Area forecast discussion 
National Weather Service Wakefield Virginia 
618 PM EDT Sat may 25 2013 


Synopsis... 
high pressure from the Great Lakes and Ohio Valley will continue 
to build into the middle Atlantic this weekend...resulting in dry and 
cool conditions. A warming trend will begin Memorial Day and last 
through next week as the high becomes situated off the East 
Coast. 


&& 


Near term /until 6 am Sunday morning/... 
latest surface analysis depicts surface low pressure deepening off the 
coast of southern Maine...as the upper level cutoff low spins over 
southern New England/eastern New York state. Mesoscale convective system situated over the middle 
MS valley has weakened this afternoon as it encountered drier air over 
the Ohio/Tennessee Valley. Still some high clouds over portions of the County Warning Area 
this afternoon...along with breezy northwest winds. Quite cool for Memorial 
Day weekend with afternoon observation holding in the 60s for most locations. 
Expect skies to become mainly clear this evening as high clouds 
are shunted south in the northwest flow aloft. Diminishing winds and 
clear skies will lead to mins tonight about 15 degrees colder than 
normal/mainly 40-45 well inland and 45 to 50 near the coast. This 
will be near but just above record lows (see climate section below). 


&& 


Short term /6 am Sunday morning through Tuesday/... 
middle/upper level pattern will be slow to evolve over the next few 
days...with ridging downstream over the central Continental U.S. And a cutoff 
low gradually pushing NE and off the New England coast by Sun afternoon. 
At the surface...pressure gradient will relax quite a bit by Sun afternoon as 
the coastal low moves off to the Canadian Maritimes and high 
pressure builds southeast from the Great Lakes. In terms of sensible weather on 
Sunday...winds will be lighter and skies will generally be sunny. After 
a very cool start...temperatures will warm rapidly with highs 70-75 
for most of the region (coolest near the coast and warmest 
along/west of I-95). Note...stayed on cool side of guidance as mav 
numbers/MOS guidance have generally been too warm past few days. 


Still chilly Sun night under mainly clear skies and light winds but 
with airmass modifying...expect mins to be a few degrees warmer than 
Sat night...went close to mav numbers with lows primarily from the 
middle to upper 40s. Stalled frontal boundary over the Gulf states will 
begin to lift northward late sun and Monday while at the same 
time...upper level ridge will finally progress eastward. As a result...a more 
significant warming trend will commence on Monday. As the ridge 
progresses eastward...a warm/moist airmass will interact with the 
boundary to produce showers and thunderstorms over the Midwest into 
the Ohio Valley Monday afternoon. Still looks too dry/stable east of the 
mountains so will keep forecast dry west/ just some scattered afternoon cumulus 
anticipated. Highs range from the upper 70s/near 80 along and west 
of I-95 to the lower 70s near the coast. Any convective activity to 
the west may form into a mesoscale convective system. Mesoscale convective system will round 
the ridge...but will likely die out before reaching the middle Atlantic. 
Boundary will continue to lift northward Monday night...much milder with lows 
from the middle 50s to the lower 60s. Boundary sets up somewhere across 
the area on Tuesday...NAM depicts a lot more moisture than the 
GFS/ECMWF...but both suggest enough moisture to include at least a 
20 to 30% for for rain showers and afternoon thunderstorms and rain across the County Warning Area. Highs mainly 
80-85 under partly to mostly cloudy skies and increasing southerly 
flow. 


&& 


Long term /Tuesday night through Saturday/... 
high pressure ridging over the east and resultant above normal 
daytime temperatures will headline the extended period. 


Strong upper trough will continue to dig over the western Continental U.S. 
Wednesday...further amplifying the central/eastern Continental U.S. Ridge as it progresses 
eastward. Ridge axis will locate from the southeast states nwwd into the northern 
plains...progressing eastward over the middle Atlantic into the Great Lakes 
region Thursday afternoon. Strong upper Bermuda high (+1 Standard dev) 
prognosticated to center just off the NC coast Thursday afternoon. 
Thereafter...medium range models in poor/fair agreement with upper 
level pattern. Main error region looks to be over central Quebec 
associated with a shortwave traversing southeast Canada (large model spread 
in ensemble runs). Models agree on compressing the ridge over the NE 
states...but 25/00z European model (ecmwf) is more amplified with the ridge axis. The 
subsequent sensible weather impact will be the location of the 
boundary over the NE states. Regardless of the differences...front 
expected to remain well to the north of the local area Wed-Fri. 
Thus...expect warm/moist Summer-like airmass to anchor over the 
region. +1 Standard dev 500 mb and 850 mb heights (as well as +1 Standard dev 850 mb 
temps) will translate to temperatures +1 Standard dev (generally in the 
middle/upper 80s) Wed-Sat. Dewpoints will also increase into the middle 
60s...as precipitation waters prognosticated to be around 1.25 to 1.5 inches Wednesday 
afternoon before decreasing Thursday. Combination of warm/humid and 
unstable airmass may be enough to interact with developing weak 
Lee side troughing to allow for diurnally driven showers and 
thunderstorms. However...confidence is not high at this time so will limit 
probability of precipitation below slight chance. Decreasing moisture Thursday-Sat will 
inhibit any chances for precipitation. 


&& 


Aviation /22z Saturday through Thursday/... 
impressive upper trough for this time of year over New England will 
slowly be lifting northeast away from the area. This will push the 
low pressure off the New England coast northeast away from the 
area tonight and Sunday. Main issue in the forecast this afternoon 
is wind speed and gusts. Looking at BUFKIT soundings and current 
observations will generally have winds 10 to 15 kts from the northwest 
with gusts from 20 to 25 kts. The strongest gusts will be near 
sby. After sunset the winds will diminish quickly and be around 10 
kts on Sunday. The direction will be northwest through Sunday. 
Continued mainly clear skies through Sunday. Some cirrus clouds 
coming off the mountains into ric this afternoon may also cross 
phf. Still looking at VFR conditions on Memorial Day then with a 
warm front approaching for Tuesday could develop scattered 
thunderstorms with potential MVFR in the storms. 


&& 


Marine... 
Small Craft Advisory dropped over southern waters as noted below. Keeping an eye on 
secondary surge later on this evening as secondary surface trough 
pushes across. Coastal waters forecast has been modified slightly from prvs issuance. 


Low pressure will continue to lift up the NE coast tonight as high 
pressure continues to build over the Ohio Valley. Cold air advection (850 temperatures 2-3 
Standard dev) will continue to result in strong northwest winds over the 
waters this evening. However...with high pressure beginning to 
extend into the southeast states...the gradient over the southern coastal 
waters and Currituck Sound has relaxed...with observed speeds 10 
to 15 knots. Seas have also fallen below 4 feet. Will end the Small Craft Advisory 
headlines at 6 PM EDT for the southern coastal zones as well as 
the Currituck Sound as a result. Otherwise...northwest winds 15 to 20 knots 
over the Bay and 20 to 25 knots over the northern coastal waters. Small Craft Advisory 
speeds are borderline over the northern coastal waters...but seas of 5 
feet still expected 20 nm out through the overnight. Small Craft Advisory headlines 
will drop off early Sunday morning as high pressure builds over 
the local area and the pressure gradient relaxes. A few Small Craft Advisory gusts 
may continue through middle morning across the Northern Bay. 
Thereafter...an extended period of sub Small Craft Advisory conds expected over the 
waters as high pressure continues to build over the region through 
the Memorial Day weekend. High pressure will slide offshore 
Tuesday as a warm front lifts over the waters...with high pressure 
remaining just off the southeast coast through the remainder of 
the week. 


&& 


Climate... 
set a record low at Elizabeth City NC this morning at 43 f (old 
record had been 47). May come close to challenging a few record 
lows again Sunday...record lows for may 26th are listed below: 


Richmond............42 (1925) 
Norfolk.............47 (1967) 
Salisbury Maryland........39 (1917) 
Elizabeth City NC...44 (1967) 


&& 


Akq watches/warnings/advisories... 
Maryland...none. 
NC...none. 
Virginia...none. 
Marine...Small Craft Advisory until 10 PM EDT this evening for 
anz635>638. 
Small Craft Advisory until 6 am EDT Sunday for anz630>632-634- 
650-652. 


&& 


$$ 
Synopsis...lkb 
near term...lkb 
short term...lkb 
long term...Sam 
aviation...jab 
marine...Sam 
climate...