Quantitative Precipitation Forecast
Issued by NWS

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000
FXUS04 KWBC 270942
QPFPFD

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


FINAL 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...

06Z UPDATE...
ONLY MINOR CHANGES MADE TO PRELIM GUIDANCE BASED MAINLY ON LATEST
SATL/RADAR TRENDS.

...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 501629 503642 502653 498674 495684 491692 482707
      473723 463737 450748 447751 443752 437758 427760 421756
      414754 405755 398752 391748 384745 381742 380737 377735
      375736 369737 360738 357737 355732 353726 354720 356712
      363706 370702 377697 393689 399683 403675 409657 415639
 0.01 535204 536191 536187 534182 532179 533174 536166 537162
      538156 538151 537147 534140 532132 530122 531108 532101
      533098 534085 533075 531068 529058 526050 526046 523041
      520035 516030 512029 509031 508036 508042 509051 511071
      511095 512113 514129 517140 518144 516150 513152 511152
      506159 505165 503167 499170 503178 504185 502202 500206
      497207 493204 491205 485204 478206 464205 462210 460212
      454215 449218 441218 442232 433241 432248 428255 426257
      426263 425266 429265 434261 437259 441259 446256 451250
      463249 470249 473248 477249 485252 491258 500268 504274
      508275 511274 515269 517265 518259 521251 523246 525244
      529243 529238 527231 526221 526215 528212 533209 535204
 0.01 520237 520231 520228 520223 520220 519216 515214 513218
      512220 511226 512228 512234 513237 516239 519239 520237
 0.01 530029 531006 532995 531984 531973 530969 530963 530954
      528944 525926 523910 521901 517897 512894 509893 508890
      504885 499886 495883 488884 485888 486896 487903 490909
      491914 490918 491926 492935 495942 499947 501954 504959
      507967 513980 516985 518994 520011 523028 525034 527037
      530029
 0.01 490234 491229 491226 487224 484224 481223 478223 475225
      474227 477229 479231 481233 484232 486233 488234 490234
 0.01 458103 456086 454080 450075 446070 443067 440067 435068
      434076 435084 434089 429089 424086 421083 421086 422093
      425098 425101 423103 418106 416108 412106 410098 408098
      406100 404104 392107 384106 380108 369114 363115 355114
      338096 336097 334101 332110 332118 335123 341127 344132
      346139 352137 356143 358150 357153 355155 355159 356162
      357170 355179 351184 349190 347192 345197 345205 348210
      353215 357219 362217 364215 363211 359206 356201 356197
      358192 360191 364192 370196 375200 379204 384208 391209
      398209 399207 399203 398200 398196 403193 410192 415190
      419185 422178 425173 430168 436165 440161 453139 458103
 0.01 415071 416065 415062 409060 404064 402066 400064 395059
      391063 386067 383072 382077 379076 377075 374077 373084
      376091 376100 380099 384093 384089 387087 390085 394085
      396086 403081 406075 413074 415071
 0.01 412784 410781 406782 399784 394789 388793 383800 380806
      378809 378813 385809 390806 397801 402797 409792 412786
      412784
 0.01 387767 383766 379765 377764 372763 368759 364760 364762
      365766 367768 371772 375776 379778 383779 382775 381773
      382769 385770 387767
 0.01 365094 366092 364090 364089 362089 360089 359089 358089
      359089 360091 360092 362092 363094 364094 365095 365094
 0.01 356750 355744 353743 350743 347743 346739 344735 340731
      337732 334736 331740 327749 325755 326762 325768 326773
      331775 335773 343766 350760 356750 356750
 0.01 362827 361823 359825 356829 354833 352837 351842 350844
      352848 354846 356841 358837 360832 362828 362827
 0.25 480616 485624 489632 489641 487652 483669 481675 477684
      460709 456715 451721 442733 434736 428738 421739 414737
      406736 400734 391723 390715 391711 393708 403697 408691
      411685 414678 416674 417669 416659 420654 426650 434646
      447637 461628 468626 471623 473619
 0.25 525185 525184 526182 525179 524178 524176 523175 522173
      520172 519171 517172 517173 516174 515177 515179 516182
      517184 519185 519186 520187 522188 523188 524187 525185
      525185
 0.25 500232 499229 498227 498224 496221 495219 494220 493222
      493225 494227 494228 495230 496231 497232 498234 500232
 0.25 447114 448109 447106 446102 444101 441101 439102 437103
      435107 436112 438115 439117 441120 443118 445116 447114
 0.25 422157 422155 422152 420151 419152 420154 418155 418156
      418158 418159 419159 420159 421159 422157
 0.25 385193 384191 382188 380187 377186 373184 370185 368187
      370190 372192 374193 377196 380197 381197 384195 385193
 0.25 340753 340752 338752 336753 335754 334756 333758 333759
      333761 334761 335760 337759 338758 339756 339755 340754
      340753
 0.50 481644 481639 478638 473637 461638 451642 445645 440648
      435653 431658 427669 424675 421680 414689 408700 403711
      403715 405717 410719 420723 429729 434727 438723 448714
      455705 461696 465691 468685 474673 478661 480651 481644
 1.00 463673 462663 461659 460662 449662 446662 442663 439668
      437674 436677 433679 425688 422693 421699 426711 428712
      432712 438709 446702 451697 454693 456686 460681 463673

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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