065 
fxus64 kshv 201212 
afdshv 


Area forecast discussion 
National Weather Service Shreveport la 
612 am CST Thursday Nov 20 2008 


Discussion... 
update to include deep East Texas as well as all of northwest and 
north central Louisiana...as well as south central Arkansas in a 
dense fog advisory through middle morning. No other changes at this 
time. 


13 


&& 


Previous discussion... /issued 336 am CST Thursday Nov 20 2008/ 


Discussion... 
patchy dense fog developing across deep East Texas into northwest 
and north central Louisiana this morning as a descent inversion 
has set up below increasing southwest winds at 1kft. For now will 
handle it with just patchy dense fog wording in the grids but if 
the fog becomes more widespread...may need a brief dense fog 
advisory this morning until we can mix the southwest wind down to 
the surface. Other than that...strong cold front extending from 
near central Oklahoma into northern Arkansas will continue to make 
descent progress southward today but will likely get hung up in 
the ouachitas briefly this morning before surging southward for 
the afternoon. Feel like with mixing ahead of the front...not to 
mention pre-frontal compressional warming...we should see temperatures in 
the 70s along and south of the I-20 corridor today so adjusted the 
maximum temperature grids up somewhat. High temperatures will likely be 
reached just before noon across our northern zones with falling 
afternoon temperatures and increasing winds. Will keep winds just 
below lake Wind Advisory criteria but this may need to be 
revisited later this morning. 


Pressure gradient remains strong through the night with gusty 
north to northeast winds areawide along with strong cold air 
advection...allowing for a pretty good temperature drop overnight. 
Winds likely to diminish a little near sunrise Friday morning 
followed by mixing with winds picking up again during the day 
Friday. Cold day Friday with northeast winds despite full sun. 
Guidance temperatures continue to go down for highs Friday and see 
no reason to argue. Winds diminish late Friday afternoon into 
Friday evening with a very cold night areawide Friday night. 20s a 
good bet areawide except across our extreme western zones where 
increasing 850mb moisture could bring some clouds into the Piney 
Woods which may offset overnight mins a little by Saturday 
morning. 


Clouds will increase across the region for Saturday as winds 
become more southeast with a little better warmup for Saturday and 
much warmer for Sunday ahead of our next cold front still poised 
to come into our region during the day Monday. Timing always an 
issue this far out but the consensus is now for a little slower 
frontal passage on Monday thus the warmer temperatures for Monday. 
Rain chances still looking pretty descent so did not change pop 
forecast much. 


Prelims to follow...13. 


Aviation... 
light and variable winds and temperature and dew point spreads of only a 
degree everywhere south of I-30...except NE Texas where 2 to 4 degree 
spreads persist. As a result...the fog machine is cranking up over 
southern and eastern sections. Already vlifr/LIFR at klfk and kmlu. 
Coming down at kshv too. Area surface winds will begin to stir out of 
the north early and fog/ceilings should lift/break by middle morning. Look 
for brisk northerly flow by afternoon as a strong Arctic front bull 
dozes over all by this evening. No fog this time tomorrow...with 
fresh northern Continental air in place. /24/ 


&& 


Preliminary point temps/pops... 
shv 71 35 50 29 54 / 0 0 0 0 0 
mlu 69 34 49 27 53 / 0 0 0 0 0 
deq 63 28 49 24 52 / 0 0 0 0 0 
txk 65 32 49 28 52 / 0 0 0 0 0 
eld 66 30 48 25 52 / 0 0 0 0 0 
tyr 71 34 51 30 55 / 0 0 0 0 0 
ggg 71 34 50 29 54 / 0 0 0 0 0 
lfk 76 37 53 30 57 / 0 0 0 0 0 


&& 


Shv watches/warnings/advisories... 
Arkansas...dense fog advisory until 9 am CST this morning for the following 
zones: arz072-073. 


La...dense fog advisory until 9 am CST this morning for the following 
zones: laz001>006-010>014-017>022. 


OK...none. 
Texas...dense fog advisory until 9 am CST this morning for the following 
zones: txz152-153-165>167. 


&& 


$$ 


13/24