Area Forecast Discussion
Issued by NWS Huntsville, AL

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FXUS64 KHUN 170148

Area Forecast Discussion
National Weather Service Huntsville AL
848 PM CDT Fri Apr 16 2021

.NEAR TERM...(Tonight)
Issued at 848 PM CDT Fri Apr 16 2021

Under scattered mid level clouds and a blanket of higher altitude
clouds, mid evening temperatures were mainly in the mid/upper 50s
with light winds. 00Z soundings indicated a substantial dry layer
between 850-700mb over the region. This dry layer was helping to
evaporate rainfall preceding a weak system nearing from the west.
Precipitation echoes via local and regional radar covered an area
roughly from the Mid South, across much of Mississippi, and extending
across central Alabama. The closest rain far as measurable amounts
were from central Mississippi and westward.

Output from the shorter term CAMs, along with 18Z NAM/GFS indicated
the bulk of the showers should remain south of the region, closer to
Gulf where deeper moisture was present. Precipitation further to the
north was showing a trend of fading as it progressed eastward. The
295K region from the RAP indicated only weak upglide, which further
suggests that rain, when it begins in the overnight, should remain
on the light side. With clouds and more moisture, low temperatures
should not be chilly as last night, but should cool into the upper
40s to lower 50s. The on-going forecast has this well in hand. No big
changes are planned for the overnight.

.SHORT TERM...(Saturday through Sunday)
Issued at 1258 PM CDT Fri Apr 16 2021

This second chance of rain will occur in the morning, mainly tied
with the upper shortwave. However, the models have been dampening the
amplitude of this wave, and this has limited the southerly low level
component of flow to our south. Thus, keeping the main
convergence/moisture zone well to our south, while the northern
precip will be more tied to weakening QG forcing aloft. In either
case, only light QPF is indicated, with a dry afternoon Saturday
expected. Lower clouds could thin some, and possibly scatter out
during the afternoon hours. Clearing will be more likely Saturday
night per RH time sections. So high temperatures Saturday will
depend on any sunshine filtering through, and may need to lower a bit
in subsequent forecasts. Likewise, cloud trends Saturday night will
dictate how cool it will get. Right now, went slightly below
suggested blends in the 40-45 degree range. Sunday should be a fine
weather day with highs in the upper 60s for most. The only caveat is
the shortwave dropping southeast into the lower OH/TN valley late in
the day into the evening. There is a bit more moisture and QPF
associated with this in middle TN that could skirt southern TN and
far north AL. For now, will keep rain out but advise next shift to
watch closely.

.LONG TERM...(Sunday night through Thursday)
Issued at 1258 PM CDT Fri Apr 16 2021

Monday should bring another mild day in the upper 60s to lower 70s
with shortwave ridging moving east. Tuesday may even be warmer just
ahead of the next cold front. The models also bring several weak
small shortwaves through the southwest flow at 5H across the Gulf
states northeast through the Southeast U.S. This could bring mid
level clouds and possibly light rain Tuesday. For now, would like
better model consistency on this and will leave out. The front
arrives either Tuesday night or Wednesday (still model timing
discrepancy here). The latest runs are showing a bit more precip
chance with or just behind the front. Will again wait for more
consistency as this was a bone dry front yesterday. One thing is a
near certainty. More unseasonably cool weather behind this next front
with highs in the upper 50s to lower 60s Wednesday. Lows in the
middle to upper 30s are expected Thursday morning, so will have to
watch for frost potential, especially in southern TN and our
northeast TN valleys.


.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 644 PM CDT Fri Apr 16 2021

VFR weather should continue into the late night, before a weak system
approaching from the southern plains brings a chance of light rain
Sat morning. Most of the shower activity should remain south of the
Tennessee Valley. General lower level VFR minimums should continue,
but MVFR CIG/VIS reductions are possible in the heavier rain. The
precipitation should end from NW-SE in the late morning and early
afternoon as the system shifts more to the east. Light winds tonight
should become NW, increasing into the 5-10kt range in the afternoon.





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