Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Baltimore Maryland/Washington District of Columbia
1016 am EDT Friday Oct 9 2015
a cold front will cross the region from northwest to southeast
this evening. High pressure will build into the middle Atlantic
Saturday and persist through Monday. Another cold front will cross
the region Tuesday.
Near term /until 6 PM this evening/...
latest surface analysis depicts a surface low just east of Lake
Huron...with a warm front extending east-southeast across New York
into southern New England and a cold front extending southwest
towards the lower Ohio River and onwards into Oklahoma. This puts
our region deep into the warm sector...with dew points climbing
above 60. Early morning pop-up showers associated with some
elevated cape are continuing to move across the area at present
and likely to continue into early afternoon. More concentrated
line expected to develop ahead of the surface cold front later
today. Cape is not that impressive...500 or so ml on GFS
bufr...but pretty good shear closing in on 40 knots on both GFS
and NAM...so if storms can fire they could get organized quickly.
That is the question though...will enough clouds break to allow
cape to develop. Right now...guidance suggests a pool of best cape
will develop near District of Columbia but might get ingested into storms passing to
the north and east...I.E. Hitting Baltimore hardest. Most of area
is under marginal risk of severe weather today from Storm Prediction Center.
Short term /6 PM this evening through 6 am Saturday/...
pop chances will diminish from north to S overnight as the tail end of the fnt
moves into southern Virginia. High pressure will build over New York/PA and into the middle
Atlantic late tonight. Fog should not be much of a problem as skies
should still be M cloudy. Low temperatures will be in the 50s.
Long term /Saturday through Thursday/...
Canadian high pressure will build overhead Saturday behind the
cold front. A northerly flow will usher in noticeably cooler
conditions compared to recent days...despite increasing sunshine.
Maximum temperatures will range from the 50s in the mountains to the middle
and upper 60s in Washington and Baltimore.
High pressure will remain overhead Saturday night. The
combination of dry air...light winds and mainly clear skies will
provide a good setup for radiational cooling. Therefore...leaned
to the colder guidance for min temperatures in rural areas and sheltered
valleys. Min temperatures will range from the middle 30s in some of the
colder valleys and rural areas to near 50 in downtown Washington
and Baltimore. Patchy frost is possible in some of the colder
valleys overnight Saturday.
High pressure will remain overhead Sunday...bringing plenty of
sunshine. After a chilly start...it will turn out warmer in the
afternoon with maximum temperatures ranging from the 60s in the mountains to
the lower 70s across most other locations.
High pressure will remain overhead Sunday night and radiational
cooling will allow for more chilly conditions in sheltered valleys
and rural areas. However...it will not be as cold as Saturday
night due to a warmer afternoon during the day on Sunday.
A cold front will move across the Great Lakes into the Ohio
Valley Monday. A southerly flow ahead of the boundary will allow
for a warm afternoon and the front will still be far enough away
to allow for more sunshine and dry conditions. The cold front will
move into the western portions of the County Warning Area Monday night before
passing through the entire area Tuesday. A few showers may
accompany the frontal passage...but rainfall amounts will be
High pressure will build overhead for Tuesday night into
Wednesday...bringing dry and cooler conditions. A reinforcing cold
front may pass through in the zonal flow aloft for Wednesday
night...but conditions should remain dry since there will be very
little moisture associated with it. High pressure will build
overhead late in the week...bringing more dry and cool conditions.
Aviation /14z Friday through Tuesday/...
after some brief fog and low clouds induced by passing
showers...VFR conds have returned and should persist overall
through the next 24 hours. Showers and thunderstorms will increase
in coverage this afternoon with most likely impact to the
dca/iad/BWI late afternoon/early evening. Winds could be gusty west/
storms. Cold front will pass shortly thereafter with winds
shifting from south southwest to northwest.
VFR conditions are expected most of the time Saturday through
Wednesday. Northerly winds may gust around 20 knots Saturday...
especially through the midday hours.
winds starting to hit Small Craft Advisory values with srly channeling. Small Craft Advisory in
effect for lower ptmc and majority of Maryland section of ches Bay
currently...then expands to all waters this afternoon. A line of rain shower/isolated
thunderstorm are expeceted to move through the waters late this aftn/eve. Smw's
may be required.
Tonight winds will shift to the northwest. Small Craft Advisory will be in effect for entire Maryland
ches Bay and lower ptmc.
Gusty north to northeast winds are expected behind a cold front
Saturday morning. A Small Craft Advisory is in effect for the
Maryland Chesapeake Bay and lower tidal Potomac River. However...
winds should weaken during the afternoon as the gradient slackens.
High pressure will build over the waters Saturday night through
Sunday. A cold front will approach the waters Monday before
passing through Tuesday. A Small Craft Advisory may be needed for
portions of the waters later Tuesday into Tuesday night. High
pressure will return for the middle portion of next week.
a southerly flow has caused tidal anomalies to average between
0.5 and 0.75 feet above normal. A southwest flow is expected to
increase today before a cold front moves through this evening. The
anomalies may increase a bit ahead of the front today...but with a
westerly component to the wind the anomalies should not increase
too much. Minor tidal flooding near high tide this afternoon into
this evening cannot be ruled out...but confidence is too low to
issue an advisory at this point. Will see how anomalies trend this
morning before making a decision on a headline this afternoon into
this evening. As of now...it appears that Annapolis will be the
closest to minor flooding near high tide this afternoon.
Anomalies will decrease behind the cold front later tonight.
District of Columbia...none.
Marine...Small Craft Advisory from 2 PM this afternoon to noon EDT
Saturday for anz530-538-539.
Small Craft Advisory until noon EDT Saturday for anz531>534-
Small Craft Advisory from 2 PM this afternoon to 6 PM EDT this
evening for anz535-536.