Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Baltimore Maryland/Washington District of Columbia
402 am EDT Friday Jul 3 2015
a stationary front over North Carolina will drift north as low
pressure moves east along the front and crosses the central middle-
Atlantic late tonight into Saturday. High pressure builds Sunday.
An upper level disturbance lingers over the southern middle-Atlantic
Monday and Tuesday before a cold front enters the area Wednesday.
Near term /through Saturday/...
as of 07z...stationary front is analyzed over NC. Clear
conditions over the area has allowed areas of ground fog to
develop with thicker fog in valleys and on the Piedmont. Will
continue to assess and issue a dense fog advisory before sunrise
Today...weak low pressure drifts east along the Ohio River...lifting
the stationary front north as a warm front. Eastern extent of prefrontal
rain currently over far western Virginia will shift NE into southwestern zones later
this morning. Rain coverage increases this afternoon with embedded
isolated thunderstorms roughly kcho and short wave. Maximum temperatures limited by increasing
high clouds and afternoon cumulus field (as well as rain in southwestern half of
cwa)...expect middle to upper 70s inland...around 80f near shore.
Tonight...warm front lifts into the area as weak low center drifts
east across the County Warning Area. Exact track will determine instability/thunderstorm
threat as well as be the axis of heaviest rainfall. Raised
categorical probability of precipitation for much of the Piedmont and west. Quantitative precipitation forecast generally a
quarter inch to an inch.
Fourth of July...weak low shifts east to the Bay in the morning with
trailing front drifting south as a cold front. Plenty of frontal
forcing to cause rain...so likelies as back in the forecast.
Widespread cloud cover should limit instability with best thunder
chances south of the front in the warm sector. Northwesterly flow begins in
the afternoon with precipitation generally tapering off from northwest to southeast. Maximum
temperatures upper 70s northwest...low 80s southeast.
Short term /Saturday night/...
by 00z sun...surface lp prognosticated to be moving away from our area. Had
a hard time removing probability of precipitation entirely until after 03z...as
uncertainty remains and...with 4th activities...its better to at
least prepare for that possibility. Same philosophy with
thunder...think chances are very low for thunder to linger beyond
00z...but thought it was at least Worth keeping through 01z for
the low-end possibility.
Once rain pulls away...expecting a gradual clearing trend through
the day sun...ahead of the next system approaching from the SW.
Temperatures expected to be in l80s with light winds.
Long term /Sunday through Thursday/...
fairly weak flow pattern at middle and upper levels through the
extended...with waves of energy moving through the flow near our
area. First wave approaches late sun or early Monday...bringing with it
a chance for showers and thunderstorms as surface low tracks near our area. Next wave
and associated cf approach the area around Wednesday and is more
progressive/compact. While thunderstorms are forecast nearly each
day...activity will be mainly diurnally driven...and with weak middle
level flow...atmosphere not expecting convective activity to be very
Quasi-zonal flow by middle-week will help to keep temperatures near
climatology norms. There is a hint of middle/upper level ridging trying to
build in towards the end of the week...which could lead to temperatures
slowly increasing to at or above climatology norms. Humidity will also be
tolerable with dewpoints generally remaining at or below 70f.
Aviation /08z Friday through Tuesday/...
stationary front over NC this morning. Clear skies have allowed
ground and some thicker fog in places. High clouds will overspread
the area rest of the night with conditions improving with sunrise.
The front drifts north through tonight as low pressure rides east
from the Ohio Valley. The low moves east of the District of Columbia metros Saturday
afternoon. Generally MVFR conds in likely rain across the terminals.
Best thunderstorm chances south of District of Columbia metros Saturday.
Conds expected to improve through the day Sunday...with light winds
and little chances for precipitation at the terminals. Next aviation concerns
possible late sun through Monday as next system approaches and brings
chances for shwrs/tstms. Sub-VFR conditions possible near thunderstorms...with
onshore flow today north of a stationary front over NC. Will raise
an Small Craft Advisory for southern Maryland waters Saturday morning as weak low pressure
crosses with southerly flow gusting up to 20 knots. Isolated gusty
thunderstorms late tonight through Saturday as low pressure
Winds are expected to remain below Small Craft Advisory levels through the extended
period under light and variable flow. However...mariners are advised
to monitor for thunderstorms...as isolated thunderstorms are possible nearly each
day...with the best chances Monday and Wednesday.
District of Columbia...none.