Area Forecast Discussion
Issued by NWS Huntsville, AL

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FXUS64 KHUN 242320

Area Forecast Discussion
National Weather Service Huntsville AL
620 PM CDT Mon Oct 24 2016

For 00Z TAFS.


.NEAR TERM...(Tonight)
Issued at 310 PM CDT Mon Oct 24 2016

A weak and cloud free cold front was sagging southwest from the MO
bootheel through southern TN to near CHA. This will drop south into
northern AL tonight. Winds will switch to the north and northeast,
but with boundary layer decoupling, they will remain light at the
surface. Ridge tops may experience winds of 5-10 mph most of tonight.
Temperatures should drop into the lower to middle 40s in valley, and
remain a bit warmer over and adjacent to area lakes and on ridge

.SHORT TERM...(Tuesday through Wednesday)
Issued at 310 PM CDT Mon Oct 24 2016

Winds should veer quickly to the southeast on Tuesday. A rather large
diurnal rise in temps is expected again with 850 mb temps of 15-16C
equating to potential highs well into the 80s. We will go closer to
the warmer NAM values in the l-m80s. Southerly flow Tuesday Night
should allow warm advection to offset radiational cooling a bit more.
So going with lows slightly above guidance in the west, but going a
bit cooler than guidance in our typical drainage cooling valleys in
our east.

Wednesday should be another warm one, although MOS is dropping back
max temps a bit due to abundant ci/cs indicated in the models. I`m
the skeptic and will go on the warm side again given a combination of
several ongoing factors including increasing southwest flow, dry
soils, and persistence forecast.

.LONG TERM...(Wednesday night through Sunday)
Issued at 310 PM CDT Mon Oct 24 2016

An upper level disturbance will continue to move eastward from
Missouri and the central Great Lakes region towards the Tennessee
Valley on Wednesday morning. The southern extent of the energy with
this system will remain over Tennessee northward into Illinois
through Wednesday afternoon. However, low level (especially 925 mb
winds) will strengthen significantly Wednesday night into Thursday
morning, as the upper level disturbance pushes through northern
Alabama. At this point, although wet-bulb temperatures lower
significantly, surface based instability is too meager for more than
isolated showers/thunderstorms. Not expecting any stronger storms
Wednesday night given nominal shear and weak instability. The big
question is how much shower/thunderstorm activity we have on
Thursday. Synoptic models show that the surface front associated with
this disturbance hangs back a bit further west of the upper level
trough axis. These models continue to forecast around 1500 J/kg (NAM
even more) developing during the morning and early afternoon hours on
Thursday. The lagging of the surface front puts it somewhere over
northeastern Alabama. Given very low wet-bulb temperatures ~ 7500 ft,
if convection occurs some strong storms could develop if they can
overcome a developing CAP aloft just above 700 mb. The main threat
with these would be small hail. Winds may need to be raised on
future shifts for Wednesday night into Thursday due to the strength
of the 925 mb jet.

Although, some drier and cooler air will move into the area via
northwesterly flow, there is not strong colder air advection that
occurs over the area Friday into Saturday. Temperatures should drop
off behind the front back into the upper 70s to lower 80s as a
result. Models hint at another dry front approaching the area over
the weekend, but are in fairly large disagreement about the strength
of low level cold air advection with this feature. Thus went with
Superblend for Saturday night into Monday.


.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 620 PM CDT Mon Oct 24 2016

VFR conditions are forecast through the TAF period. A weak frontal
boundary will push south through the area tonight. Winds will be
light and variable but tend to favor a northerly direction overnight
due to the weak frontal boundary. Winds transition over to E/SE by
late Tuesday morning.





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