Quantitative Precipitation Forecast
Issued by NWS

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000
FXUS04 KWBC 161858
QPFPFD

QUANTITATIVE PRECIPITATION FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
157 PM EST THU NOV 16 2017


PRELIM DAY 1 QPF DISCUSSION
VALID NOV 17/0000 UTC THRU NOV 18/0000 UTC
REFERENCE AWIPS GRAPHICS UNDER...PRECIP ACCUM - 24HR


DAY 1

...WESTERN U.S...

A POSITIVELY TILTED LONGWAVE TROUGH WILL CONTINUE TO MIGRATE
INLAND ACROSS MUCH OF THE WEST. THE 500 MB REFLECTION IS NOT
OVERLY ANOMALOUS...BUT THE UPPER JET STRUCTURE IS SEASONABLY
STRONG...WITH SOME CONFLUENT PHASING OF THE SOUTHERN AND NORTHERN
STREAMS INTO A 150 KNOT JET CROSSING THE GREAT BASIN THROUGH
TONIGHT. THE SYSTEM HAD TAPPED INTO A SUB-TROPICAL MOISTURE
FEED...AND PRECIPITABLE WATER VALUES OF 0.50 INCHES INTO THE
COLORADO ROCKIES AND PERHAPS 0.60 TO 0.70 OVER UTAH WILL FAIRLY
ANOMALOUS...AT 2.0 TO 3.5 STANDARD DEVIATIONS FROM CLIMATOLOGY.
THIS...COMBINED WITH RELATIVELY SLOW MOVEMENT OF THE LARGE SCALE
SYSTEM WILL RESULT IN WIDESPREAD MODERATE RAINFALL AND
HIGH-ELEVATION HEAVY SNOWFALL. THE HEAVIEST RAIN AMOUNTS WILL BE
IN THE SOUTHERN SIERRAS BACK ACROSS CALIFORNIA...MAINLY THROUGH
EVENING...BEFORE EMPHASIS SHIFTS MORE SOLIDLY TO THE INFLECTION /
ENHANCED MID LEVEL SHORTWAVE TROUGH PASSING THROUGH THE GREAT
BASIN AND CENTRAL TO NORTHERN ROCKIES. A FRONTOGENETICAL EXTENSION
OUT INTO THE PLAINS...ESPECIALLY BASED ABOVE 700 MB...COULD LEAD
TO SOME BANDED PRECIPITATION...INCLUDING SOME SNOW...ACROSS
NORTHEAST WYOMING AND SOUTHEAST MONTANA...PERHAPS THE ADJACENT
DAKOTAS. THE BANDING MAY BE RELATIVELY SHORT-LIVED AND MODEL
SIGNAL IS SOMEWHAT INCONSISTENT AS TO THE MAGNITUDE. SEE THE WPC
HEAVY SNOW DISCUSSION...QPFHSD FOR DETAILS. OTHERWISE WHAT IS MORE
EASILY FORECAST IS THE TERRAIN ENHANCEMENT LEADING TO AT LEAST 1
TO 2 INCH AREAL AVERAGE LIQUID TOTALS FROM WESTERN WYOMING THROUGH
CENTRAL UTAH AND WESTERN COLORADO FROM 18Z TODAY TO 00Z SATURDAY.
SLIGHTLY HIGHER TOTALS ARE EXPECTED IN THE SOUTHERN SIERRAS.

WPC QPF STUCK CLOSE TO CONTINUITY BUT DID INCORPORATE SOME OF THE
12Z WRF-ARW2 AND OUR LATEST IN-HOUSE ENSEMBLE MINUS THE BIAS
CORRECTION WHICH TENDS TO REMOVE TOO MUCH OF THE LIGHTER AMOUNTS.
GIVEN LARGE SCALE SYNOPTIC AND FRONTAL FORCING...WE WERE MORE
GENEROUS WITH COVERAGE...ESPECIALLY OVER THE NORTHERN GREAT BASIN
WHERE HEIGHT FALLS ARE PARTICULARLY PRONOUNCED AND WHERE THE
MODELS TEND TO BE TOO DRY. OVERALL...THE UPDATED FORECAST WAS VERY
SLIGHTLY WETTER THAN THE PREVIOUS FORECAST CYCLE OVER MUCH OF THE
GREAT BASIN AND CENTRAL ROCKIES.


...EASTERN / NORTHERN U.S...

AHEAD OF THE WESTERN U.S. TROUGH...WARM ADVECTION AND UPGLIDE ON
THE 295K ISENTROPIC SURFACE WILL CONTRIBUTE TO A LIGHT
PRECIPITATION SWATH ACROSS THE FAR UPPER MIDWEST AND GREAT LAKES.
THE WRF-NMM...WRF-ARW...AND NATIONAL BLEND OF MODELS DEPICTED QPF
THAT WAS CONSISTENT WITH THE SHAPE OF THE ECMWF ENSEMBLE AND ALSO
SREF QPF PROBABILITY FIELDS. THIS WAS ALSO SIMILAR TO WPC
CONTINUITY...JUST SLIGHTLY HEAVIER FOR THE ARROWHEAD OF MINNESOTA.

FARTHER EAST...A COASTAL LOW IS FORECAST TO FORM AND QUICKLY TRACK
NORTHEASTWARD ACROSS NEW ENGLAND...BRINGING BOTH RAIN AND
SNOW...WITH THE ACCUMULATING SNOW CONFINED TO NORTHERN REACHES OF
VT/NH/ME. TRENDS SEEMED TO FAVOR A MOVE TOWARD THE NCEP
GUIDANCE...AND THE LATEST 12Z ECMWF SEEMS TO SUPPORT THIS MOVE.
WPC QPF BLENDED TOWARD THE WRF-ARW AND NAM...ALTHOUGH THE NAM WAS
LIKELY TOO STRONG IN MAGNITUDE...SO ITS INFLUENCE WAS TEMPERED.
OVERALL THE SYSTEM HAS TRENDED SOMEWHAT FASTER...SO THAT THE NET
RESULT IS A QUARTER TO HALF INCH LESS PRECIPITATION EXPECTED OVER
DOWN EAST MAINE COMPARED TO EARLIER FORECASTS...BUT STILL WITH
WIDESPREAD TOTALS APPROACHING A HALF INCH OF LIQUID.

BURKE

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

24HR QP VT 18/00Z
 0.01 466622 479629 485631 491638 495647 498659 499667 499673
      498680 497685 490701 488704 483706 479706 476704 473703
      471705 468709 465715 461724 458734 457747 453752 444757
      437761 428776 422780 418780 419776 420771 419764 419754
      425747 432742 438736 438729 437724 436716 435709 433709
      430711 424710 423701 425689 428680 433672 435664 437653
      439644 443640 446636 449631 452626
 0.01 535209 536198 535190 536180 532173 529167 525163 518156
      499141 490129 480122 473120 470119 467117 471108 469103
      467097 466094 467090 469075 467067 468058 468053 470048
      472043 477026 482009 485994 485990 482987 479991 470014
      469017 467019 466011 463005 460998 459996 456995 452995
      450998 448004 444012 440024 431034 433040 435044 436049
      434053 430051 426049 424047 423044 423040 426030 420016
      419013 416011 415010 411015 407028 401043 399048 395050
      389051 382051 378051 377048 373047 359049 355052 354058
      356062 358067 361074 365086 362092 366095 368093 371094
      376097 383104 380110 376114 371115 364114 357114 353115
      351118 353131 354138 359140 373140 377142 380147 381149
      385150 387152 386155 382167 379171 371172 365172 360174
      348181 344186 342193 339213 338221 341226 343227 344231
      348233 353238 356239 360238 370232 374230 376225 380219
      382217 387217 394220 394224 393228 388233 385235 385239
      386243 391246 403251 416254 429256 442254 456254 466252
      473253 479257 486249 495247 500246 504241 508235 509228
      508221 507217 508211 512205 515204 520205 528213 532212
      535209
 0.01 510854 510844 508836 504825 500814 496809 491807 486805
      479806 475808 472811 456828 443845 437854 434859 431866
      422886 417897 415903 413910 412916 412921 414924 416926
      422926 424926 426924 429919 432913 434909 439904 441902
      444902 448904 451906 452908 453911 452915 450921 447935
      448941 452945 460940 464937 467934 471930 473928 476932
      476945 479950 478958 477965 477972 480977 482977 486975
      492965 497957 501943 507934 507924 507921 505918 500907
      500888 503872 510854
 0.01 480195 481190 480185 480175 476173 472172 468172 466177
      463183 458190 454194 452199 451205 453208 455208 462206
      468202 474200 479197 480195
 0.01 403188 404186 402184 400184 399185 398185 397187 396189
      396191 397193 399194 401192 401190 403188
 0.01 402943 402938 398936 391935 386938 380943 375949 371954
      370958 371959 376959 379957 384954 391950 395950 398947
      402943
 0.01 375927 372922 368918 363914 357912 351913 344917 337926
      335933 334935 334941 334950 334954 335958 336960 340961
      344967 349965 354961 358957 363954 371943 373937 374933
      375929 375927
 0.01 314949 312947 308947 305949 302954 299957 297960 295964
      294968 296967 299966 303964 307960 308958 311954 314949
      314949
 0.01 276801 275798 272797 269795 266793 261793 261788 259786
      256785 250788 245793 241799 239805 240808 245807 252805
      261804 270803 276801
 0.25 522187 523181 518178 515176 511173 507171 504172 503176
      506182 509185 511185 515187 517188 522187 522187
 0.25 499232 499220 499214 496210 487207 482206 478206 471210
      463212 456214 447215 439216 431219 427220 425222 424225
      426227 431228 441230 443233 442235 442238 452242 461241
      464238 463234 468227 472223 475222 479222 484223 489225
      493227 496231 499232
 0.25 492669 490659 485651 481643 474640 468637 461636 457637
      454640 449647 446655 448665 449670 447674 444683 441692
      442694 445695 453696 459691 465688 472690 478693 481693
      484691 489684 492674 492669
 0.25 495148 493147 492145 492144 490144 489144 490145 491147
      491148 493148 494149 495148
 0.25 491165 489160 485156 481152 476147 467140 462137 456139
      449147 439151 439156 440158 446160 450165 453164 456162
      459160 466161 471164 476164 489165 491165
 0.25 480244 481241 480239 479237 477236 476236 474237 472239
      473241 473242 475243 476243 478244 480244 480244
 0.25 487141 486139 486136 485136 484134 483133 483132 481132
      479131 478131 476131 476132 474134 473136 473138 474139
      475139 477141 478141 480142 482142 483142 485142 487141
      487141
 0.25 495876 494866 494858 491851 488845 485841 481840 478840
      473843 470849 465861 464868 464876 467883 469890 468907
      472911 479911 482911 484909 487902 491890 493884 495876
 0.25 458111 458102 457094 455091 452090 446092 441091 434092
      430088 426084 423079 422074 422067 424061 421057 409053
      403052 398055 390058 384059 383065 382067 379067 375062
      371060 367060 365062 369070 371077 372083 374086 377087
      382088 396094 404093 403097 401099 397102 389109 383116
      380121 376124 371122 367119 362120 362124 364126 373130
      383127 395127 399130 399135 397138 391146 391150 393156
      393170 395173 397173 402171 405168 408166 411165 414167
      418169 422163 423155 422148 425142 428132 430126 434122
      438119 444120 449119 453117 456113 458111
 0.25 429245 428240 423235 421233 421230 421226 419225 414229
      410231 406234 403235 405238 408242 415244 422245 427246
      429245
 0.25 448077 449075 449073 448071 448070 447069 445068 443068
      441068 441069 441071 441072 443074 444076 446077 448077
      448077
 0.25 417206 417200 412198 406208 398202 390195 377180 368178
      364178 359179 352184 349188 350192 354195 353200 354206
      352211 351218 354222 360223 364222 369212 372209 377208
      386210 396215 403221 406222 410221 414217 414214 417206
 0.25 416151 415149 415148 414147 413148 413150 412153 411154
      411155 411156 413155 415153 416151
 0.25 373053 374051 372049 371050 370051 368051 367052 366052
      365053 363053 361053 360054 359055 359056 359057 361057
      362056 363056 365055 366056 368055 369055 370054 372053
      373053
 0.50 488665 483654 480650 477647 472647 467645 463644 457647
      453656 453662 454668 455683 460683 466681 471681 476682
      482688 486684 488679 488671 488665
 0.50 488218 490216 489214 488213 487213 486212 484211 483210
      481210 479210 477212 476212 475214 477216 478217 480218
      481218 483218 485219 486219 488218 488218
 0.50 490876 491871 490866 487859 484855 480855 477857 475862
      475868 476872 477880 476890 477895 480896 485892 487886
      489879 490876
 0.50 464221 464219 463218 461217 459217 457218 456219 456221
      457222 458223 460223 462223 464221 464221
 0.50 452220 450219 449219 447219 445219 443219 442219 441219
      440220 438221 439224 441224 443224 444225 446224 448224
      450223 451222 452221 452220
 0.50 439224 438221 436222 435223 436224 437224 439224
 0.50 451107 451102 449099 442096 436096 430092 426092 429100
      428103 425103 420103 418104 415104 412101 408098 406101
      394109 389114 388117 391119 407123 415122 419122 423124
      425124 427122 431116 434114 438113 443114 447114 451107
 0.50 415073 416062 411058 408056 404055 400055 398057 391061
      385063 385069 383072 379072 376070 376065 373063 369062
      366063 371068 373071 374075 373081 376083 380083 384085
      387087 388084 384079 385077 388078 390082 392082 401082
      404081 406079 408077 412077 415073
 0.50 397210 397205 394202 388195 382189 375182 372181 367179
      359181 355184 355187 361195 365201 376204 386207 395211
      397210
 0.50 360215 358214 360215 360215
 1.00 409110 410108 409105 407103 406105 405106 405107 403108
      402108 401109 400110 399111 398112 396112 396113 398113
      399114 401115 403115 405116 406115 407114 408112 408111
      409110
 1.00 387201 384196 381192 377187 373184 367181 361182 358187
      362190 366194 371198 376201 383202 387201
 1.00 402074 402072 401069 400069 399069 398070 396071 396073
      397075 399075 401075 402074
 1.00 392075 393073 394071 393068 392067 391066 389067 388068
      387070 386072 387073 388074 390075 391075 392076 392075
 1.00 374066 373065 371064 370063 369063 369064 371066 373067
      374066
 1.50 407110 407107 405109 404109 403110 402111 403113 404114
      405114 406112 407111 407110
 1.50 380199 381194 378191 375187 371185 368183 364182 361185
      361188 365191 368193 372196 375198 380199 380199
 2.00 378196 378193 376191 374189 371186 370185 366184 363184
      364188 365189 368192 370193 372195 375196 378196

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