Quantitative Precipitation Forecast
Issued by NWS

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511
FXUS04 KWBC 191857
QPFPFD

QUANTITATIVE PRECIPITATION FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
256 PM EDT FRI MAY 19 2017


PRELIM DAY 1 QPF DISCUSSION
VALID MAY 20/0000 UTC THRU MAY 21/0000 UTC
REFERENCE AWIPS GRAPHICS UNDER...PRECIP ACCUM - 24HR


DAY 1...

...PLAINS/MS VALLEY...GULF COAST STATES...OH/TN
VALLEYS...MID-ATLANTIC...

THE STRONG CLOSED MID TO UPPER LOW CURRENTLY CROSSING THE CENTRAL
ROCKIES WILL EJECT EAST OUT ACROSS THE CENTRAL PLAINS THROUGH SAT.
THIS WILL DRIVE SURFACE LOW PRESSURE FROM THE SOUTHERN HIGH PLAINS
NORTHEAST UP THROUGH THE UPPER MIDWEST...WITH A VIGOROUS TRAILING
COLD FRONT THAT WILL CROSS THE MS VALLEY THROUGH SAT. THIS STRONG
SYNOPTIC SCALE SYSTEM WITH AN IMPRESSIVE ARRAY OF JET
FORCING/DYNAMICS WILL BE INTERACTING WITH PLENTY OF DEEPER LAYER
MOISTURE/INSTABILITY TRANSPORT FOR WIDESPREAD SHOWERS AND
THUNDERSTORMS WHICH WILL BE FOCUSED ALONG AND AHEAD OF THE COLD
FRONT. ONE OF THE MAJOR CHALLENGES TO THE FORECAST FOR THIS PERIOD
THOUGH IS THE PRESENCE OF A PRE-FRONTAL DIFFERENTIAL
HEATING/OUTFLOW BOUNDARY OVER NORTHERN TX AND SOUTHEAST OK
INCLUDING THE RED RIVER VALLEY AREA. THIS BOUNDARY WILL BECOME AN
EFFECTIVE FRONT THAT IS EXPECTED TO INTERCEPT SOME OF STRONGER
SOUTHERLY LOW LEVEL FLOW AND ASSOCIATED MOISTURE TRANSPORT WHILE
ALSO REPRESENTING A NEW WELL-DEFINED INSTABILITY GRADIENT FOR
CONVECTION TO FOCUS ALONG. MEANWHILE...AN UPSTREAM JET MAX
EJECTING OUT OF THE SOUTHERN ROCKIES WILL PIVOT THROUGH THE
SOUTHERN HIGH PLAINS AND PLACE THE RED RIVER VALLEY AREA IN A
FAVORABLE REGION FOR STRONGER JET ASCENT/FORCING WHICH SHOULD AID
CONVECTION. WHILE THERE WILL STILL LIKELY BE CONVECTION FARTHER
NORTH ALONG THE COLD FRONT...IT IS EXPECTED THAT THE MORE
ORGANIZED CONVECTION WILL BE FARTHER SOUTH CLOSER TO THE RED RIVER
VALLEY OVERNIGHT AND THROUGH EARLY SAT...WITH A CONVECTIVE AXIS
THAT EXTENDS NORTHEAST UP ACROSS CENTRAL/EASTERN AR AND MUCH OF
EASTERN MO BEFORE THEN GRADUALLY ADVANCING EAST INTO THE OH VALLEY
DOWNSTREAM. PWATS OF 1 TO 2 STANDARD DEVIATIONS ABOVE NORMAL AND A
GOOD SET-UP FOR TRAINING/BACKBUILDING CELLS WILL PROMOTE AS MUCH
AS 2 TO 4+ INCH RAINFALL TOTALS...WITH THE HEAVIEST TOTALS LIKELY
NEAR AREAS OF FARTHER NORTHERN TX AND SOUTHEAST OK. AN OTHERWISE
LARGE AREA OF 1 TO 2 INCH AMOUNTS IS STILL EXPECTED FOR THE
GREATER MID MS/OH VALLEY AREA. PLEASE CONSULT THE LATEST QPFERD
AND ERO FOR DETAILS CONCERNING THE FLASH FLOODING POTENTIAL.

BY LATER SAT...CONVECTION WILL EXTEND SOUTH DOWN ACROSS
CENTRAL/EASTERN TX WITH THE TAIL END OF THE FRONT AND WITH THIS
PORTION OF THE FRONT SLOWING DOWN...THUNDERSTORM ACTIVITY WILL
LIKELY LINGER BEYOND THIS PERIOD AS WELL. ELSEWHERE...EXPECT THERE
TO BE MUCH MORE NUMEROUS SHOWERS AND THUNDERSTORMS ACROSS PORTIONS
OF THE GULF COAST STATES AND ADVANCING NORTH UP ACROSS THE TN/OH
VALLEYS AS THE GUIDANCE FAVORS A RATHER NOTABLE TROPICAL MOISTURE
SURGE ADVANCING NORTH OUT OF THE GULF OF MEXICO AND LIFTING UP
THROUGH THE TN VALLEY. DIURNAL HEATING AND SMALLER SCALE MESOSCALE
CIRCULATIONS INCLUDING SEA-BREEZE INTERACTION WITH TEND TO BE THE
DRIVER OF THE CONVECTION OVER THE GULF COAST STATES...BUT THERE
WILL BE MORE SYNOPTIC FORCING FARTHER NORTH OVER THE OH/TN VALLEYS
GIVEN THE APPROACHING UPSTREAM TROUGH. MEANWHILE...THERE WILL BE A
BACKDOOR COLD FRONT THAT WILL HAVE SLIPPED SOUTH INTO THE
MID-ATLANTIC REGION AND WILL BE DRAPED UP OVER THE CENTRAL
APPALACHIANS BEFORE THEN EXTENDING WEST THROUGH THE OH VALLEY TO
THE UPSTREAM SYNOPTIC LOW CENTER. THIS FRONT COUPLED WITH
OROGRAPHICS WILL BE A FOCUS FOR NUMEROUS SHOWERS AND THUNDERSTORMS
THROUGH SAT AFTERNOON. WELL TO THE NORTH CLOSER TO THE SURFACE LOW
LIFTING THROUGH TOWARD THE UPPER MIDWEST...EXPECT MORE DEFORMATION
ZONE/TROWAL ENHANCED MODERATE TO HEAVY RAINS HERE AND ESPECIALLY
WITH THE CORE OF THE MID/UPPER LEVEL TROUGH AND CLOSED LOW
CROSSING THE REGION. WPC QPF ACROSS THE CENTRAL AND EASTERN
U.S...GENERALLY FAVORED A SOLUTION MUCH CLOSER TO THE LATEST
HRRR/HRRRX RUNS AND THE 12Z ARW/NSSL-WRF SOLUTIONS.


...NORTHERN ROCKIES...

THERE WILL BE ANOTHER SHORTWAVE TROUGH DIGGING SOUTHEAST ACROSS
THE NORTHERN ROCKIES BY LATER SAT WHICH IN CONJUNCTION WITH
DIURNAL HEATING AND OROGRAPHICS SHOULD PRODUCE NUMEROUS SHOWERS
OVER THE HIGHER TERRAIN. THE MOISTURE PROFILES WILL NOT BE
PARTICULARLY IMPRESSIVE...AND THE GUIDANCE GENERALLY AGREES IN
LIGHT PRECIPITATION TOTALS AT THIS POINT. SOME POCKETS OF TOTALS
MAY LOCALLY EXCEED 0.25 INCHES...ESPECIALLY NEAR THE
BITTERROOTS...BUT GENERALLY AMOUNTS UNDER THIS ARE EXPECTED.

ORRISON

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


24HR QP VT 21/00Z
 0.01 528175 527169 524164 520154 511137 509133 508128 506118
      506111 505107 506094 500090 496089 492094 491101 488103
      486100 485096 483090 483087 480085 478086 475087 473086
      464081 455076 453070 448067 443065 438064 435066 431063
      429064 426067 426072 429073 431072 434074 439076 443077
      446080 450088 453088 454091 448091 445093 442090 439086
      435085 434090 430088 426085 423081 419078 417075 417071
      417069 414068 411061 404054 401050 402047 404045 418038
      420036 423037 427037 431036 435037 439039 443046 445051
      447055 449058 453059 456059 454056 447047 446042 448039
      448034 447033 445031 442031 436030 433030 430028 428027
      428022 430017 438011 443001 445998 451998 454997 457994
      462989 466982 470975 475968 482962 488956 492930 493922
      492911 489899 488894 485889 480877 476867 472855 470849
      467848 462848 459846 453841 449834 445827 444821 442817
      440813 437809 429804 424797 421793 419787 418782 415776
      412774 411777 411780 411784 409784 406778 403775 400770
      399762 396756 395751 394743 393737 394732 395727 393723
      388718 382721 375717 371711 365716 361722 359747 354756
      350754 345753 342758 340763 340768 342777 346789 350800
      353808 350816 348837 349842 346843 341844 338843 331842
      328837 320828 313824 307824 302823 295819 289816 271810
      265810 262810 260812 257817 258819 260822 263824 267826
      270829 276833 284837 289837 292838 295840 295844 292853
      294858 295866 296870 292872 285876 280886 278891 278897
      278904 279906 281907 291912 294915 295920 297927 296932
      295938 294944 289951 285956 284962 283965 281974 276979
      268983 264990 262993 258995 252995 247993 242994 237996
      234999 234003 238008 245010 251010 254011 256013 263021
      270027 276031 285033 295034 298033 301030 310018 312012
      315009 321004 330999 337993 342990 348990 352991 356990
      364987 374985 378987 381989 385999
 0.01 385999 384009 382019 377036 371041 367043 366048 365050
      367055 371054 375056 380058 383062 385064 390065 395069
      398076 401076 403072 411074 411083 414087 412092 408095
      404103 405106 405113 407112 414114 417116 418123 417130
      415135 412155 412162 413167 418173 419176 421176 421172
      421166 424165 426166 429168 431166 428163 424154 423148
      425143 424138 426132 428128 430128 431132 431135 432139
      433148 436158 440161 443165 441172 439175 436179 436184
      437190 440193 442198 443197 445194 450193 452193 454188
      458187 460184 463188 467190 469187 474187 476189 476192
      481196 483199 480202 478203 480208 479211 475211 473214
      470214 466216 463219 459219 455219 451220 448222 444223
      447228 472226 476225 479220 482217 488219 492221 494225
      497234 498240 501243 504247 505251 507254 509252 507245
      503235 501231 503226 503220 500217 499211 498208 500204
      503201 505200 506204 507208 510211 514217 515219 518217
      519212 518208 518201 521198 523195 522189 513184 514178
      515176 518171 524175 528175
 0.01 505273 505267 502263 500258 498255 496251 493247 491253
      493257 496260 498265 499270 502274 505273
 0.01 377956 375954 373955 372956 371957 370958 371960 373960
      375958 377956
 0.25 493173 492169 491167 488165 485164 483163 480162 479165
      480167 480170 483173 485176 488177 492176 493173
 0.25 469944 470939 470933 470921 466907 462894 456886 447879
      437873 428868 426865 426861 426850 425841 423831 421824
      420817 419811 418805 416800 413796 408791 407789 403788
      396789 390791 382789 376789 370788 366782 365777 367773
      371768 380761 381759 381755 381750 379748 378741 374738
      370739 368741 365748 364754 363762 360767 355766 353767
      349765 347765 346768 347774 348778 350780 352778 354780
      356797 360810 362820 366825 368828 368833 367841 363847
      355855 351860 344859 323848 314843 309843 305846 304849
      304854 306861 307870 309876 307884 303890 301897 302907
      305923 308936 313945 316949 317957 315963 312970 303979
      293986 289993 287999 285007 282014 283018 285020 291021
      295021 300017 306010 310004 315001 325994 335986 344976
      352965 359957 366951 375945 380942 385938 393931 396929
      398930 400933 400937 397944 394952 394957 391960 387965
      382967 376969 367972 363975 363979 370977 377977 381977
      384979 389983 392991 393000 393018 394023 396026 402029
      409029 414026 421020 427011 434999 441986 449974 452969
      454962 462954 467949 469944
 0.25 387751 385749 383752 385754 387751
 0.50 446933 446923 446913 445907 442902 436895 432893 427894
      420894 417889 414884 414877 416872 415866 413856 413849
      411845 409843 404841 402836 401830 401819 402813 403807
      403804 406801 410806 411812 412812 412807 410805 411801
      407794 402792 396796 392799 386797 383795 379793 374793
      369792 362789 361791 362794 366798 370803 374806 379807
      381813 380820 380825 380830 380839 379845 374852 371861
      361863 355866 351868 346872 343875 343880 345883 348886
      356880 351900 350905 348908 345912 343916 341921 335922
      332917 330916 327917 325923 325930 323935 321945 320960
      316970 305982 297988 295994 295002 296007 300009 309000
      326990 333984 339978 352962 359954 368945 384933 391927
      398922 413907 421901 423914 424919 422926 417935 412942
      407951 403962 401967 399974 398993 398003 400009 402015
      407017 416015 422010 427001 439981 443947 446933
 0.50 337863 337860 335858 333856 329855 327854 324853 322853
      320853 319858 320860 322863 324865 326866 329868 332868
      333867 336865 337863
 0.50 336895 335887 331882 325882 320883 316888 315896 315903
      317907 321905 326900 331900 334898 336895
 1.00 437937 437933 435931 431938 428944 423949 419953 415959
      412966 410974 408982 406989 405994 406998 410004 414005
      417004 422999 429987 431982 432976 431971 431963 433954
      433946 436942 437940 437937
 1.00 402880 399858 397848 394845 395841 391837 389840 385848
      382859 378863 376868 370876 367880 368886 366891 361893
      357897 357905 351912 349916 348921 343931 341935 337936
      328939 326948 327953 325959 324964 321969 315977 309982
      302989 302995 306995 317987 320989 322988 327985 334980
      341972 346966 351958 357949 364942 368934 370929 372928
      375929 380929 384927 392920 395918 397914 392905 394901
      397896 401889 402880
 1.00 397816 397814 396813 396814 396816 397818 397816
 1.00 384913 384911 382911 380913 379913 378914 377916 378916
      380916 381916 382914 384913 384913
 1.50 424980 424975 421971 419972 418975 416980 414984 412989
      411994 413996 417996 420992 422987 424982 424980
 1.50 391915 389915 388915 389916 391916 391915
 1.50 388918 387916 385918 387919 388918
 1.50 386877 386876 385875 384874 382873 381875 379875 378877
      379878 380879 381881 382882 383883 384882 385881 385879
      386877 386877
 1.50 361934 361926 355924 351927 347932 341941 336952 330962
      327967 325974 324980 330979 338971 345963 352952 358943
      361934
 2.00 355936 354933 350935 345941 339949 335956 331965 328968
      327973 329975 331974 335971 341965 346958 350951 355943
      355936
 3.00 345952 345947 342949 340952 339954 337956 336959 335962
      336965 337964 339961 341959 343956 344954 345952

$$





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