Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

Area forecast discussion 
National Weather Service Baltimore Maryland/Washington District of Columbia
816 PM EDT sun Apr 26 2015

low pressure over the Carolinas and offshore waters will
strengthen as it moves further out to sea tonight. An upper level
trough will move through the area Monday. High pressure will move
into the area Tuesday. Another low pressure system is expected to
track across the southeastern U.S. Late in the week.


Near term /through Monday/...
only a few clouds around the middle-Atlantic this evening as high
pressure persists overhead. The parent high across the northern plains
will continue to build into the region tonight and a pressure
gradient will form across the region into Monday. Winds will
increase to 5-10kts by Monday morning and therefore places will not
radiate as well. Forecast min temperatures in the low to middle 40s east of the
Blue Ridge and the 30s across the mountains patchy frost possible
along the Blue Ridge mountains and higher elevations in the Virginia
Highlands as temperatures approach 35 degree.

An upper level trough extends from the Gulf of Maine to the lower
Great Lakes while a shortwave trough moves across Michigan. These
features will move south tonight and clouds will increase from north
to S late tonight...another aspect that will hamper temperatures from
dropping too low.

The upper level trough will move into the middle-Atlantic Monday with
embedded shortwave troughs. Cold air aloft will lead to steepening
lapse rates. Showers are expected to break out across New York/PA Monday
morning as the upper level trough axis swings southward. Showers
are expected to move into northern Maryland after 16z Monday but coverage
seems weak and therefore only scattered showers are expected. An
inverted v signiture on forecast soundings and 20-30kts at the top of
the mixing layer will lead to gusty north-northwest winds through the
afternoon Monday. Forecast maximum temperatures are in the upper 50s low 60s and
40s in the mountains


Short term /Monday night/...
winds taper off Monday evening as upper level trough pivots offshore
and the shortwave pushes south. Subsidence building in the wake
should lead to skies scattering and dry conditions. Lows Monday night
will be slightly below normal.


Long term /Tuesday through Sunday/...
dry weather then persists Tuesday through Tuesday night as the region remains
positioned between two closed lows. High pressure centered over
the Central Plains will nudge in from the north during the day
Tuesday...but will quickly retreat as low pressure over the Gulf
states begins to organize and push north. Overspreading precipitation with
this low looks to remain south through at least 12z Wednesday. Temperatures remain
just below normal for Tuesday-Tuesday night...though if the winds hold
more to a northwest flow rather than shifting to the north...could see
temperatures slightly warmer with downsloping effects.

Wednesday will be a relatively nice Spring day...with temperatures near climatology.
Clouds should start increasing by late Wednesday...especially in the low pressure along Gulf Coast begins to impact our
region. Cloudiness should help temperatures from falling too far Wednesday
night...keeping them slightly at or above normal.

Model guidance has come into slightly better agreement with overall
handling of low pressure tracking to our south on Thursday. Still appears
that the bulk of the impacts remain to our south...with mainly light
showers overspreading the County Warning Area through Thursday. However...this could
change if track of low shifts closer to our area. Could be some
wraparound precipitation lingering into Friday...although it would likely
be light.

High temperatures Sat slightly at or above normal (l70s) across County Warning Area...with low


Aviation /00z Monday through Friday/...
VFR expected through the taf period. North winds 5-10kt. Light
north-northwest flow continues. Winds increase Monday to 10-15 knots with gusts
20 to 25 knots.

VFR conditions Monday night-Tuesday night.

VFR conditions likely Wednesday...before a chance of sub-VFR in rain showers Thursday
as low pressure tracks to our south.


north-NE winds 10kt or less this afternoon. Winds shift northwest late
tonight and increase towards morning as the gradient strengthens
between low pressure offshore and high pressure well to the west.
A Small Craft Advisory remains in effect for all waters Monday for winds 15-20 knots
with 25 knots gusts. Small Craft Advisory conditions will persist for the Main Channel
of the Bay and lower tidal Potomac Monday night.

Sub-Small Craft Advisory conditions all waters Tuesday aftn-night.

Not expecting marine concerns Wednesday as flow remains light under high
pressure. Wind field increases some on Thursday...but overall strength
will depend on proximity of surface low...which is still uncertain.


Lwx watches/warnings/advisories...
District of Columbia...none.
Marine...Small Craft Advisory from 8 am Monday to 6 am EDT Tuesday for
Small Craft Advisory from 8 am to 8 PM EDT Monday for anz530-


near term...has/KS
short term...Sears
long term...mse

National Weather Service Glossary of Abbreviations