Area forecast discussion
National Weather Service Blacksburg Virginia
813 PM EDT sun may 19 2013
Synopsis...
upper level energy will move slowly across the region tonight and
Monday...resulting in rounds of shower and thunderstorm activity.
This system will then shift off the middle Atlantic coast by
Tuesday. A large low pressure system will track from the Central
Plains on Monday into the Great Lakes by Thursday. This system
will push a cold front through the area on Friday.
&&
Near term /through Monday/...
as of 330 PM EDT Sunday...
Shower activity has become scattered across the forecast region this
afternoon...with radar indicating a few of the showers and
thunderstorms producing locally heavy rain. Cell movement across
the North Carolina mountains into the mountain Empire has been
slow due to very light winds aloft near the base of the
approaching upper level trough. Will have to watch this area
closely through the next few hours for the potential of flash
flooding...especially in areas where cells begin to train. Further
east...steering winds are a little stronger...causing cells to
move more quickly.
Models are in decent agreement this afternoon that the majority of
shower and thunderstorm activity will shift more toward the
piedmonts during the evening as the upper trough continues
east. Intensity of rainfall will begin to wane after sunset as
heating ends...with only isolated to widely scattered shower
activity expected after midnight. With diminishing cloud
cover...light winds...and very moist conditions across the
area...believe that fog will become widespread once again...and
dense in a few areas. High dewpoints will keep overnight lows for
most locations in the low 60s...with a few upper 50s across the
mountains.
The base of the upper trough is expected to be over Southside
Virginia by Monday afternoon...with northwesterly flow across the
mountains as weak upper ridging builds in from the west. Will see
another round of shower and thunderstorm activity develop with
daytime heating that will be spotty in nature...but do not expect
this activity to be as widespread as today...more confined to the
piedmonts although will also see development along the ridges.
Expect better heating with the decreased cloud cover for Monday
afternoon...which will allow high temperatures to reach into the
middle and upper 70s.
&&
Short term /Monday night through Wednesday night/...
as of 150 PM EDT Sunday...
Scattered afternoon and evening thunderstorms will taper off Monday
night. The greatest chance of showers and thunderstorms will occur
in the Piedmont. After midnight cut back probability of precipitation to slight chance in
the east. With a southwest flow...it will be mild Monday night with
readings from the middle 50s in the mountains to the lower 60s in the
southeast.
Middle-level ridge builds overhead Tuesday after the shortwave trough
exits the region. With drier air aloft and absence of organized lift
translates to less coverage of convection. Played the highest probability of precipitation
along the southern Blue Ridge mountains. Highs Tuesday will range
from the upper 70s in the mountains to the upper 80s in the
Piedmont. Warm and muggy Tuesday night expected with lows in the
60s.
Weak upper air disturbances rotating around the western periphery of
the Atlantic surface high...will provide some lift for showers and
thunderstorms on Wednesday. Isolated to scattered convection will
linger into Wednesday night.
&&
Long term /Thursday through Sunday/...
as of 150 PM EDT Sunday...
An upper level closed low will spin around the upper Mississippi
Valley through at least Friday. In advance of this system...plenty
of moisture will advect northward into our region.
Pieces of energy will spiral eastward from the main system and
combine with daytime heating to create showers and thunderstorms.
HPC continues to favor a slower timing of the cold front. The front
is expected to exit our area Friday evening into Friday night. European model (ecmwf)
remains faster than GFS with timing of cold front. Do not believe
the surface low that develops off the southeast on GFS. High pressure
will ridge south from the Great Lakes on Saturday and slide east on
Sunday.
Cooling trend expect for Friday and Saturday. Highs on Friday
will range from around 70 degrees in the west to near 80 degrees
in the southeast. Saturday highs only reach the middle 60s across
the mountains to the lower 70s across the Piedmont. Highs for
Sunday will warm a couple of degrees from the middle 60s in the west
to the middle 70s in the east.
&&
Aviation /00z Monday through Friday/...
as of 800 PM EDT Sunday...
Scattered to numerous showers will continue through about midnight
before diminishing. In spite of the decreased shower
activity...anticipate areas of IFR stratus and fog which will
persist through middle morning Monday before some improvement begins.
Even with improvement Monday...daytime heating will once again
result in scattered to numerous showers and thunderstorms. Flight
conditions through Monday are expected to be poor.
The upper level trough will begin to shifting east of the area
after Monday. Expect Tuesday to be the best bet for decent flying
conditions although an isolated afternoon airmass shower or
thunderstorm is still possible. Next front approaches on Wednesday
with more showers/storms developing. This front does not appear to
be in a big hurry and looks to bring MVFR conditions...possibly
IFR at night...to taf sites for the latter half of the week.
&&
Rnk watches/warnings/advisories...
Virginia...none.
NC...none.
WV...none.
&&
$$
Synopsis...nf
near term...nf
short term...kk
long term...kk
aviation...PM
