Quantitative Precipitation Forecast
Issued by NWS

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000
FXUS04 KWBC 231958
QPFPFD

QUANTITATIVE PRECIPITATION FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
257 PM EST FRI FEB 23 2018


PRELIM DAY 1 QPF DISCUSSION
VALID FEB 24/0000 UTC THRU FEB 25/0000 UTC
REFERENCE AWIPS GRAPHICS UNDER...PRECIP ACCUM - 24HR


DAY 1

...NORTHEAST TX/SOUTHEAST OK---EAST NORTHEAST INTO PORTION OF THE
LOWER TN---LOWER MS VALLEYS AND ACROSS ALL OF THE OH VALLEY...

THE HEAVY RAINFALL THREAT WILL CONTINUE FROM THE LOWER MS VALLEY
INTO THE OH VALLEY THROUGH SATURDAY. IN FACT EXPECT SIGNIFICANT
AND POTENTIALLY LIFE THREATENING FLASH FLOODING TO DEVELOP OVER A
LONG CORRIDOR FROM AR NORTHEAST ALONG THE OH RIVER INTO KY AND FAR
SOUTHERN IN. THE OVERALL FLASH FLOOD THREAT MAY REMAIN IN A LULL
INTO THE OVERNIGHT BEFORE RAMPING UP TOMORROW. THE LEAD WAVE
CURRENTLY OVER OK WILL MOVE NORTHEAST THROUGH THE OH VALLEY
TONIGHT. THE AXIS OF RAINFALL WITH THIS ACTIVITY IS GENERALLY
NORTHWEST OF THE HEAVIEST AXIS THE LAST FEW DAYS...AND LIMITED
INSTABILITY SHOULD KEEP TOTALS AND RATES FROM GETTING TOO
IMPRESSIVE. MAY HOWEVER SEE SOME HEAVIER RATES DEVELOP TOWARDS
MORNING ACROSS THE OHIO RIVER VICINITY...AS ENHANCED 850 MB
MOISTURE TRANSPORT AHEAD OF THE WAVE RUNS INTO THE STALLED OUT
BOUNDARY IN THE AREA.

THINGS RAMP UP ON SATURDAY AS A STRONG WAVE EJECTS EAST INTO THE
PLAINS. OVERALL AN IMPRESSIVE SYNOPTIC SETUP...WITH LIFT AHEAD OF
THE WAVE AND A DUAL JET STRUCTURE IN PLACE...WITH THE REGION IN
BOTH THE LEFT EXIT REGION OF THE SUBTROPICAL JET AND RIGHT
ENTRANCE REGION OF THE NORTHERN STREAM JET. PWAT VALUES WILL
REMAIN AROUND CLIMATOLOGICAL RECORD VALUES AS WELL. ANTICIPATE
CONVECTION WILL BREAK OUT ACROSS NORTHERN TX AND SOUTHERN OK
DURING THE EARLY TO MID MORNING HOURS. THIS CONVECTION WILL
INTENSIFY THROUGH THE MORNING AND TRANSITION INTO A LINEAR LINE
MOVING ACROSS THE LOWER MS VALLEY. THIS CONVECTION WILL BE INTENSE
AND LOCALLY SEVERE IN NATURE...WITH HEAVY RAINFALL RATES LIKELY
FROM NORTHEAST TX INTO SOUTHEAST OK AND MUCH OF AR. COULD
POTENTIALLY SEE SOME CONVECTIVE ELEMENTS DEVELOP AHEAD OF THIS
LINE ACROSS AR...WHICH COULD MERGE WITH THE CONVECTIVE LINE. IF
THIS HAPPENS AMOUNTS WILL BE EVEN HIGHER OVER AR. EITHER
WAY...GIVEN THE VERY SATURATED CONDITIONS...EVEN A PROGRESSIVE
LINE DROPPING 1-2"+ OF RAIN IN A SH0RT TIME WILL PRODUCE
SIGNIFICANT FLASH FLOOD CONCERNS. A BETTER TRAINING SETUP APPEARS
TO BE UNFOLDING FROM NORTHEAST AR NORTHEAST ALONG THE OH RIVER. IT
IS HERE WHERE PERSISTENT STRONG 850 MB MOISTURE TRANSPORT WILL
PUSH NORTHEAST ALONG THE EARLIER STALLED OUT BOUNDARY. THIS SHOULD
SUPPORT SOME SOUTHWEST TO NORTHEAST TRAINING FROM SATURDAY
AFTERNOON INTO THE OVERNIGHT. THE COLD FRONT WILL REMAIN RATHER
PROGRESSIVE...SO THE DURATION OF THIS TRAINING WILL BE CAPPED BY
THAT...HOWEVER IT APPEARS LIKELY THAT THE TRAINING PERIOD WILL BE
LONG ENOUGH TO PRODUCE SIGNIFICANT FLOOD AND FLASH FLOOD CONCERNS
GIVEN SATURATED ANTECEDENT CONDITIONS.

WPC QPF STARTED CLOSE TO A BLEND OF THE AVAILABLE HIGH RES
GUIDANCE...AND BY LATE IN THE PERIOD WE STAYED CLOSER TO THE HRW
ARW AND ARW2 WHICH WHICH SEEMED TO SHOW REASONABLE EVOLUTION. THE
GLOBAL MODELS WERE SLIGHTLY FURTHER NORTH...AND WHILE WE PREFER TO
STAY CLOSER TO THE HIGH RES GUIDANCE...WE BLENDED SOME OF THESE
GLOBAL MODELS INTO OUR QPF...AS THE EXACT AXIS IS UNCERTAIN. THE
NEW WPC DAY 1 QPF IS THUS SHIFTED A BIT SOUTH FROM OUR PREVIOUS
FORECAST.

SO TO SUMMARIZE...A SIGNIFICANT FLOOD AND FLASH FLOOD RISK WILL
CONTINUE THROUGH SATURDAY...WITH THE WORST CONDITIONS EXPECTED
FROM MID TO LATE MORNING SATURDAY INTO SATURDAY
NIGHT....PROGRESSING NORTHEASTWARD WITH TIME. HIGH CONFIDENCE IN
THE LARGE AREA OF HEAVY RAINFALL...ALTHOUGH THE NORMAL
UNCERTAINTIES WITH THE EXACT AXIS OF HIGHEST TOTALS REMAINS.


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 25/00Z
 0.01 497326 485310 478304 470297 464291 462287 460283 452276
      447275 445277 440281 437282 431282 427281 418279 406275
      402271 398269 390267 388264 386260 384255 383251 384246
      384242 386240 391232 406225 410223 406220 399213 392208
      389205 387203 389201 398201 401200 400197 398193 393186
      386180 385175 386168 387154 389147 391143 394137 399140
      405142 409144 412143 412140 410136 406133 403130 404125
      406123 406119 403116 403113 403109 408107 413109 417112
      419111 421105 432094 440096 449096 455101 458106 463106
      467105 471106 471113 470117 472120 478127 487133 499146
      510159 519164 525170 531179 534184 536183 537179 539164
      544156 549147 552136 554133 554129 552123 553108 546101
      544095 544089 542082 542077 543062 543048 541037 540026
      539021 537016 537010 537005 538003 539986 541981 541976
      545974 549974 553985 555987 557988 559990 565010 566022
      566035
 0.01 500620 493622 481627 461635 421647 413653 407660 400668
      393675 390683 388691 388696 386700 383708 381706 379706
      376710 371711 365713 360716 357719 350724 345732 341740
      333754 330758 328763 328769 335771 340773 344772 350765
      353758 358750 361742 365733 367728 370724 375715 377710
      380714 383718 382726 381736 382742 381748 381752 380756
      377779 374787 368795 363800 359806 354813 352817 350822
      348827 345830 338837 330842 321844 321842 318843 315844
      309850 311853 312858 316864 320872 322876 319879 298884
      289885 280883 273881 267881 264884 263889 264893 267898
      270901 279905 288908 292908 297910 300913 302917 302922
      301926 297935 273001 276009 277018 279022 282021 285018
      287014 298011 301013 306013 311015 315016 324017 330017
      334015 340010 343008 345002 349993 352989 355987 357985
      360985 362989 365992 368990 370991 371994 370008 370016
      372021 377029 380034 380040 379047 374050 366051 358053
      355060 360062 358067 354074 351078 346079 342080 341084
      341087 339090 332094 329096 325100 323106 324111 329112
      335111 339114 344122 347130 351135 355136 361136 364135
      366132 366127 366121 365119 365115 365105 369093 373092
      376093 378096 379101 382100 387093 393088 400090 407089
      409094 411096 414096 421088 429070 439052 444044 445041
      449039 455034 462026 466018 468014 472012 476011 478007
      484002 485997 485992 484986 484982 479956 476950 474947
      468939 466934 466928 465924 463920 452906 449902 445899
      436896 433894 430890 427881 423871 421866 420858 419850
      418837 419801
 0.01 419801 420791 426788 427784 425782 422777 420771 420765
      421759 425763 431767 435768 439768 444768 446761 448759
      450758 454757 459758 462760 464762 465768 466776 465782
      464785 457788 457792 460793 463795 466794 472798 473801
      474805 473811 475817 477817 484804 490789 491786 492782
      494782 499788 501793 500798 500803 499806 503813 508813
      511809 512806 515798 518790 522781 529767 531758 534752
      538729
 0.01 523238 524235 524233 523230 522227 521226 519228 519231
      518233 518236 519237 521238 522239 523238
 0.01 521049 520043 522038 522031 520028 509040 498054 494064
      493076 493084 494090 496094 499098 497104 498108 499113
      499118 501129 507135 511136 511128 510122 510118 509111
      510105 511092 511084 510078 512073 515069 519061 519054
      521049
 0.01 481196 482192 480190 475189 470190 466190 463191 459193
      458199 461201 466203 471203 474201 478200 481197 481196
 0.01 460116 460114 459112 457113 457115 458118 460116
 0.01 426741 424739 424737 422735 420733 419735 419738 418740
      419743 419745 420747 422746 423744 425743 426741
 0.01 354799 352800 354799 354799
 0.01 324790 324786 322786 317789 313794 312798 307799 305801
      301801 291797 286793 282790 282786 280784 278786 279794
      280796 280800 281804 283806 287810 291812 299812 309805
      311805 312801 316798 321795 324790
 0.01 322771 320771 318772 319774 320774 322771 322771
 0.01 312873 312871 312869 310869 308869 306871 306873 307875
      307876 308876 310875 312873 312873
 0.01 287823 286814 282811 279806 276803 272801 272799 269793
      266788 263782 260776 256773 251771 245771 239774 232776
      229780 228785 226792 225794 222795 220799 220808 226819
      231828 232837 232844 234848 236848 241850 243852 247852
      251851 254852 253849 253842 250836 249830 249824 250818
      252816 255816 259820 262823 267825 272828 278828 284827
      287823
 0.01 269009 271007 270005 269004 268003 267002 266002 264002
      262002 261004 261006 262009 263011 265011 267011 269009
      269009
 0.01 262021 262017 260015 256012 253010 256008 258004 256000
      253000 250998 246998 247002 249004 247006 245007 246012
      249017 253020 259021 262021
 0.25 522262 518258 514253 511249 507244 503244 503249 501257
      497260 496265 496270 497276 499282 503287 508291 512290
      513289
 0.25 496228 497223 497218 495212 492207 487204 476206 467210
      456212 450212 444211 441210 438211 433213 424218 422220
      421224 421228 422231 415236 415241 417243 422246 426249
      432251 444251 454250 465246 469245 473247 479247 483244
      484240 483237 480231 473230 471228 472223 476222 481224
      485228 490229 493230 496228
 0.25 487169 486160 482154 478154 475153 469149 463146 460146
      458148 455154 453157 449157 445156 441156 439158 445162
      447165 448170 445191 447192 450191 454188 460185 464180
      467172 473172 485171 487169
 0.25 477139 478137 477136 476136 474135 473136 472138 474139
      475140 477139 477139
 0.25 446949 444941 442935 437934 434935 428937 422940 419945
      417954 417961 418972 418982 415984 414988 412996 414000
      415001 418994 425982 427975 433971 438969 442964 446949
 0.25 411789 411783 410777 407769 404763 399763 394768 391774
      388781 385786 365838 356849 350860 334878 329884 326886
      322887 309890 304893 297897 301899 306899 320895 322900
      325907 326912 325916 321920 322927 322932 321935 312946
      310951 308959 306966 308971 310973 310976 311983 313986
      317987 325987 332989 335989 338987 346978 355969 360965
      366963 380961 390955 393953 397952 402948 406943 406937
      405933 405926 406916 407897 408880 409839 409832 409821
      408803 411789
 0.25 355739 355735 352733 349736 347738 346741 344743 344746
      343748 343752 345753 348752 350749 352746 353744 354741
      355739
 0.25 264802 264800 263798 262797 261798 260799 260801 261802
      261803 263803 264802
 0.50 490219 490214 488210 485209 481208 474209 469213 463216
      456216 442215 435218 429220 425223 429229 435235 437236
      441234 445229 451226 454225 456227 458232 459232 469221
      472219 475219 483222 488221 490219
 0.50 456234 455233 454233 453233 452233 450233 448233 447233
      446234 445234 443235 443236 441237 442237 444240 445240
      446240 447241 449240 451240 453239 454238 455236 455235
      456234
 0.50 461180 462178 461176 459175 458176 456176 455177 454179
      455181 455182 457182 459182 461181 461180
 0.50 404792 404788 403783 400780 394782 391785 387790 386794
      383804 381811 379817 376828 373837 368847 365852 361855
      357858 355862 352868 348872 343878 338881 335885 331894
      329899 329906 332910 334915 335923 333929 326936 321943
      318949 316954 316966 319977 322980 329982 334982 337981
      351966 359960 366955 375950 382942 387933 391923 395912
      398900 400886 401873 401865 401858 403845 403837 402830
      400824 399816 401803 404792
 0.50 316892 315891 313891 311892 311894 311895 313894 315893
      316892
 1.00 481216 480215 479214 477212 475214 475215 477216 478216
      480216 481216
 1.00 397793 396792 396791 394789 393790 391791 390792 389794
      389797 389799 389801 390803 390806 390807 391805 392804
      393803 394802 395800 396798 396796 397794 397793
 1.00 388845 388839 387833 386831 383831 377844 367874 363876
      361878 358884 353897 351906 348913 341925 333936 330943
      328951 328958 327966 328970 331973 335973 342969 346965
      357956 366947 371942 375937 385906 387897 387889 387868
      387855 388845
 1.50 385850 385845 385841 384838 382841 381843 380846 379848
      378853 378855 378859 380861 383859 384857 384852 385850
 1.50 380904 379901 378903 374907 368916 366918 365916 366913
      369908 372901 373896 377882 378875 377871 372876 368879
      363889 357901 351911 345921 340932 337938 336945 333958
      332965 336967 341965 345963 354955 362947 370939 373934
      375929 379916 379908 380904
 1.50 364921 365918 364917 364918 363921 364921 364921
 1.50 363927 363925 363923 362921 361923 361924 360925 359927
      358930 359931 361931 361929 362928 363927
 1.50 354941 354938 354937 352938 351938 350939 349941 348943
      349945 350947 352945 353943 354941 354941
 2.00 375922 375918 374918 373920 371920 369921 368923 366926
      366929 366933 368935 370934 372932 373929 374925 375922
 2.00 369900 370895 369891 365894 361900 358905 351916 344928
      339941 337949 337956 339961 343957 346941 349935 352930
      359918 363913 366907 369900
 2.00 358945 359943 357943 355944 355945 355946 357945 358945
 3.00 343943 343941 343940 342941 343943 343943

$$





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