Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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FXUS62 KRAH 210739

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

Continental polar high pressure will extend across 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 unseasonably
cool and wet conditions early to mid next week.


As of 330 AM Saturday...

The center of the chilly, 1033 mb, surface high pressure was located
over PA 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 today 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. Highs generally 67-
72. Mostly clear skies are expected tonight with milder lows in the
lower to mid 40s.

As of 330 AM EDT Saturday...

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 128 AM Saturday...

24 Hour TAF Period: VFR conditions are expected to continue through
the 24 hour TAF period, high confidence.

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