Quantitative Precipitation Forecast
Issued by NWS

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000
FXUS04 KWBC 272233
QPFPFD

QUANTITATIVE PRECIPITATION FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
632 PM EDT FRI MAR 27 2015


FINAL DAY 1...DAY 2 AND DAY 3 QPF DISCUSSION
VALID MAR 28/0000 UTC THRU MAR 31/0000 UTC
REFERENCE AWIPS GRAPHICS UNDER...PRECIP ACCUM - 24HR


DAY 1

18Z UPDATE...
ONLY MADE A FEW SMALL CHANGES IN THE NW ADDING LIGHT PCPN EAST OF
THE CASCADES WHERE THERE WAS MULTI-MODEL SUPPORT.

CENTRAL TO EASTERN LONG ISLAND/SOUTHERN NEW ENGLAND

HEIGHT FALLS ROTATING THROUGH THE BASE OF THE ELONGATED EASTERN
TROF TONIGHT AND OFFSHORE OF THE CAROLINAS BY EARLY SATURDAY WILL
INDUCE CYCLOGENESIS OFFSHORE OF THE NORTHERN MID
ATLANTIC/SOUTHEAST NEW ENGLAND SATURDAY.  THE DEVELOPING COMMA
HEAD/DEFORMATION PRECIPITATION BAND WILL AFFECT CENTRAL TO EASTERN
LONG ISLAND INTO SOUTHERN NEW ENGLAND WITH A RAIN TO SNOW
CHANGEOVER AND POSSIBLE ACCUMULATING SNOWFALL SATURDAY.  THE 0000
UTC ECMWF WAS A DRY OUTLIER WITH QPF AMOUNTS OVER THESE
AREAS--WITH A MAJORITY OF THE REMAINING GUIDANCE IN THE .10-.25"+
RANGE.  THE 1200 UTC ECMWF DID TREND WETTER ACROSS THIS
AREA---MUCH CLOSER TO THE NAM---GFS---SREF MEAN---1200 UKMET
CONSENSUS WHICH WAS FOLLOWED FOR THE DAY 1 QPF.

MID ATLANTIC

FARTHER TO THE SOUTHWEST THRU THE MID ATLANTIC---LIGHTER
PRECIPITATION TOTALS POSSIBLE ACROSS MOST OF THE MID ATLANTIC FROM
PA INTO THE CAROLINAS AS THE STRONG UPPER TROF AXIS SWINGS
EASTWARD EARLY DAY 1.  NOT A LOT OF CONFIDENCE WITH QPF DETAILS
HERE.  THERE IS MODEL CONSENSUS FOR A SMALL AREA OF .10"+ PRECIP
TOTALS OVER SOUTH CENTRAL VIRGINIA.  HOWEVER--WITH THE SIZE OF THE
AREA SO SMALL AND NOT LOCKED TO TERRAIN---CONFIDENCE IS LOW.


LOWER MO VALLEY INTO THE LOWER MS VALLEY

ADDITIONAL HEIGHT FALLS DIVING SOUTHEASTWARD IN THE NORTHWESTERLY
MID TO UPPER LEVEL FLOW OVER THE MS VALLEY WILL ENHANCE UVVS ON
THE COLD SIDE OF THE SURFACE FRONTAL BOUNDARY STRETCHING FROM
NORTHWEST TO SOUTHEAST OVER THE PLAINS.  LIMITED MOISTURE AND THE
QUICK MOVEMENT OF THE ASSOCIATED SURFACE WAVE WILL KEEP PRECIP
TOTALS ON THE LIGHT SIDE ACROSS PORTIONS OF THE LOWER MO AND LOWER
MS VALLEY.

PACIFIC NORTHWEST INTO THE NORTHERN ROCKIES

THERE IS GOOD MODEL AGREEMENT WITH THE INLAND MOVEMENT OF STRONG
NORTHEAST PACIFIC HEIGHT FALLS THROUGH THE PACIFIC NORTHWEST
TONIGHT AND INTO THE NORTHERN ROCKIES ON SATURDAY.  STRONG UVVS
AND ABOVE AVERAGE PW VALUES ALONG THE INLAND MOVING FRONT EARLY IN
THE PERIOD AND POST FRONTAL ONSHORE FLOW IN THE WAKE OF THE FRONT
WILL SUPPORT WIDESPREAD MODERATE TO LOCALLY HEAVY PRECIPITATION
TOTALS IN THE FAVORED TERRAIN AREAS FROM NORTHEAST
OREGON---NORTHEAST WASHINGTON STATE---NORTHERN ID AND NORTHWEST MT
AND FROM THE WA/NORTHERN OREGON CASCADES---WESTWARD TO THE
NORTHERN OREGON COAST RANGE INTO THE WASHINGTON COAST RANGE AND
OLYMPIC RANGE.  QPF DISTRIBUTIONS ARE FAIRLY SIMILAR WITH THE 12KM
OUTPUT FROM THE NAM USED PRIMARILY.


DAYS 2/3...

PACIFIC NORTHWEST...

ONSHORE FLOW CONTINUING UPON THE PASSAGE OF THE SHORTWAVE TROUGH
EARLY SATURDAY WILL SUSTAIN PERIODIC OROGRAPHICALLY-ENHANCED
PRECIPITATION ACROSS THE WASHINGTON COASTAL RANGES AND CASCADES
THROUGH THE REMAINDER OF THE WEEKEND...WITH A SOLUTION CLOSE TO
THE ENSEMBLE MEANS PREFERRED FOR INFLUENCES FROM THE SUBSEQUENT
SHORTWAVE TROUGH ARRIVING ON MONDAY...WHICH GENERALLY DISCOUNTS
THE FASTER/STRONGER 00Z ECMWF.  THE MAJORITY OF HEAVIEST
PRECIPITATION WILL LIKELY INFLUENCE THE OLYMPIC PENINSULA AND
AREAS NORTH GIVEN ORIENTATION OF THE JET STREAM...WITH BASIN
AVERAGE TOTALS ALONG THE COASTAL RANGES AND CASCADES OF NORTHERN
WASHINGTON OF 0.5 TO 1.5 INCHES.

UPPER MIDWEST/GREAT LAKES/OH VALLEY/NORTHEAST...

TWO SHORTWAVE TROUGHS WILL PROGRESS FROM THE UPPER MIDWEST THROUGH
THE GREAT LAKES SUNDAY INTO MONDAY...GENERALLY IN PHASE WITH EACH
OTHER BUT REMAINING DISTINCT ENOUGH TO BE CONSIDERED SEPARATE
TROUGHS.  MOISTURE WILL REMAIN LIMITED AS WELL DUE TO UNFAVORABLE
POSITIONING OF THE EASTERN U.S. TROUGH THAT CONTINUES TO MINIMIZE
THE QUANTITY AND DEPTH OF MOISTURE RETURNING NORTHWARD FROM THE
GULF OF MEXICO.  DESPITE LIMITED MOISTURE HOWEVER...THE NORTHERN
STREAM SHORTWAVE TROUGH SHOULD BE STRONG ENOUGH TO PRODUCE
WIDESPREAD BUT LIGHT PRECIPITATION...WHILE A NARROW RIBBON OF MORE
FAVORABLE 700-500 MB LAPSE RATES WILL ACCOMPANY THE SOUTHERN
STREAM SHORTWAVE TROUGH...THUS COMPENSATING FOR THE LACK OF DEEP
ASCENT.  MODEL TRENDS...
PARTICULARLY...FROM THE 12Z UKMET/CANADIAN...FAVOR THE SLIGHTLY
FASTER SIDE OF THE GUIDANCE THAT IS BEST DEPICTED BY THE 12Z
GFS...WHILE DISCOUNTING THE SLOWER/STRONGER 00Z ECMWF.

LOWER-MIDDLE MS/TN VALLEYS/S. APPALACHIANS...

GENERALLY WEAK BOUNDARY LAYER CONVERGENCE AND MINIMAL BOUNDARY
LAYER MOISTURE FAVOR MOSTLY HIGHER-BASED CONVECTION OR STRATIFORM
PRECIPITATION AS A SHORTWAVE TROUGH PROGRESSED OVER THE REGION
SUNDAY NIGHT INTO MONDAY.  WITH PW VALUES NEARING 1 TO 1.25 INCHES
AND 700-500 MB LAPSE RATES OF APPROACHING 8 DEGREES C/KM...BASIN
AVERAGE AMOUNTS OF 0.25 TO 0.5 INCHES ARE EXPECTED...WHICH IS
ABOUT MIDWAY BETWEEN THE 12Z GFS AND 00Z ECMWF...WITH THE 12Z NAM
CONSIDERED TOO LOW AND THUS WAS NOT USED.

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

ORAVEC/SULLIVAN/JAMES

24HR QP VT 29/00Z
 0.01 454626 459632 461640 461645 458651 445672 439684 437691
      438695 440696 447694 450697 452699 455699 460696 456710
      453716 449721 445725 440729 431736 429743 422745 410742
      403744 399741 395737 391740 382750 375759 373765 376769
      380774 381780 377786 373788 363781 358778 354773 349771
      346772 338774 330776 321783 318784 315783 311778 308765
      307755 307748 309734 314723 317718 320715 325710 330706
      339698 350691 360686 368684 375682 377683 380682 386678
      391675 396670 396663 397658 399649 401643
 0.01 539199 539191 537183 536177 533171 520153 515143 512136
      511128 510121 511113 512097 513086 515079 516061 515054
      515043 515035 517024 516017 515010 511001 495013 491025
      487039 486048 485053 483059 482061 479065 473072 468083
      465087 458084 452076 450073 448072 443072 448081 450090
      446093 442091 438093 426087 424088 425093 426098 423101
      421106 421109 419113 416115 413118 420125 424129 427126
      433118 434114 437114 440119 443122 445128 448133 449141
      447144 445144 440145 436148 434153 440164 445174 443178
      442178 440185 442188 441192 439196 441199 440205 440207
      443209 449208 452206 456203 460198 463193 466193 469194
      474193 482190 489192 491196 488200 483201 475204 467207
      461207 457209 438214 427217 424219 423223 423225 426229
      425232 423233 417232 411233 406240 402242 404246 411248
      416247 427248 432248 438250 451252 455252 461254 471258
      480265 487274 495283 504290 508289 512287 518275 522261
      526244 528238 530232 531225 533220 539199
 0.01 477982 476977 472972 465966 457959 450956 430951 423943
      417937 409931 400926 396926 392924 384920 381918 380916
      376912 373909 369906 362900 358898 356894 345877 338870
      330866 326868 326869 325875 326880 329885 331889 335893
      340899 346907 351917 362932 368939 376945 385947 393947
      402952 411957 414959 417964 424969 433973 443976 447979
      453980 460984 464985 465986 470986 476984 477982
 0.01 434782 434776 433771 429764 417768 412772 408779 403783
      398788 391790 384795 380799 377805 371810 366815 365818
      360817 358816 355812 351809 344807 337805 335804 333806
      331809 331813 334819 339825 345827 348828 349833 349838
      351841 354842 355839 360834 368823 373818 379816 391810
      407809 414810 419806 429798 433790 434782
 0.01 275791 273778 269773 263773 259772 254772 251774 239787
      232802 226817 220833 221837 226837 230844 235844 239842
      244837 254822 257815 262807 273795 275791
 0.25 528202 527199 527198 526196 524194 523194 522195 521197
      522200 522201 523203 523204 525205 526205 527204 528202
      528202
 0.25 515269 517264 517259 516250 513237 502215 498208 493206
      488206 482206 462212 442220 443223 446225 452225 455225
      458227 457232 447237 448241 451242 454243 466244 471247
      475250 485260 491270 498281 503285 506285 507283 515269
 0.25 518182 518177 516171 509166 504158 504152 503147 499144
      495141 489135 486132 481130 474130 471134 471137 472140
      478144 477150 472148 469147 464145 461147 458151 455155
      454159 458162 461164 467171 475174 483179 500187 506188
      510190 514189 517185 518182
 0.25 489231 489228 487225 484224 481222 478221 474221 472221
      471226 473228 476230 478231 480234 482237 485235 487233
      489231
 0.25 465181 466179 466177 465174 463174 461174 460175 459176
      458177 457177 456178 455179 454181 454184 455185 456186
      458186 460185 462184 463183 464182 465181
 0.25 445654 437651 431651 426652 411664 405671 401681 400685
      397689 392696 382696 376698 373700 365706 358710 341720
      333726 327731 322739 317747 316757 317763 320765 323766
      326765 330763 338758 354750 364744 371740 386730 394724
      398724 402725 411727 421724 430719 434716 436712 429707
      423704 422696 423691 429683 434675 438668 445654
 0.25 251792 251788 248786 243789 240795 238799 236806 235812
      234818 236822 240817 243813 245808 247802 250797 251792
 0.50 513258 510238 501224 497214 495210 491210 482209 476210
      463216 455218 458225 463226 466226 471220 475218 479219
      488223 495238 500245 503249 505252 507262 511263 513260
      513258
 0.50 505281 506277 506273 505266 500256 494248 492243 488239
      482239 479233 475232 472235 473241 476245 481249 486257
      492266 497276 501281 505281
 0.50 494174 496169 494166 490162 485157 479156 474153 469153
      465152 462153 465159 469164 474166 479170 483174 490176
      494174
 0.50 486136 484135 482135 484136 486136 486136
 0.50 426669 425667 424668 422670 420673 418675 414676 413678
      412682 412683 414685 416684 418681 420678 421675 423674
      425672 426669
 1.00 499271 499266 497262 495257 494253 491248 490244 486243
      487249 489252 490258 492262 495267 498270 499271
 1.00 500238 500235 500232 498231 498229 497227 497226 496224
      495223 494222 494223 494225 494227 495228 495231 495232
      496233 496234 498236 498237 499237 500238
 1.00 479241 479238 478235 477235 476234 474234 474236 474237
      475239 475240 477241 478241 479241

24HR QP VT 30/00Z
 0.01 561955 561936 561913 561899 558892 555886 554876 552865
      552855 551850 550848 546844 540812 538807 536800 537791
      537780 536775 537770 536759 534752 530745 524733 519733
      515732 504735 497737 493741 467786 458792 452794 448797
      429810 420816 411822 404827 399832 396837 392841 387870
      387876 389883 393895 395900 396908 393924 391941 391946
      390951 389960 389969 390975 396985 398987 401986 405984
      408982 410985 410991 413996 417001 419006 416010 410024
      408032 408044 404056 405058 403063 401067 399070 396070
      392068 390068 389073 390080 394078 399077 402071 405071
      407072 411078 415076 420070 423069 427069 429071 430075
      434079 440080 444083 445087 444090 438092 434094 429092
      427094 430099 430104 427105 426108 428109 451121 457120
      459116 463114 466115 472116 492117 494115 493109 490101
      487098 484096 482094 477088 472084 467079 466071 469066
      473061 475057 479042 483030 498013 509007 520002 540995
      542993 545993 548988 552977 555971 558964 561955
 0.01 536212 536202 538194 536186 533179 524170 515160 513161
      513166 515168 516171 506165 504166 502171 499173 503179
      504187 506190 509192 512199 514207 517212 525215 530220
      534216 536212
 0.01 521269 522264 524259 524254 522247 520241 514229 511224
      507219 500208 490203 486205 480206 476208 472212 471215
      472218 476223 482227 483229 480229 476226 470229 463236
      462245 464252 467255 473259 478263 479270 481285 482291
      485298 489302 492303 494302 502294 509286 515281 519276
 0.01 492142 492139 491137 487135 486132 483132 479132 477132
      479134 481135 484137 485139 488142 490143 492142
 0.01 437671 436663 432659 429656 424657 421656 415660 409667
      401688 393696 386702 379710 376713 374719 374725 376732
      378736 382739 386741 392742 396743 400740 404738 409733
      416729 427723 432716 432687 437671
 0.01 373188 374186 373185 372184 372183 370182 369183 368184
      366183 364183 364184 362186 364187 366188 367188 369188
      371189 373189 373188
 0.01 379126 379124 380121 379121 378119 378118 376118 375118
      375121 375123 374125 374127 374130 375130 376130 377128
      379126 379126
 0.01 380074 379071 377069 376066 375063 373061 370060 369063
      371066 372068 373071 374074 376076 378076 380074
 0.25 547917 546900 545891 542883 540876 538871 535867 533860
      528849 525842 522837 517836 512838 507840 503843 499845
      496841 494838 491836 488833 478830 473830 468831 463832
      459835 449843 446848 443853 439863 431889 428900 427906
      433907 446952 452962 456965 462963 468954 470949 472942
      473936 474932 472929 474922 477915 482909 489908 490912
      492913 500917 506920 507923 507928 507934 507943 509949
      511955 514958 517959 520958 524954 529951 537946 541941
      543936 546926 547917
 0.25 531205 530197 529191 529186 527183 524178 521173 519178
      518180 515182 514184 515186 518192 521199 523205 528209
      531208 531205
 0.25 518271 520263 520257 516246 513236 510228 503220 498214
      495210 489210 482211 481217 484222 488229 488233 483235
      476231 473233 471239 473249 478257 484263 490271 492276
      494280 497283 500285 506282 513276 515275 518271
 0.25 470883 469879 466876 461872 455872 451874 449876 447884
      447896 446899 448901 449907 452911 458911 462905 464895
      468888 470883
 0.50 516270 517263 517256 515246 511236 510232 507228 501222
      495215 491213 487214 486220 488223 490228 491234 495241
      498245 497247 492239 488236 483238 476234 474237 474242
      478251 483258 489265 494274 496277 499280 503280 507277
      512273 516270
 1.00 513266 515260 515255 513247 510238 508235 505232 495220
      492223 492228 494236 499243 502250 502255 498253 494247
      490240 486240 484243 482246 483250 486256 492263 496270
      501276 504276 506271 507268 510267 513266
 1.00 479241 478240 477238 477240 478241 479241
 1.50 512258 512252 512249 510243 508237 501233 499228 494224
      493228 494230 496236 500242 503247 506253 507256 509259
      512258
 1.50 503273 503266 501262 499258 497254 494250 492245 488242
      486243 485246 486251 488255 491260 494263 496268 498271
      502273 503273
 2.00 510251 508246 506242 504239 501235 498232 495228 497230
      497237 500240 503244 504247 507252 510251
 2.00 501269 500265 499263 498260 496256 495254 494251 492248
      490245 487246 488249 489252 490256 491258 494261 495264
      497266 498268 501269
 3.00 494259 494256 493254 493253 492252 490252 490253 491255
      491257 493258 494259 494259


24HR QP VT 31/00Z
 0.01 545776 545763 544749 536733 524708 522699 520694 519688
      517681 516674 509676 506677 504675 500666 496660 492651
      488644 487642 484646 482649 479650 474654 469661 461669
      459676 456682 447690 430711 421723 416729 412735 406745
      403753 402755 402759 401762 401767 399770 399775 395779
      392780 390782 385786 381791 372800 362811 357816 354818
      352817 352814 355799 353781 351772 347766 351754 362729
      365724 368716 369698 361704 351713 346716 343720 338732
      333745 327757 321772 318779 316783 316786 315818 314825
      314833 315842 315850 316860 316869 317890 320909 322918
      323924 322929 322949 321955 321963 320973 325976 335980
      341982 341979 344976 352967 354964 354958 355953 357949
      360943 364935 376912 380907 385904 392897 397892 401887
      409875 412868 416862 421856 426851 435840 438836 442832
      452825 456821 458823 460827 467839 473850 484860 489864
      492866 495864 502862 505862 508859 515859 519857 525855
      529849 535838 542824 545818 545809 546800 546790 545776
 0.01 527252 520244 517239 516235 512223 507216 499209 495206
      490204 485204 482203 478203 474206 472210 468212 466216
      467220 473226 470230 466232 464238 465244 470252 468281
      469286 472290 474295 478297 488301 492301 497302 501304
      504303 508301
 0.01 535204 536196 535193 530188 528178 527174 524171 520164
      517158 506151 504155 505159 502162 498161 495161 494166
      489170 491173 491178 491184 492187 495189 497189 501189
      503192 515203 516206 520208 524209 526208 532206 535204
 0.01 537043 536032 533025 530018 526012 523009 523004 523999
      522995 515983 504971 507964 510955 511950 509945 506938
      497926 492921 486919 483919 481922 477927 482944 489959
      485975 492990 496997 498000 496003 493005 492011 493017
      494020 500036 502045 505052 511056 517051 521052 524055
      529058 533056 535053 536046 537043
 0.01 491139 490139 489137 489136 487136 486136 485136 486136
      487139 489140 490140 491139
 0.01 412068 412062 411059 409056 406056 398053 392048 385047
      379051 370041 358047 356051 356054 361058 367063 371070
      370077 372080 375085 380085 382083 384081 388080 391082
      395083 402083 410070 412068
 0.01 342096 343089 341085 339082 337078 334075 331075 327078
      326083 326087 327092 331096 334098 340098 342096
 0.01 336058 336056 336055 334055 332054 330054 329054 327054
      326055 326057 327058 328059 328060 330060 332060 334060
      336058 336058
 0.25 520269 516248 513237 509228 504220 497213 493211 489210
      481211 480216 483219 489225 490231 488234 485235 481234
      477231 474232 472236 473241 479248 484255 484268 485273
      488277 496283 501284 505284 509282 511278 516273 520269
 0.25 522195 522189 521186 518181 513177 510176 505172 502172
      502174 506179 506182 509183 511186 514188 518193 522195
 0.25 520737 520731 519727 516722 512721 507724 499731 493738
      490744 488749 486755 486763 489768 493770 499768 502765
      510758 516748 520738 520737
 0.25 357834 356831 354830 350833 346842 342854 337865 333869
      332874 330879 329887 329917 330934 330940 332947 335952
      339955 344954 348949 350943 351937 353925 357912 357904
      357896 352886 350880 350875 350870 352864 354852 357834
 0.50 512250 512241 508232 504226 500220 493217 491217 490220
      492227 494236 498243 503249 508256 511253 512250
 0.50 506274 506269 504265 502257 498250 493243 489239 486238
      482239 481243 483246 486254 489261 493268 499273 505276
      506274
 0.50 480241 480239 479237 478235 477235 476234 475235 474236
      474237 475240 477241 478242 480241
 0.50 350914 350910 349906 347901 342899 340904 339912 338919
      338928 339936 341943 345941 346934 347928 348920 350914
 1.00 505244 505240 504237 503233 502230 500228 499226 496224
      495228 497230 498232 500235 502238 503241 505244 505244
 1.00 496260 496257 495255 495254 494252 493251 492250 491248
      489248 488249 488252 489252 490255 491257 492258 493259
      494260 496260

$$




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