Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Baltimore Maryland/Washington District of Columbia
1054 PM EDT Friday may 22 2015
a cold front will push south of the area tonight. High pressure
will build overhead Saturday. The high will move off the coast
Sunday and remain in the western Atlantic through middle- week next
week with noticeably hotter and more humid conditions returning to
Near term /through Saturday/...
latest surface analy depicts cold front draped across the County warning forecast area. Isolate rain showers found
at the end of the day have since dsptd west/ the setting sun. For that
matter...most of the clouds have evaporated as well. Will still be
carrying a period of partly cloudy skies to accompany the fnt...which should
clear southern zones by or shortly aftr midngt.
Winds have also started to respond to the loss of diurnal mixing.
Most of the higher gusts should cease by 01 or 02z. However...based on
anticipated night time cold air advection...am hesitant on eliminting winds
completely. That plays into the overnight temperature forecast.
Dry and clear conditions will allow temperatures to drop into the 40s
with the exception of the metros/Bayshore seeing the 50s and the
higher elevations of the allgheny front seeing the middle-upper 30s.
Latest lamp data generally in synch west/ these thoughts. Did make a
cpl minor adjustments...mainly to shave anthr degf or two off for
sites where climatology tends to be sheltered valleys. However...considering
how low dewpoints will be by morning and the uncertainty regarding full
dcplg...did not add anyone else to current frost advisory. It remains
in place for the western fringe of the County warning forecast area between Allegany and pendltn
High pressure moves overhead Saturday. Northerly flow will keep temperatures
below climatology in the upper 60s to lower 70s.
Short term /Saturday night through Monday/...
surface high pressure will drift east into the Atlantic Ocean
Saturday night...but the return flow will be slow and lows will
only be a few degrees milder on Saturday night as compared to
Friday night. Humidity will start to come back however.
Otherwise...skies should be mostly clear as heights aloft build
ahead of an approaching ridge.
The surface high will keep drifting slowly east Sunday with the
return flow resulting in a noticeably warmer and more humid day as
compared to Saturday. Temperatures will rise around 10 degrees
while dew point rise will be more like 20 degrees. Some clouds may
increase in the afternoon as warm advection gets underway aloft
along the tail end of a warm front which will move by to our
northwest...but no precipitation is expected with heights
continuing to build aloft ahead of the still approaching and
building ridge axis.
Clouds will make for a much milder night on Sunday night as the
aforementioned warm front passes by to the north...but again no
precipitation is expected. On Monday the surface high pressure
will continue drifting slowly east. Temperatures will approach or
slightly exceed 90 degrees in many areas. Dew points still won't
be too high with readings probably staying in the upper 50s in
much of the area...but it will still feel considerably more
Summer-like than it will on Saturday. With the ridge still
building overhead...and dew points not all that high just
yet...consensus appears to be favorable for a storm-free day so
have kept thunder out of the forecast.
Long term /Monday night through Friday/...
European model (ecmwf) 500 mb ridge over middle Atlantic region slowly moving to east
allowing a short wave to affect the region Thursday. Moisture and
temperatures will generally increase on southwest flow during the
period. Hot and humid conditions will lead to an increased chance
for thunderstorms...especially during the afternoon and evening
hours each day.
Aviation /03z Saturday through Wednesday/...
high confidence in VFR conditions expected through the taf
period. Wind gusts /20 knots/ will subside by 01 or 02z. Northwest winds will
continue 10-15 knots...eventually diminishing to 5-10kt overnight. No clouds of
consequence...nor any visibility restrictions.
High pressure builds into the region Saturday. Winds will be a non-
factor...less than 6 knots...as they transition from northerly to south-southwesterly.
The high will move off the coast Sunday and Monday. Winds will
become southwesterly but VFR conditions will continue with no
thunderstorms expected. The risk for storms will increase Tuesday
afternoon and evening as hot and humid conditions increase
winds have diminished below Small Craft Advisory criteria across all waters at this time.
However...cold front analyzed to be just north of the marine area. Cold front passage for the
waters will transpire through Ely morning. Present indications are a zone of cold air advection bhd fnt will
bring a period of favorable mixing southward.
Have opted to drop the Small Craft Advisory for balt Harbor/North of Pooles isl/mid-upr
tidal ptmc /it was going to expire at 11pm anyways..and dont have
evidence to extend it/...but left the rest in place. Am thinking
that in the broader waterways there is still a decent chance at
meeting Small Craft Advisory criteria once again overnight due to the northerly surge. Do
not have the skill to time these indiv elements of above and below Small Craft Advisory
crit...so will cover it with one headline. Should be able to trim Small Craft Advisory
for the remainder of the area at or below current 8am expiration.
Hipres mvs ovrhd Sat. Winds should have diminished to 5-10 knots by
middle morning...and will continue in that range through the day while backing
High pressure will move off the coast Sunday and Monday with a
southerly flow returning. The high will remain over the western
Atlantic through the middle portion of next week...allowing for
the southerly flow to continue. A Small Craft Advisory may be
needed for portions of the waters Monday through Tuesday night due
to the increasing southerly flow...but it will be marginal due to
the relatively cooler waters.
District of Columbia...none.
Maryland...frost advisory until 8 am EDT Saturday for mdz501.
WV...frost advisory until 8 am EDT Saturday for wvz501-503-505.
Marine...Small Craft Advisory until 8 am EDT Saturday for anz531>534-