Area Forecast Discussion
Issued by NWS Memphis, TN

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FXUS64 KMEG 170436

Area Forecast Discussion
National Weather Service Memphis TN
1136 PM CDT Wed Aug 16 2017

Updated for 06z Aviation Discussion.


.PREV DISCUSSION... /issued 848 PM CDT Wed Aug 16 2017/

UPDATE...Evening Update.


Forecast looks to be in good shape, we should see morning lows
very near what we saw the middle 70s. Isolated Showers
over West Tennessee and Northeast Mississippi will likely
diminish slowly as the Track into Middle Tennessee and North
Alabama. Additional showers and thunderstorms will likely move
into East Arkansas around sunrise.



.PREV DISCUSSION... /issued 632 PM CDT Wed Aug 16 2017/

Currently...An upper ridge prevails across the southern U.S. and
a very humid airmass covers the Mid-South. Dewpoints range from
the mid and upper 70s. Low clouds have lifted and skies are partly
to mostly cloudy. Clouds have kept temps in check and as a result
heat index values remain below 105 degrees. Isolated showers are
starting to pop up as temps warm.

Tonight...Isolated to evening showers and thunderstorms, mainly
over eastern sections and NE AR/Missouri Bootheel, will dissipate
with loss of heating. Later tonight expect showers and
thunderstorms to develop ahead of an approaching cold front. This
activity should reach NE AR/Missouri Bootheel later tonight.

Thursday...The convection that moves into NE AR/Missouri Bootheel
later tonight will probably weaken early and then more activity
will develop along boundaries and in response to the approaching
upper level disturbance and cold front. The airmass will be very
unstable with SBCAPES around 3000 j/kg but the shear is weak. A
few strong to severe storms are possible along and north of I-40.
The airmass will remain very humid as dewpoints may pool ahead of
the cold front. Morning clouds and convection throughout the day
should keep temps in check and heat index values below 105

Thursday night through Friday night...Cold front will move
through the area and be located along the southern border of the
forecast area by Friday morning and remain there through Friday
night. Small chances for rain will remain mainly across the
southern counties Thursday night and Friday. By Friday night
small chances of rain shift to the west as upper level
disturbances moving through the WNW flow aloft could trigger tstms
upstream that move into eastern AR late but confidence is low.
There will be a short break in the high humidity during this
period. Many places on Friday should see dewpoints in the upper
60s to lower 70s which will be a bit of a break.

Extended...A broad upper ridge builds across the southern U.S. and
humidity level will creep back up and temps will climb to
seasonable levels. Afternoon heat index values between 100 and 105
degrees will be common through the period along with scattered
afternoon and evening thunderstorms. Medium range models are in
good agreement with an upper trough moving into the eastern U.S by
Wednesday. This will break down the upper ridge and allow a cold
front to move into the region with increased chances for showers
and thunderstorms followed by drier and cooler airmass for the end
of next week.



.AVIATION...06z TAF Cycle

VFR initially overnight with MVFR stratus/fog and a few light
sprinkles forming near or shortly after sunrise. Heavier
convection expected to form closer to noon with scattered
coverage through the mid evening hours. Activity will wane after
18/02z...with MVFR or IFR cigs potentially forming just beyond
this period. Southeast to south winds of 4-8 kts overnight...will
veer southwesterly and increase to 10-12 kts with higher gusts.




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