194 
fxus61 krlx 131044 
afdrlx 


Area forecast discussion 
National Weather Service Charleston WV 
544 am EST Sat Mar 13 2010 


Synopsis... 
a slow moving upper level system continues to affect the region 
through the weekend. Dry weather and seasonable temperatures return 
early next week...as the low exits east. 


&& 


Near term /through tonight/... 
will keep this short tonight due to flooding across the south. 


Surface low and associated deformation zone will push north this 
morning and focus more on the northern half of the County Warning Area as 500hpa 
trough axis lifts northward around the parent closed low in western 
Tennessee. Main forcing should give the hardest hit areas in the 
southern part of WV a relative break today...although spotty light 
rain this afternoon cannot be ruled out. Upper level low will 
continue to slowly spin east...but will still carry scattered 
showers tonight. Low stratus deck will dominate the sky cover. As 
has been discussed for the past few days...still have immediate 
concerns for any rain falling across the northeast mountains given 
the remaining snow pack...and also the streams...creeks...and rivers 
that are already elevated and running fast. 


&& 


Short term /Sunday through Monday night/... 
the broad upper level low pressure center will drift east of the 
area...while individual vorticity maxes rotate around its periphery 
across PA...OH...KY and WV on Sunday. Despite of some detail 
discrepancies among the NAM/GFS/ECMWF and Gem...all show these short 
waves affecting the area through early Monday. Therefore...expect 
probability of precipitation/weather to improve later on Monday. Decreased probability of precipitation from west to east 
drying up southeast Ohio first by Monday...as the atmospheric column 
dries out. Clouds and moisture hang on into Monday night on 
weakening easterly flow. 


For temperatures...generally stayed close to gmos bias corrected...with 
minor tweaks mainly a couple of degrees up over The Lowlands at day 
time. 


&& 


Long term /Tuesday through Friday/... 
European model (ecmwf) is still the way to go in the extended period. With the large 
closed low continuing to pull away from the Atlantic coast at the 
start of this period...weak high pressure is able to build in at the 
surface. Flow aloft becomes fairly diffuse as trough digs across 
the Gulf Coast with time...leaving a broad area of weak h500 low 
pressure. By the end of the period...ridging starts to take hold in 
the Thursday night/Friday timeframe. 


As far as sensible weather...there may be lingering isolated 
rain showers/shsn in the mountains Monday evening with leftover low level 
moisture and northerly flow. These will die off overnight as the 
flow slackens. Could be enough moisture and daytime instability for 
a few isolated showers across the southern counties on Tuesday...so 
maintained a slight chance pop. The rest of the period looks dry 
with increasing influence from the surface high and a slowly drying 
column. 


Temperatures will be near to a bit above normal through the period. 
HPC numbers were in decent agreement with mex/ensemble numbers and 
stayed close. 


&& 


Aviation /12z Saturday through Wednesday/... 
ceilings across the south will flirt with the 3kft level today as 
rain lifts north. MVFR ceilings expected in rain at northern 
sites...with visibilities down to low end MVFR...and brief IFR at 
times. After the rain ends...may see visibilities struggle to stay 
at VFR...and have left this as 6sm with br. 


Moderate rain expected with the system as it moves north. 


Light wind may keep fog from developing overnight...but will need 
to revisit this as we get closer to the tonight time frame. 


After 12z Sunday... 
MVFR possible in showers Sunday. 


&& 


Hydrology... 
heavy rainfall over the southern part of West Virginia has created 
new problems in addition to the ongoing concerns further north that 
have been stressed over the past few days. This heavy 
rainfall...close to 3 inches in some places...has created 
significant urban and stream flooding in Raleigh and Fayette 
counties...and will now be carefully watching the area rivers and 
creeks in response to the amount of water that has come down. Flood 
warnings have been issued for these areas...as well as further 
northwest through the I-64 corridor. Rainfall has been significantly 
less towards the tri state area thus far...although still in the 1 
to 1.5 inch range. Specific rivers that will be watched for now are 
the Greenbrier and the new. Will also keep an eye on the Kanawha and 
the Guyandotte. 


Also to note...aep is releasing water at 13000cfs on the New River 
at Claytor Lake dam near Radford Virginia. 


Back to the northeast mountains...the combination of ongoing snow 
melt and the onset of heavy rain will lead to excessive water in our 
mountains. Many river...creeks...and streams are already running at 
elevated levels. 


Due to this increasing threat...areal flood warnings remain in 
effect until Saturday night for the northern and central mountains 
of West Virginia. This is due to strong rises of area creeks and 
streams...some of which are expected to rise above bankfull 
resulting in flooding of low lying and poor drainage areas. The 
warning has been issued to maximize the lead time and to allow 
residents...and emergency management officials to have plenty of 
time to take measures. 


The rivers will continue to rise as their respective creeks 
contribute the water from the snow melt...combined with expected 
rainfall tonight and over the weekend. Flood warnings for the Tygart 
Valley River at Belington and Philippi and the Greenbrier River at 
Buckeye and Marlinton are in effect. 


Other rivers that will see strong rises are the upper Gauley...upper 
Elk...Kanawha rivers and especially the Ohio River. A Flood Watch 
remains in effect for the Ohio River...which continues to rise and 
may eventually lead to significant water problems. 


&& 


Rlx watches/warnings/advisories... 
WV...Flood Watch through Wednesday morning for wvz005>011. 
Ohio...Flood Watch through Wednesday morning for ohz075-076-085>087. 
Kentucky...Flood Watch through Wednesday morning for kyz101-103. 
Virginia...none. 


&& 


$$ 
Synopsis...26/arj 
near term...26 
short term...arj 
long term...cl 
aviation...26 
hydrology... 

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