIFTS NEWD FROM SRN CA/NRN MEX INTO THE GT BASIN AND
EVENTUALLY AS A WEAK POS TILTED S/WV ACRS WY/UT REGION BY WED
MRNG.  DECENT PLUME OF 1 INCH PWS OF THE EAST SIDE OF THE UPR TROF
IS FCST TO WEAKEN AS EVOLVING SWLY 7H-5H FLOW ALLOWS SOME DRIER
AIR ALOFT TO OVERSPREAD THE SW WITH TIME AS UPR TROF LIFTS NEWD.
THIS SHOULD RESULT IN A GENL WEAKENING AND SOMEWHAT DISORGANIZED
AREA OF SHOWERS TO OCCUR OVER PARTS OF CNTL CA/THE GT BASIN.
GIVEN THE WEAKENING TREND IN MID LEVEL FORCING AND MSTR..PCPN
PATRN IS EXPECTED TO BE RATHER DISORGANIZED AND LIGHT MOST
AREAS..AND AS A RESULT HAVE TAKEN A MULTI-MODEL BLEND APCH TO PCPN
ALONG WITH CONTINUITY.


DAYS 2/3...

...NORTHERN PLAINS/UPPER MS VALLEY/GREAT LAKES/MIDWEST/NEW
YORK/NEW ENGLAND...

THE NEXT SHORT WAVE WITH A CLOSED 850 MB LOW TRACKS ACROSS THE
UPPER MS VALLEY AND GREAT LAKES ON DAY 2 WITH LOW-MID LEVEL
WARM/MOIST ADVECTION OCCURRING IN ADVANCE OF THE WAVE.  2 AND INTO
DAY 3 PRODUCES MAINLY LIGHT QPF AMOUNTS ACROSS THE REGION.
ABOUT A QUARTER INCH LIQUID EQUIVALENT WAS FCST NEAR LK SUPERIOR
ON DAY 2.
AS A LITTLE MORE MOISTURE IS TAPPED MORE SHOWER DEVELOP IN ADVANCE
OF THE COLD FRONT IN THE OHIO VALLEY...AND DEVELOP IN THE LOWER
LAKES TO WESTERN NY...WITH ASCENT AIDED BY THE TERRAIN IN THE FUG
HILL TO THE ADIRONDACKS.  THERE REMAINED GOOD MODEL AGREEMENT
CONCERNING THE TRACK OF THE MID LEVEL SYSTEM AND ITS ATTENDANT
SURFACE SYSTEM DAY2 WITH TIMING DIFFERENCES DEVELOPING ON DAY 3.
THIS IS WHEN THE 00Z GFS AND 21Z SREF MEAN BECOME A LITTLE FASTER
MOVING THE FRONTAL SYSTEM ACROSS NY/NEW ENGLAND. THE WPC QPF WAS
BASED ON A BLEND OF THE 12Z ECMWF/GFS/00Z UKMET/NAM QPF TO
MITIGATE THE TIMING DIFFERENCES.


...SOUTHWEST/SOUTHERN ROCKIES...

THE MODELS FCST A MID-UPPER LEVEL TROUGH TO MOVE ONSHORE AND
INLAND ACROSS THE SOUTHWEST...WITH AN 850-700 MB CIRCULATION
FORMING EN ROUTE.
PRECIPITATION BREAKS OUT IN AZ AS 700 MB CONVERGENCE OCCURS...WITH
CONTINUATION OF THE CONVERGENCE MAXIMA DOWNSTREAM INTO NM.
GFS FCST PRECIPITABLE WATER VALUES INCREASE TO 0.75 TO 1
INCH...WHICH IS 2 STD DEVIATIONS ABV NORMAL.
CONSEQUENTLY...A HEALTHY HALF TO THREE FOURTH OF AN INCH OF
RAINFALL IS FCST.  THE 00Z ECMWF/NAM/UKMET/GFS HAD SIMILAR TIMING
OF THE 700-500 MB TROUGH...WITH A CONSENSUS APPROACH USED FOR
QPF...WITH SLIGHT ENHANCEMENTS IN THE MOGOLLON RIM IN AREAS OF
UPSLOPE FLOW.

SULLIVAN/PETERSEN

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


24HR QP VT 28/12Z
 0.01 495611 495615 497619 501629 503641 502653 498673 496683
      491692 482706 473723 464736 461741 458742 450748 444752
      437758 429760 420760 415760 412759 402761 397761 394760
      391758 387754 380738 378735 376736 371737 360738 355733
      354727 354721 356713 363706 369702 377698 393689 399683
      403675 409657 415639
 0.01 535201 535192 535186 534182 532179 533174 536166 538162
      538155 538151 537147 534139 531130 530121 531108 532102
      533098 534085 533076 531068 526047 520034 514029 511029
      509031 508036 508042 509052 511063 512067 511074 511096
      511107 511110 512113 512118 513124 515131 517141 517147
      516150 510152 506160 505165 502167 499170 502177 503181
      505180 503189 502201 499206 495207 493204 480206 472206
      465204 462210 456214 451218 443217 441218 439222 442223
      443228 441233 439235 434240 432243 432247 429252 426260
      426264 428263 441259 447256 451251 454249 458249 460248
      465249 470248 478249 486252 491258 501269 505274 509275
      511273 515268 517265 519259 521251 523246 525244 529242
      530240 528237 527230 526220 527214 529211 533207 535201
 0.01 520237 520231 520228 520223 520218 519216 515214 514218
      513221 512223 512226 512228 512234 513237 516239 519239
      520237
 0.01 530029 531007 532996 531984 531973 530970 530964 530955
      529950 528944 525927 523910 521902 517897 512894 509893
      508890 504885 499887 495883 488884 485887 485895 487903
      490909 491925 492934 495942 498947 501953 504959 507967
      512979 515984 518994 523028 524034 527037 530029
 0.01 490234 491229 490227 487225 484224 481223 478223 475225
      477229 479231 481233 484232 486233 488234 490234
 0.01 458103 456087 454080 451075 447070 443067 439067 437068
      434070 434076 435083 434088 431089 427089 425086 423086
      422091 425097 426101 423103 418105 416108 413106 409097
      407099 405102 404104 400106 395107 387106 384106 380108
      375111 364116 356114 351111 344102 342098 340097 337096
      336097 334101 332117 335123 339126 343131 345137 347139
      350137 352137 354140 355142 358149 359152 356154 355160
      356167 357172 356176 353182 349187 345196 344204 348210
      357219 361218 364213 361208 356202 355198 356194 358192
      362192 368194 373199 383207 391209 397208 399208 400204
      397197 399194 402193 408192 414191 418185 425173 443159
      446151 450147 453142 454130 456114 457107 458103
 0.01 415071 415063 413061 409060 404063 402065 400064 395059
      391063 386066 383072 382077 380076 377075 374077 373085
      376091 375100 380099 384094 384089 387087 390085 394085
      396086 403081 406075 409074 413074 415071
 0.01 412784 411781 406782 399784 394789 388793 383800 380806
      378808 378813 385809 390806 397801 402797 409792 412786
      412784
 0.01 376778 374774 371772 367768 364767 361765 358765 358772
      361774 364778 367780 370782 372783 375779 376778
 0.01 365094 366092 364090 364089 362089 360089 359089 358089
      359089 360091 360092 362092 363094 364094 365095 365094
 0.01 356750 355745 353743 350743 347743 346740 344735 340731
      337732 334736 331740 327749 325755 326762 325768 326773
      331775 335773 340770 343766 350760 356750 356750
 0.01 362827 361823 359825 356829 354833 352837 351842 350846
      352848 354846 356841 358837 360832 362828 362827
 0.25 480616 485623 488631 489637 489641 487652 483668 481675
      477684 460709 457715 451721 442733 435736 428739 421740
      412739 405738 400735 395730 391723 390716 391711 393708
      403697 407692 411685 414678 416675 417669 416660 420654
      426650 434646 440642 447637 461628 468626 471623 472619
 0.25 525185 526184 526182 525179 524178 524176 523175 522173
      520172 519171 517172 517173 516174 515177 515179 516182
      517184 519185 519186 520187 522188 523188 525187 525185
      525185
 0.25 500232 499229 498226 498224 496221 495219 494220 493222
      493225 494227 494228 495230 496231 497232 498234 500232
 0.25 447114 448109 447106 446102 444101 441101 439102 437103
      436107 436112 438115 439117 441120 443118 445116 447114
 0.25 422157 422155 422152 420151 419152 420154 418155 418156
      418158 418159 419159 421159 422157
 0.25 395173 395170 394172 395173 395173
 0.25 381195 379192 378190 377189 376189 375186 374184 373184
      372184 370185 369185 368187 369189 370190 371191 372192
      374193 375195 377196 379196 381195
 0.25 340753 340752 338752 336753 335754 334756 333758 333759
      333761 334761 335760 337759 338758 339756 339755 340754
      340753
 0.50 481644 481640 479638 475636 469636 463637 452642 445645
      440648 431657 427669 425674 421680 414689 409700 406705
      401710 400716 400721 403722 406724 414724 419726 423728
      428730 432730 435727 443719 451711 458700 465690 471680
      476667 479655 481644
 1.00 463658 462653 459652 454658 441664 436677 426686 422692
      421699 424705 425709 427712 433713 439711 445707 449702
      455690 462677 463669 463660 463658

24HR QP VT 29/12Z
 0.01 474619 478623 483620 488619 491620 495627 497634 499640
      499646 500651 499654 497660 492671 485682 477689 469696
      466701 462704 457704 451701 448698 444696 422706 419707
      417706 413706 411704 409700 408693 409691 408686 411680
      416672 419666 423662 430654 438645 441634 442630
 0.01 536048 536041 535034 531024 522004 517982 517969 516957
      515895 511873 508863 506859 507854 508841 507832 506826
      505817 503811 502806 500800 498794 496791 494787 491783
      485780 479779 469781 464784 459785 451790 447792 443796
      439803 440817 441823 439828 433833 430835 424836 415833
      410833 409835 406836 402838 398837 393837 389840 384845
      377850 374851 371853 365858 359867 357870 357876 359881
      363884 367886 369884 379880 381877 387877 395876 400876
      403877 402880 396880 391881 388884 389888 393891 399891
      409890 415898 421900 427905 431914 433920 433928 436938
      438942 442945 448950 458950 461950 462953 462960 462971
      462978 463984 463999 466005 468009 475014 480015 482017
      487019 488027 492046 495056 496061 499067 501071 503077
      505081 508084 514080 517078 519073 520068 522065 524066
      529063 534056 536048
 0.01 491139 489137 487135 486133 483130 481129 479130 476131
      474133 474136 475137 479137 482138 484136 487139 489140
      491139
 0.01 483168 481162 479157 474153 469148 466144 463144 462146
      465152 465157 467158 469165 469168 472169 479171 483168
 0.01 462238 463233 463231 460228 458226 456227 454230 452233
      450235 448236 449240 452241 454240 458240 460239 462238
 0.01 454110 449080 449068 450060 448053 446050 443049 434049
      431046 427046 426054 418055 409054 405053 401054 397058
      393059 391061 385065 383067 382073 380080 382086 407084
      406096 404100 404105 402109 400112 394114 393118 393124
      395131 398137 402142 405144 409145 414142 421131 428128
      434124 439121 444121 450119 452115 454110
 0.01 433090 431085 431080 429070 424070 422072 419075 418081
      417090 417099 419102 422101 425100 426096 421091 421088
      425086 430089 433090
 0.01 411164 411157 407155 406154 401155 398158 396161 393165
      393170 396175 398175 402174 405170 408167 411164
 0.25 493651 492643 489640 484641 481644 478649 476654 475657
      472663 471668 476668 481665 484663 488660 491656 492651
      493651
 0.25 500914 500898 500886 499873 497861 491841 487831 483826
      478819 475817 471818 468820 466824 468833 467838 468846
      469856 473877 477900 480911 484919 489917 492914 498914
      500914
 0.25 455651 454643 452639 449640 446644 444649 442652 440658
      439663 443665 446663 449660 452656 455651 455651

24HR QP VT 30/12Z
 0.01 511287 514274 515261 513253 508247 506251 505258 504260
      501262 497262 495265 496273 498281 500285 503288 508290
      511287
 0.01 520721 519712 518705 516699 512695 510692 505689 501688
      497685 488681 486681 483678 481672 475659 473657 469658
      467661 463662 454661 443663 434662 428661 425664 420666
      416670 405677 396685 393687 389688 386686 382688 374693
      369696 364699 360702 357707 351713 334731 319750 316759
      312768 311772 310778 308792 308798 307805 305818 302831
      302835 304837 308844 313838 318829 329812 341794 347783
      350778 355772 363765 366762 373761 377758 380758 382761
      381774 380781 377787 369796 362806 353814 347820 344824
      340827 333836 330845 327858 329864 335865 340863 346862
      349861 351865 353872 387870 398874 403878 407882 411885
      415889 425896 434899 439900 444901 455901 457899 460899
      464901 470900 474895 476879 478871 482865 488854 493846
      496842 499837 502832 504826 508815 509807 509796 509791
      510788 513782 518768 520753 518735 518730 519727 520721
 0.01 398115 396106 394101 395094 396089 398082 399076 400067
      398064 395065 384065 381060 379055 376051 372048 360036
      353029 350026 345024 338023 329019 314026 301037 295045
      290054 280067 274076 272081 271087 272097 274106 276110
      279114 283118 288120 303129 314132 318134 325136 335138
      342143 346145 352147 358148 364148 367146 370145 372147
      376150 376149 375143 377142 383132 389122 395119 398115
 0.01 387198 387194 385191 382183 378178 371173 362171 359172
      356176 355178 356182 360188 369192 373196 380199 384200
      387198
 0.01 349174 350170 348167 345164 338162 332162 328167 323169
      320173 324174 330175 336177 343178 347176 349174
 0.25 508280 510275 510270 511265 509262 506263 505265 503267
      501270 501272 501277 503281 504282 507282 508280
 0.25 493733 492729 490726 484723 477721 472721 466724 455732
      447739 444741 439743 432744 426750 423758 423764 424772
      425778 422782 415785 398792 388801 383809 383815 386820
      390825 397828 404830 409831 415830 420830 426831 433836
      436838 441839 443841 447842 456842 459843 461840 463835
      467832 472826 475820 479811 482801 486793 488785 490774
      490768 490759 487753 488745 491739 493733
 0.25 363119 365112 364106 360095 359089 358084 358069 357063
      355059 350055 345054 335055 323051 318052 314053 310056
      307062 296080 293088 292096 292102 294107 297109 310113
      318117 329122 337128 342131 347133 351132 355130 359127
      362121 363119
 0.50 345118 347110 346106 345104 341101 339093 338087 336082
      331078 327077 323077 319080 314082 311083 310085 306091
      304097 306102 312102 317104 328111 336118 340121 345118

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