Scientific Forecaster Discussion
Area forecast discussion...updated
National Weather Service Baltimore Maryland/Washington District of Columbia
1028 am EST Friday Dec 26 2014
high pressure over the area today...moving offshore Saturday. A
weak cold front will cross the region late Sunday...with another
low pressure system approaching from the southeast into Monday.
Colder high pressure will follow for middle week.
Near term /until 6 PM this evening/...
in near-perfect symmetry...an upper trough encompasses the western
half of the Continental U.S. While a high pressure ridge resides over the eastern
half. After an active past few days over the eastern Seaboard...high
pressure has wiped away much of the area clouds and dropped off
winds. Barely a breeze at the surface and certainly no discernible
direction. The surface high itself is elongated over the southern Appalachians
and stretches from Alabama to southern Maryland.
Though at a more southern latitude and typically warmer than areas to
the north...the lower shen valley and Piedmont - kcho area - are
cooler than the District of Columbia/balt metropolitan areas and closer to the Bay. Most
all guidance members...including adjacent and bias-corrected
derivatives show an inverse of these conditions...so hourly temperatures
as well as the expected maximum temperatures were modified to account for
these differences. Dewpoints are fairly uniform in the
l30s...keeping conditions fairly moderated and allowing for only a
slow/steady temperature climb this afternoon. Most areas will peak in the
l-m50s west/ near calm winds for a cool but warmer than average late Dec
Short term /6 PM this evening through 6 PM Saturday/...
high pressure will gradually slip east off the Carolina coast by
Saturday as an upper trough digs into the Desert Southwest. As the
jet stream strengthens and shifts back to the south...high level
clouds will begin to spill across the area...especially by Saturday
afternoon. However overall the will continue to be tranquil and
mild. Tonight should feature effective radiational cooling
again...although the subsidence inversion will mean warmer lows at
the higher elevations. High temperatures for Saturday inch up...with
perhaps a few spots topping 60.
Long term /Saturday night through Thursday/...
low pressure over the Great Lakes Saturday night will move along
the to the Canadian Maritimes by 00z/Monday and drag a weak cold
front across the region. Low pressure will form across the lower
Mississippi Valley early Sunday and move northeast along the
trailing frontal boundary Sunday night. Precipitation chances increase as
decent uplift move across the County Warning Area late Sunday/Sunday night as this
low system moves across the Carolinas. Temperatures will be warm
enough to keep precipitation all rain on Sunday...but towards the Mason-
Dixon line at higher elevation areas...some wet snow could mix in
The surface low moves offshore Monday. Then colder high pressure
builds across the region late Monday and continues for the
remainder of the week. This high will feature seasonal to below
normal temperatures for much of next week. But the air mass is dry
so not expecting any precipitation...except for a few Western Mountain snow
showers Wednesday and Thursday. The next low pressure system that could
impact the middle Atlantic is starting to show up in the model for
next weekend...but low confidence at this point.
Aviation /15z Friday through Tuesday/...
high pressure in control through the taf period...with VFR
conditions. Light/variable winds will become southerly around
midday today but remain less than 10 knots.
Winds remain light and southerly through Saturday...VFR likely.
MVFR to locally IFR conditions expected Sunday as precipitation
overspreads the region.
winds will remain below Small Craft Advisory-levels through Saturday from
generally a southerly direction as high pressure gradually moves
A weak front will cross the region on Sunday into Monday...winds
are expected to remain below Small Craft Advisory levels.
klwx 88d will remain out of service until Saturday...when the parts
to repair the radar are expected to arrive.
District of Columbia...none.