Quantitative Precipitation Forecast
Issued by NWS

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000
FXUS04 KWBC 181859
QPFPFD

QUANTITATIVE PRECIPITATION FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
159 PM EST THU DEC 18 2014


PRELIM DAY 1 QPF DISCUSSION
VALID DEC 19/0000 UTC THRU DEC 20/0000 UTC
REFERENCE AWIPS GRAPHICS UNDER...PRECIP ACCUM - 24HR



DAY 1...

...TX/LA GULF COAST REGION INTO THE FAR SOUTHERN MS VALLEY...

THERE WILL BE A RELATIVELY SHORT WINDOW OF OPPORTUNITY FOR LOCALLY
HEAVY RAINFALL DURING DAY 1 ALONG AND JUST NORTH OF THE GULF COAST
FROM EASTERN TX INTO THE LOWER MS VLY. THIS AS A FAIRLY ROBUST
INFLUX OF SUBTROPICAL MOISTURE (PRECIPITABLE WATER VALUES CLIMBING
TO 1.5+ INCHES) WITH THE SOUTHWEST FLOW ALOFT AHEAD OF THE
SHORTWAVE TROUGH CURRENTLY ACROSS THE SOUTHWEST AND WESTERN
MEXICO. THE FAVORABLE SOUTHERN STREAM FORCING...SPECIFICALLY THE
WAA/WARM CONVEYOR BELT DYNAMICS AND ATTENDANT LOW LEVEL MOISTURE
FLUX FROM THE WESTERN GULF OF MEXICO...WILL COUPLE WITH THE
INCREASING UPPER LEVEL RIGHT ENTRANCE REGION FORCING (LOW-MID
LEVEL FRONTOGENESIS) VIA THE NORTHERN JET AXIS TO FAVOR A FAIRLY
ELONGATED AREA OF MOD-HEAVY RAINFALL AMOUNTS. WHILE THE
PRECIPITABLE WATER AVAILABILITY (ABOVE THE 75TH PERCENTILE
ACCORDING TO CLIMO) WILL BE SUPPORTIVE FOR POTENTIALLY EXCESSIVE
SHORT TERM RAINFALL...THE DEGREE/DEPTH OF INSTABILITY (OR LACK
THEREOF) ALONG WITH THE STRENGTH OF THE DEEP-LAYER SHEAR WILL
LIMIT THE FLASH FLOODING THREAT. SPECIFICALLY...THE MODELS SHOW
MUCAPES LESS THAN 500 G/KG (HIGHER OVER THE GULF)...WHILE THE
STRONG VERTICAL SHEAR WILL PROMOTE GOOD FORWARD/DOWNWIND
PROPAGATION AND THUS FAIRLY PROGRESSIVE CELL MOTION WITH THE
HEAVIER RAIN BANDS. THE UPSHOT IS AREAL-AVERAGE RAINFALL AMOUNTS
BETWEEN 1.5 AND 3.0 INCHES OVER A FAIRLY BROAD AREA FROM EASTERN
TX NEAR THE GULF EASTWARD THROUGH CENTRAL LA AND SOUTHWEST
PORTIONS OF MS. HOWEVER...THE MODELS CONTINUE TO STRUGGLE WITH THE
AXIS OF HEAVIEST RAINFALL (LOWER RES GUIDANCE CONTINUES TO BE
FARTHER N COMPARED TO THE HIGH RES). THE MORE FAVORABLE
THERMODYNAMICS WOULD SUPPORT THE HEAVIER RAINFALL POTENTIAL CLOSER
TO THE GULF COAST AND OFFSHORE...AS PER THE RGEM...WRF-ARW...AND
NSSL WRF...AND AS SUCH THE LATEST WPC QPF SHIFTED THE AXIS OF
HEAVIEST RAINFALL A LITTLE FARTHER SOUTH FROM CONTINUITY -- WITH
FURTHER SHIFTS TO THE SOUTH (CLOSER TO THE GULF COAST) CERTAINLY
POSSIBLE.


...WEST COAST...

THE EXITING NARROW UPPER RIDGE IS CURRENTLY GIVING WAY TO
INCREASING WAA AND ONSHORE FLOW AS NEXT UPSTREAM SYSTEM RAPIDLY
APPROACHES THE CNTL/NRN PAC COAST REGION TONIGHT INTO FRI. RETURN
MSTR AXIS IS EXPECTED TO BE FAIRLY NARROW BEING SO CLOSE ON THE
HEELS OF CURRENT SYSTEM BUT SUFFICIENT HEIGHT FALLS ALONG WITH A
30+ KT SWLY 85H FLOW SHOULD SUPPORT A PD OF MDT TO LOCALLY HEAVY
RAINS FROM THE NRN COASTS OF CA NWD INTO THE OLYMPICS/NRN WA
CASCADES. AS WITH THE 00Z RUN...THE 12Z NAM CONTINUED TO BE ON THE
DRIER SIDE OF THE MODEL CONSENSUS...WHICH ALONG WITH THE HIGHER
RESOLUTION GUIDANCE SUPPORTED A WIDESPREAD SWATH OF
OROGRAPHICALLY-ENHANCED AMOUNTS BETWEEN 1 AND 1.5+ INCHES ACROSS
THE FAVORED HIGHER TERRAIN OF THE COASTAL RANGES...CASCADES...AND
NORTHERN SIERRAS.

HURLEY

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


24HR QP VT 20/00Z
 0.01 475618 480620 483623 490628 496635 499639 501645 502654
      501659 499665 497669 486686 479691 472686 464683 458677
      464670 467666 467661 461663 458665 452667 448667 441662
      440658 441652 442646 444641 450634 452629 455628 460626
      464622
 0.01 524258 524253 522248 518238 515229 512221 511215 512209
      516207 518213 521216 525218 530220 532219 533217 535212
      535204 535198 535190 532183 526176 522168 515161 510154
      503147 497143 493140 490137 487133 485130 476128 471128
      471131 470135 469138 467138 461134 458136 453136 451138
      450145 446147 442144 437138 427136 422135 419137 415139
      414142 417145 420150 422154 420155 414149 410145 408146
      394145 391146 392149 395152 395156 396159 396163 392165
      388169 394175 401181 405184 407187 407192 404195 397197
      387194 378190 374191 371195 375202 375207 373210 363208
      359207 356209 353211 351217 350223 351228 351235 350241
      351244 356246 360245 363248 365249 366252 363258 360265
      356274 354277 357280 366285 370285 374283 377287 377291
      382293 385296 389297 393296 401294 408292 422287 430284
      438282 445280 453278 460277 467276 471275 476276 481279
      486282 489291 492297 508299
 0.01 460704 446710 438724 431729 431733 434732 439733 441736
      440741 436744 420742 420752 422763 427771 424778 408786
      393793 388797 384800 381804 382807 384805 391801 396800
      399798 404795 407798 408805 409815 413823 418820 420816
      420809 422802 431786 434778 436769 438758 439755 443752
      448746 449742 449737 450726 452716 460704
 0.01 455103 453098 448093 443095 437095 434096 429093 427093
      430099 430101 429103 423105 421108 424110 426113 430116
      432117 434115 438119 438124 440127 444126 447121 452111
      451106 454105 455103
 0.01 430866 430864 429862 428860 427859 426857 424857 422857
      420858 419860 418863 419865 421867 423868 424868 426867
      428867 429867 430866
 0.01 413073 412068 408066 405065 405061 409061 402055 393059
      390059 388056 386055 385052 380044 378042 375041 369041
      365043 363047 363055 366057 371056 377056 380056 381059
      377062 373063 368061 365064 359065 360067 365070 370071
      372073 372077 373083 373086 375087 384084 386083 387079
      392080 394078 397078 401076 403070 409074 413073
 0.01 368941 349930 348910 346899 343891 340882 336874 334867
      330861 322847 317842 314841 310841 305845 302852 298868
      295874 288878 280880 270881 263883 257888 258897 262901
      267907 272913 277918 281925 280930 279933 275940 268951
      262957 257962 255965 255970 259976 255992 260996 266999
      269001 273002 280005 293013 304022 309027 310036 310040
      310045 307051 304060 306068 312073 320076 323077 326079
      331084 335089 338093 340093 341082 341074 340065 343055
      343052 342049 341041 338034 341032 346031 349024 351021
      351015 345001 344990 345980 346976 346971 349967 352965
      359952 368941
 0.25 522267 521261 518253 514240 512233 510227 504215 499210
      494205 490201 489195 499190 504186 507185 511182 508175
      501165 496163 491164 485164 481164 479167 477172 476177
      477180 478184 477188 476194 475200 471204 466207 461204
      458204 457207 455211 452213 446211 441211 436213 433214
      430212 426208 423207 420209 419213 415211 412210 408210
      405208 401205 394203 387201 383202 382206 382209 383214
      381218 379219 375217 370218 366223 368230 373234 381243
      384249 385252 384257 384261 387263 391265 403266 409265
      415264 422265 427264 437261 446258 453256 459255 464256
      471257 478259 483263 497285 507290 511289 516284
 0.25 518188 518185 517185 516185 514186 513187 514188 515190
      517189 518188
 0.25 492240 492237 491233 490231 489228 486225 484224 481224
      479226 480229 482232 482237 485233 488235 489237 492240
      492240
 0.25 469172 469167 470163 468157 465154 462156 464163 466169
      465172 463174 453171 452165 447166 445169 444174 442179
      438182 438189 440195 442201 447192 450194 454190 463183
      469172
 0.25 445111 445108 444107 443106 442105 441105 439105 437106
      436107 436109 437110 438111 440111 442112 443112 445111
 0.25 332924 333913 333905 331895 329889 325881 322877 317872
      311871 308871 306873 303879 299893 296899 292903 285906
      286909 288912 290914 290917 289924 285939 281953 277968
      275982 274986 275990 280993 287996 293998 300997 306994
      321975 324967 326961 328945 332924
 0.50 516272 518264 516257 514247 510236 506226 503220 500215
      492212 488208 483206 479207 475209 472211 467213 460210
      457215 453217 448217 442217 424219 421222 420225 419229
      417230 415229 415227 416219 414214 406215 400209 395205
      392204 389206 389209 392214 394217 395221 392224 388224
      385222 381223 378228 385236 390244 393249 398252 407256
      417256 425254 443250 453248 462249 473251 481256 488264
      493272 496278 500282 506283 509282 514278 516272
 0.50 496247 495238 492230 488223 481220 474220 471222 469225
      466227 466230 469228 472228 476227 480231 482238 485237
      489238 493243 496247
 0.50 459182 460180 459179 457178 456179 455182 457183 459182
      459182
 0.50 327930 328915 327908 326901 322891 319887 316883 309882
      305885 302895 297904 293908 292914 292921 290926 288937
      285948 282960 280972 280979 280987 283990 289991 293991
      298989 305983 312976 317967 321956 326932 327930
 1.00 503273 502264 498257 490242 481239 478232 474231 472234
      469237 465237 462237 458236 452235 448236 446238 448241
      452241 460242 467243 476246 483250 488256 495270 499275
      503273
 1.00 506245 505239 504234 502229 501225 498219 493219 492224
      493229 495233 497238 500242 503245 506245
 1.00 462223 462222 461220 460220 459219 459220 457222 458223
      460224 462224 462223
 1.00 444240 440238 439239 433239 426238 420236 416235 414236
      408239 410242 411245 414247 421247 427247 431246 436245
      441242 444240
 1.00 413221 413219 412217 410218 409218 408220 407220 407222
      407224 406227 406229 406231 406232 407234 409234 410232
      410231 409230 410230 411228 412226 412224 413222 413221
 1.00 407241 406240 405238 403238 401238 399238 398239 399240
      401242 402242 403242 404242 406241 407241
 1.00 400216 400213 398211 396211 396212 396213 397215 398215
      399216 400216
 1.00 321917 320907 317898 313895 308896 303903 298909 295918
      293923 293928 292935 290937 288941 287946 285952 285958
      284968 285979 285982 286984 290985 293984 297981 302975
      308969 312962 316954 319943 320932 321917
 1.50 498268 498263 496257 495254 493248 490245 487242 486248
      488252 490255 493260 495265 498268 498268
 1.50 499235 499232 499229 498226 497225 497224 496222 494222
      494223 494225 495228 495229 496231 496233 497234 498235
      499235
 1.50 479241 479238 479237 478235 477235 476234 474234 473236
      473239 474239 475241 476242 478242 479241
 1.50 427242 426241 424241 422240 421240 419240 420242 420243
      422244 423244 425245 426244 427242 427242
 1.50 317930 318921 317911 315905 313902 310903 307908 305916
      301930 296943 295950 294958 289972 290976 292977 297975
      301969 305963 309959 312954 315947 316939 317930
 1.50 291943 291941 291939 290939 289941 288942 288943 288945
      288947 287949 287952 288952 289952 289949 290947 290945
      291943
 2.00 492253 492252 491250 491249 489247 489249 489250 491250
      491253 492253 492253
 2.00 315922 315917 313911 310910 309912 307918 304928 303935
      300939 298952 295962 295966 298965 300960 301954 303952
      306954 308952 310946 313935 315922 315922

$$





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