Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Wakefield Virginia
648 am EDT Wednesday Mar 12 2014
low pressure will track from the Ohio Valley to the New Jersey coast
today...pushing its associated cold front into the area from the
west. The front will cross the region this evening. High pressure
returns Thursday and Friday.
Near term /until 6 PM this evening/...
a mild start over the region at this time...W/ temperatures mainly from the u40s to m50s.
There aprs to be an area of MVFR/IFR conds just off the Eastern Shore
(based on GOES-east probs)...will any of that make it onshore in the
next few hours. Otherwise...cloudiness remains slo to increases from the west-southwest. The next
weather system continues to gather west and SW of the mountains there is a southern stream
short wave tracking near the Gulf CST...responsible for rain spreading east-northeast
through Georgia into SC/southern NC. Meanwhile...surface low pressure found over SW
in...W/ its associated cold front SW into southeast Texas. There is separation
between these two systems right now. The bulk of the precipitation west/ the low
in vicinity of western Ohio Valley along/north of the low and associated frontal extending to
the east. At this time...limited convection accompanying the cold front south-southwest of
that surface low pressure area (up until now...the only T has been limited
to north of the developing surface lo).
Cloudiness will continue to lower/thicken through early/middle morning. Some of the
rain from the southern system beginning to gradually spread northward into western NC
(as models continuing to suggest). The models bring that area of moisture
into/across the forecast area from SW to NE (btwn about 14z and 21z). The RUC/GFS
have a very narrow line of convection associated west/ the cold front
arriving from the west after 21z...which continues to the east into the evening hours.
Will hold onto 50-60% probability of precipitation for today. Much of forecast area away from the CST and
NE NC in slight risk severe...limiting factors will be the lack of
instability (due to area of rain pushing through the region during the
day) and lack of convergence ahead of/along the cold front (w/ deep layered
low level winds - to about 5kft - from the SW parallel to the cold front
crossing the fa). There will be an increases in surface south-southwest winds today...but
again...due to widespread cloudiness and precipitation...will limit spds to 15-20
miles per hour/gusts to 25-35 miles per hour (highest near eastern portion) by afternoon. Hi temperatures
in the l/m70s.
Short term /6 PM this evening through Friday/...
surface low pressure will intensify as it continues to move NE to just off the
eastern new eng CST (lt) tonight. Strong northwest winds will usher a much drier
and colder airmass into the region (potential gusts to 40-45
miles per hour...esply eastern/NE portions) tonight and Thursday. May need a Wind Advisory
for a portion of the area. Becoming clear to partly cloudy after
mdngt tonight with lows ranging from the middle 20s to middle 30s.
Sunny/mostly sunny Thursday with hi temperatures only ranging from the u30s to
Hi pressure then builds over the area then slides out to sea Thursday night and
Friday. Clear/mostly clear and cold Thursday night with min temperatures ranging from
the upper teens to m20s. Mostly sunny and a bit better again on Friday
with highs ranging from the u40s to u50s.
Long term /Friday night through Tuesday/...
not expecting a prolonged period of cold temperatures as high pressure that
builds in from the west quickly moves east and a return flow results
helping to push a warmer airmass back into the area Friday evening.
Flow remains out of the SW on Sat as models indicate convergence
along a surface trough may produce a line of light showers on Sat.
Due to model differences...confidence is not high enough to add weather
into the forecast at this point. High pressure centered north of the
Great Lakes begins to nose down into the middle-Atlantic Sat night
ahead of the next approaching surface low that will be forming in
the southeast US and moving NE on Monday. Chances for precipitation
increase Sun night into Monday with the approach of that low
pressure system. Northwest surface flow/clouds/precip will create cool
conditions sun through Tuesday.
Expect temperatures in the middle 60s for Sat...falling into the middle 50s for
Sunday and into the low 50s/upper 40s on Monday. Cool/near seasonal
morning temperatures in the 30s expected through the weekend.
Aviation /12z Wednesday through Sunday/...
mainly VFR through the 12z taf period. Low pressure and an associated cold
front over the Ohio Valley this morng will approach the middle Atlantic
through the day. Southerly winds will pick up later this morng and gust to
25-35 miles per hour into the afternoon. There will be a chance for thunderstorms during the
late afternoon and Erly eveng hours with strong to severe wind gusts
possible. For now...included just rain showers at the taf sites. IFR conds are
possible with heavier precipitation.
Skies clear by late tonight. Northwest winds may gust to over 30 miles per hour Thursday
and near 40 miles per hour at sby. Dry/VFR weather prevails Thursday through sun. A cold
front moves through late Sat. There will be a chance of rain by Monday.
surface hi pressure remains off the southeast CST this morng with a stalled frontal
boundary north of the local area. Southerly flow will average 10-15 knots this morng as
low pressure and an associated cold front approach form the west. Gale
warngs remain in effect for the Bay/coastal waters as winds pick up this
afternoon and eveng...shifting to the west/northwest aftr midnite as the cold front
crosses the waters. Winds will be strong Small Craft Advisory over the rivers/sound. The
strongest winds (gusts to 45 kt) will occur over the northern coastal waters
late tonight into Thursday morng. As for waves/seas...expect waves to
increase over the Bay form 2-3 feet midday today to 4-5 feet tngt/Thu. Seas
will approach 7-8 feet out 20 nm (especially over northern wtrs) and 3-5 feet
nearshore. Will keep inherited end time of Erly Thursday eveng for all
hazards...with winds diminishing as surface hi pressure builds in form the west.
Next chance for (marginal) Small Craft Advisory conditions comes Friday night as low pressure
passes north of the middle Atlantic.
Marine...Small Craft Advisory from 1 PM this afternoon to 8 PM EDT
Thursday for anz633-635>638.
Gale Warning from 1 PM this afternoon to 8 PM EDT Thursday for