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Area forecast discussion 
National Weather Service Birmingham Alabama
326 PM CST Wednesday Mar 4 2015


Folks who are enjoying today's warmth are in for a rude awakening
tomorrow with 24-hour temperature changes as much as 50 degrees
behind an Arctic cold front. This rare late-season blast will also
be accompanied by Post-frontal precipitation as a large trough
axis approaches from the west.

Models are in better agreement today regarding an impulse that
will develop in the the right rear quadrant of the upper jet...
ahead of the 500mb trough axis. Have raised precipitation amounts
in the 09-21z timeframe...with some models indicating quantitative precipitation forecast up to
3/4 inch along and northwest of Interstate 59. What could make or
break the forecast appears not to be precipitation amounts...but
instead...temperatures. There is a spread of 3-6 degrees between
the warmer NAM/Gem and colder GFS/ECMWF. This forecast splits the
difference between the two model camps...but we will have to keep
a close eye on the trends of the upstream cold advection. Judging
by the current hunch is that the end result may be
closer to the colder solutions. It is possible that the Winter
Storm Warning could have to be expanded southward later this
evening or overnight.

Ice accumulations are expected to have a significant impact in the
Winter Storm Warning area. Some sleet may also mix in toward the
back edge of the precipitation between 15-21z...but the main impact will
be from ice accumulations up to 1/3 inch. Forecast soundings show
a sharp drop in temperatures from the surface up to 2500 feet...
and impacts are expected to be much greater in areas of higher
elevation. Another concern for those higher elevations is wind
gusts of 25-35 miles per hour causing additional stress to trees.

The precipitation should come to an end across the northern half
of the area during the afternoon. Very cold conditions are
expected Thursday night...with lows ranging from the upper teens
northwest to lower 30s southeast.



18z taf discussion.

Expect some improvement through the morning...but MVFR conditions
are expected to continue through the day. South to southwesterly
winds will increase this afternoon and rain showers ahead of an
approaching cold front will affect northern terminals. Winds will
decrease slightly this evening and shift to the northwest to
north. Expect a return of LIFR to IFR conditions tonight with rain
remaining across the north. Went ahead and added in freezing rain to the
northern sites after 15z.



Preliminary point temps/pops...
Gadsden 36 38 21 42 26 / 100 90 10 10 0
Anniston 40 42 23 44 27 / 100 80 10 10 10
Birmingham 34 36 21 41 27 / 100 90 10 10 10
Tuscaloosa 35 36 21 42 28 / 100 90 10 10 10
Calera 37 39 22 42 28 / 100 90 10 10 10
Auburn 60 62 29 45 31 / 70 70 20 10 10
Montgomery 52 56 27 49 30 / 80 70 20 10 10
Troy 62 64 29 49 33 / 60 70 30 10 10


Bmx watches/warnings/advisories...
Freezing Rain Advisory from 3 am to 3 PM CST Thursday for the
following counties: Bibb...Calhoun...Cherokee...Etowah...
Greene...Hale...Jefferson...Pickens...Shelby...St. Clair...

Winter Storm Warning from 3 am to 3 PM CST Thursday for the
following counties: Blount...Fayette...Lamar...Marion...Walker...




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