Area Forecast Discussion
Issued by NWS Birmingham, AL

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FXUS64 KBMX 221320

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

Morning Update.


Today and Tonight.

Sunny skies are prevailing across the local area this morning
with expansive surface high pressure centered over northern
Arkansas. Temperatures dropped below freezing across much of our
counties located along and north of the Interstate 20 corridor.
With full sunshine, temperatures have quickly risen above freezing
over the past hour across much of our forecast area. A pleasant
day is expected with mostly sunny skies and highs warming into the
mid 60s across our southwest counties while cooler reading will
be found across our northeast counties with highs in the upper
50`s. Lows tonight will be slightly warmer compared to this
morning so patchy fog will remain possible across the the normally
colder locations in our northeast counties. The expected patchy
nature and limited areal coverage of frost does not appear to
warrant a frost advisory for tonight 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.



12Z 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 Friday. 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 will increase 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 at
the surface calm after 01-02Z. and the atmosphere dries out even




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  36  62  48  71 /   0  10   0  10  40
Anniston    59  36  64  47  72 /   0   0   0  10  30
Birmingham  60  41  67  52  74 /   0   0   0  10  30
Tuscaloosa  64  42  70  52  76 /   0   0   0  10  20
Calera      61  39  68  51  75 /   0   0   0  10  20
Auburn      59  39  66  48  74 /   0   0   0  10  10
Montgomery  63  39  71  50  79 /   0   0   0   0  10
Troy        63  39  71  49  78 /   0   0   0   0  10




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