Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Wakefield Virginia
347 PM EST Sat Dec 27 2014
high pressure will remain offshore and drift east along for a
more southwesterly flow. A weak low pressure system will track northeast
through across the Tennessee Valley Saturday night and into the
middle Atlantic Sunday as a cold front approaches from the northwest.
This cold front drops through the region Sunday night. Another
area of low pressure tracks along the front and crosses the
region Sunday night...before moving off the coast Monday.
Near term /until 6 PM this evening/...
dry conditions continue this afternoon and through the evening.
High pressure slowly drifting off the coast remains in control and
looks to hold precipitation off until after daybreak Sunday. There
remains a lot of cloud cover west of the mountains and this cloud
cover will start to make its way east overnight. Models continue
to show a strong speed maximum rounding the base of the upper trough
Sat night with the upper ridge axis remaining off the southeast coast.
Middle and high clouds will thicken overnight in the upper SW flow.
With increasing clouds expect milder overnight temperatures in the low-
Short term /6 am Sunday morning through Tuesday night/...
while models agree on the overall pattern the timing of the
perturbations in the SW flow but the handing of the best upper
divergence differs just enough to make exact timing of
precipitation tricky from Sunday through early Monday. A cold
front drops into the area sun as a weak wave of low pressure lifts
NE along the front and over the region. A series of upstream
shortwave perturbations and increasing upper divergence will
provide lift as the front crosses the region late Sunday morning
through the afternoon. With increasing deep moisture in the southwesterly
flow the result will be widespread precipitation spreading SW to NE
across the region through the day Sunday. Best chances appear to be
across the western and northern portions of the forecast area and
perhaps as far south as central Virginia. Have kept likely probability of precipitation in the
forecast, but probability of precipitation may eventually be raised to categorical once
the exact track of the best precipitation is known. Highs sun in the middle-
upper 50s inland to low 60s southeast where chances for rain will be
lower. This initial wave of precipitation lifts through the area Sun
afternoon allowing for a break in the widespread rainfall Sunday
The front stalls just off the middle- Atlantic coast...extending
southeast into the southeast coastal plains as southwesterly flow and deep
moisture continues. The lull in precipitation sun evening will be short
lived as the next shortwave deamplifies and lifts into the region
late Sun night into Monday morning. A stronger surface low develops
along the front...lifting into NC early Monday morning. Another round
of widespread precipitation is expected late Sun night into Monday. This
round of precipitation should be more focused over the southern half of
the area across south central and southeast Virginia as well as NE NC.
Models are in a little better agreement now lingering some
moisture over the area into Monday evening. Maintained chance probability of precipitation
through Monday afternoon and evening. Highs Monday range from the middle 40s
in the north to near 50 in the south.
Upper jet and additional shortwave energy lifts into the region
Monday night into Tuesday...providing additional uvm. Remnant low level
moisture will result in additional light precipitation Monday night into
Tuesday morning. Temperature profiles expected to remain above freezing through
Tuesday morning...as the best cold air advection arrives as precipitation pushes offshore
late Monday night. Have maintained slight chance probability of precipitation through Tuesday
morning to account for potential wrap around moisture. Lows Monday
night in the middle to upper 30s with high Tuesday only in the low to
Long term /Wednesday through Saturday/...
GFS/European model (ecmwf) remain in good agreement through through the daytime
hours on Friday with regard to overall pattern. A cold zonal flow
will prevail aloft across the region Wednesday/Thursday...with
high pressure building into and across the area. Weather is
expected to be dry with temperatures at or a bit below normal for
late December. Low temperatures Tuesday night and Wednesday night in the
24 to 30 degree range /a bit warmer near the coast/. Lows Thursday
night in the upper 20s northwest to the Lower/Middle 30s southeast...with min temperatures
expected to occur before 06z...as clouds increase overnight. High
temperatures Tuesday through Thursday in the 40s...and in the 40s all
areas Friday... except southeast Virginia/NE NC...where 50s look likely.
GFS/European model (ecmwf) continue to diverge from next Friday night through
Saturday night with regard to timing of low pressure and associated
complex frontal system. GFS remains 12-18 hours faster than
European model (ecmwf)...which develops wave along the front Saturday
night...delaying frontal passage until Sunday. Regardless...Friday
night into Saturday night next week look to be unsettled...with
clouds and shwers. However...temperatures will warm to above
normal on Saturday...with many areas potentially in the 60s.
Aviation /20z Saturday through Thursday/...
a light southerly flow and scattered high clouds prevailed over the area
states Saturday afternoon. Middle and high level clouds will increase
tonight and Sunday as a cold front approaches from the west. Precipitation is
expected to develop to the west and spread into portions of the Middle
Atlantic States Sunday. The 12z NAM has trended drier through 18z
and held off on putting precipitation through then.
No fog issues are expected Sunday morning with temperatures being
held up by cloud cover and warm air advection.
Outlook...rain develops from the north/west Sunday afternoon and evening with
periods of IFR indicated Sunday night and Monday morning. A
temporary drying should occur late Monday and Monday evening. Low
pressure moving along the front to our south to bring another round
of rain and possible IFR late Monday night into Tuesday. VFR and dry
weather are expected Wednesday and Thursday.
fairly tranquil conditions expected on the marine area through
Sunday...as high pressure prevails along/just off the Virginia/NC coast.
Some increase in winds likely tonight/early sun...with speeds in the
10-15 knots range. Next frontal system approaches the area late
Sunday...and crosses the area Sunday night/Monday morning. Winds
gradually drop off ahead of the front on Sunday...but are expected
to increase out of the north/NE on Monday. Models have come into line
with earlier forecast reasoning...and are now indicating a stronger
surge...with wind speeds near Small Craft Advisory criteria possible Monday/Monday
night. Also expect that seas will eventually build to 5 feet over at
least the southern coastal waters late Monday-Tuesday in north/NE flow of
15-20 knots. May need some Small Craft Advisory headlines during that timeframe. Surface
high pressure slowly builds into the area by midweek...with
kdox 88d radar is expected to be out of service through at least
Wednesday 12/31. See ftmdox (free text message) for details.