Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Wakefield Virginia
430 PM EDT sun Mar 16 2014
high pressure slowly moves east across the Great Lakes tonight
into Monday. Low pressure tracks northeast from the lower Mississippi
Valley this evening...then intensifies off the Carolina coast on
Monday. A second area of low pressure lingers off the southeast
coast through Tuesday.
Near term /through Monday/...
***no headline changes/see latest wswakq for details***
Latest surface analysis showing cold surface high centered over Lake
Michigan...ridging southeast into NY/NJ. Surface low currently over SW
Tennessee/northern MS...and tracking east-northeast. Light rain has overspread
portions of southeast Virginia/NE NC as well as the Piedmont...with precipitation
struggling to reach the ground over central portions of the County Warning Area.
Rapidly deteriorating conditions over the next 6 hours...as rain
initially overspreads the entire region through 00z...changing to
snow/sleet from northwest to southeast between 00z-06z. Overall...only made
minor changes to ongoing forecast. Wind Advisory has been raised for
far southeast Virginia and coastal NE NC for this evening through early Monday
afternoon. Northeast winds of 30 to 35 miles per hour with gusts up to 45 miles per hour will
make travel difficult for high profile vehicles and may cause
sporadic power outages due to falling tree limbs.
Could struggle to reach warning criteria over southeast portions
of the warned area...mainly the middle peninsula and southeast sections
of King And Queen/King William counties over to the Maryland coast. This
is due to current conditions and model trends suggesting that cold
air takes a few longer to arrive...thus inhibiting snow/sleet
accumulations prior to midnight. Potential dry slot (currently can
be seen on visible satellite over MS/al) may result in limited quantitative precipitation forecast
after 06-09z for at least some of the County Warning Area...especially SW zones per
BUFKIT soundings. This would also limit potential accumulations
across much of the adsy areas of central and southern Virginia as well.
One thing to note is that models continue to point to some
potential for freezing rain across southern Virginia...as warm nose aloft
hangs in place over this region. With the potential for at least a
light glaze...decided to keep the adsy in place even though
snow/sleet totals down in these areas are likely to be less than
1". Highest snow totals are likely over the far
north...particularly the interior Maryland Eastern Shore where banding
potential is most likely and snow/sleet will likely persist
through Monday morning.
During the day Monday...bulk of precipitation will be light west/ additional
snow/sleet accumulations generally less than 1" (1-2" possible eastern
shore). Temperatures will remain very cold...generally at or below freezing
over most of the Maryland Eastern Shore and central Virginia. Highs Monday...upper
30s/lower 40s NE...to lower 30s northwest.
Short term /Monday night through Tuesday/...
GFS/NAM/ECMWF into better agreement with handling of 2nd wave of
moisture/secondary area of low pressure Monday night/Tue...although
the NAM remains more aggressive at bringing the surface low off the southeast
coast farther north on Tuesday. Generally followed closer to a blend
between the GFS/ECMWF. This yields little to no precipitation/very low
quantitative precipitation forecast Monday night/Tuesday morning. This is critical because the cad/wedge
holds strong over interior zones through late Tuesday morning/early
afternoon. As such...have trimmed back to only low chance probability of precipitation south/dry
north for the period. BUFKIT soundings show substantial dry air
in the dendritic growth zone (-10 to -20c) so expecting mostly
just drizzle or very light precipitation (for now have grids worded as
"light" rather than drizzle. Enough of a warm nose above 850-900 mb
that the ptype outside of far southeast Virginia/NE NC would be either
freezing rain/drizzle or sleet. May eventually need a winter weather
adsy for portions of the County Warning Area and will mention in severe weather potential statement for now.
Temperatures should rise above 32 f all areas by Tuesday afternoon and as
somewhat deeper moisture attempts to surge north...ptype should
become all rain. Went west/ low end likely probability of precipitation far southeast/low chance
elsewhere. Still well below normal for highs...upper 30s far northwest to
upper 40s southeast. Generally dry Tuesday night as weak upper ridge builds in
along the East Coast...but light low level onshore flow should
keep skies mainly overcast. Continued dreary on Wednesday despite winds
slowly shifting to the S/se. Could see some sunshine by afternoon but
would not count on it unless pressure gradient were to increase. Went
several degrees cooler than MOS...highs mainly 50-55 f.
Long term /Tuesday night through Sunday/...
a change to drier and milder weather can be expected during the
latter part of the week. Temperatures then drop to below normal by
Sunday. Precipitation is possible with the cold front around Saturday.
As the shortwave trough exits the region Wednesday...the dominant
upper flow across much of the Continental U.S. Becomes fast and almost zonal.
Thursday and Friday will feature slightly above normal
temperatures. Upper level heights gradually lower and a cold front
drops through the Middle Atlantic States Saturday...bringing a return
to below normal temperatures by Sunday. There is a chance for
showers with the cold front Saturday.
High temperatures Thursday range from the 50s on the lower Eastern
Shore to the lower 60s across most inland areas. Highs on Friday
and Saturday are expected to be from the upper 50s to around 60 on
the lower Eastern Shore to the upper 60s over inland southern
Virginia. Highs on Sunday cool to 50 at the coast to the middle and
upper 50s inland. Lows around 40 Thursday morning lower to the 30s
Friday morning...increase to the 40s on Saturday morning then fall
back to the 30s Sunday morning.
Aviation /20z Sunday through Friday/...
low pressure over the Gulf Coast states and Carolinas will gradually
slide to the east as strong high pressure remains to the north. A
northeast flow will continue during the 18z taf period.
Precipitation will spread northeast from the Carolinas. Precipitation begins as rain
and changes to snow or sleet at ric and sby. Some accumulation can
be expected at these locations. Precipitation will be mainly rain at the
other sites with some sleet or light snow possible at phf. Expect
periods of IFR at all the taf sites later tonight. IFR ceilings should
continue Monday even as precipitation diminishes in the late morning.
Northeast winds will increase overnight...especially after
midnight...as the low approaches the region and the pressure
gradient tightens. Expect NE winds of 25-30g40kt at kecg/korf/ksby...
NE winds of 20g30kt at kphf...and NE winds of 15-20g25kt at kric
from roughly 17/04-18z before diminishing.
Outlook...IFR ceilings will prevail into Tuesday (mav is more optimistic
than the met)...especially inland areas...as low level moisture
remains locked in by wedging. Conditions begin to improve on
Wednesday when a few showers are possible. Dry and VFR conditions will
prevail Thursday and Friday.
high pressure slides across the eastern Great Lakes tonight.
Meanwhile...a warm starts to lift into coastal waters south of the
Virginia border this evening as a low pressure system in the southeast states
advances on the coastal Carolinas. The surface low will travel eastward
along the warm frontal boundary overnight and move off the Virginia
convective available potential energy during Monday morning. A persistent NE/onshore wind will
noticeably increase this evening (especially after midnight
tonight through early Monday morning) as the low deepens and the
pressure gradient tightens in response. Wind speeds will reach
25-30 knots with gusts up to 40 knots over the ocean/ches Bay/Currituck
Sound...and 20-30 knots for the rivers. Seas will quickly build to
8-12 feet southern waters around midnight and 8-10 feet northern waters late
tonight/early Monday morning. High seas at or above 8 feet will
persist through at least late Monday morning/early afternoon before
slowly subsiding. Low- end Small Craft Advisory wind gusts in southern ches Bay have
been bouncing between 20-25 knots this afternoon. Short-lived Small Craft Advisory criteria
winds this afternoon/early evening will quickly give way to gale speeds
by late this evening. Have decided to start gale warnings for all
coastal waters/ches Bay/Currituck Sound with the forecast package
this afternoon. Small Craft Advisory flags continue for the rivers beginning early this
evening and continuing into early Monday evening. Also...a high surf
advisory has been issued for all Atlantic coastal areas...including
the Norfolk Waterfront...for seas of 8 feet which will likely reach
up to 10 feet along outer Currituck up to roughly the sandbridge
area of Virginia Beach.
Low pressure lingers off the coast through Tuesday...as high
pressure remains north of the region. Small Craft Advisory conditions will persist
through at least early Tuesday evening due to continued onshore
flow and slowly subsiding/diminishing winds/waves/seas. Seas may
stay around 5 feet long enough for sca's to persist through the
middle of the week...otherwise overall conditions become rather
benign late Tuesday night through the rest of the week.
a coastal Flood Advisory has been issued for the ocean side of the lower
Maryland Eastern Shore with strong NE winds and a full moon. This is for the
Monday morng hi tide cycle...with Ocean City Maryland hi tide occurring at
921 am. Minor coastal flooding of low lying areas and roadways is possible
with levels forecasted to reach right around 4.0 feet at Ocean City
(which is the minor flooding threshold there). Other areas along
the Atlantic CST and southern Bay are expected to be about 0.5 feet on
average short of minor thresholds.
may challenge some record low maximum temperatures for Monday 3/17:
Ric...40 in 1900
orf...38 in 1893
sby...33 in 1916
Maryland...high surf advisory from 4 am to 11 am EDT Monday for mdz025.
Winter Storm Warning from 8 PM this evening to 5 PM EDT Monday
Coastal Flood Advisory from 7 am to 11 am EDT Monday for
NC...Wind Advisory from 8 PM this evening to 2 PM EDT Monday for
High surf advisory from midnight tonight to 5 PM EDT Monday
Virginia...Winter Weather Advisory from midnight tonight to 5 PM EDT
Monday for vaz065-066-079>081-087>089-091-094.
Winter Weather Advisory from 10 PM this evening to 5 PM EDT
Monday for vaz060-067-068-070-071-082>084-086-090-099-100.
Winter Storm Warning until 5 PM EDT Monday for vaz048-049-
Wind Advisory from 8 PM this evening to 2 PM EDT Monday for
High surf advisory from midnight tonight to 2 PM EDT Monday
High surf advisory from 4 am to 11 am EDT Monday for vaz099-
Winter Storm Warning from 8 PM this evening to 5 PM EDT Monday
Marine...Gale Warning until 2 PM EDT Monday for anz630>634-650-652-654-
Small Craft Advisory until 8 PM EDT Monday for anz635>638.