Area Forecast Discussion
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FXUS61 KAKQ 231956
Area Forecast Discussion
National Weather Service Wakefield VA
356 PM EDT MON MAY 23 2016
Low pressure lingers over the Mid Atlantic today and then gradually
moves offshore tonight into Tuesday. High pressure builds in from
the west for the remainder of the week.
.NEAR TERM /THROUGH TUESDAY/...
Series of weak perturbations/disturbances on the back side of
persistent upper low will continue to set off some additional sct
showers with some iso thunder possible along and west-northwest of
I-95, where some modest instability (MUCAPE ~500-750 j/kg) is
noted per MSAS data.
The upper system gradually pushes offshore and begins to fill
tonight. Some additional upper energy wraps around the low as it
slides offshore this evening, so likely POPS have been
maintained for the Nrn Neck over to the Ern Shore this evening.
PoPs this evening taper off to 30-40% for central/se VA/coastal ne
NC, and 20-30% from the sw Piedmont counties to interior ne NC.
The chc for showers then diminishes sw-ne after midnight. Early
morning low temperatures are expected to be in the low to mid 50s.
.SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY/...
Conditions drastically improve Tuesday, as the upper trough
continues to weaken as it ejects northeast toward the
northeast/New England coast. While a gradually clearing sky and
dry wx is anticipated inland (mostly sunny by afternoon in the
piedmont), mostly cloudy conditions and some slight to low end
chance pops continue along coastal third of the area. This is in
association w/one last upper disturbance rotating through behind
the upper trough. Again, while surface-based instability looks to
be minimal, LI`s and Showalter numbers indicate some modest,
albeit mainly elevated instability. Warmer with highs ranging from
the upper 70s to around 80 inland,and mid 70s closer to the coast
(low 70s at the immediate coast).
Broad upper level ridging builds northeast from the Deep South
into the Mid-Atlantic and Southeast region Tuesday night into
Wednesday, before sliding overhead into Thursday. 850mb
temperatures rise to ~15C by Wednesday afternoon...and 16-17c by
Thursday afternoon. BL mixing will reach to around 850mb, and
should result in highs reaching the mid/upper 80s inland, with
low/mid 80s closer to the coast, and upper 70s for the immediate
Atlantic coast of the Ern Shore. After morning lows in the 50s to
near 60, high temperatures creep up about a category area wide
into the upper 80s/around 90 inland (low to mid 80s coastal
sections) on Thursday. Forecast soundings/model cross-sections
indicate rather dry conditions aloft,owing mainly to subsidence
and light downslope flow aloft. Will therefore keep pops in silent
range <10% on Wed, with only slight chc for more seasonally
typical diurnally-driven pulse convection on Thursday afternoon
and early evening. Light downslope flow will likely keep areal
coverage of any convection on the low side, and will also serve
to mix dewpoints down into the mid/upper 50s in the mid to late
afternoon hours both Wed/Thu.
.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
Bermuda sfc high pressure resides over the wrn Atlantic Ocean
through the long term periods as mid-upper level ridging moves
over the ne CONUS during this time. Although the GFS is trying
to develop low pressure over the Caribbean/Bahamas during
Thu night/Fri and then tracking it into the Carolinas Sat-Mon,
the ECMWF is keeping this system suppressed farther south due
to mid-upper ridging well-rooted across the ne CONUS through
at least Sun night before beginning to impact the Mid Atlantic
Region. WPC forecast is also very similar to the ECMWF and am
starting to lean more twd this warmer and drier solution...
especially since GFS ensembles support the GFS as more of an
outlier at this point. Will trend the long range forecast in
this direction regarding precip and temperatures.
High temps continue to run above normal throughout the extended
forecast periods and are now closer to being around 10 degrees
above normal Fri (highs in the upper 80s inland...upper 70s to
mid 80s immediate coast). For Sat-Mon, temps are around
5-7 degrees above normal (highs in the mid 80s Sat/Sun and
lower 80s Mon). Low temps also still trending around
5-10 degrees above normal Thu-Sun nights (lows generally in
the mid 60s).
.AVIATION /20Z MONDAY THROUGH SATURDAY/...
Low pressure continues off the coast bringing showers onto the
coast and over the CWA. The low will gradually but slowly move NE
over the TAF period and most of the rain is expected to end by
sunset. TAF sites are generally VFR this afternoon although with
clouds cigs from 3500 to 10K feet and periods of rain. Winds are
mostly from the N-NE 10-15 Kt with some gusts up to 25 kt along
the coast. Gradual improvement expected overnight as the surface
low moves away.
OUTLOOK...With all of the moisture from previous day`s rains, if
it clears out Mon night, it is conceivable that some fog could
develop especially at KRIC which would have the best chance for
winds becoming light. Otherwise...high pressure builds across the
area for the rest of the week leading to a more late spring/early
summer pattern across the region. Generally, VFR conditions would
be expected unless patchy fog develops overnight.
SCA flags cancelled for srn Ches Bay/Sound/Lower James River
as of 330 PM. North winds averaging 10-15kt this aftn...with
gusts to around 20kt over the coastal waters. Winds will
diminish through this evening as sfc low pressure located
about 200 miles east of Ocean City (as of 300 PM today) tracks
nnewd well off the NJ coast overnight. Meanwhile, seas are
averaging 4-5ft (up to 6ft possible near 20nm) and are expected
to subside below 5ft after midnight tonight. Waves 2-3ft. A
secondary surge in wly winds is possible late tonight into Tue
morning from the mouth of the Bay to the coastal waters south
of Cape Charles Light as sfc high pressure starts to build into
the region from the west. Speeds will stay aob 15kt during this
surge, therefore additional SCA flags are not anticipated during
this time. Conditions finally quiet down Tue through Sat as
stacked high pressure settles over the area. Winds will generally
be s-sw aob 15kt. Seas 2-3ft/waves 1-2ft.
Although the GFS model is trying to develop low pressure system
over the Caribbean/Bahamas during Thu night/Fri and then tracking
it into the Carolinas Sat-Mon, the ECMWF is keeping this system
suppressed farther south due to mid-upper ridging well-rooted
across the ne CONUS through at least Sun night before beginning
to impact the Mid Atlantic Region. Therefore WaveWatch guidance,
which is based on the GFS, was not utilized for seas for Fri-Sat.
As of 20 UTC/4 pm EDT Observation at Richmond (KRIC), unofficial
rain total for the day is 0.72". This would bring monthly total to
8.53" for May. May 2016 is currently the 4th wettest month of May
on record at Richmond.
Top 5 wettest months of May at Richmond
1. 9.13" 1889
2. 8.87" 1972
3. 8.59" 2003
4. 8.53" 2016 (to date)
5. 7.73" 1946
MARINE...Small Craft Advisory until 1 AM EDT Tuesday for ANZ650-652-654-