Weather

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fxus63 kjkl 060345 aaa 
afdjkl 


Area forecast discussion...updated 
National Weather Service Jackson Kentucky 
1045 PM EST Monday Jan 5 2009 


Short term.../the rest of tonight/...updated 


An area of rain continue to overspread the area from the 
southwest...with mainly SW sections experiencing rainfall so far. 
Temperatures are in the middle and upper 30s in most areas...though 
the high ridgetops along the Virginia border are in the lower 40s. More 
problematic is Ridgetop temperatures hovering near freezing along and 
north of the mountain parkway corridor at Koomer Ridge and Triangle Mountain. 
Further north...the 10 PM temperature at fgx...Fleming Mason Airport was 29. 
Roadway sensors indicate roadway and subsurface temperatures around 
40. 


Although warm advection and warm rain will gradually lead to areas at 
or just below freezing rising above freezing toward dawn from south 
to north...some very light ice accumulation in elevated surfaces 
cannot be ruled out...but recent warm weather has led to the warm 
surface temperatures. Other than a possible slick spot or two on 
bridges or overpasses...impact to travel is not expected and opted to 
issue an Special Weather Statement rather than a west-southwest for these areas. Otherwise...rain 
should overspread the area overnight... gradually reaching the 
northern and eastern areas around or shortly after midnight. Based on 
most recent model quantitative precipitation forecast guidance the current flash flood advisory still appeared on 
track. Overall...just some minor pop and hourly T adjustments based 
on the latest trends other than the mention of possible -zr on 
northern ridgtops. 


The previous short term forecast discussion follows... 


/tonight through Tuesday night/ 


A thin band...or finger of patchy rain and drizzle is rolling through 
our area from central Kentucky...with an area of more moderate rain 
developing and moving northeast from western Tennessee. Models have a good 
handle on the developing storm system...and bring rain back into 
eastern Kentucky this evening. There appears to be two significant 
waves of weather...more intense rainfall. The first towards dawn 
Tuesday morning and then again late Tuesday afternoon into Tuesday 
night. Models have cut back on overall rainfall totals for this event 
but still range between around three quarters of an inch inch in the 
far northern portions of the County Warning Area and closer to two...and three 
quarter inches in our south. With a very saturated ground...expect 
the bulk of any rainfall to become runoff and as such...will continue 
with Flood Watch for areas already posted. 


Another concern centered around the potential for freezing rain in 
the extreme north...particularly Fleming County. Northern fringe of 
County Warning Area appeared cold enough to support some freezing rain there for a 
few hours during the early morning time frame. But ground...or surface 
temperatures are relatively warm with Road sensors showing lower 40s in that 
area. Also...a quick glance at the 18z NAM trended warmer with surface 
temperatures in that area. In addition...rainfall rates should be intense 
enough that mass transport of warmer air from aloft should help keep 
any freezing rain from forming. Decided to forgo any advisory for 
now...but will pass any concerns on to the next shift so a close 
watch can be kept on surface observation in that area. 


Otherwise...do not expect any frozen precipitation through the period 
as temperatures remain warm into Wednesday morning. 


Long term.../Wednesday through Monday/ 


Rain is likely to be ongoing over much of the area at the start of 
the period...especially in the southeast. As surface low pressure 
and upper level support continue to pull away to the east and 
northeast during the day Wednesday...precipitation will further diminish. 
Colder air arriving from the northwest will cause remaining precipitation 
to transition to snow showers late in the day in northwest counties. 
The complete transition to snow showers is expected Wednesday 
evening. There is disagreement in the models concerning minor 
impulses on the back side of the system. There will be lingering low 
level moisture in cold air advection with at least some upslope 
component in the flow on Wednesday night into Thursday. Any dynamic 
support would serve to enhance the snow showers. Will hold onto 
chance probability of precipitation in the most favored upslope areas in the east and 
southeast...with slight chance elsewhere. However...the picture is 
too uncertain to be very specific. As a surface ridge with drier air 
builds in on Thursday...the last snow showers will taper to 
flurries. 


A short break in the weather will then last through Friday. After 
this...the models are showing more diversity. The European model (ecmwf) looked more 
consistent and it and its ensemble were favored by HPC. Relied 
heavily on the European model (ecmwf) and HPC guidance for the forecast from Friday 
night on. This brings another cold front through on Saturday. Temperatures 
should warm enough for any precipitation to be rain along and ahead of the 
cold front Friday night into Saturday...with any remaining precipitation 
again changing to snow showers on Saturday and Saturday evening as 
the precipitation wanes behind the front. 


&& 


Aviation.../00z to 24z/ 


Light rain showers ongoing at all taf sites as of taf issuance. 
Latest radar loops reveal a large area of light to moderate rain 
moving across western and central Tennessee. This area of 
precipitation will move begin to affect loz and sme by 3z tonight. 
Until then...IFR ceilings associated with a low stratus deck will 
prevail. Jkl will continue to experience LIFR ceilings and vlifr visibilities 
until after 4z. Once the more intense and widespread sets in some of 
the Ridgetop fog will thin to MVFR levels for a while. With a 
throughly saturated boundary layer however...there will be periods of 
LIFR to vlifr conditions at jkl for the remainder of the taf period. 
Loz and sme experience a similar scenario...with periods of IFR 
occurring from time to time when the rain lets up. Ceilings at all taf 
sites will likely not improve above IFR until Tuesday evening or 
later. Loz and sme will experience a period of moderate to heavy 
rainfall after 12z Tuesday...with some potential for flooding 
throughout the day. 


&& 


Jkl watches/warnings/advisories... 
Flood Watch from 7 am EST Tuesday through Wednesday morning for 
kyz068-069-079-080-083>088-107>120. 


&& 


$$ 


Short term...ray/jp 
long term....hal 
aviation...jp 

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