Scientific Forecaster Discussion
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Area forecast discussion
National Weather Service Birmingham Alabama
1102 PM CST Thu Nov 23 2017
for 06z aviation.
A high amplitude pattern persists across the nation on this
Thanksgiving day with a deep upper-level longwave trough that
extends southwest from the northeast states down The Spine of the
Appalachian Mountains and into the Florida Panhandle while an
expansive upper-level ridge was centered offshore just southwest
of Southern California. Toward the surface, an elongated area of
surface high pressure extended from western Pennsylvania southwest
through the Ohio River valley and into portions of the mid and
lower Mississippi River valleys. To our southeast, a surface low
was moving northeast across the central Florida Peninsula.
An inverted trough associated with the surface low pressure area
over central Florida remains across southwest Georgia and
extended through western Carolina and into western Virginia. Skies
were partly cloudy across our southeast counties due to the close
proximity to this feature while the rest of our area is
experiencing mostly sunny skies this afternoon.
Surface high pressure will continue to heavily influence our
weather through the short term period. Expect fair skies with
another cold night across our northern and western counties
overnight with strong high pressure nearby, light winds are
expected with good radiational cooling conditions expected
overnight with freezing temperatures expected north and west. Lows
tonight will range from the upper 20's northwest to around 40
southeast with coldest temperatures expected in the lower
elevation areas north and west.
Only a few adjustments made to the long-term portion of the
forecast with a cold front expected to arrive during the day on
Saturday in largely dry fashion followed by the potential for
freezing temperatures across our northern and central counties on Monday
morning. The next chance of rain continues to be in the midweek
time frame next week.
Friday through Thursday.
Prospects for appreciable rainfall through the extended part of
the forecast look rather slim due to persistent north to northwest
flow aloft. An embedded shortwave will bring a cold front our way
on Saturday into Saturday night, but moisture appears insufficient
for rainfall at this time. Temperatures should be noticeably
cooler on Sunday with highs 3-6 degrees lower than Saturday.
Widespread low to mid 30s are expected for morning lows on Monday
as high pressure moves into the region. A warming trend should
begin on Monday afternoon and continue into Tuesday and Wednesday
due to rising heights in advance of an upper-level trough in the
plains. This system could bring our a chance of rain Wednesday
into Thursday, but moisture may once again be rather limited.
06z taf discussion.
VFR continues this period. Toward southeastern Alabama, high-res
models are suggesting some low-level moisture could advect from
the east overnight into early morning hours Friday. They may be
overdoing this scenario to some extent based on forecast low-level
streamlines originating from the drier air mass farther
northwest, and wrap-around moisture from the storm system over the
southeast U.S. Atlantic coast; thus, only mentioned a few clouds
around 020-025, with more extensive low clouds most likely to
exist farther southeast/into southern Georgia and Florida.
Otherwise, the inverted trough located south erodes and the
surface high from the north settles overhead. Winds will start to
veer to a southerly direction but remain light.
The forecast features dry conditions and near normal temperatures
through the weekend and through early next week. There are no
fire weather concerns at this time.
Preliminary point temps/pops...
Gadsden 32 63 40 62 37 / 0 0 0 10 0
Anniston 32 65 41 64 38 / 0 0 0 10 0
Birmingham 37 64 43 63 40 / 0 0 0 10 0
Tuscaloosa 31 64 41 65 39 / 0 0 0 10 0
Calera 38 64 41 64 39 / 0 0 0 10 0
Auburn 40 65 43 64 41 / 10 0 0 10 0
Montgomery 36 66 42 67 40 / 0 0 0 0 0
Troy 36 67 44 68 41 / 10 0 0 0 0