FXUS64 KMEG 210443
Area Forecast Discussion
National Weather Service Memphis TN
1143 PM CDT Thu Jul 20 2017
Updated to include 06z aviation discussion.
.PREV DISCUSSION... /issued 829 PM CDT Thu Jul 20 2017/
Quick cosmetic update to remove evening POPs and to remove
references to Excessive Heat Warning in NE AR and Dunklin County
PREV DISCUSSION... /issued 342 PM CDT Thu Jul 20 2017/
DISCUSSION...Water Vapor Satellite trends this afternoon place an
upper level ridge of high pressure over the Lower Mississippi
Valley. Regional WSR-88D radar trends have shown some isolated
showers and thunderstorms occurring across portions of extreme
Northeast Mississippi late this afternoon. Otherwise, the
remainder of the forecast area remains dry at this time. As of 3
PM CDT, temperatures across the Mid-South are in the middle to
upper 90s. Heat concerns will remain the predominant challenge in
the short term and increasing rain chances thereafter.
Isolated showers and thunderstorms occurring across portions of
extreme Northeast Mississippi should gradually diminish by early
this evening with the loss of daytime heating. A very hot airmass
with temperatures in 90s combined with surface dewpoints in the
70s have resulted in heat index values between 105 to 112 degrees
with the highest values across portions of Northeast Arkansas and
the Missouri Bootheel. A Heat Advisory is in effect for the entire
forecast area and portions of Northeast Arkansas and the Missouri
Bootheel were upgraded to an Excessive Heat Warning this afternoon
until early evening. Not much change in the overall forecast is
expected through Friday evening as the very hot airmass combined
with the high low level moisture will produce conditions conducive
for a heat advisory across the Mid-South. Shower and thunderstorm
chances will remain minimal at best during this timeframe.
Short term models indicate the potential for slightly more
convective coverage on Saturday mainly over portions of North
Mississippi. At this time it appears that an extension of the Heat
Advisory may need to be considered into Saturday if current trends
persist. Any additional pooling of low level moisture will be
monitored in the event Excessive Heat Warnings would be needed
during this timeframe.
Long term models today do indicate some relief from the very hot
and dry conditions will come late this weekend into early next
week as the upper level ridge retrogrades a bit west and an upper
level trough settles across the Eastern United States. This will
allow for increased shower and thunderstorm coverage during this
period with more isolated coverage as next week progresses.
06z TAF Cycle
VFR conditions expected to persist for much of the period. The
exception to this will likely be KMKL where patchy fog has
developed near the airfield, likely causing MVFR category
visibility overnight. Also included a TEMPO for the same at KTUP
where winds will be light and recent obs indicate some fog
development across north Mississippi. Else, light to calm winds
overnight become SSW at less than 8 kts during the day.
AR...Heat Advisory until 8 PM CDT Friday for Clay-Craighead-Greene-
Heat Advisory until 7 PM CDT Friday for Crittenden-Cross-Lee AR-
MO...Heat Advisory until 8 PM CDT Friday for Dunklin.
Heat Advisory until 7 PM CDT Friday for Pemiscot.
MS...Heat Advisory until 7 PM CDT Friday for Alcorn-Benton MS-Calhoun-
TN...Heat Advisory until 7 PM CDT Friday for Benton TN-Carroll-
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