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Area forecast discussion...updated
National Weather Service Baltimore Maryland/Washington District of Columbia
623 PM EDT Mon Oct 21 2019

Synopsis...
a cold front will approach from the west tonight before
crossing the region later Tuesday into Tuesday night. High
pressure will build back across the region Wednesday. Another
storm system may approach the region during the weekend.

&&

Near term /through Tuesday night/...
low pressure over the upper Midwest will drift into Ontario by
Tue evening with associated cdfnt approaching the area Tue
morning. A secondary area of low pressure is expected to develop
along frontal zone Tuesday afternoon over southern Virginia. Pre-
frontal showers/rain expected to develop late tonight over the
Appalachians and spread northeast by daybreak Tue. Widespread
showers are expected Tue into early Tue evening with half to
three quarters of an inch expected. A rumble of thunder is also
possible, but model soundings show little or no instability.
Gusty winds of 25 to 30 kt are possible with frontal passage.
Showers will end from west to east between 00z and 03z Wed.

&&

Short term /Wednesday through Wednesday night/...
high pressure will be in control Wed through Thu with clear
skies and fair weather conditions.

&&

Long term /Thursday through Monday/...
high pressure remains over the region on Thursday, resulting in a
dry day with seasonable temperatures in the upper 60s. Overnight lows
on Thursday night will be into the low to mid 40s under mostly clear
skies.

High pressure will then push offshore into Friday, with highs again
in the mid to upper 60s. Dry weather is expected at this point,
however, there will be an upper-level disturbance nearby which could
end up spawning some showers across the area, resulting in some
slight chance, to low end chance, pops across the area, especially
into the afternoon hours. At this point though precipitation chances
appear to be on the decrease during the day on Friday at least, and
likely even into Friday night.

Rain chances return for the weekend, but are not a certainty at this
point. Lot of discrepancy among the global guidance still in regards
to timing and track of the potential storm system next weekend. The
European model (ecmwf) still wants to cut off an upper-low from the main shortwave
pushing through the area Friday into the weekend. Then it bring the
low across the area late weekend, or even early next week.
Meanwhile, the GFS has a much deeper trough and doesn't cut off a
low over the Southern Plains. This results in a quicker progression
of the system, bringing it in late Saturday/early Sunday. At this
point, there is just far too much uncertainty to go with one
solution over another. For now, carrying chance pops through the
weekend, but the entire weekend should not be a washout.

&&

Aviation /22z Monday through Saturday/...
showers develop Tue morning with cigs lowering to IFR by 15z
Tue. Wind shift associated with frontal passage comes in around
00z Wed. Expect IFR cigs and brief wind gusts to 25 kt with
frontal passage. Rain ends by 03z Wed if not sooner with cigs
improving. Fair weather late Tue night into Thu.

VFR conditions expected on Thursday and Friday, as high pressure
slides across the region and offshore.

&&

Marine...
winds will strengthen Tuesday afternoon with Small Craft Advisory gusts likely in
showers ahead of a frontal passage. Smws may also be required.
Winds remain gusty into Wed morning behind frontal passage.

High pressure will be sliding across the region Thursday into
Friday, which should result in much more calm winds across the area,
remaining below Small Craft Advisory criteria.

&&

Tides/coastal flooding...
tidal anomalies are on the rise this evening thanks to southerly
flow and higher anomalies over the Lower Bay making their track
northward. As such, have issued coastal flood advisories for
Anne Arundel and southern Baltimore counties in Maryland for
tonights high tide cycle. As we continue to monitor anomalies
this evening and digest the 18z guidance, will reassess the
coastal flooding threat for the remainder of our service area.

&&

Lwx watches/warnings/advisories...
District of Columbia...none.
Maryland...coastal flood advisory until 4 am EDT Tuesday for mdz014.
Coastal flood advisory from 11 PM this evening to 4 am EDT
Tuesday for mdz011.
Virginia...none.
WV...none.
Marine...Small Craft Advisory from 2 PM Tuesday to 6 am EDT Wednesday
for anz530>543.

&&

$$
Synopsis...lfr
near term...lfr

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