Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Baltimore Maryland/Washington District of Columbia
324 am EDT Wednesday Jul 30 2014
Upper level low pressure over eastern Ontario continues to spin
cool air into the middle Atlantic. This will gradually recede as the
week progresses. A coastal front will develop this weekend and
last into early next week.
Near term /today/...
Well..if you have to be awake overnight at the end of Jul this is the
way to do it - gnrly clear skies west/ temperatures More Lake late Sep than late
Iad record low for today is 51 set in 1981. This was tied at 3 am.
The 2 am temperature round up shows temperatures in the lm60s in the cities and
along the water...but dropping into the lm50s west of I-95. This
courtesy of the western ridge/eastern trough which has remained fairly stationary
for the past weak. On the other side of the country phx was reading
100 degrees at 11 PM their time.
The Tuesday highs were all in the 70s! Again all in line west/ the latter
half of sept. Expect west/ light winds today this will allow for some surface
warming so expect to see highs in the l80s east of the blu ridge..70s west.
Models are implying some instability late this afternoon...but rather
than talking about a thunderstorm outbrk it looks More Lake rain shower forming over the
eastern Great Lakes during middle afternoon and then tracking southeast. Have some low end
probability of precipitation west of the blu ridge late this afternoon/this evening.
Short term /tonight through Thursday night/...
Any rain shower should die out during the evening..then again no probs tonight. Lows
in the 50s outside of the cities/along the water.
Temperature modification of the air mass should begin on Thursday - the final
day of Jul..but still highs should still be sltly below climatology norms
- in the m80s. Lows Thursday night in the lm60s away from the cities. No
organized cvctn foreseen through Thursday night...possibly isolated thunderstorms over the
mountains Thursday afternoon. Winds fields look to be light so anything that would
go up would probably quickly come down.
Long term /Friday through Tuesday/...
The weekend forecast will feature hipres in the western Atlantic and a trough axis across
the Great Lakes/MS River Valley. County warning forecast area will be west/in zone of positive advection...both
temperatures and dewpoints. Flow will still be light...thx to influence of low level
ridging...but will have origins from both Gulf of Mexico and Atlantic sources. Dont think
there will be too much instability around Friday. Both weekend days will be better.
Continued probability of precipitation for all three...W/ diurnal thunder emphasis.
Upper trough will flatten Ely next weak. As heights rise...pttn will return to
something more typical for Aug...though still a little cooler than normal.
Aviation /07z Wednesday through Sunday/...
VFR conds expeceted today through Thursday night.
VFR will prevail for a majority of the time Fri-sun...though flgt
restrictions likely in vicinity of scattered shra/tsra.
No probs foreseen on the waters in next 48 hours.
Southeasterly winds Friday-sun as air circulates around large hipres in the western Atlantic.
Ridge close enough that spds should be at or below 10 knots. May have a few storms.
Lightning biggest threat.
District of Columbia...none.