Quantitative Precipitation Forecast
Issued by NWS

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000
FXUS04 KWBC 170658
QPFPFD

QUANTITATIVE PRECIPITATION FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
158 AM EST SAT FEB 17 2018


PRELIM DAY 1 QPF DISCUSSION
VALID FEB 17/1200 UTC THRU FEB 18/1200 UTC
REFERENCE AWIPS GRAPHICS UNDER...PRECIP ACCUM - 24HR


DAY 1

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

THE MODELS TODAY SHOW ONE UPPER JET MAX PROGRESSING INLAND AND A
LOW AMPLITUDE RIDGE CROSSING FROM THE PACIFIC NORTHWEST AND THE
NORTHERN ROCKIES. RAINFALL REDEVELOPS LATER TONIGHT OVER THE
NORTHEAST PACIFIC...AND THEN MOVES ONSHORE IN RESPONSE TO A
REINVIGORATED UPPER JET. FROM 18Z SAT TO 00Z...THE NAM FORECASTS
300 MB 150 KT JET MAXIMA INTO NORTHWEST WA WITH UPPER DIVERGENCE
EXTENDING ACROSS
THE OLYMPICS AND CASCADES...CONTINUING INLAND INTO THE RANGES OF
NORTHERN ID/WESTERN MT.

THE COMBINED STRENGTH OF THE DEEP LAYER FLOW WITH THE UPPER
DIVERGENCE TO PROVIDE LIFT ALONG WITH ASCENT IN WINDWARD TERRAIN
WITH ABOVE NORMAL MOISTURE AND MOISTURE ADVECTION RESULTS IN
WIDESPREAD VALLEY RAIN AND MOUNTAIN SNOWS. HIGHEST TOTALS ARE
EXPECTED IN WA STATES ACROSS NORTHERN ID AND NORTHWEST MT DUE TO
THE LONGER JET RESIDENCE TIME THERE. WPC QPF WAS COMPRISED OF A
MULTI-MODEL BLEND OF BOTH GLOBAL AND HIGH-RES GUIDANCE....WITH 1-2
INCHES OF LIQUID EQUIVALENT PRECIPITATION EXPECTED IN THE WA
OLYMPICS/CASCADES AND RANGES OF NORTHERN ID.  SEE THE WINTER
WEATHER DESK GRAPHICS FOR POTENTIAL SNOWFALL AMOUNTS.


...LOWER-MID MS VALLEY / TN-OH VALLEYS / CENTRAL-SOUTHERN
APPALACHIANS / MID ATLANTIC / NORTHEAST...

A RATHER DYNAMIC SETUP IS IN STORE FOR THE DAY 1 PERIOD, WHICH IS
NOT REFLECTED VERY WELL IN THE MASS FIELDS PER THE RELATIVELY FLAT
UPPER FLOW AND WEAK SURFACE LOW. SOUTHERN STREAM SHORTWAVE ENERGY
EMANATING FORM THE SUBTROPICAL JET WILL QUICKLY TRAVERSE THE
SOUTHERN PLAINS EARLY TODAY, THEN MOVE ACROSS THE TN VALLEY BY
LATE AFTERNOON AND THE MID ATLANTIC REGION THIS EVENING.
MEANWHILE, AT THE SAME TIME A STRENGTHENING/AMPLIFYING NORTHERN
STREAM JET AND ROBUST VORT LOBE WILL MOVE FROM THE CENTRAL CONUS
AND ACROSS THE NORTHEAST. THE NORTHERN STREAM WAVE AND ASSOCIATED
150+ KT 250 MB UPPER JET STREAK IN THE LEE OF THE TROUGH WILL
PROVIDE A BROAD (SE-NE) AREA OF ROBUST RIGHT ENTRANCE REGION
FORCING (UPPER DIVERGENCE AND LOW-MID LEVEL FRONTOGENESIS).
MEANWHILE, THE NEARBY PRESENCE OF THE ELONGATED SOUTHERN STREAM
AND INFUSION OF SUBTROPICAL MOISTURE AND FAST-MOVING SHORTWAVE
IMPULSES WILL RESULT IN IMPRESSIVE (ANOMALOUS) MOISTURE PARAMETERS
FOR MID FEBRUARY -- ESPECIALLY SOUTH OF 40N -- INCLUDING 850-700
MB MOISTURE FLUX ANOMALIES AROUND 3-3.5 STANDARD DEVIATIONS ABOVE
NORMAL PER THE SREF/GEFS. THE SWIFT PROGRESSION OF BOTH
NORTHERN/SOUTHERN WAVES ALONG WITH THE ABSENCE OF ELEVATED
INSTABILITY (AT MOST <200 J/KG) WILL MITIGATE THE RISK OF
EXCESSIVE RAINFALL ACROSS THE TN VALLEY-LOWER OH INTO THE WESTERN
SLOPES OF THE SOUTHERN AND CENTRAL APPALACHIANS. HOWEVER, GIVEN
THE ANTECEDENT CONDITIONS/WET SOILS AND THUS STILL LOW FFGs, WPC
WILL MAINTAIN THE MARGINAL RISK ACROSS THIS AREA FROM YESTERDAY`s
DAY 2 ERO.

IN TERMS OF THE QPF, WPC DISCARDED THE GFS NORTH OF THE MID
ATLANTIC DUE TO WHAT LOOKS LIKE CONVECTIVE FEEDBACK (I.E.
NOTICEABLY LIGHTER TOTALS NORTH OF AN AXIS OF 0.50-1.0" AMOUNTS).
OTHERWISE, A NON-GFS MULTI-MODEL BLEND WAS UTILIZED, WHICH
COMPARED FAVORABLY TO THE CONTINUITY (PREVIOUS FORECAST).

HURLEY/PETERSEN

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



THIS DISCUSSION WILL TRANSITION TO MIXED-CASE FEB 26, 2018.  THE
LISTING OF ISOHYET POINTS CONTAINED BELOW WILL ALSO BE ELIMINATED
FROM THE PRODUCT FEB 26, 2018.  ISOHYET GRID INFORMATION WILL
CONTINUE TO BE GENERATED IN A VARIETY OF BINARY FORMATS AND MADE
AVAILABLE THROUGH THE WPC GIS PAGE.

24HR QP VT 18/12Z
 0.01 528248 528230 527215 526201 527191 526183 527176 529172
      529168 528163 520142 514131 510120 505109 504101 504092
      503087 503080 501068 499039 498031 498023 495008 492994
      489982 481964 478960 476954 474949 471944 463938 459937
      455940 452953 450960 450968 437002 439009 442013 447022
      452025 453029 453033 453041 451045 449046 442038 439039
      441043 443046 446048 444050 440060 434070 434073 436075
      439079 440083 437084 431082 422078 419081 417085 415091
      416097 413101 409102 405102 402106 402111 404116 413123
      417127 416136 414152 413157 413161 415166 415171 414177
      413182 413190 411195 405206 399205 396205 395207 398212
      401216 405219 408218 411214 413213 414215 414218 412220
      409224 394230 391234 390242 388251 389255 393260 396266
      399270 404271 408272 413272 419274 423278 428280 431283
      436284 440283 447285 451285 454287 456290 457297 458302
      460307 463312 466313 467316 477320 481319 483316 485308
      487303 489296 490292 492293 500296 505294 510292 514288
 0.01 535848 535839 534831 529820 518804 515801 511799 507794
      505787 501778 496767 495762 499760 505754 509747 510742
      510734 509728 508723 503713 497707 491704 487704 485708
      489718 494728 495735 494738 491737 484730 481725 478721
      476720 473725 474729 477733 476739 473740 470743 465745
      460746 457748 456754 456760 455771 457775 460776 462778
      462782 460785 456786 455779 451780 448783 447789 447797
      445802 441805 435806 430809 430814 432818 433823 431828
      429833 426838 421847 418851 415851 411849 411843 410838
      411835 413823 416816 422810 424807 426801 430791 461709
      469691 472683 474678 474672 473667 470663 465660 462656
      460648 458644 455642 450641 444642 440642 434643 423646
      417649 413652 397666 390672 384680 376696 371704 366710
      359716 353722 346727 341731 333739 332744 332750 334762
      329770 324777 332781 336782 340787 341795 341799 340801
      333808 329814 327822 323829 320838 318848 319858 320861
      320864 318868 314879 312884 307884 300893 298902 297913
      293923 289934 286944 283953 279962 277971 279974 282976
      288976 291985 288994 287999 285003 285011 283014 281015
      269014 265013 259012 258016 260019 265017 270018 273022
      274026 294033 301028 303025 305021 306009 307003 308998
      312979 314973 316970 318977 319983 321986 323986 330987
      333986 338977 345969 348966 354963 362959 366957 372957
      383957 386956 389952 391947 392940 395929 395917 393908
      389899 391895 394897 401901 408910 415914 419914 419918
      417922 415927 416933 419945 422950 426952 432952 435950
      442945 449940 452936 455933 459925 462914 463909 465905
      470898 475893 478892 483890 486889 488891 490898 492907
 0.01 492907 495919 499926 504929 505927 512921 517913 521905
      524897 527886 530873 531862 534851 535848
 0.01 490825 488823 487824 485826 484827 482829 484831 486831
      487831 489828 490825
 0.01 464201 463199 463198 462196 460196 459195 457195 455196
      454196 453197 453198 451200 451203 451205 452206 453206
      454205 456205 457204 458204 458202 460201 461201 463202
      464201
 0.01 457057 457054 457052 456050 456049 455047 453047 451049
      451051 451054 453056 454058 456059 457057
 0.01 311102 311091 310085 308083 305079 303076 296071 287071
      282072 279074 279080 280084 280091 282093 286093 289091
      295091 298093 303101 308104 311102
 0.01 313862 313850 312839 306835 301840 289849 284855 278860
      273865 270872 270876 271878 269880 263882 264886 267889
      269896 278896 284890 286887 291885 296882 300880 303876
      305875 307871 313862
 0.01 271073 271069 269066 264061 259057 252053 247049 244048
      241048 238051 239054 245058 251063 256067 260072 267074
      271073
 0.01 256803 253799 248800 244796 240795 237790 233790 230794
      231800 236810 237821 236824 237827 239831 240838 244839
      249838 252834 253829 252822 251815 253810 256803
 0.25 516270 518257 518249 516244 512222 509212 509201 509191
      509180 508167 505156 508149 505139 498123 492107 489096
      486087 483077 479067 477063 474060 470059 467062 465064
      464071 463082 461094 457095 451093 436094 434095 431092
      424087 427102 423104 420107 420111 418112 415114 417117
      422119 429123 434119 438117 441118 443120 447122 448126
      447128 439137 436135 432138 431150 432154 434158 438164
      443169 445173 446177 441186 444190 447192 451192 455190
      462186 467184 472184 475186 477189 477196 474200 472202
      466207 461206 457209 454211 449212 446213 442213 429216
      422221 423226 426229 425233 421234 416234 412236 409237
      409241 416246 423249 430250 437250 447251 456252 459252
      465253 480263 494273 507272 514274 516270
 0.25 440667 439660 437656 434652 430651 423653 416658 411662
      406668 399673 393678 388684 384692 377708 373715 369722
      360731 355739 353742 354746 357745 360742 362740 366740
      366748 366758 368775 367788 366797 361815 356823 351827
      346831 342836 340847 340856 342867 342880 344889 342898
      341906 340915 339928 338938 333956 334961 336962 339961
      343956 350945 355937 360931 366927 370924 373920 375913
      376903 378884 380862 387844 392830 398814 404797 405791
      403785 403781 405778 409773 411765 414758 419752 426734
      428730 429724 432716 435708 437699 438680 440673 440667
 0.25 450078 450077 449075 448073 446071 446070 445069 443068
      441068 440069 440072 441073 443074 444076 446077 446078
      448079 449079 450078
 0.50 503246 505241 505236 504227 503211 502202 503196 501182
      500174 499165 496151 497145 495138 491128 488123 483118
      478116 475115 473112 472106 469102 460101 462106 466110
      469115 469118 467120 465125 461129 452134 450137 450142
      449146 446146 442144 438141 437140 436143 434149 435155
      439160 447169 449176 450179 450184 454187 458185 462183
      465179 470177 476179 484189 484193 481198 473203 469208
      465209 459210 457212 453213 435218 425221 425225 428226
      432231 434235 432236 430238 435241 442242 467246 473247
      478250 488256 495258 498252 503246
 0.50 480228 479226 479225 477224 476225 475226 473226 473227
      475228 477229 478229 480228
 0.50 455103 453098 451095 445097 441095 437095 435097 432095
      429091 427090 425091 430099 430103 427105 425106 428110
      430114 434114 441115 444117 446116 450114 452112 451107
      455103
 0.50 448077 448075 446072 445070 443070 441072 443073 444075
      446076 447077 448078 448077
 0.50 429243 428240 426240 424240 423241 422241 421243 422244
      423245 425245 427244 429243
 0.50 429666 426660 421658 413665 404674 395681 391686 387691
      382702 378713 374724 374756 376765 378771 382774 386774
      393771 395765 402757 408745 411741 413735 415728 417722
      421710 424705 426698 428683 429666
 0.50 396800 396795 394791 392789 389789 384792 381798 373808
      367818 360828 352837 349843 352849 351862 348895 347903
      348911 351916 353918 356916 360911 363905 367894 370877
      373864 375856 377848 382837 388824 393812 396800
 1.00 496226 495222 495217 494213 493209 487205 482203 476205
      473206 472208 470212 466212 461213 449215 442216 439216
      438219 436221 437224 444227 448228 451227 454227 458228
      464228 467227 469224 474221 481222 485224 489224 494225
      496226
 1.00 483242 479233 474232 467233 465230 461230 455233 452234
      448233 447238 449240 456240 463240 470239 476243 480244
      483242
 1.00 486164 485158 481153 476150 471147 466143 460143 458145
      457150 458155 460157 464161 467167 469169 471168 474167
      477168 483166 486164
 1.00 476134 474133 474134 476135 476134
 1.00 463178 463176 463175 461173 459175 458177 457177 456179
      455181 455182 457183 458182 459182 460182 461181 462179
      463178
 1.00 446111 446109 445108 445106 444105 443103 442103 441101
      439102 438103 438105 437106 437107 435109 437111 438110
      439110 440110 441110 442112 443113 445112 446111
 1.00 433097 432097 431096 430094 429094 431097 432097 433097
 1.00 392722 391714 389707 388705 385705 382710 380716 379723
      379732 382741 385742 389738 392732 392725 392722
 1.00 378825 379821 375820 370822 362832 359837 358843 356858
      354872 354880 354886 356890 358890 359883 362870 365856
      366849 368844 374833 378825
 1.50 490219 489213 486209 480206 476207 474209 472212 468213
      459216 454215 450218 444217 441217 441219 444224 449225
      453222 456224 462226 464224 467226 470221 473219 485220
      489220 490219
 1.50 479241 480239 479236 478234 476234 474234 473237 474238
      475240 477241 478241 479241
 1.50 457237 457236 455235 454236 455236 456237 457237
 1.50 468155 467152 466150 465149 464148 463146 463145 461146
      462148 460150 460151 461153 462154 463156 464156 465157
      466157 467156 468155
 1.50 387719 386717 384717 383720 383721 383722 383724 383727
      384728 385726 385725 386724 386721 387720 387719
 2.00 486215 485214 485212 484211 483209 481209 479208 478209
      476209 475209 474210 473211 472214 472216 473217 475217
      476217 478217 480218 481218 483218 484217 485215 486215
 2.00 478238 477236 476236 475237 475238 477239 478238
 2.00 471218 470216 469215 468215 466215 465217 465219 465221
      466222 467223 468222 468220 469219 471218
 2.00 462223 464221 463219 461218 459218 457218 456217 454216
      453218 454220 454221 455222 457223 458223 460224 462224
      462223
 3.00 480213 479212 477212 476212 477213 479213 480213

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