Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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FXUS62 KRAH 211351

Area Forecast Discussion
National Weather Service Raleigh NC
950 AM EDT Sat Apr 21 2018

Chilly high pressure will extend south through the middle
Atlantic states through the weekend. Low pressure is forecast to
track east across the Gulf Coast states this weekend, then turn up
the eastern seaboard early next week. This will bring cool and
wet conditions early to mid week.


As of 950 AM Saturday...

Main areas of surface high pressure were across the eastern Great
Lakes into the Delmarva region late this morning. The ridge axis
extended down the eastern seaboard into GA and FL. Very dry air was
in place along the eastern states and this will be the case for this
afternoon and tonight. The high pressure will gradually move off the
Mid-Atlantic coast later today and tonight allowing some
modification in temperatures tonight. Sunny skies are expected today
with only a few cirrus. Mostly clear skies are expected tonight with
lows in the lower to mid 40s.

As of 950 AM EDT Saturday...

Forecast for Sunday and Sunday night remains on track.  Surface high
pressure is expected to be reinforced over the Great Lakes into New
England, then down into the Mid-Atlantic states Sunday into Sunday
night. This occurs as a "closed" circulation or mid/upper low will
track east across the Gulf Coast states. There will be increasing
pressure gradient and wind associated with these features. There
will be a very deep and moist sub-tropical connection that will be
tapped and pulled NW into NC by late Sunday night as the mid/upper
low approaches the TN valley region. The rain should hold off until
Monday, but the cloudiness will increase Sunday and Sunday night. It
will cap temperatures somewhat on Sunday, but keep them very mild
Sunday night as the E-SE flow increases. Increasing cloudiness can
be expected Sunday with highs in the 67-74 range N to S. Thickening
and lowering cloudiness can be expected Sunday night with lows in
the 50s. &&

As of 335 AM EDT Saturday...

...Another widespread soaking rain expected Monday afternoon into
Tuesday night...

A very impressive plume of deep sub-tropical moisture is expected to
be tapped from the Caribbean and southwestern Atlantic into the
developing storm system, as it tracks slowly toward our region from
the Gulf Coast states and Tennessee Valley Monday into Tuesday. Rain
is expected to develop/overspread the southern and western areas of
central NC Monday morning, then eventually envelop the entire region
by late Monday into Tuesday. Models are in general agreement in the
track/strength of the mid/upper low as it tracks from northern MS NE
toward the upper TN valley by 12z/Tuesday, then slowly northward
into the lower Ohio Valley by 12z/Wednesday. The surface low track
still is more uncertain given the spread in the guidance, especially
by Tuesday night and Wednesday. However, it appears that a very deep
influx of subtropical moisture will be lifted up and over the
warm/occluded front as the low pressure approaches SC/southern NC
late Monday into Tuesday. QPF of 1.5 to 2+ inches can be expected,
with the higher totals likely in the western Piedmont where the
stronger lift associated with the mid level low will be aided by the
long SE fetch of deep subtropical moisture up into the higher
Piedmont. A flash flood watch may be needed early next week given
the current wet antecedent conditions, but highly dependent on the
track of the aforementioned storm.

Regardless, it appears to be a wet and cool start to the week aided
by rain, clouds, easterly winds, and at least some form of Cold Air
Damming early in the event. The chance of rain and showers will
decrease after the system lifts north of the region mid-week, though
another quick moving s/w disturbance may swing through the area on
Thursday/Thursday evening. This would allow for another chance for
showers on Thursday/Thursday evening. High temps are expected to
rebound to near normal by the end of the week, with highs in the 70s.


As of 950 AM Saturday...

24 Hour TAF Period: VFR. surface winds less than 10 knots.

Outlook: An approaching low pressure system early next week will
increase the threat for MVFR/IFR VSBYS and CIGS with rain and
fog across central NC. The threat for adverse aviation conditions
appears greatest from late Monday afternoon through through
Wednesday morning.





NEAR TERM...Badgett/Franklin
SHORT TERM...Badgett/Franklin
AVIATION...Badgett/Franklin is the U.S. government's official web portal to all federal, state and local government web resources and services.