Quantitative Precipitation Forecast
Issued by NWS

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000
FXUS04 KWBC 290605
QPFPFD

QUANTITATIVE PRECIPITATION FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
205 AM EDT SUN MAR 29 2015


PRELIM DAY 1 QPF DISCUSSION
VALID MAR 29/1200 UTC THRU MAR 30/1200 UTC
REFERENCE AWIPS GRAPHICS UNDER...PRECIP ACCUM - 24HR


DAY 1

...EASTERN U.S...

A COMPACT SHORTWAVE TROUGH OVER MONTANA AND THE DAKOTAS FEATURED
IMPRESSIVE COLD ADVECTION EXTENDING UP ABOVE 700 TO 500 MB PER THE
00Z ANALYSIS. THIS SYSTEM WILL DIG SOMEWHAT WHILE ALSO PROGRESSING
RATHER QUICKLY EASTWARD TODAY. HEIGHT FALLS WILL BE STRONGEST
ACROSS THE GREAT LAKES STATES. A SWATH OF 0.10 TO 0.40 INCH LIQUID
AND LIQUID EQUIVALENT PRECIPITATION IS LIKELY ACROSS THE NORTHERN
LAKES AT THE NOSE OF THE LOW LEVEL JET AS IT TRANSLATES EAST WITH
THE SYSTEM. TWELVE HOUR 700-500 MB HEIGHT FALLS OF AT LEAST 20-40
METERS WILL EXTEND AS FAR SOUTH AS TENNESSEE. MOISTURE WILL BE
LACKING IN THE ZONE BETWEEN THE FAVORABLE DEEP LAYER FORCING OVER
THE GREAT LAKES AND THE RETURNING MODIFIED GULF AIRMASS SOUTH OF
I-40...BUT THE MODELS DO GENERATE MEASURABLE PRECIPITATION UP TO
AROUND 0.10 INCHES OVER MUCH OF IL/IN/KY/OH.

FARTHER SOUTH...THE MODELS FEATURE A WSW TO ENE ORIENTED SWATH OF
MORE SUBSTANTIAL CONVECTIVE PRECIPITATION ANYWHERE FROM NORTHEAST
TX TO SOUTHERN TN TO THE GEORGIA PIEDMONT. WPC REMAINED
CONSERVATIVE WITH RESPECT TO PRECIP AMOUNTS GIVEN THE STRONG WIND
FIELDS...0-6 KM MEAN WIND 30 KNOTS OR BETTER...AND CONTINUAL
VEERING OF THE INFLOW. WITH DRY AIR INITIALLY AT LOW LEVELS AND
ESPECIALLY AT MID LEVELS...OUTFLOW MAY DRIVE THIS EVENT MORE
QUICKLY THAN THE MODELS SUGGEST. WE LIMITED HALF INCH AREAL
AVERAGE AMOUNTS TO NORTHERN MISSISSIPPI WHERE THE UPPER LEVEL
FORCING IS BEST PHASED WITH LOW LEVEL INFLOW AND MOISTURE AT THE
MOST UNSTABLE PART OF THE EVENING. GIVEN THE ANTICIPATED QUICK
MOTION...WE HEDGED EAST WITH THE EASTERN EXTENT OF PRECIP THROUGH
12Z MONDAY. WE WERE MORE CONSERVATIVE WITH COVERAGE BACK ACROSS
EAST TEXAS WHERE NAM FORECAST SOUNDINGS INDICATE A SHALLOW
SFC-BASED MOIST LAYER BENEATH A STRONG CAP. ACTIVITY THERE IS MORE
LIKELY TO BE POST FRONTAL AND MOVE ALONG TO THE ESE RATHER QUICKLY.

WPC QPF WAS DERIVED MAINLY FROM THE 12Z ECMWF AND 12Z
WRF-NMM...ALTHOUGH WITH SOME GENERAL SUPPORT ALSO SEEN IN THE 00Z
GFS. THE 00Z NAM MASS FIELDS APPEARED OKAY...BUT ITS QPF WAS LIGHT
AND DISPLACED NORTH OF CONSENSUS OVER THE SOUTHERN STATES..


...WESTERN WASHINGTON / BRITISH COLUMBIA...

SUNDAY/SUNDAY NIGHT WILL BE A TRANSITION DAY BETWEEN THE SHORTWAVE
DEPARTING INTO THE EASTERN U.S. AND THE NEXT LARGER SCALE TROUGH
DIGGING OFFSHORE. HEIGHT RISES WILL OCCUR OVER THE PACIFIC
NORTHWEST...LEADING TO A NORTHWARD MIGRATION OF THE GRADIENT
TOWARD STRONGER WINDS AND DEEPER MOISTURE PROFILES. THIS WILL
DIRECT MOST RAIN INTO SOUTHWESTS CANADA...ESPECIALLY THE COASTAL
RANGE...WITH SOME SPILLOVER INTO THE CANADIAN ROCKIES WITHIN THE
COLUMBIA RIVER BASIN. THE SOUTHERN EXTENT OF THIS MOISTURE STREAM
WILL CLIP NORTHWEST WASHINGTON... ESPECIALLY EARLY IN THE DAY. WPC
QPF REQUIRED ONLY VERY MINOR ADJUSTMENT HERE. WE TRENDED TOWARD
THE 00Z WRF-ARW WHICH ALSO MATCHED QUITE WELL TO THE GEFS
REFORECAST DATA WHICH IS SOMETIMES ESPECIALLY USEFUL IN THE
WESTERN U.S. FORECAST AMOUNTS REMAIN JUST UNDER ONE INCH ON THE
OLYMPIC PENINSULA...AND CLOSER TO 0.25-0.50 INCHES IN THE NORTHERN
CASCADES.

BURKE

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

24HR QP VT 30/12Z
 0.01 538205 537196 535191 532188 525170 521163 515157 509153
      504152 505156 510162 500161 496161 495163 488170 491178
      491184 493189 498189 506194 511199 514203 516207 522213
      528219 532219 534217 536212 538205 538205
 0.01 526255 522246 518237 514229 508220 504213 497206 488203
      480206 474212 474216 475219 478220 484225 484228 483231
      478228 473228 471231 469236 470243 478261 477268 477272
      478278 480284 485290 489294 493297 510296 520280 526255
 0.01 527068 527058 526049 523041 520035 517029 512024 507021
      500018 491010 486012 484020 484025 485027 489033 494037
      499042 503045 508053 513066 516072 521076 525073 527068
 0.01 508908 508892 508883 508880 506877 506872 504867 502862
      500859 497852 496840 494835 491830 485822 479814 473788
      469781 463775 460770 457762 454748 453741 452738 450736
      445734 441732 433730 430732 425735 422737 419741 412745
      405752 398753 393751 390748 385749 377758 371766 365773
      356787 349797 343805 332822 328831 324840 321844 321848
      319858 317870 318885 318894 320900 320915 321929 320944
      320955 321960 323965 325969 326971 329971 332968 334963
      336956 340952 343949 346943 354925 361909 365899 370889
      374885 375888 375892 374900 375907 378911 382911 384909
      387911 385916 384926 384932 386937 386940 387943 391945
      400938 405931 414924 421919 433919 440923 443927 444931
      446937 447946 445952 445961 443966 443975 445981 447983
      450983 454983 458980 464973 476962 487944 494935 497930
      501926 505919 508908
 0.01 491139 490139 489137 489136 487136 486136 485136 486136
      487139 489140 490140 491139
 0.01 405778 405776 405773 403771 402772 400774 399777 398777
      397778 395778 393780 392781 391783 392784 393785 394785
      396786 398786 399785 401785 402783 403783 404780 405778
 0.01 374051 375048 375046 374045 373044 373043 371041 370041
      369043 369046 368048 367049 366050 366052 367053 368053
      369052 370051 372051 374051 374051
 0.25 530202 528193 526180 525175 522170 516166 515170 514171
      511169 506168 503169 499172 500177 502184 508190 514195
      520203 524205 527206 530205 530202
 0.25 516270 519263 518257 515245 513237 508227 498211 495209
      492209 487210 482211 482216 483219 489228 490233 489235
      485235 482236 480234 476231 474233 472237 473243 477251
      483258 485261 487266 488278 492282 494282 498282 502283
      507282 509280 512275 514272 516270
 0.25 492899 493893 492888 490881 488871 485864 481848 478840
      474835 462805 461802 460797 457791 450790 450795 450802
      450804 446806 441809 439812 438816 440818 444819 450820
      453826 454828 454834 449840 440847 434852 427855 428860
      433864 438866 445868 453868 457872 458880 458893 458901
      461905 467908 475908 481910 484912 486910 491905 492899
 0.25 356881 356871 355861 353856 352854 351852 352846 353839
      355834 352830 347832 342838 340846 336853 334860 333869
      334879 335889 334896 333902 334908 339913 342913 344910
      351897 354890 356881
 0.50 527201 525193 525182 524178 522174 520178 516178 512173
      508171 505172 503174 505179 508185 513190 518196 524200
      527201
 0.50 512255 513249 512244 511239 508233 504224 500217 498213
      492212 485212 488223 492231 492236 495241 501247 507254
      509257 512255
 0.50 506274 503265 499256 495246 491238 486237 482239 478233
      474234 473240 477248 485254 490263 491267 494271 498273
      502277 505276 506274
 0.50 470895 470893 470890 470889 469888 468887 467888 466888
      466890 466893 466895 466898 467898 468898 469898 470895
      470895
 0.50 468880 468878 468877 466878 465881 465883 466885 467883
      468882 468880
 0.50 468861 467858 467856 467853 467852 466851 465849 464849
      463847 462849 462851 461852 461854 461856 461859 461861
      462864 464866 465865 467863 467862 468861
 0.50 452850 452848 451847 451848 449849 448849 446851 444852
      443853 442853 441855 441856 441858 443859 445859 446859
      448858 448857 449855 450854 450853 451851 452850
 0.50 351884 350879 345878 343877 340882 340889 340895 340899
      342902 346900 347897 349891 350886 351884
 1.00 507248 508244 507241 506237 503231 502228 500222 498219
      496216 494216 490219 491224 493230 494235 497239 500242
      503244 506248 507248
 1.00 496260 496257 494254 493251 493248 491244 490241 487239
      484240 483242 481244 481247 484249 487251 488254 490256
      491258 494261 496260
 1.50 503238 502236 501233 500229 499225 498222 496220 493220
      492222 493225 493229 495233 496236 497238 501239 503238
 1.50 491253 491250 491248 490247 490244 488243 487241 486243
      485246 486247 488248 488249 489250 490252 490253 491253
 2.00 500235 500233 499232 499229 499228 499227 497225 496223
      495223 494224 494225 494226 494228 495230 496231 496234
      498236 499236 500235

$$




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