Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Baltimore Maryland/Washington District of Columbia
1029 am EDT Tuesday Apr 28 2015
high pressure will build into the area today. Low pressure will
impact the region Thursday and Friday. High pressure will return for
Near term /until 6 PM this evening/...
upper level low pivoting off the East Coast this morning. Subsidence
building in the wake has led to mostly sunny skies with only a
weak vorticity maximum over WV producing increased cloud cover for extreme
portions of the County Warning Area. Winds incrsg now with heating...with gusts up
to 20-25 miles per hour possible mainly east of Blue Ridge. Under the mostly
sunny skies...temperatures have warmed quickly this morning...but remain
on pace for highs to reach the middle to upper 60s.
Short term /6 PM this evening through 6 PM Wednesday/...
low pressure which has been spinning in the Gulf of ME for the past 2
days will be moving very slowly further out to sea as high pressure moves
closer to the east CST. This will provide a mainly clear overnight. Majority
of the forecast will see lows in the 40s...l50s in the cities..mu30s in
Middle altc remains in between systems Wednesday. Clouds will likely be on the increases by
afternoon as the next low pressure area over the Gulf states becomes better
organized. Highs will be near climatology norms for the end of Apr west/
Long term /Wednesday night through Monday/...
although substantially less potent a system than the 00z run at this
time the previous night...the recent run of the GFS still favors a
relatively stronger closed low from the Great Lakes and over the
area to close out the work week. The dynamics of this feature are
less impactful since it does not sync-up west/ the southern stream moisture
that it had earlier runs. Both the GFS and Euro are closer in
solutions now...W/ better convergence on handling the moisture over
the deep south - the initial wave that had been pulled northward in
earlier runs but now barely crossing into southern Virginia late Wednesday/early Thursday.
However...as a bulk of this feature moves off the Carolina
coast...an upper vorticity that the Euro continues to show as a weaker
feature - begins to push into the back side of the offshore system.
A somewhat brief connection is then made between the two and some
scattered bands of light rain develop during the day on Thursday. This
would also keep cooler temperatures and cloudy skies over the area for much
of the day.
Strengthening as it moves into the already offshore low...the two
systems will intensifying but well off the middle Atlantic coast. Winds
will pick up quickly but mainly off the Delaware-Maryland-Virginia waters...tapering
off toward the middle Atlantic coastal zones. Some scattered showers may
linger into Friday but drier and cooler air will be wrapped back down
into the area behind the exiting system. This system will likely
continue its slow/steady pace away from the coast and keep the track
of northwest flow pulling-in subsequent upper vorts...attempting to slide
them over the area into the weekend. Near zonal upper flow however
will quickly push from the northern plains into the Great Lakes...pushing
an in-situ upper ridge over the area this Sat & sun - bringing back
a decent warm-up. Highs into the early part of next week are
expected to slide back above average...W/ the potential for u70s/l80s
sun and espec on Monday.
Aviation /15z Tuesday through Saturday/...
VFR conditions through the taf period. Northwest gusts up to 18-22 kts possible
today...mainly District of Columbia and Baltimore terminals. Wind direction will
shift between 300 and 350 throughout the afternoon before becoming
Better confidence the passage of an upper level system from Thursday into
Friday. Mainly some scattered showers...cloudy skies and some low-end
northwest breezes. Possible MVFR or lower conds at peak on Thursday. Conds
improving Friday into weekend.
Small Craft Advisory remains in effect for all waters through 20z with gusts as of 14z
being reported between 18-25 kts. Gusts should diminish there
after...with sub Small Craft Advisory conditions in place through Wednesday.
A potent low pressure will affect the coastal waters late this
week...but mainly well offshore west/ lesser effects back toward the Maryland
ches Bay and tp river. Periodic Small Craft Advisory gusts from late Wednesday into
Thursday...then again on Friday and Sat aftns.
District of Columbia...none.
Marine...Small Craft Advisory until 4 PM EDT this afternoon for