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Area forecast discussion 
National Weather Service Huntsville Alabama 
312 am CST Friday Nov 21 2008 


Short term...through Sunday... 
this is not the coldest night we have seen lately...but it may feel 
like it. Wind gusts have approached 30 miles per hour at times this morning. 
Though winds have relaxed some since midnight...wind chill values 
are still in the 20s at 09z. Temperatures have fallen into the Lower/Middle 
30s for most locations despite the stratocu...which is rapidly 
breaking up per latest satellite imagery...and the upper trough axis 
is approaching the MS-Alabama state line. Meanwhile...dewpoints are 
dropping rapidly as well...with most areas already in the teens. 


Short term concerns continue to involve extremely cold and dry air. 
And today should certainly affect anyone heading outdoors...since 
persistent cold air advection and gusty northwesterly winds will greatly inhibit any heating 
despite abundant sunshine. Still suspect that MOS may be too 
warm...so it would not be surprising if few areas make it to 40. 
Higher elevs will not make it much above freezing. Winds will gust 
to 20-25kt early in the day...before the low-level gradient relaxes in 
response to the approaching high. The high will be centered just 
north/NE of the area by daybreak Sat...which coupled with clear skies 
should optimize radiational cooling. With dewpoints likely to be in the 
low/middle teens...still believe most of the area will fall to at least 
20 degrees. Typical cold spots like Valley Head or Lynchburg may see 
middle or even lower teens. Per hsv/mean sea level records for Saturday /see 
below/...will continue with near-record lows in the zone forecast product. 


Conditions will begin to moderate on Saturday as the high drifts eastward 
and limited return flow sets up...and 850mb temperatures suggest high temperatures 
around 50 degrees. However another cold night is expected and 
conditions should decouple nicely...allowing most locations to fall 
into the low/middle 20s. Weak southeast flow could set up a strong inversion 
in some higher elevations in NE Alabama. 


Limited moisture may begin to return Sunday as more pronounced 
southerly flow sets up. This will create quite a warm up but it will 
still be rather dry. GFS MOS hints at temperatures cracking 60...but 
this seems to be a little high given the strength of the warm air advection. 


Long term...Sunday night through Thursday /Thanksgiving day/... 
1st round of rain in the extended will come as early as Sunday night 
as a potent trough digs into the Ohio Valley. Models have trended 
just a bit faster with this system...with precipitation onset probably coming 
Sunday night and moving out as early as Monday afternoon. Will need to 
watch if conditions continue to accelerate...since some cooling and 
lingering low-level dry air over NE Alabama might allow for initial precipitation to 
fall as -fzra or sleet. This is a long shot though...and pronounced 
warm nose aloft and surface warming would quickly end any concerns. 


A more moderate air mass will follow this system...and currently do 
not expect middle-week temperatures to come anywhere close to the cold 
conditions we have seen recently. Thanksgiving day looks to be a day 
of transition as a Pacific-based trough moves through the Central 
Plains...increasing clouds and warming many areas to near 60 degrees. 
&& 


Fire weather... 
next two days will pose an increased fire weather risk. Dewpoints 
are falling rapidly...more than indicated by many models...and gusty 
winds will enhance the fire danger. Northern Alabama may approach the 20 miles per hour 
sustained wind criteria...but due to the much cooler air...doubt relative humidity 
criteria will be met. Will urge caution in the fwf and severe weather potential statement but a 
warning does not appear warranted at this time. However...drier conditions 
are expected Saturday with temperatures increasing but moisture 
lagging behind...and indications still point to roughly 6 hours of 
20-25 percent relative humidity. Will continue with Fire Weather Watch at this time but expect a red 
flag warning will be needed. 
&& 


Climate... 
record low maximums for friday: 
huntsville: 36...1964 
muscle shoals: 38...1937 


Record lows for Saturday morning: 
huntsville: 17...1964 
muscle shoals: 19...1914 
&& 


Preliminary point temps/pops... 
Huntsville 41 20 50 23 57 / 0 0 0 0 0 
Shoals 42 18 50 23 58 / 0 0 0 0 0 
Cullman 42 19 50 25 55 / 0 0 0 0 0 
Fayetteville 39 17 48 23 54 / 0 0 0 0 0 
Albertville 43 21 51 25 56 / 0 0 0 0 0 
Fort Payne 43 17 50 20 54 / 0 0 0 0 0 
&& 


Hun watches/warnings/advisories... 
Alabama...Fire Weather Watch from Saturday morning through Saturday 
afternoon for the following zones: Colbert...Cullman...De 
Kalb...Franklin Alabama...Jackson...Lauderdale...Lawrence... 
Limestone...Madison...Marshall...Morgan. 


Tennessee...none. 
&& 
$$ 


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