Quantitative Precipitation Forecast
Issued by NWS

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000
FXUS04 KWBC 271859
QPFPFD

QUANTITATIVE PRECIPITATION FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
158 PM EST SAT DEC 27 2014


PRELIM DAY 1 QPF DISCUSSION
VALID DEC 28/0000 UTC THRU DEC 29/0000 UTC
REFERENCE AWIPS GRAPHICS UNDER...PRECIP ACCUM - 24HR


DAY 1

...LOWER MISSISSIPPI VALLEY INTO THE LOWER TENNESSEE VALLEY...

THE PREVIOUS SLIGHT RISK AREA OVER THE LOWER MS VALLEY REGION WAS
EXPANDED A LITTLE FARTHER DOWNSTREAM (NORTHEASTWARD) ACROSS THE
LOWER TN VLY AND INTO NORTHWEST GA. THE MODELS CONTINUE TO SUPPORT
AN AREA OF HEAVY TO POTENTIALLY EXCESSIVE RAINFALL ACROSS THIS
AREA...ALTHOUGH STILL SHOW NOTABLE DIFFERENCES IN TERMS OF WHERE
THE AXIS OF HEAVIEST RAIN WILL BE (ESPECIALLY THE HIGHER
RESOLUTION GUIDANCE). WPC CONTINUED TO SIDE WITH THE SOUTHERN
FRINGES OF THE GUIDANCE SPREAD... CLOSER TO THE ENSEMBLE OF HIGHER
RESOLUTION GUIDANCE (INCLUDING THE RGEM)...BUT MOST NOTABLY
CORRELATING CLOSEST TO THE 4 KM NSSL-WRF AND NAM CONEST RUNS IN
TERMS OF THE AXIS OF HEAVIEST RAINFALL (LOCATION)... THOUGH NOT AS
ROBUST AS THESE MODELS WITH RESPECT TO AMOUNTS.

CONVECTION SHOULD CONTINUE TO EXPAND AND INTENSIFY ACROSS THE
LOWER MS VLY AND INTO THE LOWER TN VLY THIS AFTN AND
EVENING...ALONG AND AHEAD OF A SLOWLY EASTWARD MOVING FRONTAL
BOUNDARY. PW VALUES AND 850-700 MOISTURE FLUX WILL CONTINUE TO
RISE ACROSS THE AREA...AND AS WITH PRIOR EXPECTATIONS...PEAK
AROUND 2.5 STANDARD DEVIATIONS ABOVE THE NORM OR ABOVE THE 75TH
PERCENTILE. DYNAMICAL FORCING WILL ALSO BE FAVORABLE... WITH
COUPLED CONTRIBUTIONS VIA THE THE RIGHT ENTRANCE REGION OF THE NRN
STREAM JET STREAK (ENHANCING THE LOW-MID LAYER FGEN)... WHILE THE
FORCING AND FAVORABLE THERMODYNAMIC PROFILE CONTINUES TO BUILD
OVER THE AREA OUT AHEAD OF THE SOUTHERN STREAM TROUGH. A KEY
CONTRIBUTOR TO THE EXCESSIVE RAINFALL THREAT WILL BE THE POTENTIAL
FOR TRAINING CONVECTION... AS FOR A WHILE (THIS EVENING AND
OVERNIGHT AHEAD OF THE HEIGHT FALLS) SOUTHWESTERLY LOW LEVEL FLOW
(30-40 KTS) WILL BE ALIGNED NEARLY PARALLEL TO THE MEAN 850-300 MB
WIND...THUS SUPPORTING WEAKENING CORFIDI VECTORS AND ENHANCED
UPWIND PROPAGATION. THE MAIN INHIBITOR TO THE EXCESSIVE RAINFALL
THREAT -- AT LEAST IN TERMS OF SHORT TERM RAINFALL RATES (1-3
HOURS) WILL BE THE LACK OF DEEP LAYER INSTABILITY... PARTICULARLY
OVER THE NORTHERN PORTION OF THE AREA WHERE MUCAPES WILL STRUGGLE
TO REACH 500 J/KG. THIS IS THE KIND OF SETUP THAT WOULD LIKELY
FAVOR LONGER DURATION FLOODING (6-12+ HOURS)... THOUGH THE
DECISION TO MAINTAIN A SLIGHT RISK FOR SHORT TERM EXCESSIVE
RAINFALL WAS BASED ON CONTINUITY AS WELL AS THE LATEST SSEO 40 KM
NEIGHBORHOOD PROBABILITIES OF 3-6 HR QPF EXCEEDING 3-6 HOUR FFG
RESPECTIVELY (GENERALLY 20-30 PERCENT OVER A LARGE PORTION OF THE
AREA).


...NORTHERN TENNESSEE VALLEY INTO THE OHIO VALLEY...

NORTH OF THE AXIS OF HEAVIEST RAINFALL...A SWATH OF MODERATE
PRECIPITATION AMOUNTS ARE EXPECTED ACROSS TN INTO THE OHIO VALLEY.
A MULTI-MODEL CONSENSUS SUPPORTS AREAL-AVERAGE AMOUNTS BETWEEN .25
TO 1.00 INCH ACROSS THIS REGION...HIGHEST FARTHEST SOUTH (TN) AND
LOWEST FARTHER NORTH (NRN OH AND WRN PA/WV).


...UPPER GREAT LAKES INTO NORTHERN MAINE...

THE FIRST AREA OF HEIGHT FALLS TO EJECT OUT OF THE ROCKIES UPPER
TROF WILL CONTINUE TO PUSH NORTHEASTWARD INTO THE UPPER MS
VALLEY/UPPER LAKES REGION TODAY...THEN ACROSS SOUTHEAST
ONTARIO...SOUTHERN QB...AND TOWARD NORTHERN MAINE TONIGHT INTO
EARLY SUNDAY.  MODEL CONSENSUS IS FOR A STRIPE OF GENERALLY LIGHT
ADDITIONAL PRECIPITATION AMOUNTS (AREAL AVERAGE AMOUNTS .10 TO .25
INCH) FROM EASTERN UPPER AND NRN LOWER MI EASTWARD INTO UPSTATE NY
AND NRN NEW ENGLAND.


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

MODELS ARE IN GOOD AGREEMENT WITH THE SOUTHEAST PUSH OF WELL
DEFINED HEIGHT FALLS FROM COASTAL B.C. INTO THE PACIFIC
NORTHWEST/NORTHERN ROCKIES.  WHILE PW VALUES ARE NOT EXPECTED TO
BE ANOMALOUS DAY 1 AHEAD OF THESE HEIGHT FALLS... GENERALLY AT OR
SLIGHTLY ABOVE AVERAGE... THE ONSHORE WESTERLY TO WEST
NORTHWESTERLY FLOW WILL BE STRONG AND PERSISTENT THROUGH THE DAY 1
PERIOD (ESPECIALLY THROUGH SAT AM).  THIS WILL SUPPORT WIDESPREAD
MODERATE TO HEAVY PRECIPITATION TOTALS IN THE FAVORED TERRAIN
AREAS FROM NW WY...NW MT...NORTHERN ID...NORTHEAST OREGON AND
WESTWARD FROM THE WA/OREGON CASCADES TO THE WA/OREGON COAST RANGE
AND OLYMPIC RANGE. IN TERMS OF THE QPF DETAILS...THE HIGH
RESOLUTION GUIDANCE WAS UTILIZED CONSIDERABLY GIVEN THE BETTER
RESOLUTION OVER THE TERRAIN.

HURLEY

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

24HR QP VT 29/00Z
 0.01 533168 532161 528156 527153 528149 528140 530129 529126
      526134 522137 519135 516129 511122 509117 505113 502107
      500100 498087 493078 488074 486068 483059 483055 486053
      501064 501057 500052 498046 496041 491032 487035 484032
      481027 474025 469014 463006 456000 448995 445993 441995
      437999 435004 430013 433030 432040 431044 432048 432052
      431055 428056 424057 420060 400055 397057 393061 389063
      387065 387068 387075 391080 395077 400080 402084 405089
      405100 404104 402105 398108 390114 386117 384122 388123
      391118 396121 398123 400127 404130 408130 412128 416131
      415140 415144 414147 409148 400155 403165 406168 411170
      416183 421188 423192 421198 417199 411200 409204 410207
      412208 414211 414215 411221 409228 407233 404238 401242
      400244 402246 405251 409252 411254 414258 419256 425257
      430259 435269 438275 441276 445275 448271 450267 453268
      456269 458272 464280 467285 473287 474283 476281 479280
      482281 486285 489282 492276 491271 490265 489262 490259
      494262 496268 497270 496274 496278 498281 499283 501281
      504276 506260 509241 513237 514231 516224 517219 519200
      522184 523174 524169 527169 531171 533168
 0.01 523723 523708 522701 520697 515690 510685 509679 509671
      509662 503635 500627 497625 493625 489626 487626 480627
      473627 467629 459633 449637 442641 435645 420654 413661
      411666 408669 396681 391687 386694 381700 378707 372713
      369714 367717 359727 358734 360733 362730 365726 367726
      369728 367737 365746 363751 363758 361766 358775 347803
      337814 330829 327836 325840 322841 320840 320837 321833
      320829 318830 309847 304852 309857 309863 307867 303874
      294886 290891 288890 289887 291880 291876 289872 286870
      284872 278876 271880 269886 269899 266909 262928 262933
      260936 254941 248951 241955 236959 234963 235965 237973
      232990 233999 235007 238013 240016 243018 247017 255013
      257010 261009 274007 278008 281011 285018 285023 286027
      286033 287036 286041 285044 281049 277056 275064 275068
      278071 280074 284075 290075 294073 299068 304060 308053
      312045 314041 315035 315028 317019 309005 307997 303990
      308984 312979 319971 324964 327960 330959 338958 341956
      344953 348947 352943 355937 364922 371907 378893 385879
      391871 396865 402857 405849 413836 423825 428820 434816
      440813 447807 453806 457806 460808 467811 471816 479821
      486824 490826 492823 497815 501809 502806 503801 504789
      505779 507759 508748 510739 513731 516733 519733 522728
      523723
 0.01 490196 487193 486190 485187 483187 479186 472186 465187
      459192 457194 455199 457203 460202 467202 474200 479197
      486196 490196
 0.01 486987 486982 486977 486974 484969 484967 482964 481967
      480969 480974 479977 480979 480984 482987 484988 486987
 0.01 477847 476837 474835 474830 470828 467833 465831 463832
      462835 462839 461849 462856 465871 466876 464880 463888
      465896 466900 468900 473888 475882 475872 471858 475852
      477847
 0.01 451850 451848 451845 451843 451840 449841 447843 447846
      448848 448850 448853 450853 451850 451850
 0.01 445082 444078 440077 436074 434073 435071 440068 440065
      436064 431062 427066 424066 422067 420075 418083 416090
      416095 417097 418101 420103 425102 427101 426098 423093
      423088 426088 428090 433094 436094 438091 441090 440086
      444084 445082
 0.01 283902 282898 280900 279903 277906 275908 274910 273913
      272915 273917 277914 278912 279910 280906 282904 283902
 0.25 507701 500685 494676 492674 494671 494667 491666 484668
      487671 491677 495681 497686 492685 489687 487690 485692
      483690 479684 476684 478686 478691 474697 474702 472704
      470709 466715 465718 468721 471726 473733 472741 469749
      477757 477765 477771 479774 483773 487768 489762 491752
      496740 496732 493724 491718 493713 496708 498706 501705
      505704 507701
 0.25 504145 503141 502137 498131 494123 490118 481106 478100
      477096 474094 470090 467091 467097 465102 462103 459103
      459108 463114 469119 464127 463131 460133 453135 449141
      446143 444143 440142 437144 435148 434152 436160 439165
      443171 445175 445178 441185 441190 441194 443197 447199
      451197 453193 458188 462184 464182 466177 468174 470172
      477169 482168 487166 492158 495161 498163 499159 501150
      504145
 0.25 491216 490210 486206 476206 468210 459212 439213 430218
      426219 422222 423227 426229 428232 429234 429236 425238
      425243 431244 435242 440242 459242 465241 470242 474245
      478246 480244 481240 480233 475231 471232 467232 469227
      472223 476222 486221 491216
 0.25 476672 474667 473665 470664 467664 465663 463663 461664
      460666 461670 463673 465673 467675 469676 471678 474680
      475680 475674 476672
 0.25 457232 458229 459227 458227 457227 456227 455226 453226
      452227 451229 450229 448231 448232 450233 452233 454232
      455232 457232 457232
 0.25 455653 454651 451650 448650 446650 443652 441654 440658
      442661 444662 446664 449662 451661 452659 454656 455653
 0.25 454115 455102 451099 446099 442100 438099 430102 423106
      424113 421117 423122 425126 428125 432121 436120 441121
      446121 450120 453117 454115
 0.25 445712 444712 442713 442716 443716 443715 444714 445712
 0.25 439757 438755 437751 438748 438746 435744 432744 430745
      428748 427750 427755 428759 431759 434761 436761 437760
      439757
 0.25 431171 430170 430168 430166 429165 428163 428162 427163
      426165 427168 428170 429171 430171 431171
 0.25 417799 417794 416790 412789 408791 405793 400794 395794
      391795 380801 366807 362811 361814 359813 355813 349814
      345816 341821 327844 319854 312867 305880 299891 293904
      291912 287918 283924 280929 272939 265950 256962 251975
      246986 243993 242000 243004 247006 255003 264996 273988
      285981 291978 297974 303970 307965 316956 320952 325948
      331943 336937 344926 350915 357903 365891 380870 388858
      396844 408819 414809 417799
 0.25 414073 413072 413071 412070 410068 409068 410069 411070
      412072 412073 413074 414073
 0.50 486215 486212 482210 476209 472212 467213 456215 446216
      442215 439216 435219 430222 430226 431229 436230 440228
      450225 455223 460225 463226 465224 469221 474219 480218
      484217 486215
 0.50 478241 479238 479237 478235 477235 476235 474237 475239
      475240 477241 478241 478241
 0.50 485143 487139 486134 484133 481131 478131 476131 473131
      471135 472139 475140 478141 480142 483144 485143
 0.50 482161 479156 474153 469148 466143 460142 458143 457147
      457155 458159 461160 466164 468166 471166 475164 481163
      482161
 0.50 460237 458235 457235 455236 454236 455236 456238 458238
      460237
 0.50 462181 463176 461174 458175 456175 455172 453169 452167
      450169 449173 450175 452178 453181 453186 455187 456186
      458184 460183 462181
 0.50 447114 447110 446107 444105 441104 438105 435106 433107
      432111 435114 438113 440115 443116 445115 447114
 0.50 393831 393826 392822 386820 380825 378828 376826 374823
      370825 365829 360830 358826 353823 348823 344825 340828
      334837 329846 315868 310877 305888 301899 297914 292924
      286932 279939 275945 272951 266959 260968 255980 254987
      257992 262991 266988 275982 283976 287971 292968 308955
      317949 326941 333931 339921 350899 363881 369871 376860
      382850 384845 388841 393831
 1.00 465157 465156 464154 463154 462151 461153 462155 462156
      463157 465157 465157
 1.00 447219 447218 445218 444217 442216 440217 440219 441221
      443221 444220 445220 447219 447219
 1.00 356857 349837 346835 341836 336841 327855 319870 312886
      309894 307903 306913 306916 308916 312918 311923 310926
      305931 299937 296940 292941 283945 279949 270966 267973
      268978 271978 283968 294956 297949 301947 305948 312945
      317940 322933 326924 332908 341893 345885 348877 353866
      356857
 1.50 342856 343851 342845 341841 339843 331852 324865 320879
      315892 313898 312907 312912 315914 319911 326898 331887
      337873 341860 342856
 2.00 339858 340853 339849 334851 331857 329861 326868 325872
      323879 325883 329880 332875 335869 337863 339858

$$




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