Area Forecast Discussion
Issued by NWS Huntsville, AL

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FXUS64 KHUN 230540

Area Forecast Discussion
National Weather Service Huntsville AL
1240 AM CDT Wed May 23 2018

For 06Z TAFS.


.NEAR TERM...(Tonight)
Issued at 900 PM CDT Tue May 22 2018

A few lingering areas of showers/tstms continue to develop along a
weak convergent axis from srn mid TN into portions of N cntrl/NW AL
this Tue evening. This activity is very pulse in nature, with the max
core aloft not lasting more than a few volume scans on radar.
Nevertheless, the storms are resulting in some brief heavy downpours
and perhaps gusty winds to 30 mph for the few areas that are still
experiencing some rainfall. Convection though should begin to taper
off further within the next few hrs heading into the late evening as
buoyant energy continues to weaken. Quiet wx conditions should then
prevail past midnight, with skies remaining partly/mostly cloudy.
Overnight temperatures will also continue to be quite mild, with
early morning lows Wed xpcted to be mainly in the mid/upper 60s for
most locations. Given the rainfall in a couple of areas coupled with
light/var winds, some patchy fog is possible overnight as well.

.SHORT TERM...(Wednesday through Thursday Night)
Issued at 204 PM CDT Tue May 22 2018

On Wednesday, an upper level ridge continues to build northward into
the plains while another weak upper low forms over N. AL. This will
actually bring dry air to the mid and upper levels, keeping the low
level moisture locked in place with a weak cap around 700-800mb.
Hires guidance and GFS/ECMWF/NAM are all in decent agreement in
developing showers and thunderstorms again by the early afternoon,
with the highest chances east of Huntsville. BUFKIT soundings are a
bit at odds with NSHARP forecast soundings with BUFKIT showing a mid
level cap holding, with weaker instability. NSHARP forecast
soundings are not showing this, almost tripling the amount of CAPE
available Wed afternoon. This will make all the difference in how
strong of storms we get Wed. DCAPE never gets above 1000, but if the
higher instability is realized, small hail and gusty winds, thanks to
the dry air, could still occur. As usual, storms should diminish
shortly after sunset. Highs Wed will be in the 80s with lows in the
mid to upper 60s.

Thursday looks to be a carbon copy of Wednesday, as a mid level
shortwave continues to linger near the area. It looks like
Thursday could be the better day for strong to severe storms. We`ll
see higher DCAPE, better instability, lower wet bulb zero/freezing
level heights and higher PW values. Thursday highs remain in the
lower to upper 80s. With winds shifting southeasterly Thursday
night, lows will be slightly warmer and in the mid to upper 60s.

.LONG TERM...(Friday through Monday)
Issued at 204 PM CDT Tue May 22 2018

The long term is shaping up to be wet once again. An upper low will
be near the Yucatan Peninsula on Friday and move north through the
weekend. It will end up situated over N. AL by Monday. A weak surface
high pressure over the Atlantic will keep southeasterly winds over
the area which will help the near continuous feed of tropical like
moisture. This will continue through the weekend with PW values
increasing to 1.8-2 inches by Friday and remaining there through
Monday. This is basically above our climatological max for this time
of year. Heavy rain will definitely be the highest threat for the
long term. Wind profiles are less than 10kts all the way through the
atmosphere so any storms that form won`t move and could lead to the
potential for flash flooding. Although strong storms would be
possible at any time, hail looks to be the higher probability over
gusty winds.

It`s too difficult to predict what day has the highest chances of
showers/storms so have stayed close to the blended pops which is
scattered showers/storms through Mon with a few afternoons of likely
pops. Either way, looks like we`ll have a wet few days ahead.

With the continued clouds and rain, highs will remain in the lower
80s all week with lows in the upper 60s.


.AVIATION...(For the 06Z TAFS through 06Z Wednesday night)
Issued at 1240 AM CDT Wed May 23 2018

Convective activity is done for the night and showers have moved
passed the KHSV terminal. VFR conditions will prevail until light
fog development around 09Z creates MVFR conditions til sunrise.
Isolated to scattered shra/tsra are possible again Wed afternoon,
however confidence regarding exact timing is too low to include in
the TAF at this time.





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