315 
fxus61 krlx 191852 
afdrlx 


Area forecast discussion 
National Weather Service Charleston WV 
250 PM EDT Friday Mar 19 2010 


Synopsis... 
high pressure in control through Saturday. Low pressure system 
passes Sunday night into Monday...with showers lingering Monday 
night into early Tuesday. Warmer and drier through midweek. 


&& 


Near term /through Saturday/... 
a high pressure system will provide dry weather tonight and Saturday. 
Went below MOS guidance for lows tonight as models have been too 
warm with the good radiation conditions. Some moisture increases in 
southeast Ohio on Saturday...so think some afternoon cumulus could 
form there. 


&& 


Short term /Saturday night through Monday/... 
with flooding...if not snow...not too distant in the rear 
view...fire rears its head this period with the dry weather pattern 
forecast to last into the weekend. Two out of the three criterion 
for fire danger become present again Sat afternoon...with wind the 
only missing ingredient. With min relative humidity in the middle to upper 20s Sat 
afternoon...we may again be flirting with fire Special Weather Statement criterion. 
Threat should ease somewhat sun as dew points climb 
farther. 


Models are in reasonable with system that feature an upper level 
closed low that tracks east across the area sun nt and Monday. This is a 
similar track as the system that gave rise to flooding about a week 
ago with one key difference...no Rex block. This ought to 
translate into a smaller chance for precipitation setting up over a 
particular area for any length of time...and hence the smaller 
chance for an excessive rainfall threat. 


Maintained thunder chance in the forecast for Sun afternoon and nt 
although the timing will need fine tuned in later shifts based at 
least in part of the orientation of the Theta-E ridge ahead of the 
occlusion sun nt. If the system becomes any slower in future 
runs...the chance for thunderstorms Sun afternoon with the aid of 
daytime heating will wane. 


Nothing more than minor adjustments needed to temperatures Sat and 
Sat nt but raised highs sun to reflect latest higher guidance with 
slower timing of the next weather system. Used low level GFS 
temperatures for sun nt through Monday nt. Minimized the chance for 
late Monday nt and snow Tuesday morning...confining to just the higher 
terrain given vertical temperature profiles. 


&& 


Long term /Monday night through Friday/... 
the upper level low continues to slowly track eastward...with the 
surface low moving through the Ohio River valley and will be east 
of our area by Tuesday morning. Higher probability of precipitation linger over the eastern 
high terrain in WV through Monday night. 


Given the previous model disagreement over the large pattern...the 
models have a surprisingly moderate level of agreement with the 
large pattern throughout the remainder of the extended 
forecast...therefore the extended forecast was equally influenced by 
the European model (ecmwf)...GFS...and HPC guidance. High pressure will begin to 
settle in Tuesday...and it will bring warmer daytime temperatures 
and drier conditions with it. Skies will be clearing as the system 
approaches...daytime highs will reach above 60...except in the 
higher elevations where daytime highs will be in the lower to middle 
50s. Skies will clear at night and radiational cooling will cause 
nighttime lows to be in the upper 30s and lower 40s. 


The chance of precipitation will return late in the week with the 
approach of the next shortwave trough...the most likely chance of 
precipitation will occur Friday afternoon. 
&& 


Aviation /19z Friday through Wednesday/... 
VFR conditions through the period. 


After 18z Saturday... 
brief IFR possible in showers/isolated thunderstorms Sunday 
afternoon and night. 


&& 


Fire weather... 
with recent warmer daytime temperatures and dry weather...fire 
danger has reached moderate to high across the area...especially at 
lower elevations. Some lowland locations in southern to southwestern 
West Virginia have even reached a very high fire danger. Relative 
humidity levels this afternoon are reaching into the middle 20s to middle 
30s percent range...with mixing down of very dry air aloft. Luckily 
the winds are fairly light. 


Dew points will be slightly higher Saturday afternoon...yet so will 
temperatures. So fire danger will be enhanced again...by upper 20s 
to middle 30s relative humidity during peak heating hours. Accidental 
escaped debris Burns are by far the number one cause of 
wildfires...and are generally prohibited by law for most of the area 
this time of year in the afternoon hours. 


&& 


Rlx watches/warnings/advisories... 
WV...none. 
Ohio...none. 
Kentucky...none. 
Virginia...none. 


&& 


$$ 
Synopsis...ktb/jem/rpy 
near term...rpy 
short term...trm 
long term...mdp/jem 
aviation...rpy 
fire weather...mdp