Area Forecast Discussion
Issued by NWS Birmingham, AL

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FXUS64 KBMX 220759

Area Forecast Discussion
National Weather Service Birmingham AL
259 AM CDT Thu Mar 22 2018

Today and Tonight.

High pressure is centered of the Mississippi valley this morning and
has allowed winds to calm down across much of the area. Already
beginning to see some of that radiational cooling in the normally
colder spots, with near freezing temperatures across the north.
Freeze Warning and Frost Advisory areas still look pretty good and
will continue those through 8 AM. Temperatures will warm up a little
bit more today with readings in the upper 50s to mid 60s. Winds will
be less breezy today as the high settles into the area. As the high
begins to slide to our east and elongate over the Ohio Valley
tonight, winds will shift to more of an easterly flow. Dewpoints
will not drop down as low so temperatures will be a touch warmer
overnight. Coldest areas will be in the northeastern counties, where
the winds stay more northeasterly. At this time looking at most
areas staying above freezing and even above 34 degrees, so frost
will be more patchy at best, with only an isolated location near
freezing. Since the expectation is for only patchy areas Friday
morning will not issue an advisory at this time.


Friday through Thursday.

Surface high pressure continues to slide across the area with
ridging aloft as the upper level trough shifts eastward off the East
Coast Friday into Saturday. By early Saturday morning, the center of
high pressure is over the Florida Peninsula, leading to southern
flow for much of Central AL. A surface low moves through the Central
Plains and into the TN Valley on Saturday, stretching a east to west
oriented cold front that will push into the region for the weekend.
This will lead to increased chances of rain both Saturday and
Sunday. However, models disagree on how long the cold front lingers
around into Sunday. Both the GFS and ECMWF develop a cold air
damming pattern and a backdoor cold front moves into the area Sunday
night. The GFS tries to keep moisture from the first cold front in
the area and produces showers for both Sunday and Monday. The ECMWF
pushes that first cold front through and has the backdoor cold front
move in with less available moisture. Have opted to continue with 30-
40% chance of rain for both days due to the uncertainty of moisture
availability and movement of frontal boundaries.

Ridging builds back into the area on Tuesday. The GFS tries to
maintain a moist airmass in the area with southerly flow around a
high pressure center positioned over Southern Georgia. However, the
ECMWF slides the high pressure closer to us and limits any precip.
Therefore, will only carry slight chances of rain Tuesday into
Wednesday, but this could be decreased if models trend to the high
pressure being more directly over Central AL.

Meanwhile, deep troughing slides through Southwestern States
Wednesday into Thursday and models hint at a few impulses that move
through providing increased rain chances along a stalled frontal
boundary along the MS River Valley. However, models have been
inconsistent on the timing of this front moving into our region and
the evolution of the trough , so will only mention chance PoPs on
Thursday for portions of Central AL.



06Z TAF Discussion.

VFR conditions expected throughout the period. Time segments were
based on wind speeds alone. High pressure will be building into
the region through Thursday and the atmosphere dries out even
more. Expect mostly clear skies with some mid and upper level
moisture entering from the north and west toward the tail end of
the period. Winds have diminished through the evening hours.
Winds will increase again after 14-15z and range between 6-11kts
with some gusts to 18kts. Wind gusts should be much lower than
the previous few days. Winds just above the surface will still be
in the 25-30 kt range overnight but will remain below LLWS values.




Dry weather continues today with next chance of rain coming over
the weekend. RHs drop into the 30s this afternoon, but winds will
be weaker than the past couple of days. There are no fire weather
concerns at this time.


Gadsden     58  38  62  47  72 /   0  10  10  10  30
Anniston    59  37  64  47  73 /   0   0  10  10  20
Birmingham  60  41  66  51  74 /   0   0  10  10  20
Tuscaloosa  63  42  69  51  77 /   0   0  10  10  10
Calera      61  41  67  50  75 /   0   0  10  10  20
Auburn      60  40  66  48  73 /   0   0   0  10  10
Montgomery  64  41  71  50  78 /   0   0   0  10   0
Troy        63  40  70  49  77 /   0   0   0   0   0


Frost Advisory until 8 AM CDT this morning for the following
counties: Autauga...Barbour...Bibb...Bullock...Chambers...

Freeze Warning until 8 AM CDT this morning for the following
counties: Blount...Calhoun...Cherokee...Clay...Cleburne...
Etowah...Jefferson...Marion...Randolph...Shelby...St. Clair...


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