Quantitative Precipitation Forecast
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000
FXUS04 KWBC 310656
QPFPFD

QUANTITATIVE PRECIPITATION FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
256 AM EDT TUE MAR 31 2015


PRELIM DAY 1 QPF DISCUSSION
VALID MAR 31/1200 UTC THRU APR 01/1200 UTC
REFERENCE AWIPS GRAPHICS UNDER...PRECIP ACCUM - 24HR


DAY 1...

...SOUTHERN U.S...

A BROAD INSTABILITY AXIS WILL DEVELOP TO EITHER SIDE OF A
QUASI-STATIONARY BOUNDARY FROM OKLAHOMA TO GEORGIA...AND EXTENDING
ALONG A TROUGH INTO THE TEXAS HILL COUNTRY AND SOUTHWEST TEXAS.
THIS WILL OCCUR AS A MODIFIED GULF AIRMASS WITH DEWPOINTS UPPER
50S/LOW 60S ADVECTS NORTH AND WESTWARD BENEATH STEEP EARLY SPRING
LAPSE RATES. FORCING FOR ORGANIZED LIFT IS NOT PARTICULARLY
STRONG...BUT CONVECTIVE INITIATION IS EXPECTED IN A FEW AREAS. A
LOW AMPLITUDE SHORTWAVE SHOULD PROVIDE SUFFICIENT LIFT DOWNSTREAM
OF THE MORE STRONGLY CAPPED ENVIRONMENT OVER THE PLAINS...WITH
THUNDERSTORMS BREAKING OUT FROM ARKANSAS ESE-WARD EITHER EARLY
MORNING WITHIN WARM ADVECTION OR MID AFTERNOON AS CONVECTIVE
TEMPERATURES IN THE MID 70S ARE REACHED. A SECOND LOW AMPLITUDE
WAVE WILL APPROACH EASTERN OKLAHOMA IN THE AFTERNOON WHERE SOME
MODEL SOLUTIONS BREAK OUT CONVECTION ALONG THE EDGE OF THE MORE
STRONGLY CAPPED ENVIRONMENT. A FEW OTHER ISOLATED CELLS MAY FORM
AHEAD OF A SHARPENING LOW LEVEL TROUGH FROM WESTERN NORTH TEXAS TO
SOUTHWEST TEXAS...AND POSSIBLY OVER WESTERN OKLAHOMA. THESE
REGIONS LACK MID LEVEL FOCUS FOR ASCENT...HOWEVER...SO WE PLACED
HEAVIER AND MORE ORGANIZED AREAL AVERAGE PRECIPITATION AMOUNTS
FARTHER TO THE EAST WHERE CONVECTION IS MORE LIKELY TO CONGEAL AND
GROW UPSCALE SOMEWHAT. IN ADDITION TO THE SOUTHEAST STATES AND THE
RED RIVER...A THIRD AREA OF INTEREST WILL BE AHEAD OF A RELATIVELY
DEEP MID LEVEL TROUGH APPROACHING SOUTH TEXAS. ALTHOUGH MODELS
DISAGREE AS TO PLACEMENT...SEVERAL DO SIGNAL DEVELOPMENT OF AN MCS
IN THE UPSLOPE FLOW NEAR THE SIERRA MADRES...WITH SUBSEQUENT
MOVEMENT INTO FAR SOUTHWEST AND SOUTH TEXAS. INSTABILITY DROPS OFF
WITH EASTWARD EXTENT TOWARD THE COAST...SO WE TAPERED QPF AMOUNTS
THERE TOWARD WEDNESDAY MORNING.

OVERALL...WPC QPF IN THIS REGION ON DAY 1 RESEMBLES A BLEND OF THE
00Z WRF-ARW WITH THE 12Z ECMWF.


...GREAT LAKES INTO THE NORTHERN MID ATLANTIC STATES...

A SHARPLY DEFINED CLIPPER SYSTEM WILL PRODUCE A PERIOD OF STRONG
LIFT AND ORGANIZED PRECIPITATION TODAY AS IT TRACKS FROM THE LOWER
GREAT LAKES TO THE MID ATLANTIC COAST. THE MODELS HANDLE THIS
SYSTEM SIMILARLY. THE NAM/SREF ARE CHARACTERISTICALLY FARTHER
NORTH WITH THE HEAVIER AMOUNTS...OFF BY ABOUT 70 MILES FROM
CONSENSUS. THE NAM IS ALSO HEAVIER THAN CONSENSUS...AS IS THE GFS
ALTHOUGH THE GFS PLACEMENT MEETS CONSENSUS. WITH THE MODELS
DISPLAYING THEIR TYPICAL BEHAVIOR...THIS IS A GOOD CASE FOR USING
OUR IN-HOUSE PSEUDO BIAS-CORRECTED ENSEMBLE. ITS OUTPUT IS VERY
CONSISTENT WITH THE PREVIOUS WPC FORECAST PACKAGE...AND HELPS TO
CUT DOWN ON THE 0.75 TO 1.00 INCH LIQUID AMOUNTS SEEN IN SOME OF
THE MODEL SOLUTIONS. THOSE AMOUNTS APPEAR UNREALISTIC BASED ON
UPSTREAM REPORTS WHICH STRUGGLED TO REACH 0.25 INCHES ACROSS THE
GREAT LAKES. THIS HAS ALSO BEEN A COMMON THEME IN THE NORTHERN
BRANCH OF THE JET AS OF LATE...WITH THE MODELS PERFORMING WELL AS
TO PLACEMENT BUT ERRING ON THE HIGH SIDE WITH RESPECT TO AMOUNTS.
WPC MADE VERY LITTLE CHANGE TO THE FORECAST HERE...WITH GENEROUS
COVERAGE OF 0.25-0.50 INCH AMOUNTS...AND LIMITING 0.50+ AMOUNTS TO
SOME OF THE FAVORED TERRAIN IN CENTRAL PA.


...PACIFIC NORTHWEST INTO THE NORTHERN ROCKIES...

A STRONG MID/UPPER LEVEL TROF WILL PUSH THROUGH THE PACIFIC
NORTHWEST AND NORTHERN ROCKIES. THE SYSTEM HAS TAPPED INTO ONLY A
MARGINAL PLUME OF SUB-TROPICAL MOISTURE...HOWEVER...WITH
PRECIPITABLE WATER VALUES LESS THAN 0.75 INCHES AT THE COAST AND
LESS THAN 0.50 INCHES INLAND THROUGH TIME. IMPRESSIVE HEIGHT
FALLS/MID LEVEL DYNAMICS/FORCING ALONG WITH SOME MODEST BUT
PERSISTENT LOW LEVEL ONSHORE FLOW BEHIND THE FRONT...SHOULD
SUPPORT WIDESPREAD PRECIPITATION FROM WA AND OR INTO ID AND
WESTERN MT. HEAVIEST TOTALS ARE EXPECTED IN THE FAVORED HIGH
TERRAIN OF THE COASTAL RANGES/CASCADES. IN THOSE HIGHER
ELEVATIONS..SOME 0.25-0.75 INCH WATER EQUIVALENTS ARE LIKELY. WE
TRIMMED BACK AMOUNTS JUST SLIGHTLY TO GET CLOSER TO THE RECENT
MODEL CONSENSUS. ONE SOLUTION WORTH MENTIONING IS THE 00Z
GFS...WHICH WE DID NOT INCORPORATE. THAT MODEL ODDLY PLACES A
FOCUSED STRIPE OF HEAVIER PRECIPITATION JUST OFFSHORE RATHER THAN
IN ALIGNMENT WITH THE COASTAL MOUNTAIN RANGES. WE HAVE SEEN THIS
BEHAVIOR IN A FEW WEST COAST EVENTS EVEN DATING BACK BEFORE THE
RECENT UPGRADE.

BURKE

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

24HR QP VT 01/12Z
 0.01 534201 535191 534184 531173 528161 526154 524148 522142
      520137 514131 511128 508130 503140 500141 497140 494136
      486129 482127 476125 471123 472115 478107 483099 487089
      490078 493071 495066 500057 510037 514025 514018 513012
      513006 509003 504003 500005 494013 488020 476040 472048
      468058 465062 462067 453071 448070 443071 439072 437078
      438093 436096 434095 431091 427088 426090 426094 429102
      426104 424106 424108 428112 429116 431118 434119 439120
      443124 443128 442130 440138 437142 434148 435153 437163
      435168 429168 430171 433174 436175 436179 435182 432183
      429185 426189 427194 428201 436204 436209 434211 432210
      424205 422207 422213 421219 417222 414224 411228 405236
      403240 403247 405250 411252 415263 421265 426264 432260
      435259 441260 452263 462261 471262 476261 480266 485275
      489278 494281 497285 502286 508283 510277 510270 506260
      505256 507254 510256 512254 514253 515250 515245 515230
      512207 512203 514201 519200 524203 525209 529211 531206
      534201
 0.01 514939 514930 512923 508913 505908 501904 498901 495898
      491896 487892 478889 467870 460861 453857 447857 445858
      444861 446866 449870 453884 455888 460891 467895 473905
      481910 486919 489924 493928 497937 501942 504945 509945
      512942 514939
 0.01 494656 489647 485647 483651 481657 478660 469663 465672
      462681 459692 456700 450708 447711 442713 446730 451728
      455725 460719 465712 469704 472698 475695 479687 485679
      489673 492663 494656
 0.01 494238 494236 493233 492232 490232 490234 491237 492239
      494238
 0.01 489195 486191 483189 479180 479177 476175 473173 470173
      466175 465181 462185 457192 455196 454203 458206 462207
      470204 474202 477202 482201 484198 489195
 0.01 449843 448837 445833 441829 438827 431822 429807 429791
      427783 426778 422769 421756 420741 417727 419718 417702
      415687 413679 412674 410669 406667 401668 397671 386675
      377680 372686 367695 364699 362704 360715 360726 362730
      366730 371733 374737 376752 377765 380775 384780 385787
      380798 375805 373808 371813 372817 378816 387812 389815
      394816 398817 404816 408819 411822 418829 423834 429835
      431838 436842 439844 442844 447846 449843
 0.01 419161 420159 420157 421154 421152 420151 419151 418151
      417153 416153 416156 415158 414160 416161 417161 419161
      419161
 0.01 415116 416111 414111 411108 409105 408110 406114 404116
      408117 411120 413118 415116
 0.01 401081 401074 398071 385070 382065 377064 372062 368063
      367065 371068 374071 376074 374077 372080 375084 384086
      384090 382092 379096 382094 384093 387093 393085 396086
      399083 401081
 0.01 379053 379051 378048 374048 370048 369050 367050 363052
      360051 359054 359056 363056 365054 368054 370053 374053
      377053 379053
 0.01 365843 362828 358828 356830 353830 348827 349820 346815
      342811 339810 334814 331817 328817 327814 329807 329802
      328788 336765 337760 337750 335743 331739 327740 324743
      317750 311758 305766 302772 300776 298788 297795 295800
      291805 289810 288815 287818 285820 282823 286826 290829
      293834 299841 301849 305852 311861 316870 319876 320883
      318895 320907 323918 325930 327937 327945 327952 326958
      315979 306985 301987 297984 289979 279976 268979 265983
      262988 258998 256004 257010 258016 261021 264029 268033
      271036 277044 283068 279072 277074 277078 281081 288082
      293084 297088 300091 303089 305085 310086 314088 315086
      312079 309076 305073 300071 295067 292062 290061 290059
      294055 298048 300046 302045 307044 306033 310022 313016
      316012 320010 324006 329997 330993 332990 335989 338991
      342992 346990 352983 354977 359974 362968 363965 361958
      358952 356947 353943 353925 352908 349895 349884 350875
      351870 353865 354859 356854 361850 364847 365843
 0.01 344098 340091 337084 333079 331072 328070 326066 323065
      322067 324074 327078 327081 331088 336093 340098 341100
      344098
 0.01 332058 332057 331055 330053 329052 327051 327050 326048
      325048 324048 322048 322050 323052 323053 325055 325057
      326059 328058 330058 332058 332058
 0.25 524190 524182 523176 519168 517167 513167 505163 498165
      493164 489166 486169 489173 493181 498183 501186 504189
      508192 516192 521192 524190
 0.25 499229 500221 499213 497209 493207 488206 481207 474209
      463215 460216 456215 449216 442216 439217 436221 436223
      436228 442229 446230 450229 456228 460230 463228 469224
      472223 476224 484226 491225 496231 499229
 0.25 488257 487249 485240 482234 480232 476231 471233 464232
      460230 457231 452233 448232 444233 439235 433237 428240
      426243 428247 433249 444247 457246 464246 467246 470247
      476251 483254 488257
 0.25 490139 489137 487135 486135 484134 482134 481134 480135
      479137 480138 482139 484140 485141 487141 489140 490140
      490139
 0.25 476159 475154 472151 471148 470143 467137 463135 460138
      456142 452149 449157 452160 454161 459160 468161 471163
      473162 476159
 0.25 457182 457181 455180 455181 455182 457182 457182
 0.25 456177 456176 454175 453174 453173 451173 452176 452177
      454178 456178 456177
 0.25 409707 408698 406689 403682 400686 399693 399700 398707
      397714 397719 399722 401724 405722 407717 408709 409707
 0.25 416793 415780 413767 410754 408742 406737 403734 400739
      399747 397751 397763 398774 400786 405794 408797 413798
      416793
 0.25 390697 389693 388689 386689 384690 381693 380695 378698
      377700 376703 377707 378709 380712 384711 385709 387707
      388704 389700 390697
 0.25 350965 349956 348952 346948 344946 343941 344936 346932
      344921 344909 343891 342879 340870 337863 334856 319830
      316823 312816 306814 304815 304821 306830 308838 312845
      316851 319858 323865 327881 329890 329899 328908 328919
      330928 333937 334945 333954 331974 330978 332978 337976
      343975 347972 349968 350965
 0.25 327766 327762 324760 319763 314767 311771 308777 308784
      311790 313791 317790 320785 322780 324774 327768 327766
 0.25 296027 296025 296023 294023 294025 294026 295027 296028
      296027
 0.25 285014 286006 287001 286997 284993 279989 275993 273999
      273005 271011 269017 273021 276023 279024 283020 285014
 0.25 453238 452238 453238 453238
 0.25 457236 456236 456237 457236
 0.50 517188 519184 518180 515177 510176 507174 502171 499170
      499173 502176 505179 507185 510187 515189 517188
 0.50 493220 492217 487213 482211 479210 476210 472213 469215
      468220 473220 477220 481221 486222 490221 493220
 0.50 459225 459220 457219 454218 452218 449219 447219 443219
      441219 441223 444225 446226 448226 451225 453225 456225
      459225
 0.50 468152 467152 466151 464151 464154 465155 466154 467153
      468152
 0.50 464149 464146 464144 463143 462143 461145 460146 461148
      462149 464149
 0.50 345965 346960 345956 343954 341952 340949 339946 337944
      336947 336952 335954 334958 336961 337960 339960 341963
      343965 345965
 0.50 341928 341924 339921 338919 337916 335913 334913 332915
      332919 333924 334927 335930 336934 337935 339934 341930
      341928
 0.50 341906 340899 338893 338889 336880 334874 334871 331872
      331880 333887 334895 335902 338908 341906
 0.50 318843 317841 315839 313837 313839 314841 315843 316844
      318844 318843
 0.50 283005 283003 283001 283999 282998 281997 280997 279997
      277999 277001 275003 275005 275007 276009 276011 278012
      280011 281009 282007 283005
 1.00 478215 477214 475214 475215 477216 478215

$$





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