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Area Forecast Discussion (AFD)

Issued by Huntsville, AL (HUN)

FXUS64 KHUN 150307

Area Forecast Discussion
National Weather Service Huntsville AL
907 PM CST Thu Dec 14 2017

.NEAR TERM...(Tonight)
Issued at 907 PM CST Thu Dec 14 2017

Mid/high cloud cover continues to gradually work its way nwd into
more of the cntrl TN Valley this Thu evening. This cloud cover is
embedded within a broad WSW flow regime in place across the wrn/cntrl
Gulf regions, that should continue to inch further to the N into the
early morning hrs Fri. Most of this cloud cover is also overspreading
a reinforcing cold front that is now making its way into cntrl AL/GA.
Other than possibly some lower level stratus developing shortly after
daybreak Fri, no sig impacts are xpcted from this surge of mid level
moisture to the ENE. Current temp trends range from around 30F across
srn mid TN to predom the mid/upper 30s over N AL. Even with the mid
level cloud cover, light sfc flow out of the NNW in the wake of the
frontal passage should allow temps to fall near/just below the 30F
mark across most of the area well after midnight. Other than 
adjusting overnight lows a couple of degrees based on the latest 
trends and increasing cloud cover just a bit, no major changes are 
needed to the ongoing forecast attm.

.SHORT TERM...(Friday through Saturday)
Issued at 307 PM CST Thu Dec 14 2017

Not much weather to speak of in the short term. A shortwave will 
move through the region during the day Friday, with a slightly 
cooler airmass building southeastward through the day. Cloud cover 
will persist through at least early afternoon and prevent some 
diurnal heating. Thus, temperatures will be a few degrees cooler 
than those observed today, with highs in the mid to upper 40s. Skies 
will clear overnight providing another cold night across the area, 
with lows on Friday dropping into the upper 20s once again. These 
cool conditions will be short-lived, however, as a weak ridge tries 
to build northward on Saturday as a shortwave moves ashore the west 
coast of Mexico. Meanwhile, high pressure will develop along the 
Gulf of Mexico, with surface winds shifting the south. The 
combination of southerly flow and height rises will help 
temperatures warm into the lower to mid 50s by Saturday afternoon. 

.LONG TERM...(Saturday night through Wednesday)
Issued at 307 PM CST Thu Dec 14 2017

A pattern of ridging west, troughing east will change somewhat by 
the weekend and early next week, as a cut-off low off of the
southwest coast induces troughing over the western third of the 
lower-48. This upper low situated across the southern Arizona border
late Saturday night, will send a few upper level disturbances 
towards the north and east. It will bring unsettled weather across 
the Tennessee Valley, after midnight Saturday night. Temperatures, 
even over our far northern areas of Franklin and Moore in Tennessee 
should remain above freezing, so will keep the precipitation all 
liquid for now. More showers will overspread the Tennessee Valley 
during Sunday and Sunday night, with the best rain chances during 
Sunday morning, especially across northwest Alabama. General 
atmospheric instability parameters suggest it will be too stable for
thunder, so am keeping the precip character as showers. As a few 
disturbances move across the region, scattered showers should 
continue on Monday and Tuesday. 

Shower activity should end Tuesday night as a cold front finally 
passes across the region, bringing drier air back into the region. 
Unlike the past few cold fronts, the air behind this one is not as 
cold, with lows "only" in the mid/upper 30s. The dry trend continues 
into Wednesday night. Another surge of moisture from the south 
should bring isolated showers on Thursday. 


.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 540 PM CST Thu Dec 14 2017

VFR conds prevail for now at both main terminals, although mid/high
clouds are approaching in a large swath from the S. Cigs in the 
10-12K ft range look to develop after 06Z, and then lower more into 
the 5-7K ft range between 14-15Z Fri. Clouds may begin to sct late in
the afternoon hrs. Light/var sfc winds will turn more toward the NW 
near 7-8KT Fri morning.





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at weather.gov/huntsville.