Quantitative Precipitation Forecast
Issued by NWS

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000
FXUS04 KWBC 200734
QPFPFD

QUANTITATIVE PRECIPITATION FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
333 AM EDT SUN AUG 20 2017


PRELIM DAY 1 QPF DISCUSSION
VALID AUG 20/1200 UTC THRU AUG 21/1200 UTC
REFERENCE AWIPS GRAPHICS UNDER...PRECIP ACCUM - 24HR


DAY 1


LOWER MO VALLEY INTO THE MID AND UPPER MS VALLEY AND UPPER GREAT
LAKES

MCS/EMERGING MCV ACROSS EASTERN NE-WESTERN IA DURING THE PRE-DAWN
HOURS SUNDAY WAS NOT CAPTURED WELL BY THE ECMWF...AS THE CONSENSUS
AMONG THE OTHER MODELS IS FOR A EASTERLY TRACK OF THE MCV ACROSS
NORTHERN IL BY SUN EVENING BEFORE DAMPENING CONSIDERABLY AS IT
MIGRATES INTO THE UPPER OH VALLEY. WPC UTILIZED PREDOMINATELY
NSSL-WRF AND WRF-ARW2 HIGH-RES CAM GUIDANCE WITH THE QPF FOR THE
INITIAL MCS...WITH THE HEAVIEST ACTIVITY MOVING SOUTHEAST INTO
NORTHWEST MO SUNDAY MORNING -- PARALLEL TO THE 850-300 MB
THICKNESS AND ALONG THE ELEVATED INSTABILITY GRADIENT.

THE MODELS ONCE AGAIN ADVERTISE ADDITIONAL MCS DEVELOPMENT SUNDAY
NIGHT-EARLY MONDAY...HOWEVER ALSO DEPICT DISTINCT LATITUDINAL
DIFFERENCES WITH THE QPF MAXIMA...WITH THE HIGH-RES CONSENSUS
GENERALLY FARTHER SOUTH OF THE GLOBAL MODELS (AS IS
TYPICAL...THOUGH SOME WITH A BI-MODEL DISTRIBUTION OF HEAVIER
AMOUNTS). SUBTLE RIGHT-ENTRANCE REGION UPPER JET FORCING WOULD
FAVOR A NORTHERN GENESIS REGION BETWEEN 00-06Z MON (I.E. IA INTO
NORTHERN MO)...HOWEVER GIVEN THE STRENGTHENING SW-WSW LOW LEVEL
JET/INCREASING UPWIND PROPAGATION OVERNIGHT...THE MODELS SHOW
MBE/CORFIDI VECTORS VEERING MORE NORTHERLY ~10-15 KTS OVERNIGHT.
AS A RESULT...WPC OPTED TO REMAIN SOUTH OF THE GLOBAL CONSENSUS
WITH THE STRIPE OF HEAVIEST QPF FROM 00-12Z MON...CLOSER TO A
BLEND OF THE WRF-ARW/PARALLEL ARW RUNS ALONG WITH THE PARALLEL
HREF MEAN. ONE CAVEAT: THE NSSL-WRF AND WRF-ARW2 ARE EVEN FARTHER
SOUTH (INTO KC METRO)...WHICH IS CERTAINLY PLAUSIBLE GIVEN THE
SOUTHWARD PROPAGATION POTENTIAL AND POOL OF UNTAPPED DEEP-LAYER
INSTABILITY...AND WILL AT LEAST TO SOME DEGREE DEPEND ON HOW FAR
SOUTH THE EFFECTIVE SURFACE FRONTAL BOUNDARY GETS WITH THE WEAK
~700 MB CAPPING IN PLACE. AS A RESULT...SUBSEQUENT FORECASTS MAY
CONTINUE A SOUTHWARD TREND.


SIERRA NEVADA / AZ-NM INTO SOUTHERN CO

A SHORTWAVE TROUGH WILL REMAIN ACROSS CA SUN-SUN NIGHT...WHILE THE
COMPACT WARM CONVEYOR BELT (WCB) ON THE EASTERN FLANK WILL
CONTINUE TO IMPORT MONSOONAL MOISTURE ACROSS EASTERN AZ AND THE
SOUTHERN ROCKIES. HIGHEST MOISTURE ANOMALIES WILL BE WITHIN THIS
QUASI-STATIONARY WCB...WITH PWAT VALUES AVERAGING 2-2.5 STANDARD
DEVIATIONS ABOVE NORMAL ACROSS MUCH OF NM. MEANWHILE...THE MODELS
CONTINUE TO DEPICT A MESO/CONVECTIVELY-ENHANCED VORT MAX ALONG THE
SOUTHERN AZ-NM BORDER EARLY SUNDAY LIFTING SLOWLY N DURING THE
DAY...THEN MORE NORTHEAST ACROSS NORTH-CENTRAL AND NORTHEAST NM
INTO SOUTHEAST CO SUNDAY NIGHT. GIVEN THE FAVORABLE DYNAMICAL AND
THERMODYNAMICAL SETUP...THERE CONTINUES TO BE A MULTI-MODEL SIGNAL
FOR OROGRAPHICALLY-ENHANCED HEAVY RAINFALL ACROSS FAR WESTERN TX
AND SOUTHERN NM INTO THE SOUTHERN ROCKIES. THE GUIDANCE CONSENSUS
(INCLUDING THE HIGH-RES MEANS) SHOW A FAIRLY WIDESPREAD...SOMEWHAT
ATYPICAL SWATH OF 0.25-0.50" OF AREAL-AVERAGE RAINFALL
TOTALS...WITH SOME OF THE CAMS INDICATING FAIRLY PRODIGIOUS
SMALLER-SCALE TOTALS (2-4"). AS A RESULT...WPC WILL CONTINUE TO
HIGHLIGHT A MORE ENHANCED (I.E. "SLIGHT") RISK OF EXCESSIVE
RAINFALL OVER MUCH OF NM INTO SOUTHERN CO WITH THE NEW DAY 1 ERO.

ACROSS THE SIERRA NEVADA...MODEST DEEP-LAYER INSTABILITY (MUCAPES
1000-1500 J/KG) ALONG WITH ANOMALOUS MOISTURE (PWAT VALUES ~2
STANDARD DEVIATIONS ABOVE NORMAL)...DIFLUENT UPPER FLOW/PERIODIC
DPVA...AND OROGRAPHIC ENHANCEMENT WILL FAVOR MORE WIDESPREAD
DIURNAL CONVECTION ALONG THE SIERRA...PARTICULARLY THE WESTERN
SLOPES. PER THE HIGH-RES GUIDANCE...LOCAL AMOUNTS BETWEEN 1-2+
INCHES ARE ANTICIPATED.


SOUTHEAST

A STALLED FRONTAL ZONE WITH POCKETS OF DEEP MOISTURE CONTENT WILL
CONTINUE TO YIELD MAINLY DIURNAL SCATTERED SHOWERS/STORMS ALONG
THE CAROLINAS COAST INTO SOUTHEAST GA AND BACK UPSTREAM INTO TO
THE WEST CENTRAL GULF COAST AREA OF LA UP INTO AR. ALSO, DIURNAL
SEA BREEZE ACTIVITY IS ANTICIPATED ACROSS FL...BASICALLY AROUND
THE PRONOUNCED UPPER RIDGE. OVERALL WPC FOLLOWED A BLEND OF THE
GLOBAL MODELS WITH HI-RES SUITE FOR QPF AMOUNTS.


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

HURLEY/MUSHER


24HR QP VT 21/12Z
 0.01 538210 538204 535199 532196 528195 524196 521200 517209
      514213 511215 509219 508227 506243 507248 506255 503260
      500263 495268 492271 489276 492285 495289 500292 506290
      510287 513283 517273 519257 522245 523237 525232 530224
      538210
 0.01 521773 521767 520760 518750 516738 514730 509722 505717
      502707 498701 493696 487695 485694 482697 479706 479714
      483718 486728 489737 492744 499745 506748 510752 514760
      517769 521773
 0.01 520908 520895 519884 516877 512873 509872 505875 501878
      496883 493889 490896 487902 481907 475910 472915 472922
      474927 477929 481928 488927 492927 494925 498924 500923
      504919 506916 510914 515912 519910 520908
 0.01 490680 488665 487658 485656 479650 473651 471655 465661
      460669 459679 463688 466690 471690 476688 479691 483691
      487689 489685 490680
 0.01 503842 502833 501828 500821 498816 494809 491810 488813
      487810 488805 487796 486790 482786 478787 468799 456815
      450824 446829 445833 436848 426864 420873 414881 410885
      406887 402891 400895 394916 387921 382915 380914 379910
      379903 381891 388870 384870 380873 376876 374880 370889
      370895 369898 367905 365907 363906 360903 354902 345906
      343912 342918 343924 345928 349931 352933 357933 361935
      364943 369953 369960 371965 373970 376974 380977 384976
      394970 396971 397974 398979 402000 404006 406010 410013
      415013 419008 422004 424993 426991 427994 429999 432009
      434018 436023 436031 439040 443043 448045 461045 465044
      471045 478049 482049 485046 486043 486039 484035 479029
      470024 465016 460005 457992 457965 457957 456950 456935
      456926 458921 462912 467901 471889 473878 475872 479868
      486864 492859 500850 503842
 0.01 433783 433778 432773 432768 431764 430762 429764 429767
      429771 428776 428779 429783 429788 430790 431788 432785
      433783
 0.01 405215 404211 402209 396203 386194 387191 383190 381190
      378187 373183 365181 351185 347190 346194 348198 350196
      349191 350187 355187 358186 362188 366189 369192 374196
      380201 385206 393208 399213 402215 405215
 0.01 412103 411098 408095 405098 401099 396095 392093 390096
      389102 386106 382106 379108 376111 370115 363117 349108
      349104 350102 354098 357095 359094 361095 366094 368088
      371087 375089 378090 380087 381083 382076 382067 384063
      387062 389063 391068 394067 398065 403067 407068 410067
      414060 415054 414052 411049 408051 400055 397049 389044
      381040 376034 372029 364024 359023 354024 350024 347027
      339031 331036 327038 323038 312037 306034 302035 300038
      291039 285043 279049 263056 260055 255055 253058 254062
      259068 261076 262080 264083 271089 279092 285095 286099
      287109 291116 292119 297120 302121 304123 312122 310119
      310117 312116 319117 323115 325112 329114 335115 338117
      340126 345132 346136 341137 336136 333138 331142 335143
      339148 340152 333156 337157 340157 341160 345161 349161
      353160 356163 361168 363168 364166 365161 368158 369151
      368140 373137 377136 382129 385126 389123 398113 402109
      407110 412103
 0.01 411842 411835 410830 405831 401834 398836 395839 393842
      395844 398842 401841 403843 406846 409845 411842
 0.01 392195 390194 390195 392195 392195
 0.01 392792 388786 383783 376785 372790 371793 371799 373801
      373806 368811 364814 354824 351837 352842 354841 357837
      360828 363823 371813 382806 387802 390796 392792
 0.01 364726 362722 359719 355719 352720 348720 346725 340731
      335733 330734 325735 322737 318742 313749 299760 292766
      282768 279770 276774 272782 268788 262791 246796 240797
      237800 232807 228821 226832 226839 232845 235848 239848
      243846 245842 245836 247832 251835 251837 251841 255843
      257845 259848 263854 268856 271859 273861 273865 267884
      263925 264932 265935 268939 272941 277942 281940 284939
      286943 288946 292948 291951 289954 284960 284965 286966
      301958 310954 319952 325947 330941 332938 333931 329926
      321923 319918 319911 315902 313897 313890 314886 313882
      311882 309884 306884 304882 304880 305877 305865 304858
      304853 310846 313843 314838 314835 316833 320832 327826
      332819 339806 342797 344793 345787 346783 343778 343775
      344770 351753 359740 363732 364726
 0.01 312922 313920 313918 312916 310918 310920 312922 312922
 0.01 305884 302883 300884 295887 288893 285904 285911 286916
      292925 294924 295921 293916 289906 289898 293895 295897
      298901 302904 303902 303899 303886 305884
 0.25 482849 480840 477835 473833 471836 468843 464841 461840
      458842 449850 446858 444865 444871 445877 447884 448887
      452889 458890 461896 466893 469886 469875 468870 468864
      470855 471852 475851 480852 482849
 0.25 443899 443893 440888 432887 427887 423890 418896 406908
      396924 392931 389935 389940 393949 396957 401966 404968
      407967 423960 428953 432945 435934 436921 438910 442901
      443899
 0.25 387201 386199 385200 385201 387201 387201
 0.25 383198 382196 382195 381194 379194 377194 376193 376194
      377194 379196 379197 380198 382198 383198
 0.25 373191 373189 371188 371189 371190 372191 373191
 0.25 369187 368186 366186 366187 367188 369187
 0.25 378071 378069 376067 375065 373064 371063 370063 368063
      369066 371067 372068 373069 374071 374072 375073 376074
      377073 378073 378071
 0.25 382952 381947 380942 379936 379931 377925 373924 371927
      370932 370936 372940 373947 375951 378954 381954 382952
 0.25 363076 365066 359060 363056 364053 364051 361049 355049
      352047 353044 358038 358034 352033 346038 335045 332046
      328045 318044 313048 307050 298050 294050 291051 285055
      279056 272058 266060 264064 266067 271071 283080 291089
      295094 298097 301098 309097 316097 323096 324091 327092
      336102 350081 363076
 0.25 355737 355733 354731 349734 341739 336744 331752 326758
      324759 321755 307764 301766 298768 290773 283778 278784
      273791 265795 258799 250804 248806 243807 238810 236814
      235822 234827 232830 230834 233838 236838 239834 244818
      246815 250815 260816 266823 272825 275822 276817 282815
      286817 291817 295816 304812 306808 309806 318802 325786
      334784 337774 345759 347752 350745 355737
 0.25 332804 332802 331800 330800 329802 328803 327804 326805
      326806 325808 324810 324811 326812 328811 329809 331807
      331806 332804
 0.25 323814 324812 322811 321811 320812 319813 317815 316817
      315817 314818 312820 311822 312824 314823 316822 317821
      318821 319819 320819 321817 322817 323815 323814
 0.25 324934 323933 323932 321931 319931 318932 318935 319936
      321936 323935 324934
 0.25 297832 293828 291824 285821 283822 281825 277833 270833
      266831 266827 265825 260825 258830 257836 265841 268846
      272848 277848 283850 286850 289848 290845 290836 295834
      297832
 0.25 287929 287925 286922 284920 282918 279917 277916 273917
      272917 270919 269923 270925 272928 274929 277930 281930
      285930 287929
 0.50 466888 467881 466877 465872 465866 465859 463855 462850
      460849 453852 449858 448862 448867 450877 452879 456881
      460886 462890 465891 466888
 0.50 421942 422935 422928 420923 417919 412913 408912 406915
      402924 396931 394934 393940 396951 403955 410951 416949
      419947 421942
 0.50 362067 361065 360065 360067 362067
 0.50 347745 346742 344745 342744 339744 338747 337749 336754
      336756 337760 341759 342757 343752 344750 345747 347745
 0.50 349057 349054 346052 339050 332050 327048 324047 320048
      320053 315055 310056 303056 297054 292055 287058 276063
      271063 271066 273068 282076 285079 290081 297083 303086
      307087 309085 308082 309076 314073 320072 323076 332086
      334091 336097 339095 339090 340086 342084 340082 337080
      336078 332074 327070 329066 333064 339064 344062 349057
 0.50 329772 329770 327769 326770 325771 325773 326773 328773
      329772
 0.50 321769 320767 320765 319764 319763 317761 315761 315762
      314763 313764 312766 310767 311769 313771 315771 317772
      319773 320772 320771 321769
 0.50 314796 306784 303783 301781 302778 302774 300773 296774
      293776 286780 281786 279792 277795 273796 264798 259802
      256804 255808 257810 261809 267806 271806 275807 280810
      287812 295812 302808 307803 312799 314796
 0.50 278840 277838 275838 274838 274840 275841 277841 278840
 0.50 263835 262833 262835 262836 263835
 1.00 456869 456867 455866 454866 453867 454869 455869 456869
 1.00 412933 413926 412922 410924 407928 403930 400933 398938
      398940 400946 403948 406945 408940 410937 412933
 1.00 335058 334056 332055 330054 329055 327055 328057 329057
      330058 332058 334058 335058
 1.00 298796 298794 297792 295791 293792 291793 291795 290797
      290799 292801 294801 296800 297798 297797 298796
 1.00 284802 284800 283799 281799 279800 279801 278803 280804
      281804 283803 284802

$$





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