Quantitative Precipitation Forecast
Issued by NWS

Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46
000
FXUS04 KWBC 191844
QPFPFD

QUANTITATIVE PRECIPITATION FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
244 PM EDT SUN MAR 19 2017


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


DAY 1...

...WESTERN U.S AND NORTHERN PLAINS....

A DEEP CYCLONE IN THE CANADIAN PRAIRIES AND WELL NORTH OF THE U.S.
BORDER WILL DRAG A PACIFIC FRONT THROUGH THE PLAINS...WHILE THE
TRAILING PORTION OF THE FRONT REMAINS STALLED OVER THE
INTERMOUNTAIN NORTHWEST U.S...AWAITING LOW PRESSURE AND THE NEXT
ORGANIZED LARGE SCALE SYSTEM TO APPROACH OFF THE PACIFIC. THE LEAD
SYSTEM OVER THE MIDDLE OF THE CONTINENT WILL DRAG WITH IT A NARROW
PLUME OF MODESTLY FAVORABLE MOISTURE...PRIMARILY AT MID
LEVELS...WITH OROGRAPHICALLY ENHANCED LIGHT TO MODERATE
PRECIPITATION IN THE NORTHERN ROCKIES SPILLING OVER IN A LIGHT
FORM ONTO THE NORTHERN HIGH PLAINS THROUGH SUNDAY NIGHT.
MEASURABLE PRECIPITATION MAY HAVE A DIFFICULT TIME FORMING FARTHER
DOWNSTREAM INTO THE LOWER TERRAIN OF THE EASTERN DAKOTAS GIVEN DRY
LOW LEVEL CONDITIONS AND A RELATIVE LACK OF SUSTAINED FORCING.

BACK WEST...HEIGHT FALLS WILL BRUSH THE CA/OR COASTLINE MONDAY.
ASSOCIATED SURFACE LOW PRESSURE WILL REMAIN OFFSHORE AND TRACK
NORTHWARD PARALLEL TO THE COAST BEFORE A SECOND SHORTWAVE
DUMBBELLS AROUND THE SOUTH SIDE AND THE UPPER TROUGH MOVES MORE
BODILY INLAND MONDAY NIGHT AND TUESDAY. OVERALL...WPC FAVORED A
NON-NAM CONSENSUS...BUT ON DAY 1 ISSUES WITH THE NAM ARE
MINIMAL...AND ITS QPF WAS SUPPORTIVE OF OTHER SOURCES SUCH AS THE
ECMWF...GEFS REFORECAST DATA...AND NDFD...WITH ALL SUGGESTED A
SLIGHT REDUCTION OF QPF INTENSITY RELATIVE TO THE PREVIOUS
FORECAST CYCLE. WPC BEGAN WITH A 50/30/20 BLEND OF ECMWF / OUR
IN-HOUSE ENSEMBLE / PREVIOUS WPC FORECAST. WE USED SOME HI-RES
MODEL SIGNAL AND ENSEMBLE PROBABILITIES TO ADJUST SOME OF THE
DETAILS WITHIN THE INTERMOUNTAIN REGION OF OR/ID/WY/MT. GENERALLY
THE 12Z GEM REGIONAL LOOKED GOOD...BUT WAS TOO AGGRESSIVE WITH
PRECIPITATION DOWN INTO UTAH WHERE THE TANDEM OF MOISTURE DEPTH
AND FORCING SHOULD NOT SUPPORT MORE THAN SMALL COVERAGE OF LIGHT
MEASURABLE PRECIPITATION.


...GREAT LAKES / MIDWEST / OHIO VALLEY...

MODEL AGREEMENT IS USUALLY HAMPERED WHEN THERE IS POTENTIAL FOR
WIDESPREAD LIGHTER AMOUNTS UNDER A HALF INCH. THIS IS THE CASE
THROUGH MONDAY AS A RIDGE-TOPPING CYCLONE IN CANADA DROPS
DOWNSTREAM AND BRINGS SOME FLOW AMPLIFICATION AND MODERATE HEIGHT
FALLS TO THE GREAT LAKES THROUGH MONDAY. A MODIFIED GULF AIR MASS
WAS RETURNING AHEAD OF THIS SYSTEM...BUT THERE WILL BE LITTLE
OVERLAP OF HEIGHT FALLS AND DEEP LAYER FORCING WITH THE TONGUE OF
MOISTURE UNTIL THE MID LEVEL HEIGHT FALLS PROGRESS INTO LOWER
MICHIGAN AND BORDERING INDIANA / OHIO. UNTIL THEN...DRIER LOW
LEVELS UP NORTH MAY YIELD SPOTTY AND FAIRLY LIGHT RAIN. FARTHER
SOUTH...UPGLIDE ALONG THE 300 K ISENTROPIC SURFACE WAS WELL
MATCHED TO ONGOING SCATTERED CONVECTIVE RAINS IN MISSOURI...AND
WOULD SUGGEST A FOCUS REDEVELOPING TONIGHT FROM EASTERN IOWA INTO
CENTRAL/SOUTHERN ILLINOIS. WPC PREFERRED QPF GUIDANCE THAT
EXPRESSED ALL OF THESE ASPECTS...USING A BLEND OF THE 00Z ECMWF
AND 12Z NAM/GFS WITH THE PREVIOUS WPC FORECAST. THE RESULTING
FORECAST SHIFTS THE OVERALL AXIS OF PRECIPITATION SLIGHTLY
NORTHWARD...BUT QPF MAGNITUDE AT ANY GIVEN LOCATION DID NOT CHANGE
MORE THAN ONE OR TWO TENTHS OF AN INCH.

BURKE

GRAPHICS AVAILABLE ON THE WEB AT
WWW.WPC.NCEP.NOAA.GOV/QPF/QPF2.SHTML

24HR QP VT 21/00Z
 0.01 470620 470626 469631 465639 458655 449670 440683 429695
      425703 422706 419707 413704 410701 408698 409693 411690
      417684 421677 425669 428661 430651 432643 435635 437632
 0.01 535201 536196 535193 535188 533185 532184 530183 528185
      528188 529194 529196 528199 528204 529207 533206 534203
      535201
 0.01 478243 480239 480234 478230 474231 469229 462222 461215
      457214 453215 448213 447210 448206 450202 461185 464175
      466163 468157 470149 470143 469137 467124 466117 466109
      469098 470083 471066 470053 471040 472025 470014 467009
      466003 462991 460988 457985 455983 452983 450988 449994
      450000 451007 451015 450023 449029 442033 441038 443043
      446048 445055 441059 435059 431061 431068 437074 444080
      447085 443088 432088 427089 426092 425101 427102 427106
      427113 426121 426130 425137 423144 418150 415153 414157
      412160 413169 416175 420176 425177 428178 428181 425184
      423188 424191 429189 434190 435195 430203 426205 424199
      420197 416198 413201 410205 407206 401206 390204 386205
      385208 382209 374210 363208 359210 355212 348218 345221
      342225 340230 341235 341239 339243 338251 341255 346257
      351259 356260 359261 360263 364273 366277 370279 374279
      380281 390283 395283 400285 412286 420286 424285 428282
      436280 443279 450275 457269 462267 464264 473253 478243
 0.01 497853 496842 496840 493839 491835 486833 477830 472828
      467829 465831 462831 456831 453828 450826 451823 453817
      450813 447807 446802 437775 434771 429771 423772 420775
      412776 408778 403781 400785 396786 392791 389796 388801
      386815 386831 386845 383857 380864 379870 379875 380877
      380881 377891 376896 378902 380911 381917 384922 387926
      389930 394932 407932 412936 415939 418944 421949 423947
      425943 425926 426917 428912 430906 433902 436897 439894
      449889 455887 459886 469881 479877 488872 493862 497853
 0.01 416102 415097 413094 408093 405095 402097 400102 397106
      396110 396115 401116 403114 407110 411108 413106 416102
      416102
 0.01 307032 307030 307028 306028 305027 303027 302027 301029
      301032 302034 303034 304034 305034 306033 307032
 0.01 291073 291070 289068 287068 285070 283072 280073 278075
      278076 279079 283079 286078 287076 289074 291073
 0.01 292027 293023 293018 291016 289015 285015 282015 280017
      280018 281021 283023 286024 288027 290027 292027
 0.25 459632 456630 453632 449636 444641 441646 439651 437658
      438663 441665 446661 450655 453650 455644 458638 459632
 0.25 452255 454250 454246 452240 447236 443234 438234 434234
      432232 429228 425224 418221 414217 411217 408218 405222
      400225 396226 383225 378225 374227 371231 374236 377240
      379243 378246 373255 369260 371266 375269 381272 393273
      404275 411276 416276 425273 434269 443264 452255
 0.25 460101 458095 452093 446094 443095 440094 436097 433104
      435112 438115 441117 445116 448113 450111 454112 458108
      460101
 0.25 461050 461049 461050 461050
 0.25 450168 451166 451163 451161 451159 450158 449157 448155
      446153 445152 443152 442154 442157 443159 444161 444162
      445164 446164 447166 448167 448168 450168 450168
 0.25 424832 425827 424822 421816 418811 415814 413821 412828
      409833 409838 413844 415846 417844 421839 423834 424832
 0.25 415872 414870 414868 413865 412865 411866 410866 409866
      408866 407868 407871 408873 408875 409876 411877 412877
      413877 414875 414874 415872
 0.25 414912 413907 410904 404899 406887 405876 402874 398876
      392883 388890 386895 387900 392907 398913 401915 407915
      413914 414912
 0.25 368235 368230 363227 359229 356232 354236 351242 350246
      349249 350251 354250 358248 360244 363241 365238 368235
 0.50 441256 442251 441247 432245 426241 417239 406229 400231
      393233 387235 387238 388241 390245 389250 384255 380261
      382265 385267 393267 399270 406271 413272 427268 438260
      441256
 0.50 443108 443106 442104 441103 439105 439108 440109 442110
      443108

$$





USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.