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Area forecast discussion 
National Weather Service Baltimore Maryland/Washington District of Columbia
345 am EDT Friday may 22 2015

Synopsis...
a cold front will approach the area today before passing through
tonight. High pressure will build overhead Saturday before moving
off the coast Sunday through the middle portion of next week.
Noticeably hotter and more humid conditions are expected next week
as a Summer-like air mass enters the region.

&&

Near term /through tonight/...
skies have cleared pretty much everywhere xcpt in the far SW
corner. A cold front currently moving across the eastern Great Lakes will
move southward through the area this evening. A few showers may pop up
along the Mason-Dixon line this afternoon so included a slight
chance for that area. It will also be breezy this afternoon with
winds gusting up to 25 knots under a somewhat tight pressure gradient.
Unusually chilly and strong high pressure will build quickly
southward and be centered over southern PA by 12z Sat. Very cool and
dry air mass along with diminishing winds will lead to a rapid
dropoff in temperatures overnight with patchy frost likely over far western
areas. For now included patchy frost in grids but will let
dayshift monitor dewpoints and let them decide whether a frost
advisory will be needed or not. Latest MOS guidance suggests that
temperatures will fall low enough for frost to form in that area.

&&

Short term /Saturday through Saturday night/...
Canadian high pressure will remain over the region
Saturday...resulting in plenty of sunshine along with dry
conditions. After a chilly start...the sunshine will allow for
temperatures to rebound into the lower to middle 70s for most areas.

The surface high will begin to shift toward middle-Atlantic coast
Saturday night. A light southerly flow will allow for temperatures to be
a few degrees warmer compared Friday night...but it will still
turn out chilly due to radiational cooling. Min temperatures will range
from the lower and middle 40s in sheltered valleys to the middle and
upper 50s in downtown Washington and Baltimore.

&&

Long term /Sunday through Thursday/...
the surface high will continue to shift east into the Atlantic
Ocean for Sunday through the middle portion of next week. Upper-
level high pressure will build over the southeastern Continental U.S. And the
upper-level ridge axis will extend north into the mid-Atlantic.

The southwest flow around the high will allow for a warming trend
Sunday and Monday. Dry conditions along with plenty of sunshine
are expected due to the upper-level ridge axis extending into our
area.

Hot and humid conditions are expected for the middle portion of
next week as the southwest flow continues. The hot and humid
conditions will lead to an increased chance for thunderstorms
Tuesday through Thursday...especially during the afternoon and
evening hours each day.

&&

Aviation /07z Friday through Tuesday/...
VFR conditions expected everywhere next 30 hours. Scattered afternoon
clouds expected over mrb with ceilings 040-050. Winds gusting 20-25 knots
at all taf sites xcpt lighter winds at kcho.

High pressure will bring VFR conditions and light winds for
Saturday through Saturday night. The high will move off the coast
Sunday and Monday. A southwest flow is expected...but VFR
conditions will persist. There is a better chance for
thunderstorms Tuesday afternoon and evening as hot and humid
conditions increase instability.

&&

Marine...
solid Small Craft Advisory conditions this afternoon with gusts 20-25kt
especially north.

High pressure will remain over the waters Saturday before moving
off the coast Sunday and Monday. A southerly flow will return
during this time. High pressure will remain over the Atlantic Ocean
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...but it
will be marginal due to the relatively cooler waters.

&&

Climate...
unusually cool high temperatures were observed Thursday...may
21st. Washington Dulles broke a daily record for low maximum
temperature. The maximum temperature was 58 degrees and this
breaks the old record of 59 degrees set back in 2002.



&&

Lwx watches/warnings/advisories...
District of Columbia...none.
Maryland...none.
Virginia...none.
WV...none.
Marine...Small Craft Advisory from 10 am this morning to 8 am EDT
Saturday for anz539.
Small Craft Advisory from 10 am this morning to 11 PM EDT this
evening for anz530-535-536-538.
Small Craft Advisory until 8 am EDT Saturday for anz531>534-
537-540>543.

&&

$$
Synopsis...bjl
near term...lfr
short term...bjl
long term...bjl
aviation...bjl/lfr
marine...bjl/lfr
climate...bjl

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