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000
FXUS62 KRAH 200649
AFDRAH

Area Forecast Discussion
National Weather Service Raleigh NC
245 AM EDT Fri Apr 20 2018

.SYNOPSIS...
Chilly high pressure will build south over the region tonight
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.
&&

.NEAR TERM /TONIGHT/...
As of 245 AM Friday...

...Frost Advisory 400 AM through 900 AM for all but the SE...

1035+ mb cold surface high pressure was located over the upper
Midwest early this morning. CAA will continue this morning, then the
pressure gradient is forecast to relax this afternoon. This will
lead to much, much lighter winds today. Very dry air will also be in
place today. We expect sunny skies and light north winds at 5-10
mph. Highs will only be able to reach the lower 60s NE ranging into
the mid 60s SW, or about 10-12 degrees below normal.

A frost advisory was considered again tonight. However, the trends
in the statistical guidance have been a bit upward, now indicating
35-40 may be more likely than lower to mid 30s. If this trend
continues, we may escape widespread frost concerns tonight. We will
hold off on an Advisory for now and evaluate again late morning or
early afternoon. It appears that the culprit in the slightly higher
temperatures with the statistical guidance may be related to the
expected weak reinforcing cold front that should push south into the
area this evening. This would generate mixing, slowing the cooling
process. This is depicted best by the forecast increase in surface
pressures by 5+ mb between 06z and 12z/Saturday. Statistical
guidance is forecasting a bump in dew points into the 30s overnight
with a more ENE flow. Given these trends, we will continue the
forecast of clear tonight with lows in the 35-40 range. Any frost
should be scattered and confined to the low lying areas where cold
air drainage is common.

&&

.SHORT TERM /SATURDAY THROUGH SATURDAY NIGHT/...
As of 245 AM Friday...

The chilly high pressure center is forecast to drift off the VA/NC
coast late Saturday with another reinforcing high expected to follow
Saturday night. Expect only a few jet related cirrus at times,
mainly Saturday night. Highs Saturday with light winds should be in
the 65-70 range. Lows Saturday night creep up just a bit into the
upper 30s to mid 40s.

&&

.LONG TERM /SUNDAY THROUGH THURSDAY/...
As of 300 PM Thursday...

The weekend is expected to be dry as surface high pressure moves
into the mid-Atlantic and New England states. With easterly flow
expect temperatures slightly below normal with highs in the mid 60s
to near 70 degrees and lows in the 40s. By Sunday afternoon cloud
cover will begin to increase from the west as the high slides into a
pattern more favorable for cold air damming.

On Monday, attention will turn to a low pressure system crossing the
deep south which will encroach on central NC from the southwest.
With isentropic lift increasing, better chances of some stratiform
rain will come into play by Monday afternoon give or take a few
hours, which is a much better agreement in model timing than prior
simulations. The ECMWF is still the slower of it and the GFS but the
differences are much smaller. Once rain chances begin, expect them
to continue through Tuesday night when the actual low is progged to
cross the eastern half of the state. Lower chances will then
continue through Wednesday and into Thursday morning with wrap
around precip associated with the back side of the surface low as
well as the upper level low which will pass behind the surface low.
Therefore expect wet and unsettled conditions through the bulk of
the week next week with temps highs in the 60s, moderating into the
lower 70s by Thursday. Lows generally in the upper 40s to low 50s.

&&

.AVIATION /06Z FRIDAY THROUGH WEDNESDAY/...
As of 145 AM Friday...

24-Hour TAF Period: High confidence VFR conditions will prevail
through Saturday.

Looking ahead: Expect VFR conditions to persist through the weekend.
A storm system is forecast to bring IFR CIGS and VSBYS with rain and
fog late Monday or Monday night into Wednesday morning.

&&

.RAH WATCHES/WARNINGS/ADVISORIES...
Frost Advisory from 4 AM to 9 AM EDT Friday for NCZ007>011-
021>028-038>043-073>076-083-084.

&&

$$
SYNOPSIS...Badgett
NEAR TERM...Badgett
SHORT TERM...Badgett
LONG TERM...Ellis
AVIATION...Badgett