Area forecast discussion
National Weather Service Blacksburg Virginia
348 PM EDT Tuesday Jun 18 2013
Synopsis...
low pressure will move east across the Middle Atlantic States this
evening and offshore tonight. Showers and thunderstorms will
continue this evening into tonight. Weak high pressure will build
north of the area Wednesday and Thursday resulting in somewhat
drier weather into the end of the week.
&&
Near term /through Wednesday/...
..as of 320 PM EDT Tuesday...
A midlevel shortwave trough and associated surface low over
Virginia will progress eastward to the coast tonight. Flash Flood
Watch continues until 6 PM. Showers with embedded thunderstorms...
heavy rain at times continues across our area with greatest
threat for any flooding problems over east portions of County Warning Area. High
precipitable waters and good lift combined with a strong upper jet/diffluence
across the low level Theta-E gradient supports very efficient
rainfall. The strong upper disturbance...responsible for the heavy
rain will move into the Atlantic on Wednesday. The broad trough
across East Coast will shift slightly eastward as the upper
ridging builds.
In general...taper off probability of precipitation from west to east this evening into
tonight. Added areas of fog to the isc grids. It will remain warm
and humid overnight with low temperatures from the middle 50s in the
mountains to the middle 60s in the southeast. Kept the light probability of precipitation in
for Wednesday with best chances across the south. Played highs
Wednesday closer to cooler MOS values from the upper 60s in the
western mountains to the lower 80s in the Piedmont.
&&
Short term /Wednesday night through Friday night/...
as of 345 PM EDT Tuesday...
Subsidence and drying aloft increases for the later half of the
week as high pressure builds into the area from the north
Wednesday night and Thursday...with a broad easterly component to
the wind as the high drifts to along the coast late Thursday into
Friday. With heights building aloft...and a dry middle level easterly
wind...looking at mainly tranquil weather with little or no precipitation
threat.
Temperatures will be near seasonal...not too hot...not too cool.
&&
Long term /Saturday through Tuesday/...
as of 345 PM EDT Tuesday...
Moderating temperatures expected over the weekend and into early
next week as the upper level ridge continues to build...850 temperatures
creeping toward +2oc for Monday and Tuesday. This suggests surface
temperatures will top out mainly in the 80sf...testing 90f degrees for
the urban areas. No real focus for deep convection during the
period except for convergence over the mountains...so kept any precipitation
threat mainly diurnal and primarily targeted to the mountains
&&
Aviation /20z Tuesday through Sunday/...
as of 135 PM EDT Tuesday...
Poor aviation conditions expected throughout the taf valid
period. Area of widespread rain showers/isolated thunderstorms and rain with MVFR-IFR ceilings and
MVFR visibilities...locally IFR...moving northeast with ul shortwave.
System will begin to exit the region from the west after 00z...but
expect low- level air mass to remain very moist and areas of MVFR-
IFR ceilings/visibilities in -dz/br likely to persist throughout the
night...especially lwb and Dan. Isolated thunderstorms and rain can also be
expected...but instability is minimal...so not expecting a lot of
thunderstorms and rain...best chance lyh/Dan. Light winds become west-northwest behind upper
short wave/associated surface trough late afternoon/evening from W-E.
Expect areas of fog to linger tonight into Wednesday morning.
Extended aviation conditions...for Wednesday...low IFR ceilings/visibilities
may persist through mid-morning...but expect improved conditions
as the day progresses with little to no rain showers activity. Ceilings/visibilities
should improve to VFR by afternoon. For Thursday into the
weekend...increased diurnal convection...especially along the
Appalachians...with locally brief MVFR-IFR ceilings/visibilities in thunderstorms and rain.
Areas of MVFR-IFR visibilities br...locally IFR fog...also possible during
the morning hours.
Medium confidence in ceilings through taf valid period.
Medium confidence in visibilities through taf valid period.
Medium to high confidence in wind speed/direction through taf valid
period.
&&
Rnk watches/warnings/advisories...
Virginia...Flash Flood Watch until 6 PM EDT this evening for vaz018>020-
022>024-033>035-045>047.
NC...none.
WV...none.
&&
$$
Synopsis...kk
near term...kk
short term...PM
long term...PM
aviation...jh/kk/rab
