Area Forecast Discussion
Issued by NWS Huntsville, AL

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FXUS64 KHUN 200237 AAB

Area Forecast Discussion...UPDATED
National Weather Service Huntsville AL
837 PM CST Fri Jan 19 2018

.NEAR TERM...(Tonight)
Issued at 837 PM CST Fri Jan 19 2018

An eastward moving shortwave trough will swing from Texas into the
Mississippi Delta region overnight, as light SSW winds aloft (ahead
of this system) help moisture creep back into the Tennessee Valley.
A broken to overcast deck of 4-5 kft clouds will continue to move
into the area overnight. As of 0230z, all but our far eastern areas
along the Alabama/Georgia border are overcast and underneath this
cloud shield. In areas that remained clearer longer, radiational
cooling helped lower temperatures into the mid/upper 30s, while
readings in the low to mid 40s are being experienced across central
and western areas underneath these clouds. By 04z, think the entire
area will be overcast and remain so for the remainder of the night.
These clouds will help to keep low temperatures a couple degrees
warmer than previously thought. Still, with dewpoints in the 20s,
temperatures will fall off a few more degrees -- with a gradient from
the low to mid 30s in Northwest Alabama to the upper 20s in
Northeast Alabama existing by early Saturday morning.

.SHORT TERM...(Saturday through Sunday)
Issued at 230 PM CST Fri Jan 19 2018

The shortwave over Texas will strengthen somewhat as it slides
eastward along the Gulf Coast. However, as it largely remains south
of TN Valley, the only impact to the sensible weather pattern is an
continued increase in clouds. Despite these clouds, southerly flow
will persist and continue to advect warm and moist Gulf air across
the region. This will help temperatures warm into the upper 50s
Saturday afternoon and only fall into the upper 30s to lower 40s
overnight. By Sunday, an upper trough will eject east of the Rockies
and move into the Central Plains. This will strengthen an upper
ridge across the southeast, with warm air advection persisting over
the region. The combination of WAA and upper level height rises will
allow temperatures to warm as much as 10 degrees above normal
values on Sunday, with highs expected to reach into the lower 60s.

.LONG TERM...(Sunday night through Thursday)
Issued at 230 PM CST Fri Jan 19 2018

The extended`s warmer pattern is welcomed after being stuck
in this cooler weather pattern. However, in return we will start off
the work week with a chance of rain and isolated thunderstorms.

Breezy southerly winds ahead of our next system will have warmer
than normal overnight lows on Sunday in the mid to upper 40s. A
strong trough will deepen as it lifts into the Great Lakes on Monday
while a sfc low develops in the Midwest and heads northeast. Showers
and thunderstorms will develop along the trailing cold front that
stretches all the way to the Gulf. The front will move quickly
across the forecast area on Monday, bringing showers, isolated
thunderstorms and breezy conditions, before exiting by late Monday
night. Soundings continue to show PWATs just over 1 inch, a good
wind field and a lack of CAPE. Overall, models are in pretty good
agreement on the timing of the system. The ECMWF still the slower
solution and it looks like the latest GFS is wrapping in more dry air
causing the precip to end a little bit earlier, but continued with a
blend of getting the precip out of here after 06Z Tuesday.

Temperatures will warm up towards 60 on Monday and since this will
be a Pacific and finally not an arctic front, temps will not
drastically drop behind the front. You will feel the biggest change
in the overnight lows on Monday as temps will be back in the mid
30s. However, sfc high pressure will keep conditions dry and temps
near normal Tues and Wed with highs in the lower 50s and overnight
lows in the lower 30s. Thursday the sfc high will shift eastward but
warm temps up a tad above normal in the mid 50s and put lows around
40 degrees.


.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 549 PM CST Fri Jan 19 2018

A weak upper-level disturbance will bring a broad broken to overcast
shield of 4-5 kft clouds into the region late this evening and
overnight. Winds will remain from the SSE reinforcing the flux of
moisture in the low/mid levels -- and the cloud cover throughout the
day on Saturday. Still, VFR conditions will reveal through the
remainder of the period.





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