Area forecast discussion
National Weather Service Baltimore Maryland/Washington District of Columbia
929 PM EDT Wednesday may 22 2013
Synopsis...
high pressure persisting over the Atlantic with warm and humid
conditions until a cold front Thursday night. An upper trough
will linger over the area Friday with high pressure building
through Saturday. A frontal boundary stalls out across the middle-
Atlantic Sunday night through early next week.
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Near term /through Thursday/...
convective activity on the decrease acrss County Warning Area at this time. Looking at
line of rain showers/thunderstorms and rain roughly along I-81 that will slowly make its way
across the County Warning Area late tonight. Expecting mainly showers with isolated
elevated thunderstorm in this activity as the upper-level trough
continues to slide closer to our area. Min temperatures tonight will
range from the 50s in the mountains to the lower and middle 70s in
downtown Washington/Baltimore. Areas that received rainfall today
will be apt to fog-up overnight.
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Short term /Thursday night through Friday/...
heights continue to drop Thursday as cold front approaches. Although instability will be
lower...shear will be greater. There may be two rounds of weather...first
coming midday with the disturbance and ribbon of instability...and then
second nearer the cold front and diurnal heating. Have raised probability of precipitation into
the def range rather quickly...and holding it there throughout the day.
Cold front passage Thursday night. Will scale back probability of precipitation and transition from thunderstorms and rain to rain showers in
the evening. After frontal passage...only lingering rain showers will remain.
Friday...upper trough drifts east over the area with back edge of
clouds slow to come in the afternoon. Gusty northwesterly flow Friday
continues as high pressure builds through Saturday.
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Long term /Friday night through Wednesday/...
shortwave from Tennessee Valley on Sunday now looks to expand east across the
southern-central mid-Atlantic. Convergence along this boundary would
set off showers. Pattern is stalled into middle next week...so a
prolonged cloudy/rainy period is possible. This would result in
below normal temperatures.
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Aviation /02z Thursday through Monday/...
VFR-MVFR conditions at all terminals overnight. Threat for storms
continue until cold front passage Thursday night. Northwesterly flow with gusts 25 to possibly
30 knots with middle level ceilings Friday. Northwesterly flow continues through
Saturday as high pressure builds.
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Marine...
high pressure will remain over the Atlantic Ocean overnight. A
southerly flow will continue over the waters during this time. A
Small Craft Advisory remains in effect for portions of the waters
through tonight. Scattered showers and thunderstorms are possible
later this afternoon and evening. Any thunderstorms that do
develop will be capable of producing gusty winds and hail.
Southerly flow ahead of a late Thursday night cold front. Small Craft Advisory expanded
through Thursday. Expect an extension Thursday night for prefrontal
southerly flow...then northwesterly flow around 25 knots Friday through Saturday as
high pressure builds.
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Lwx watches/warnings/advisories...
District of Columbia...none.
Maryland...none.
Virginia...none.
WV...none.
Marine...Small Craft Advisory until 6 PM EDT Thursday for anz530>534-
536-537-539>543.
Small Craft Advisory from 9 am to 6 PM EDT Thursday for anz535-
538.
&&
$$
