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Area forecast discussion 
National Weather Service Baltimore Maryland/Washington District of Columbia
306 PM EDT Monday Jul 6 2015

a weak low pressure system and warm front will lift northeast out
of the area tonight. High pressure will dominate Tuesday. A cold
front will move in from the Great Lakes on Wednesday. The front
will slide slowly south across the area Thursday and Friday before
slowly moving back north over the weekend.


Near term /through Tuesday/...
convection developing as of 18z reflectivity...mainly west of
I-95 corridor...with incrsg coverage to the west. 17z surface analysis
indicating warm front still hovering across northern portion of
County Warning noted with southerly flow over majority of County Warning Area. The flow has
allowed for sufficient heating...despite the broken-overcast skies...with
temperatures currently in the 80s. Destabilization on going with cumulus
fields noted on the visible Sat...especially to the south and west. The upper
level trough has nudged a bit further to the east...providing
support aloft to aid in triggering convection. Generally expecting
incrsg coverage across the entire County Warning Area late afternoon into this evening
as the forcing aloft pivots east with the trough...and combining
with the nearly stationary frontal boundary and incrsg
instability. Shear remains on the weaker end...but with the
placement of the frontal boundary...backing winds at the surface could
provide just enough directional shear for rotating storms...with
strong/damaging winds and isolated tornadoes being the main severe
threats. Precipitable waters around 1.7- 1.8 inches and the possibility of
training storms will lead to a heighten flooding threat...though
with the scattered nature of the storms...confidence too low to pinpoint
if/where would see flooding.

Most activity expected to taper off late this evening with loss
of daytime heating/resulting instability. Could see lingering
showers through the night as the trough pivots to the east and
north...with dry conditions in central Virginia by the second half of
the night.

Tuesday looks to be relatively dry as the upper level trough pushes
to the north. Precipitation possible over the northeastern corners of the County Warning Area
where the southern edge of the trough will hover through most of the
day. At the surface...low pressure trekking through the Great Lakes will
drag the associated cold front near the region...reaching the
western areas overnight Tuesday. Chance of precipitation will accompany the


Short term /Tuesday night through Wednesday night/...
high pressure slides east to our south Tuesday night as cold front
approaches from the northwest. The front will cross into the County Warning Area
by Wednesday night. Clouds will start to increase Tuesday night but
think most showers or storms hold off until during the day
Wednesday. Main issue Wednesday are some timing differences with
the front. The slower guidance keeps the storms away early on and
allows temperatures to spike into the 90s...while faster modeling brings
storms in early on Wednesday and keeps temperatures down in the 80s.
Either way...storms should diminish or move away Wednesday night
with modestly cooler temperatures and lower dew points.


Long term /Thursday through Monday/...
frontal boundary will linger around the region Thursday into Friday.
Upper level disturbances will impact the County Warning Area on the weekend and
into next week. Isolated/scattered showers and/or thunderstorms are possible
each day. Temperatures will be near normal for this time of the year.


Aviation /19z Monday through Saturday/...
mainly VFR conditions through the taf period. Scattered showers and thunderstorms
will impact all terminals through 22-00z...with possible lingering
showers through 03z. Ceilings/visible MVFR and possibly IFR with storms this
afternoon...with minimal impacts to conditions with any showers
overnight. Patchy fog late tonight could reduce visible...but
confidence of occurring/timing too low to include at this time.

Southerly flow around 10 kts outside of storms through the evening...becoming
light/vrb overnight. Winds increase from the west on Tuesday...up to
around 10 kts. Occasional gusts will be possible Tuesday afternoon.

Main concern Wednesday/Wednesday night has to do with approaching
cold front. Thunderstorms look likely...with a few periods of sub-
VFR ceilings/visible and perhaps a few strong wind gusts mixed in with
otherwise VFR conditions. Timing is still in question however.
Winds shifting from southwest early to northwest by Wednesday
night...possibly some non-storm gusts into the 20 knot range.

VFR conditions expected for Thursday night and Friday. Sub-VFR conditions
possible due to showers and/or thunderstorms.


Small Craft Advisory remains in effect through tonight with gusts up to 20 kts possible.
Mainly sub-Small Craft Advisory conditions on Tuesday...though occasional gust up to 20 kts
may be possible on the Chesapeake Bay. Winds are too marginal at this time to
up another Small Craft Advisory.

Main concern Wednesday/Wednesday night has to do with approaching
cold front. Winds will pick up ahead of the front with gusts
possibly reaching Small Craft Advisory levels. In addition...thunderstorms look
likely...with some stronger gusts and heavy rain et cetera. Timing is
still in question however. Winds shifting from southwest early to
northwest by Wednesday night.

Sub-Small Craft Advisory conditions expected for Thursday night and Friday. Possible showers
and thunderstorms across the waters during this period.


Lwx watches/warnings/advisories...
District of Columbia...none.
Marine...Small Craft Advisory until 8 am EDT Tuesday for anz533-534-537-


near term...Sears
short term...Sears/rcm
long term...imr

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