Scientific Forecaster Discussion
fxus61 kakq 241117
Area forecast discussion
National Weather Service Wakefield Virginia
717 am EDT Tue Oct 24 2017
a weakening cold front slowly push across the local area this
morning...before pushing offshore tonight. High pressure builds
across the Gulf of Mexico Wednesday and Thursday...as low
pressure lingers from the Great Lakes to New England.
Near term /until 6 PM this evening/...
latest analysis indicates ~1028mb sfc high pressure well off
the New England coast. To the west, deepening low pressure
continues to slowly lift across the upper Great Lakes this
morning. Attendant surface cold front pushing toward the coast
this morning, with quick clearing behind the front. Aloft,
dampening upper disturbance over the local area pushing
offshore, as lead shortwave currently over the mid-Mississippi
River valley continues to dig longwave trough into the OH/TN
Regional radar mosaic showing convection of earlier this morning
now diminishing to a narrow line of showers with locally heavy
rainfall across the Virginia Northern Neck and coastal plain. Have
accelerated the clearing trend to the west this morning, with
clearing by mid to late morning for all but immediate coastal
zones, where clouds and showers will linger into late this
morning. Influx of higher precipitable water air will lift S to north along the
front just offshore. Still rather warm as winds remain from the
SW. Highs today in the mid 70s west to the lower 80s southeast as cold air
lags well behind off to the northwest of the local area.
Short term /6 PM this evening through Thursday/...
overall, good model agreement between the 00z GFS and 12z European model (ecmwf)
(due to an unspecified error...00z European model (ecmwf) is unavailable at this
hour). NAM now strongest/deepest with the clipper wave and
amplitude of the East Coast upper trough by late Wed/Thu.
Will side a little more to the aforementioned 00z GFS/12z European model (ecmwf)
consensus with this package. Surface cold front finally gets
pushed farther offshore this evening, with clearing along the
Maryland coast overnight as cooler and drier air filters in after
00z. Lows will range from the upper 40s west of I-95 to the
mid/upper 50s closer to the coast by Wed morning. On Wed...local
area looks to remain in between the sfc cold front well
offshore and upper trough axis/cold pool aloft approaching from
our west-northwest Wed afternoon and evening. Some scattered/broken cu will tend to
linger due to some shortwave energy aloft, but should be dry
with highs mainly in the M-u60s. For Wed night/Thu, shallow
layer of overrunning moisture could portend to a sprinkle or
two as the upper trough axis crosses. However, drier air in low
levels should make measuring rainfall unlikely. And therefore
have maintained rain chances aob 10% for now for Wed night and
Thu morning. Lows Wed night mainly in the 40s. High pressure
will build across the southeast Seaboard up into the local area.
Look for gradual clearing with highs in the low to mid 60s on
Thursday, as high pressure builds north across the local area
from the southeast coast.
Long term /Thursday night through Monday/...
long term period starts off dry Thu night/Fri with sfc high pressure
over the immediate area and west/SW flow aloft. With light sfc winds
under a clear sky, expect low temps Thu night in the low/mid 40s
most of the area, and highs in the mid/upr 60s Fri. Attention then
turns to an approaching deep upper-level trough Sat. Although any
pcpn will likely hold off until after daytime Sat, included a 20%
chance of a shower in case the faster ensemble member solutions pan
out. Better chance of rain (40-50%) arrives Sat night/sun as strong
sfc low pressure forms out ahead of the upper-level trough. There is
still plenty of uncertainty over the track of this low, but the
possibility is there for moderate to heavy rain sun. High temps in
the mid/upper 60s Sat drop to the upr 50s to mid 60s sun.
Aviation /11z Tuesday through Saturday/...
low pressure to the north and associated surface cold front
bringing ceilings down into MVFR/local IFR range this morning. Southeast
or S winds 10-15 kt, with gusts up to 25 kt possible during
this time period, with higher gusts possible in stronger showers
or tstms. This front will push to the coast by daybreak, with a
return to VFR for all terminals but sby by 15z, with clearing
reaching the coast by early afternoon. Mainly VFR conditions
expected later Tue aftn/evening through Fri.
a cold front will push east and approach the marine area around
8-10am. The cold front is then expected to slow down and take
its time pushing east and offshore through this afternoon.
Southerly winds 15-25 kt with gusts into the low 30kt range
will occur this morning all waters as the front nears. Once the
front passes, expecting the wind direction to remain S/SW
through the afternoon but with speeds diminishing to 10-15 kt
Bay/rivers and 15-20 kt Currituck Sound and coastal waters.
Waves will build up to 4 ft on the Bay and to 6-8 ft on the
Secondary cold front crosses the area tonight with sub-Small Craft Advisory northwest winds
developing behind the front into Wed. Will maintain the Small Craft Advisory over the
ocean through the day Wed due to a prolonged period of 5+ ft seas
and into Wed night for the coastal waters north of Cape Charles.
Lighter winds and sub-Small Craft Advisory conditions expected Thu and Fri with sfc
high pressure over the area.0
both Cambridge and Bishops Head touched minor flooding
thresholds this morning with tidal anomalies running 1.0-1.5ft
above normal due to strong south-southeast winds ahead of a cold front.
Water levels at these locations could potentially remain
elevated for the next high tide cycle this aftn/early evening,
which is the higher astronomical tide, despite lessening winds.
A coastal flood statement may be needed later today.
Marine...Small Craft Advisory until 10 am EDT this morning for
Small Craft Advisory until 4 PM EDT this afternoon for
Small Craft Advisory until 7 PM EDT this evening for anz633.
Small Craft Advisory until 6 am EDT Thursday for anz650-652-
Small Craft Advisory until 7 PM EDT Wednesday for anz656-658.