Area Forecast Discussion
Issued by NWS Memphis, TN

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FXUS64 KMEG 211730

Area Forecast Discussion
National Weather Service Memphis TN
1230 PM CDT Mon Aug 21 2017

.UPDATE... /issued 1030 AM CDT Mon Aug 21 2017/

Currently temperatures are already in the mid to upper 80s across
the region. Latest GOES-16 satellite imagery depicts some clouds
present over the region, with thin cirrus most prominent since
early this morning. Clouds will be present throughout the day,
but should not be enough cover to greatly inhibit eclipse
viewing. The forecast is on track, with no updates warranted at
this time. Temperatures will top out in the low to mid 90s this



.PREV DISCUSSION... /issued 346 AM CDT Mon Aug 21 2017/

A broad subtropical ridge extends from west to east from the
Southern Plains into the western Atlantic this morning. The flow
is aloft remains rather weak, but we continue to see high-level
convective debris clouds streaming across the Ohio Valley and Mid-
South, emanating from upstream convection. As this convection
weakens over the next several hours, we should see a gradual
decrease in high clouds through mid-morning. A diurnal cumulus
field will begin to blossom by mid/late morning, resulting in
partly cloudy skies across much of the Mid-South by midday.
However, these clouds will remain scattered and should provide
decent viewing conditions for this afternoon`s solar eclipse,
although some areas could be temporarily blocked by individual
cumulus clouds.

Isolated showers and thunderstorms are expected to develop after
1 PM. Convective coverage should not be all that great, but be
prepared for occasional lightning and brief heavy downpours if you
plan to be outdoors. Any convection that develops will largely
remain of the single cell variety with a short life-span, although
additional regeneration is possible along outflow boundaries
resulting in a few multicell clusters. Expect convection to
dissipate by sunset. Temperatures today will be near climatology
for late August with highs in the low to mid 90s. Hourly
temperatures will be tricky this afternoon as insolation wanes
during the eclipse. This should result in a temporarily cooling
before temperatures resume their normal diurnal tendencies. Heat
indices are forecast to approach Heat Advisory criteria, but
should they reach 105 degrees, it will be brief and is only
expected in a few pockets across the CWA. Thus, no Heat Advisory
will be issued at this time.

Rain chances will be on the increase Tuesday afternoon as a cold
front approaches the area from the north. Generally dry conditions
are anticipated during the morning hours with showers and
thunderstorms likely north of I-40 by mid/late afternoon. There
should be sufficient shear/instability to support the threat for a
few strong/severe thunderstorms, with the primary hazards being
isolated damaging wind, dangerous lightning, and localized heavy
rainfall. This front will move slowly south Tuesday night into
Wednesday, with rain chances shifting south along with the front.
These rain chances will taper off Wednesday evening as drier air
advects into the Mid-South.

Generally benign weather conditions are anticipated Thursday and
Friday. Temperatures will be pleasant (by August standards) with
afternoon highs in the low/mid 80s. Overnight lows will be
seasonally cool given the light winds, clear skies, and dry air in
place. Most areas will see lows in the low/mid 60s. However, some
areas will likely dip into the upper 50s Friday morning.

The upper-level ridge is progged to build over the western CONUS
over the weekend, putting the Mid-South under northwest flow
aloft. The synoptic pattern looks a little messy over the weekend
with several weak shortwave troughs embedded within the
westerlies. Timing of these features will be the key to rain
chances, at this time it appears that rain chances will ramp up
late in the weekend and early next week. We are carrying slight
chance PoPs for a portion of northeast MS on Saturday, but most of
the area is dry until Sunday. Temperatures are forecast to warm a
bit over the weekend, but still remain below seasonal norms.




18Z TAF Set

VFR conditions should continue for much of the forecast period.
Scattered afternoon thunderstorms are expected, but at this time
not enough confidence to put anything more than vicinity wording
in the forecast. Some fog may develop overnight mainly over the
KMKL area. Winds will be light and variable through the overnight
period. Winds will turn around to the southwest at 8 KTS by





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