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Quantitative Precipitation Forecast (QPF) Discussion
 
(Caution: Version displayed is not the latest version. - Issued 1913Z Dec 19, 2014)
 
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Abbreviations and acronyms used in this product
 
Geographic Boundaries -  Map 1: Color  Black/White       Map 2: Color  Black/White


QUANTITATIVE PRECIPITATION FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
213 PM EST FRI DEC 19 2014


PRELIM DAY 1 QPF DISCUSSION
VALID DEC 20/0000 UTC THRU DEC 21/0000 UTC
REFERENCE AWIPS GRAPHICS UNDER...PRECIP ACCUM - 24HR


DAY 1...

...LOWER MISSISSIPPI VALLEY INTO THE SOUTHEAST...

WIDESPREAD AREA OF GENERALLY LIGHT-MODERATE RAIN OVERRUNNING THE
LLVL WARM/STATIONARY FRONTAL BOUNDARY WILL CONTINUE TO EXPAND
EASTWARD ACROSS THE LOWER MS VLY AND INTO THE SOUTHEAST REGION
DURING THE PERIOD. THE AREA OF RAIN IS IN RESPONSE TO COUPLED
UPPER LEVEL DYNAMICAL FORCING...OUT IN FRONT OF THE SOUTHERN
STREAM SHORTWAVE (CURRENTLY NUDGING INTO THE WESTERN GULF COAST)
WHILE THE UPPER LEVEL CONFLUENCE TO THE NORTH (ENHANCED RRQ UPPER
JET FORCING AND LOW-MID LEVEL FRONTOGENESIS) ALLOWS FOR A MORE
SLOPED S-N OVERRUNNING SURFACE. BECAUSE OF THE NORTHERN STREAM
INFLUENCE (INCREASED DRY NERLY LOW-LEVEL ADVECTION ON THE NORTHERN
PERIPHERY)...THERE WILL REMAIN A SHARP N-S GRADIENT TO THE QPF
ACROSS NORTHERN PORTIONS OF THE DEEP SOUTH INTO THE LOWER MID
ATLANTIC REGION (I.E. ACROSS NRN MS/AL/GA/SC). WPC UTILIZED A
GENERAL MODEL CONSENSUS WITH THE QPF...THOUGH WITH FEW CAVEATS.
MORE HIGH-RES GUIDANCE WAS UTILIZED CLOSER TO THE GULF COAST
(RGEM...NSSL-WRF...WRF-ARW...AND NAM CONEST)...GIVEN THE SHARP N-S
GRADIENT OF FAVORABLE DYNAMIC AND THERMODYNAMIC
PROFILES. MEANWHILE...OPTED TO REFRAIN FROM USING THE GFS/GFSP
OUTPUT GIVEN THAT THESE SOLUTIONS WERE A LITTLE TOO WET ON THE
NORTHERN PERIPHERY.


...WESTERN U.S....

INITIAL SHORTWAVE TROUGH AND ASSOCIATED PRE-TROUGH WARM CONVEYOR
BELT (WCB) MOIST AXIS CONTINUES TO PUSH EAST AND ACROSS THE
NORTHERN INTERMOUNTAIN WEST EARLY THIS AFTN. BEHIND THIS
SYSTEM...A BRIEF LET UP IN SHOWER/SHOW SHOWER ACTIVITY IS NOTED
ACROSS THE PAC NW... THOUGH THE ONSHORE FLOW AND STEEP MID LEVEL
LAPSE RATES ARE MAINTAINING OROGRAPHICALLY-ENHANCED PCPN. LATER IN
THE PERIOD (ESPECIALLY ON SAT)...A POWERFUL W/E PAC JET BRINGS
NEXT COLD FRONT RAPIDLY TOWARD THE PAC NW COAST BY SAT AFTN. 
THERE HAS BEEN GENLY GOOD RUN TO RUN CONTINUITY WITH THE HANDLING
OF BOTH SYSTEMS WITH MAIN QPF FOCUS ALONG THE COASTAL RANGES OF
OREGON/WA AS WELL AS PARTS OF THE NRN SIERRA RANGE. STRONG
LOW-LEVEL W-WSW FLOW (40-45 KTS AT 850 MB) WILL COMBINE WITH
ANOMALOUS MOISTURE TRANSPORT/FLUX (3-3.5 STANDARD DEVIATIONS ABOVE
NORMAL BTWN 850-700 MB PER THE SREF/GEFS) ALONG AN AXIS OF MAXIMUM
PWATS OF 1-1.25 INCHES TO PRODUCE AN AREA OF HEAVY
OROGRAPHICALLY-ENHANCED RAINFALL ALONG THE WA/OR/NRN CA COASTAL
RANGES...TO THE TUNE OF 2-4+ INCHES IN TERMS OF AREAL-AVERAGE.
SLIGHTLY LESSER AVERAGES (GENERALLY 1-3") ARE EXPECTED OVER THE
CASCADE RANGES. SEE QPFHSD FOR WINTER WEATHER DETAILS.

HURLEY

GRAPHICS AVAILABLE ON THE WEB AT www.wpc.ncep.noaa.gov/qpf/qpf2.shtml


24HR QP VT 21/00Z
 0.01 471324 484338 502346 512331 518318 527319 533303 537275
      526255 522245 517235 513225 509220 507214 506210 506206
      507203 509199 511197 512200 517206 522213 525216 528218
      535213 536210 535207 532203 530198 528190 530186 530180
      527171 525167 522165 520162 515160 508154 501146 496144
      493140 490135 486131 480127 474127 466122 467117 471115
      471107 468102 464104 460101 456101 449094 447094 444096
      438093 436095 433094 429091 427089 424090 425093 427098
      426102 421103 416109 408100 400112 396112 394116 394119
      397120 400123 399127 398143 396146 393146 393150 396153
      394160 389167 388171 389174 392182 396189 399192 402198
      400200 398200 391198 381193 372187 369188 370192 373198
      378207 376210 373212 369214 365214 362211 357209 354208
      353211 357222 356234 355243 355251 358250 365245 377231
      380229 379235 378244 378250 383258 388265 394270 400275
      405277 409277 414278 419282 430286 435289 441291 450295
      454298 456301 457307 459310 464317 471324
 0.01 504947 504940 504934 500928 496920 496916 494913 491911
      489905 488896 486893 482895 478900 475909 472915 466921
      462927 460935 463936 460939 459942 460945 462947 466948
      470948 473950 481950 485950 489952 493957 495960 498959
      502952 504947
 0.01 454086 453083 453080 451077 450075 446073 445070 441071
      439072 440074 443076 444078 448080 449082 451085 452087
      454086
 0.01 426705 425703 423702 422701 421700 420700 418700 418699
      416699 414700 414701 413702 412704 411706 412706 413707
      415707 417706 419706 420706 421706 422707 424707 426706
      426705
 0.01 415076 415071 412067 409064 405065 401069 398071 397076
      399076 403074 406075 409077 413078 415076
 0.01 224876 228883 236887 244890 248892 255892 263893 268893
      271895 275902 276905 275908 273918 270927 272931 270937
      266946 266956 269958 274959 283958 288954 295950 301944
      307939 314931 318926 322920 326914 330906 338891 342882
      343867 346862 351857 363846 368840 371835 373831 374826
      374822 374815 371812 368810 364811 359816 354822 349827
      346830 344829 344826 342814 343802 344790 345782 347775
      349765 348754 345744 344741 342741 338739 330737 324744
      320748 313747 305745 301747 299749 298754 298759 299765
      301770 302777 304781 304784 303786 298789 288790 283791
      279790 276790 274793 272795 277797 294800 302803 306805
      309810 311813 310816 310820 308824 304832 300838 294843
      287849 281855 273860 266863 257863 240861 229860 222860
 0.25 501294 512298 522302 529293 525281 522266 512233 499210
      496203 494195 487179 486172 483167 480168 480173 480176
      478180 474184 468182 464184 464177 463175 461174 456175
      455173 453169 452161 446158 443159 443165 442171 440175
      426179 424181 422185 423188 426191 431194 434199 439203
      442206 446207 451202 456196 460191 464192 465197 466204
      464207 462206 461203 457201 455204 454210 451211 448214
      440212 430210 426205 423204 419204 418216 405212 400207
      395203 390200 386199 383200 384208 386211 390213 394214
      397217 401223 398227 392230 389235 387240 388244 390250
      394256 400261 408266 414269 421270 426271 433275 440277
      449280 464288 476293 483296 490297 495296 501294
 0.25 482138 481136 479135 479134 477134 476133 474134 474136
      472137 471138 472139 473140 475140 477140 478139 479139
      480139 482138
 0.25 447114 447108 446104 443102 439102 434104 429106 425105
      424109 425112 419114 413118 418122 423123 429118 431115
      435114 441115 446115 447114
 0.25 340768 340760 339753 336748 330749 322754 317759 315762
      313773 313786 313794 316796 324801 327802 329801 330796
      335787 339775 340768
 0.25 331861 331841 331833 329830 326831 321843 318847 313852
      307854 303859 301865 297869 284873 280876 272876 266876
      261879 261882 264883 269885 279892 287898 289900 291905
      289913 287927 287931 289934 296933 301930 305926 313915
      319907 326894 330883 331877 332869 331861
 0.50 514282 518268 516255 511238 507229 502219 497212 494211
      491209 485201 482201 477203 471204 469208 465210 462208
      460205 458207 456212 452213 444216 439213 436215 431215
      428213 426218 423219 420222 419225 417226 415224 414220
      413218 410218 407221 405226 394235 392241 394247 401253
      407258 415262 424263 433261 441260 447260 455266 458268
      463268 475275 481281 485284 489286 493288 501289 507290
      510289 514285 514282
 0.50 487228 485227 484227 485230 487230 487228
 0.50 461180 461178 461177 459176 458177 457177 456178 455179
      454181 455183 457183 459182 460181 461180
 0.50 453174 453173 452171 451170 450169 449170 449173 451175
      453174 453174
 0.50 445201 445198 444198 443201 444202 445201
 0.50 445111 444108 444107 442106 440107 440108 441110 442111
      443112 445111
 0.50 395210 396208 395206 395205 394204 392203 390203 389203
      389204 389206 390208 391209 393210 395210 395210
 0.50 333772 332765 328761 324761 322763 320767 318774 318781
      318789 322791 328789 330783 332776 333772
 0.50 327863 326858 324855 320858 313862 308867 301878 298880
      293881 287883 284886 286890 291893 297898 298902 298908
      296917 297920 301921 307916 310911 315905 318899 322891
      324885 326875 326866 327863
 1.00 513258 513253 511249 509241 506234 502227 498221 494220
      492222 493231 497239 501246 504252 508260 512261 513258
 1.00 505281 507275 506269 504263 502258 493244 487238 484240
      482237 479230 477228 475228 471230 468230 468225 474217
      477216 480217 488218 488213 484211 479210 475211 469213
      464213 461210 456215 447216 439216 437219 433220 430219
      425221 423221 423224 425225 426228 427233 417231 410230
      404236 401237 398241 399244 403247 410252 415254 420255
      427254 434252 450247 456246 465247 473252 481259 490273
      493277 499282 502283 505281
 1.00 452230 452228 451226 451227 449229 447228 446228 444228
      445230 447231 449230 450230 452230
 1.00 318881 316879 312881 311883 309884 308888 307892 307894
      307899 308901 309900 311898 313895 315892 316890 316888
      318883 318881
 1.50 504276 503268 500261 495251 491245 489243 486243 485246
      483245 481239 479233 476231 473232 469234 462231 441234
      435236 429236 418235 411234 406239 407244 410248 418250
      424250 429250 434248 444245 454243 460242 467243 479248
      483252 486259 492269 495273 499277 503278 504276
 1.50 507248 507245 507244 506242 505240 505239 504237 504236
      503235 501235 500235 500237 501239 501241 502242 503244
      505246 505247 506248 507248
 1.50 499232 498230 498229 497227 496226 496225 496226 495228
      496231 497232 498234 499232
 1.50 469218 468215 466217 468219 469218
 1.50 463226 463223 464221 464219 463216 461214 460215 459216
      458216 457217 456217 454217 453218 453220 454221 455222
      457224 458225 460227 461227 463226
 1.50 450224 451220 449218 442216 440217 440219 436223 432222
      427221 423223 429226 433227 439225 446227 450224
 2.00 502272 501267 499262 497257 495253 492249 489247 488252
      490256 492261 494264 496268 499272 502272
 2.00 479241 480239 479236 478233 476233 474233 473234 472234
      470236 468237 467237 466237 467238 468239 470240 471241
      473242 475242 476243 477243 478243 479241
 2.00 464239 463236 461235 458235 455234 452235 450235 446236
      444236 442237 442240 445241 447241 451241 452240 456240
      458239 461239 464239
 2.00 462223 462221 462220 461219 459219 457219 456221 457222
      458223 460224 462224 462223
 2.00 445221 445220 443219 443218 442217 441217 442219 443220
      442222 443223 444223 445222 445221
 2.00 431246 431242 430240 426238 423237 419237 417237 414236
      412238 410240 411242 413245 414246 418247 421248 423248
      427247 428247 431246
 3.00 426242 424240 423239 421239 419239 418240 417242 418243
      420244 422245 423245 425244 426243 426242