Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

fxus61 klwx 211524 

Area forecast discussion
National Weather Service Baltimore Maryland/Washington District of Columbia
1024 am EST Thu Nov 21 2019

high pressure will pull offshore tonight. A cold front will
follow for Friday. Low pressure is expected to develop over the
mid-Mississippi Valley Friday night, then track across the area
this weekend. High pressure will likely return early next week
before another area of low pressure develops to the west by the
middle portion of next week.


Near term /through tonight/...
an area of high pressure overhead today will move to the East
Coast by this evening. Mid to high level clouds are quickly
moving east into our area this morning under light and variable
winds. Southwest to southerly winds will build in this
afternoon ahead of an approaching cold front. Temperatures will
be near average this afternoon and slightly above average


Short term /Friday through Saturday night/...
a cold front will slice across our County Warning Area Friday. Model guidance shows
the frontal passage in western Maryland to be around 9 am or mid-
morning on Friday and across southern Maryland to be around 3 PM or
mid-afternoon on Friday. Although no thunderstorms are expected with
this frontal passage, rain showers are expected to accompany the
front from west to east. It seems that there could be more
persistent shower activity across the Potomac Highlands due to the
front and upslope wind, and across the Virginia Piedmont to southern
Maryland as there may be slightly more instability in these regions
and less of an influence from downsloping wind ahead of and along
the front. Rain amounts will probably range between one quarter to
one half inch at higher spots.

As the front makes its way farther south toward the Virginia and
North Carolina border Friday evening, noticeably cooler and drier
air will filter in from the northwest due to high pressure building
into the region. High pressure will remain in control of the region
Saturday by shoving this cooler air southward along and east of the
Blue Ridge mountains. As we venture into Saturday afternoon into
Saturday night, some increasing moisture and warmth on the back side
of the high will lead to areas of rain arriving from the


Long term /Sunday through Wednesday/...
low pressure will be deepening rapidly as it moves offshore Sun
morning with rain showers ending by late morning. Gusty northwest winds
will take over with gusts 30-35 mph expected. High pressure will
gradually build over the area late Sunday night through Tuesday.

The latest 00z European model (ecmwf) trended significantly weaker and faster
with next storm system fcst to impact the region mid next week
while the 00z GFS and gfes remained more consistent moving a
strong storm system over the upper Midwest. Needless to say, it
appears a lot of uncertainty in the fcst for the second half of
next week. Temperatures are likely to trend cooler than normal
for the second half of next week.


Aviation /15z Thursday through Monday/...
VFR conditions through tonight as high pressure overhead slowly
moves to the East Coast. A cold front will slice across the region
Friday. Rain showers will develop at the terminals with higher
amounts possible at the cho, and dca terminals. MVFR conditions
possible with these showers. Winds will increase from the southwest
ahead of the front and then from the northwest behind the front.
VFR conditions reture Friday night and much of Saturday. Some areas
of rain could move into cho, mrb and iad Saturday afternoon and
reduce conditions to MVFR or IFR once again. Other terminals will
follow Saturday evening with an approaching low pressure system.

Gusty northwest winds expected sun into sun evening.


small craft advisories may be needed Friday ahead of the front
then again early Saturday behind the front.

Small craft advzy conditions expected sun-Sun night.


Lwx watches/warnings/advisories...
District of Columbia...none.
Marine...Small Craft Advisory from 8 PM this evening to 6 am EST Friday
for anz530>543.


near term...imr/klw

National Weather Service Glossary of Abbreviations