Area Forecast Discussion
Issued by NWS Huntsville, AL

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FXUS64 KHUN 230842

Area Forecast Discussion
National Weather Service Huntsville AL
242 AM CST Mon Jan 23 2017

.NEAR TERM...(Today)
Issued at 242 AM CST Mon Jan 23 2017

After a few days of rainy and stormy weather, we will finally get a
break. The center of the 986mb surface low pressure system that has
been rotating showers through the area is over Chattanooga as of
2AM. The pressure continues to fall with the pressure gradient
tightening over the area and winds beginning to gust within the last
couple hours.

This surface low will weaken and track east-southeast today. With
surface high pressure following quickly behind today, the pressure
gradient across the region will still increase at least through 18z
today. That, coupled with a 40-50kt LLJ will allow winds to increase
quickly this morning. Sustained winds of 20-25mph with gusts of 35-
40mph are expected. The highest gusts will be between now and around
12-15z. Subsidence and much drier air aloft move in between 15-18z
creating a steep inversion around 925 mb and will inhibit some of the
stronger winds from mixing down. By that time, the LLJ will be
weakening as well. The Wind Advisory will remain in effect from 9z/3AM
this morning through 00z/6PM but it will likely need to be cancelled
early, especially in areas to the west.

In terms of rainfall, the rain has become much more scattered in
nature in the last few hours. A steady stream of scattered showers
though is continuing basically in areas of Huntsville and east.
Given the fact that drier air is already filtering in from the north
and the main support for the upper system has already passed to the
east, hires guidance is showing that we shouldn`t see much of an
increase in coverage than we are seeing now. The bands of rain will
continue to slowly shift east and should be out of NE AL by 18z. We
still have ongoing flooding around Indian Creek in Madison County so
an Areal Flood Warning will replace the Flash Flood Warning in
effect. Flooding also continues along the Big Wills Creek in DeKalb
County as well as a few other locations in the county itself. Given
the expected continuing rain there and in parts of NE AL, an Areal
Flood Warning will be continued for parts of Jackson/Dekalb
counties. River gauges at Brownsboro as well as the Paint Rock River
at Woodville are expected to rise over action stage but are not
expected to get to flood stage today.

Temperatures overnight have cooled but when the winds kicked in, we
mixed out and temps rose about 3-5 degrees with current temps in the
lower to upper 50s. They will likely remain steady, maybe fluctuate
a deg or two depending on the wind, through the rest of the
overnight hours. Given the north to south gradient of the wind, we
may actually get some light cold advection from the north today.
That, combined with cloud cover and slackening winds should cause
temps to decrease slightly through the day causing our "afternoon
highs" to only be in the middle 50s.

.SHORT TERM...(Tonight through Wednesday)
Issued at 242 AM CST Mon Jan 23 2017

Much quieter weather returns tonight as weak ridging and surface
high pressure return. Another trough begins to develop in the west
and will become the focus for a system on Wednesday. Until then,
skies should clear out tonight leaving sunny skies for Tuesday and
highs warming into the upper 50s. Clouds return Tuesday night with
mild lows in the middle to upper 40s.

A surface low will develop Wednesday over the midwest in response to
the previously mentioned upper trough. This will drag a cold front
across the region on Wednesday. The main dynamics will be well to
the north with this system and there is very little moisture present
outside of a shallow layer below 850mb. Rain chances appear low at
this time and will keep a slight chance across the area with a chance
in the SE areas where a slightly stronger wave will develop and help
with shower development. Given a southerly flow ahead of the front,
highs on Wed will rise into the lower 60s. Unfortunately much colder
air makes a return behind this front with lows Wed night dropping
into the upper 30s.

.LONG TERM...(Wednesday night through Sunday)
Issued at 242 AM CST Mon Jan 23 2017

High pressure will slowly build across the region through much of
the extended period. The forecast area will remain on the southern
fringe of a broad upper level trough, with near zonal flow across
the area. With weak NW flow, dry and cooler air will continue to
filter into the region. Despite mostly clear to partly cloudy skies,
temperatures will finally return to, or slightly below, seasonal
norms. Daytime highs will struggle to make it out of the 40s, and
overnight lows will be near to slightly below freezing. Guidance is
in fair agreement that the broad upper trough will amplify late next
week and into the weekend, however as the TN Valley remains on the
southern periphery, only an increase in clouds is expected. Thus, no
rain is forecast from Thursday through the first half of the next
work week.


.AVIATION...(For the 06Z TAFS through 06Z Monday night)
Issued at 1144 PM CST Sun Jan 22 2017

Strong surface low located across nw GA is forecast to shift rapidly
enewd off the southern mid-Atlantic coast by end of TAF period.
Widespread ra on the nwrn periphery of this system will primarily
impact locations from HSV ewd for the next 4 hrs before pushing
further into TN/GA. However, a few lighter shra will be psbl invof of
both terminals thru 10-14Z. Otherwise, low stratus clouds will
prevail for the duration of the forecast period, with bkn cigs
expected arnd 1500 ft. Sfc winds will remain from the nw, with speeds
increasing to 12g22 kts by 14Z and continuing in this range thru
late aftn before gradually diminishing.


AL...Wind Advisory until 6 PM CST this evening for ALZ001>010-016.

TN...Wind Advisory until 6 PM CST this evening for TNZ076-096-097.




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