Quantitative Precipitation Forecast
Issued by NWS

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000
FXUS04 KWBC 211933
QPFPFD

QUANTITATIVE PRECIPITATION FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
232 PM EST WED FEB 21 2018


PRELIM DAY 1 QPF DISCUSSION
VALID FEB 22/0000 UTC THRU FEB 23/0000 UTC
REFERENCE AWIPS GRAPHICS UNDER...PRECIP ACCUM - 24HR


DAY 1...

...EASTERN PORTIONS OF THE SOUTHERN PLAINS / LOWER-MID MISSISSIPPI
VALLEY / TN/OH VALLEY...

HEAVY RAINFALL AND FLASH FLOODING CONTINUES ACROSS PORTIONS OF
EAST TX INTO CENTRAL AND NORTHERN LA AND SOUTHERN AR. IT IS HERE
WHERE THE SURFACE FRONT HAS STALLED OUT...AND STRONG 850 MB
MOISTURE TRANSPORT CONTINUES TO POINT INTO THE BOUNDARY. THIS
SETUP FAVORS CONTINUED TRAINING OF CONVECTION INTO THE EVENING.
THE LATEST HIGH RES GUIDANCE SUGGEST THE HEAVIEST RAINFALL RATES
CONTINUE THROUGH ABOUT 02Z...THEREAFTER THE THE MID LEVEL WAVE AND
UPPER JET BEGIN LIFTING OFF TO THE NORTHEAST RESULTING IN BOTH
LESS SYNOPTIC ASCENT AND DECREASED LOW LEVEL MOISTURE TRANSPORT
INTO THE BOUNDARY. THUS WOULD EXPECT RAINFALL INTENSITY AND
COVERAGE TO DECREASE AFTER THIS TIME...WITH A BROAD AREA OF
MODERATE TO LOCALLY HEAVY RAINFALL THEN SHIFTING NORTHEAST INTO
THE TN AND OH VALLEY THROUGH THE OVERNIGHT HOURS. ANTICIPATE AN
ADDITIONAL 2-4" (LOCALLY AS HIGH AS 4-6") ACROSS CENTRAL/NORTHERN
LA INTO PORTIONS OF FAR SOUTHERN AR AND POSSIBLY INTO FAR WESTERN
MS. FURTHER NORTHEAST...LOOKING AT 0.75"-1.5" TOTALS INTO PORTIONS
OF THE TN AND OH VALLEYS. LOCALLY HIGHER AMOUNTS ARE LIKELY
HERE...AS WHILE MOST OF THE RAIN SHOULD BE MORE STRATIFORM IN
NATURE GIVEN LIMITED INSTABILITY...SOME EMBEDDED CONVECTIVE
ELEMENTS AND HEAVER RATES ARE PROBABLE. WOULD ANTICIPATE AN
ISOLATED FLASH FLOOD RISK WOULD EXIST WHERE ANY HIGHER RATES DO
MATERIALIZE WITHIN THIS TN/OH VALLEY CORRIDOR THROUGH THE
OVERNIGHT HOURS.

FURTHER SOUTH LIKELY TO HAVE AT LEAST SOME CONTINUED CONVECTIVE
COVERAGE ALONG THE STALLED OUT BOUNDARY OVER PORTIONS OF
TN/MS/AR/LA INTO THURSDAY. GIVEN THE WEAKER FORCING NOT EXPECTING
THIS ACTIVITY TO BE AS INTENSE OR ORGANIZED...BUT STILL COULD
PRODUCE SOME ISSUES GIVEN INCREASINGLY SATURATED CONDITIONS.
ANOTHER ROUND OF BETTER MID/UPPER LEVEL FORCING BEGINS TO EJECT
INTO THE SOUTHERN PLAINS AND LOWER MS VALLEY BY THURSDAY
AFTERNOON. THIS WILL EVENTUALLY HELP TRIGGER A MORE ORGANIZED AREA
OF SHOWERS AND THUNDERSTORMS. DETAILS BY THIS POINT ARE LOW
HOWEVER...WITH A WIDE RANGE OF SOLUTIONS DEPICTED BY THE HIGH RES
AND GLOBAL MODELS.

OVERALL WPC QPF THROUGH THE DAY 1 PERIOD STARTED WITH A BLEND OF
THE 12Z HREF, 16Z NBM, 12Z HRW ARW/ARW2 AND 12Z GFS...WITH SOME
MANUAL ADJUSTMENTS BASED ON RECENT RADAR TRENDS ALONG WITH BOTH
HRRR AND EXPERIMENTAL HRRR RUNS.

CHENARD




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 23/00Z
 0.01 553150 549150 546154 544158 541162 539164 535169 532169
      528169 529175 532179 534184 533190 534195 536202 538205
      539205
 0.01 533233 525220 523217 521213 518204 517201 514200 510193
      506189 504186 501186 495189 490190 484194 481200 479201
      475201 471204 459207 458210 456211 454208 453202 454196
      456191 457185 460176 460138 460131 454132 449133 447135
      444133 448116 456115 456110 455106 452104 451107 445107
      442110 441115 440125 439127 437129 436126 436121 434117
      437110 437107 434107 431108 427108 423107 420104 415101
      411100 408098 404097 402093 406088 411084 416079 419072
      419064 416057 413052 411054 407054 405055 401054 395052
      392053 388052 381050 376047 369048 357051 354052 352056
      346060 344062 346064 348067 349071 349076 348079 343085
      339089 337091 336095 337098 339100 343098 346096 349095
      354092 359088 360092 363093 375088 384089 389093 394098
      396097 397100 395103 391109 384113 377119 373123 371126
      372131 395122 401125 406121 406119 409119 414125 415128
      413132 411136 408138 400138 392139 388139 385140 382146
      381153 384157 386160 384162 379165 377167 377173 377180
      382186 383188 380188 377186 373184 364183 359185 363189
      374201 379206 383210 394217 404220 408221 407224 403225
      399224 393223 379224 374225 368228 367228 367232 368236
      370238 377244 383249 394257 406263 413265 419269 425274
      429280 457284 461286 464285 467284 470282 483276 487272
      489263 495246 498227 501225 504228 507236 512250 519252
      521250 522245 522242 524242 525246 525254
 0.01 471947 471934 469923 465915 462907 458901 454903 450910
      446911 442910 433901 425902 422902 420904 414909 410908
      408905 401900 401894 403889 408872 413851 416838 421821
      423812 425804 427795 429785 431778 433770 436753 437743
      438734 438722 437709 435670 433657 430651 426651 424650
      419655 408665 398674 391680 387687 383694 381698 376701
      370713 366717 363723 360729 359738 355746 352751 348752
      345754 343758 343762 343763 347761 351760 353758 358752
      362746 370731 374725 376723 378724 379732 376739 375746
      375756 373766 371774 370782 369792 368796 366798 360803
      355808 350814 344819 341828 339843 337860 336865 332868
      326872 320877 317878 314877 312875 308874 305876 302888
      304897 305902 304906 301910 298913 291918 286922 283927
      282930 279933 273935 265937 260940 252941 247946 243950
      239955 238964 237967 239971 238976 237980 235981 236987
      233993 234998 236001 253018 258016 260009 267005 271003
      275003 281005 284004 288004 291003 294002 296004 302007
      305009 309009 316006 325003 331000 345004 361006 370007
      376011 379013 381019 382026 387024 390018 394013 399016
      404021 407031 409034 412036 422037 431027 437024 442020
      450010 455003 457995 464979 469962 469953 471947
 0.01 450102 450100 450097 448096 446096 445096 444096 444099
      444101 446102 448102 449102 450102
 0.01 364223 365220 364220 363220 362220 362222 362223 364223
      364223
 0.01 354233 354229 354226 353224 349223 349225 350227 351230
      349234 347236 345237 345239 346241 348241 349237 352235
      354233
 0.01 364827 364823 363820 361822 360824 358825 356828 357831
      357834 356837 357840 359837 360834 361832 362829 364827
 0.01 344173 343168 340164 333161 329161 327162 323165 320171
      316176 310175 305176 302178 300182 301186 303191 310201
      314204 319204 323204 325203 325198 326189 325183 334178
      342177 344173
 0.01 290782 288774 283770 276769 267771 265775 268777 271780
      272783 276790 278799 278802 280805 283806 285804 288795
      289792 291789 290782
 0.01 267806 266798 264794 260791 258793 255798 254801 251801
      246798 244795 244788 247785 250780 249776 245771 241771
      231775 227779 225784 224797 221807 221821 223829 225834
      231842 233848 236852 240854 247854 251850 252845 252838
      250836 250832 249824 249817 250812 252807 255806 258807
      261809 265808 267806
 0.25 455241 450232 442227 440224 436222 427223 423223 419225
      415232 413238 415242 418245 423247 427247 431246 433242
      437240 440242 445245 450246 454243 455241
 0.25 439256 438254 436254 436255 438256 439256
 0.25 442161 443159 442158 441156 439154 438153 437153 436152
      434152 432154 432157 433159 433161 434162 434164 434167
      434168 435167 436165 438166 439165 440164 441164 442162
      442161
 0.25 431730 430724 427719 422721 418726 411723 408720 407715
      406707 404706 402712 398716 397720 397728 395738 381782
      376803 376809 374816 369825 364835 358846 353853 348862
      337880 332888 326895 322898 319903 312912 307920 303929
      298938 294947 286953 279958 274960 270964 267969 266974
      270976 274976 280970 285967 288964 291964 293965 297968
      306971 314971 317975 320980 324984 329983 347978 352975
      354971 358968 363970 369977 373979 378977 384977 390975
      401972 405970 408967 413958 419947 420941 418935 415933
      410933 406934 402937 399941 394944 390947 384950 375954
      372956 370958 367957 364955 361951 360948 361943 362938
      364927 367914 374906 381897 392881 402865 407854 410842
      413830 416817 423796 426785 428772 429760 431747 431736
      431730
 0.25 398208 398206 397205 396203 394202 393201 391202 390204
      391206 392207 393208 395209 397210 398208
 0.25 385203 386200 384200 382197 384200 385203 385203
 0.25 386063 384058 381053 376052 370052 366054 362056 359061
      356064 357070 362072 371077 375080 379080 381078 382075
      383071 382069 373062 370059 371055 375055 381058 386063
 0.25 265988 265986 265984 264984 262984 261985 260986 259988
      258990 259992 260992 262992 264990 265988
 0.25 254992 253990 251988 248986 246985 244987 242989 241992
      241996 243998 246999 249998 251996 253994 254992
 0.25 243823 243817 240813 238811 238808 238800 236790 232787
      230791 230797 230802 231810 232822 233828 235832 237836
      238838 240839 242839 242835 243825 243823
 0.50 421766 420761 419759 412757 408760 405765 400776 397782
      393787 389792 387794 388799 388808 386815 383820 379824
      374828 369830 362841 356852 351862 345873 331892 324900
      321905 318911 313924 307934 305938 303945 303948 305950
      309951 312951 318949 321947 323949 330957 330971 334971
      338967 346956 351946 354941 356935 357927 355921 358913
      361907 364903 368898 377891 384881 391871 398862 401858
      404851 406836 410821 412808 418796 419790 420782 420772
      421766
 0.50 376073 377071 377069 376067 375065 373064 372064 371064
      370063 368063 367066 367067 368068 368070 369071 370073
      371073 372074 374074 376074 376073
 0.50 249994 249992 248990 248989 246989 245990 244990 243992
      242994 243996 244996 246997 247996 247995 249994
 1.00 408796 407792 406789 403789 400788 398788 396789 395791
      395796 395799 397802 398805 398807 400808 402806 404804
      405801 407799 408796
 1.00 391835 391829 389826 384829 372837 367844 364850 356861
      348873 340884 330896 326900 324903 323909 317922 314928
      313933 317933 321935 324934 330930 335928 341921 358899
      366887 375875 378867 382863 387857 386855 382857 375861
      374858 375855 381851 386845 390841 391835
 1.50 377844 378841 377841 375844 377844 377844
 1.50 364865 364858 359861 352870 345879 338888 331896 327900
      326905 331908 333913 339912 343908 350899 356889 359883
      361878 364865
 1.50 328919 328917 328915 327913 326912 324912 324913 323915
      323916 322917 322919 322922 321924 321926 323928 325928
      326927 327926 328924 328921 328920 328919
 2.00 356874 354871 352875 348879 343884 338890 334895 332899
      336897 339897 338900 338904 340903 345897 349891 352883
      354877 356874

$$




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