Quantitative Precipitation Forecast
Issued by NWS

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000
FXUS04 KWBC 262210
QPFPFD

QUANTITATIVE PRECIPITATION FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
509 PM EST MON JAN 26 2015


FINAL DAY 1...DAY 2 AND DAY 3 QPF DISCUSSION
VALID JAN 27/0000 UTC THRU JAN 30/0000 UTC
REFERENCE AWIPS GRAPHICS UNDER...PRECIP ACCUM - 24HR


2200 UTC UPDATE

NO SIGNIFICANT CHANGES MADE TO THE DAY 1 QPF FOR THE FINAL
ISSUANCE.  THE 1800 UTC GFS CONTINUES TO SHOW AN EASTWARD TREND
OVER THE PAST SEVERAL MODEL CYCLES WITH THE QPF AXIS OVER NEW
ENGLAND---BEING FARTHER TO THE EAST WITH THIS AXIS THAN THE EC AND
NAM.  THE 1800 UTC NAM IS SHOWING AN OPPOSITE TREND TO THE 1800
GFS---PUSHING HEAVY PRECIP TOTALS SLIGHTLY FARTHER WESTWARD FROM
FAR EASTERN PA---THROUGH NJ AND INTO SOUTHEAST NY STATE.

ORAVEC


DAY 1...

...EASTERN U.S. BLIZZARD...

INTENSE CYCLOGENESIS WILL YIELD A SMOOTHLY DEFINED SYNOPTIC
PRECIPITATION DISTRIBUTION OVER NEW ENGLAND AND PORTIONS OF THE
MID ATLANTIC. THE MODELS SHOW GOOD AGREEMENT ON A LARGE
SCALE...BUT DIFFER IN FORWARD SPEED AND IN THEIR MESOSCALE
DETAILS. FOR THE 18Z QPF ISSUANCE WE BLENDED OUR PREVIOUS FORECAST
TOWARD THE 12Z NAM AND 00Z ECMWF. THOSE MODELS WERE SLIGHTLY
SLOWER THAN THE ENSEMBLE CONSENSUS...BUT FORECASTS FROM THE RAP
LEND SUPPORT THROUGH 06Z TONIGHT. A STRONG NEGATIVE TILT TO THE
UPPER TROUGH AND PRONOUNCED DOWNSTREAM RIDGE ALSO CAUSED US TO
THROW A LITTLE MORE WEIGHT TOWARD THE SLOWER SOLUTIONS. THE MAIN
IMPACT OF THIS CHOICE WAS TO NUDGE THE CENTROID OF HEAVIEST DAY 1
QPF SOUTHWARD...DOWN THE COAST...CATCHING MORE OF EASTERN
NJ...LONG ISLAND...AND WESTERN CT IN 1.5 INCH AREAL AVERAGE LIQUID
AMOUNTS. THERE WAS A CORRESPONDING DECREASE TO AMOUNTS OVER MAINE
THROUGH 28/00Z...PUSHING MORE OF THE EVENT INTO DAY 2. THESE
CHANGES WERE COORDINATED WITH THE WPC WINTER WEATHER DESK...GIVEN
IMPLICATIONS FOR SNOWFALL TOTALS...INCLUDING IN AND AROUND NEW
YORK CITY. THE 12Z ECMWF THEN CAME IN WITH A FORECAST THAT WAS NOT
AS SLOW AS THE 00Z RUN...BUT WAS IN GOOD AGREEMENT WITH THE WPC
QPF...WHICH HAD RETAINED SOME INFLUENCE FROM THE PREVIOUS - MORE
ENSEMBLE MEAN DOMINATED - PACKAGE. BOTH THE NAM AND ECMWF...ALONG
WITH SOME OTHER HIGH RESOLUTION MODELS...PREDICT DISTINCT BANDS OF
MAXIMUM PRECIPITATION EMBEDDED WITHIN THE SYNOPTIC SHIELD. ONE
BAND SEEMS TO CORRESPOND TO THE MID LEVEL
FRONTOGENESIS/DEFORMATION BAND EXPECTED IN THE VICINITY OF WESTERN
LONG ISLAND UP THROUGH WESTERN CT/MA...WITH ANOTHER BAND FOLLOWING
THE TRACK OF STRONGEST HEIGHT FALLS ALONG THE IMMEDIATE LEFT SIDE
OF THE SURFACE LOW TRACK...AND AFFECTING EASTERN MA AND RI. WE
ATTEMPTED TO POINT TO THESE BANDS IN OUR QPF AND WINTER
PRODUCTS...BUT WITH ONLY MODERATE CONFIDENCE GIVEN THEIR
NARROWNESS. PLEASE REFER TO THE HEAVY SNOW
DISCUSSION...QPFHSD...FOR WINTER WEATHER DETAILS.


...SOUTHWEST...

A HIGHLY AMPLIFIED...NEGATIVELY TILTED MID/UPPER LEVEL TROUGH
PIVOTING TOWARD NORTHWEST BAJA AND SOUTHERN CA WILL PROVIDE
STRENGTHENING UPPER LEVEL DIVERGENCE/DIFFLUENCE AND ANOMALOUS
MOISTURE (PWATS INCREASING TO 3-4 STANDARD DEVIATIONS ABOVE
NORMAL) INTO FAR SOUTHERN PORTIONS OF THE SWRN U.S. (SOUTHERN
CA-AZ). THE TROUGH IS EXPECTED TO WEAKEN WITH TIME AS IT BEGINS TO
OPEN UP AND LIFT TOWARD THE NORTH BY TUESDAY MORNING. DESPITE THE
WEAKENING TREND...THE COMBINATION OF INCREASING MOISTURE AND LIFT
WILL PRODUCE GENEROUS COVERAGE OF LIGHT PRECIPITATION...AND SPOTTY
MODERATE PRECIPITATION ACROSS SRN CA/AZ. WE BLENDED OUR PREVIOUS
FORECAST TOWARD THE 00Z ECMWF AND 06Z NAM. RECENT GFS RUNS
APPEARED TOO WET GIVEN THE DEPTH OF DRY LOW LEVEL AIR PRESENT IN
THE 12Z SOUNDINGS ACROSS THIS REGION. MUCH OF THE PERIOD OF
GREATEST MID LEVEL ASCENT WILL GO INTO MOISTENING THE LOW
LEVELS...LEADING TO A LIMITED WINDOW FOR EFFICIENT PRECIPITATION
TO OCCUR BEFORE THE TROUGH WEAKENS.


DAYS 2/3...

...NORTHEAST...

THE MAJOR WINTER STORM WHICH HITS THE NORTHEAST ON DAY 1 WILL
CONTINUE TO PULL AWAY FROM THE AREA BY THE START OF THE DAY 2
PERIOD.  THE CIRCULATION AROUND THE STORM CENTER WILL BE COVER A
LARGE AREA AND THERE SHOULD BE PLENTY OF MOISTURE EMBEDDED WITHIN
THE CYCLONIC FLOW.  THAT MEANS THAT ADDITIONAL PRECIPITATION
SHOULD STILL BE FALLING AT THE START OF THE PERIOD.  IN DUE
TIME...THE SYSTEM PULLS FAR ENOUGH AWAY FROM THE AREA SO THAT ANY
LINGERING TROWAL AND WRAP AROUND PCPN WILL BE TAPERING OFF ON DAY
2.  BY THE START OF DAY 3...29/00Z...THE MODEL CONSENSUS INDICATED
THAT THE PCPN WILL HAVE MOVED OFF SHORE.

THE 26/12Z MODELS TEND TO CLUSTER WELL...ALTHOUGH THE GFS WAS A
FAST OUTLIER LIKE IT HAS BEEN FOR A DAY AND A HALF OR TWO
DAYS...WHILE THE ECMWF WAS ON THE SLOWER SIDE.  THAT LEFT THE
GEFS/NAM/EC ENS MORE CLUSTERED IN THE MIDDLE.  GIVEN THE NEGATIVE
TILT OF THE TROF AND THE RAPID DEEPENING THROUGH A DEEP
LAYER...THE THINKING AT WPC FAVORED THE SLOWER SOLNS ESPECIALLY ON
DAY 2.  CONSEQUENTLY WE MAINLY USED THE NAM/ECMWF AND A LITTLE BIT
OF THE WPC ENSEMBLE BIAS CORRECTED QPF IN PREPARING THE GRAPHICS.

PLEASE REFER TO THE LATEST WPC WINTER WEATHER SUITE OF PRODUCTS
FOR MORE INFORMATION ON DETAILS.


...NORTHERN PLAINS/GREAT LAKES/MIDWEST...

THE NEXT SHORT WAVE TRACKING ACROSS THE GREAT LAKES AND MIDWEST
DURING THE LATTER PART OF DAY 2 AND INTO DAY 3 PRODUCES MAINLY
LIGHT QPF AMOUNTS ACROSS THE REGION. FOR THE MOST PART...THERE
REMAINED GOOD MODEL AGREEMENT CONCERNING THE TRACK OF THE MID
LEVEL SYSTEM AND ITS ATTENDANT SURFACE SYSTEM...SO THE WPC QPF WAS
BASED ON A BLEND OF THE 12Z ECMWF/GFS/WPC ENSEMBLE BIAS CORRECT
QPF AND THE 09Z SREF MEAN.


...CA/GREAT BASIN/NORTHERN AND CENTRAL ROCKIES...

A SHORT WAVE TRACKING FROM CENTRAL CA ACROSS NV AND UT.  IT WILL
WEAKEN AND LOSE MUCH OF ANY MOISTURE THAT IT INITALLY BROUGHT
INLAND AS IT CROSSES THE VARIOUS MOUNTAIN RANGES IN THE GREAT
BASIN AND FINALLY THE CENTRAL ROCKIES.

FOR THE MOST PART...THE 12Z ECMWF/NAM BLENDED SOLUTION OFFERS THE
BEST SOLN WITH THIS FEATURE ON DAY 2 IN THAT IT MAINTAINS
CONTINUITY WITH THE PREVIOUS RUN IN TERMS OF PLACEMENT.  THERE WAS
AN OVERALL DRYING TREND NOTED WHICH WAS ACCOUNTED FOR IN TERMS OF
QPF ON THE MANUAL WPC PROGSM.

BURKE/BANN

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


24HR QP VT 28/00Z
 0.01 538199 539192 537185 531175 528166 520159 518155 514154
      513157 512167 511170 508169 505171 507175 508188 509195
      506202 504214 502214 499211 497208 494206 490206 486204
      481206 473211 470213 466214 459217 455221 455224 458226
      456230 455232 450233 446233 443235 436242 430251 427257
      426263 425266 429265 436260 444252 448249 449248 452249
      461249 462252 461255 462258 464262 468263 469266 475269
      479268 481268 484271 486275 491282 494286 501289 506289
      509286 515279 520270 522262 522257 521249 524245 527244
      530239 533225 535218 537209 538199
 0.01 520237 520231 520228 521223 520220 519216 515214 513218
      512220 511226 512228 513233 514237 516239 519239 520237
 0.01 499633 498627 495623 493621 488621 483624 479625 476625
      462629 447636 440639 430642 421645 417646 414649 394666
      388672 383678 375691 367700 359711 356719 352721 347722
      337724 331728 324732 320736 313746 298771 295776 297781
      303783 309786 314786 317785 320782 322781 325782 333781
      338786 346794 350798 357801 384811 390813 395811 412808
      421806 424804 429803 435798 439792 442786 444778 444771
      440765 442761 444759 452753 461741 468730 476717 482702
      488685 491677 493670 496655 499633
 0.01 490234 491229 491226 488223 484224 481223 478222 475222
      474227 477229 479231 481233 484232 486233 488235 490234
 0.01 493878 493873 489868 482867 476864 467865 464867 458868
      450872 437873 407864 401863 397862 389858 378850 371846
      366840 361840 360843 358850 356854 358859 362859 367860
      371864 376866 378868 391877 402885 417894 431897 436897
      440899 450899 455903 462901 475890 479885 481881 482880
      485882 491881 493878
 0.01 422188 419179 423167 422145 426129 427120 425115 422114
      418112 416109 412106 409101 398106 391109 388110 383110
      376109 369110 366108 364104 363099 369100 372100 372097
      367090 355091 352086 347081 344077 341074 333069 330068
      326070 319069 312059 304047 300040 297036 293035 292033
      289037 289045 297056 301061 304068 307077 310087 311091
      310097 310109 310117 314123 317127 320130 321134 322138
      320142 314148 313154 314158 316166 323177 333188 335191
      336195 337200 339204 344209 348218 351224 356225 360218
      364216 368217 369214 366211 365207 365202 368197 370199
      373202 378204 383207 391210 396215 400216 404219 403226
      405229 410228 412224 414220 413216 410216 406216 404214
      402210 403205 407197 410195 413194 419190 422188
 0.01 386086 384081 381078 379076 375075 373080 373084 375089
      376096 376101 379099 382097 384092 386086 386086
 0.01 383784 383782 381780 380782 379782 378783 376783 374785
      376787 378786 380786 381786 383784
 0.01 371786 369784 367784 363783 361781 359781 357779 354779
      356781 358783 362785 364786 365787 369788 371786
 0.01 363820 361821 358825 356829 354833 352837 351842 350844
      352848 354846 356841 358837 360832 362828 362823 363820
 0.25 530200 531194 528189 527184 526179 523175 521173 518175
      518180 518185 520189 522194 525198 529201 530200
 0.25 517267 518262 517258 515253 510241 506234 502230 498226
      494223 494229 496235 502246 505253 505260 504265 502264
      497261 495262 496265 500269 501272 504275 509273 513271
      517267
 0.25 482641 480637 476635 468635 459638 450642 427648 419651
      412656 406665 399672 393677 388682 383692 379700 376708
      369713 366716 364721 366727 370728 376726 378731 379737
      377748 378754 380758 385765 391769 410761 416759 424753
      432747 437740 448728 459711 468698 474688 476678 479669
      481660 482649 482641
 0.25 481247 481246 481244 480242 479241 478240 477238 475237
      474237 473239 473241 473242 474243 476245 477245 478246
      479246 481247 481247
 0.25 381197 381194 380192 376189 374186 370183 369178 365176
      361177 358181 355184 360187 365189 369191 372193 376196
      381197 381197
 0.25 371163 371161 371160 369159 368158 366158 365157 364157
      363156 361155 359156 358156 358158 359158 360160 361161
      362161 364162 365163 367164 369164 371163 371163
 0.25 355131 355123 352119 349114 345109 341105 338107 338111
      342115 346118 341120 340124 340128 344131 349135 353133
      355131
 0.25 345180 345178 343176 343177 343179 343180 345182 345180
 0.25 344171 343169 343168 341168 341170 342172 344171
 0.25 346752 346747 344745 341739 337738 333741 330746 328753
      328759 329766 331768 334768 339764 342759 345754 346752
 0.50 516264 516262 516261 514259 513258 512260 512263 514265
      515266 516264
 0.50 474652 474645 471642 469640 464640 459641 453644 444648
      436649 423652 416656 411662 403671 391682 388687 385694
      383702 384708 385711 385718 385726 385737 384746 384751
      386754 389755 393754 395755 401755 409753 422747 428743
      433737 441728 446721 450714 456702 459694 463688 467674
      472662 474652
 0.50 340753 340751 340750 338750 336751 334752 333754 333755
      333756 333759 335759 337758 338756 339755 340753 340753
 1.00 448675 447667 443666 438668 434667 426660 423659 417661
      410669 404675 397683 392690 392715 392722 393727 392738
      394742 397747 401748 406747 412745 416742 424737 431730
      437723 442713 445705 447698 448692 448680 448675
 1.50 439697 439690 438684 435682 432682 428682 424684 421686
      418687 415684 414679 411676 409676 400687 395694 396701
      401720 401739 408741 412737 417729 421725 428724 433719
      436711 438704 439697
 2.00 423706 421698 416696 411695 409688 406689 405691 406701
      406708 407717 410721 413717 418714 421711 422708 423706

24HR QP VT 29/00Z
 0.01 493611 498622 502636 503641 503647 502658 487697 481706
      477715 472723 467732 466738 464742 459749 452756 449760
      446763 441770 434775 429776 426774 424770 419769 415767
      414761 416756 412753 403751 397752 396754 390746 387744
      382743 377742 371743 366745 362744 357743 355740 355735
      354729 352724 352717 353714 356711 372700 382697 390692
      397686 402678 404673 406668 408660 415639
 0.01 537164 538154 538151 537147 535141 534134 533103 532087
      530074 527070 524069 525066 528063 532059 534054 536046
      536037 535032 532026 531019 531001 531985 531976 530970
      530960 529953 528943 527936 525920 522905 520899 517897
      513892 513884 511878 510871 509864 506858 504852 503844
      499832 497827 495825 492825 488823 485826 481835 476846
      472855 469866 466873 465879 463885 463893 463902 465910
      467915 470920 473924 474932 475937 474943 474959 472967
      472974 472990 472997 473006 476021 480032 492047 496060
      501070 501078 501087 500094 501101 503108 505114 509125
      516147 516150 514152 511152 509153 507158 505165 501167
      499170 501175 503181 504182 504186 503194 503200 500205
      496207 493208 481206 477206 471205 465204 463208 448220
      444223 442232 437240 436244 434247 436247 439246 443242
      446240 452240 457240 458236 456234 457232 460228 470226
      475225 479222 485223 490225 495229 499229 504220 506215
      509212 513210 513204 513200 514198 518196 525187 532174
      537164
 0.01 521010 521007 519004 519002 519999 518996 518994 518991
      517989 515991 515994 515996 515999 516001 516004 516007
      518009 519012 521010
 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 463143 462146
      465152 465157 467158 469165 469168 472169 479171 483168
 0.01 455137 457115 456113 457108 458103 457093 456086 453078
      450074 449058 448053 446050 442050 437054 431054 428056
      425055 418054 410053 403053 394061 390060 389062 385068
      382074 379078 377081 377085 380092 381097 384092 388091
      391092 395097 398092 402088 404084 406085 407088 405098
      403105 402107 398107 394110 390114 386119 382124 382127
      385126 388124 391124 394127 395129 397136 399138 397142
      391144 387143 384145 380144 375145 371147 370149 376150
      378149 382150 385154 388157 389161 387164 386168 386172
      382172 378168 375168 374173 371174 368173 362170 364179
      364187 369191 376193 381197 385202 389202 391201 402198
      406194 412191 415191 419190 421188 422185 423176 425172
      427171 432170 436165 438163 441162 444162 446160 450153
      451147 455137
 0.01 433087 431085 431080 430073 427071 424070 419074 419083
      418088 416090 415094 415099 417102 420103 425101 424096
      422094 420088 421083 426087 430088 433087
 0.01 394798 393795 391793 388794 386796 384798 383801 381802
      380805 378807 378812 380812 382811 385809 387807 389804
      390802 392801 394798
 0.01 364820 361820 360823 358825 356827 355829 353831 351834
      351837 353839 354839 355837 357833 358830 359828 360825
      362823 364820
 0.25 446629 450634 455635 461633 466629 472625 479623 483620
      488622 492628 495636 496647 495655 493662 490669 487673
      483678 475681 469683 457685 454692 450696 440694 436696
      431701 427705 422709 415711 409711 406710 406707 408700
      416690 421677 426665 428659 429651 428640 432633
 0.25 511926 510924 510923 510921 509920 507920 506921 506924
      507925 508926 509927 510927 511926
 0.25 501911 501906 500903 498898 498896 497893 495890 493892
      493896 493901 494904 495909 497910 499911 501911
 0.25 447114 447109 445104 444099 439097 432101 427108 421112
      412113 408114 409119 418122 421122 423124 426126 431125
      434121 436118 440116 445116 447114
 0.25 418159 418156 416157 415158 414160 414161 414162 414163
      415163 416163 417161 418159 418159
 0.25 401711 399708 397707 394708 392710 390711 387714 386715
      384718 383722 387724 389724 392723 394722 397719 399717
      400714 401711
 0.25 409070 410068 408067 407067 406068 406070 406071 408071
      409070
 0.25 393077 393075 392074 391075 390077 392080 393077
 0.50 492648 491641 489636 485635 483636 479640 477643 476649
      475654 475661 479663 484662 487660 490657 492651 492648
 0.50 445109 444107 442107 440106 439106 437107 437108 436110
      437110 438110 440110 441110 442109 444109 445109 445109


24HR QP VT 30/00Z
 0.01 467621 467630 467637 464648 459659 456663 451665 442670
      432677 429678 425674 425671 427665 432655 435652 438646
      441635 442630
 0.01 506746 504730 503723 501720 497719 492719 486721 477724
      470729 462735 459739 456743 450750 441754 431756 427758
      423760 414774 406776 399783 394784 390787 384793 380801
      378805 375808 357839 352847 353859 355863 357866 356876
      356881 357886 358891 362892 378884 388893 393893 397892
      406890 411890 413895 415898 418900 423902 427905 431916
      433921 433929 435933 435938 438947 442952 445954 448957
      452957 461957 463955 466955 467962 467970 465976 465984
      465988 463991 463996 463999 465002 467009 458007 453007
      455008 459012 462014 468019 474020 476014 479015 481017
      485017 488015 492014 498021 501022 502016 497008 494004
      494000 495998 496991 497987 499972 502946 504934 504919
      505913 505905 505890 506885 506876 506868 504862 502849
      503836 504831 504823 501811 500803 499798 499791 500785
      504761 506746
 0.01 417064 418061 414059 409056 404053 400055 397057 396066
      395071 397072 399074 403075 406077 410073 414068 417064
 0.01 410882 409880 405878 404878 400877 397877 393877 390877
      386877 385879 386881 390880 393880 397880 399882 401883
      404884 407884 410882
 0.01 391204 391200 389197 386189 383183 378177 371173 362172
      359172 358176 357181 359184 365189 370192 377197 384201
      386203 390204 391204
 0.01 386881 384879 383880 381882 383883 384882 386881
 0.01 324200 325193 325188 319179 313174 309173 303174 296177
      292179 288181 283181 279183 272188 265192 257197 249200
      244201 243206 250210 254213 260214 269218 277224 288227
      294228 297226 304219 309212 323200 324200
 0.25 489864 489856 488849 487836 486821 485814 484809 480799
      478793 475790 471790 468792 461799 458802 453802 449805
      448809 446821 444832 442842 441849 444851 453849 458849
      461850 465853 465858 467866 469870 471880 473883 475883
      477882 481884 484881 488871 489864
 0.50 467834 468828 467824 465821 464819 462817 459817 459820
      458825 458827 459830 460834 462835 466835 467834

$$




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