Scientific Forecaster Discussion
fxus62 kilm 211317
Area forecast discussion...cor
National Weather Service Wilmington NC
916 am EDT sun Jul 21 2019
hot and humid conditions, and breezy afternoons, will prevail
through Monday, with heat indices reaching above 100 degrees.
A cold front late Tuesday will bring cooling and a chance of
thunderstorms Tuesday afternoon through Wednesday morning.
Temperatures below normal, will overspread the region middle
through late week in wake of the unseasonably strong cold front.
Near term /through Monday night/...
as of 916 am Sunday...few changes needed to a scorcher of a
forecast, heat indices area-wide 103-108 degrees today, even at
beaches where air temperatures are cooler, higher humidity there
will be felt in high 'apparent' temperatures. Many will likely
welcome, the unseasonably strong cold front forecasted mid to
late week, particularly after today and tomorrow, as the heat
switch remains in the 'on' position, as another heat advisory
may be needed again Monday.
As of 300 am Sunday...very similar setup to yesterday with deep
layered high pressure just offshore leading to more heat concerns
and limited precip chances. Main change to previous forecast was to
extend heat advisory to the coast. While it is hard to completely
rule out a shower/tstm with the heat, think convective activity will
struggle again today with subsidence inversion around 6-8kft.
Otherwise will see a period of breezy SW/south-southwest winds this afternoon
and abundant sunshine. Tonight will be dry with above normal temps
within persistent SW flow regime.
Still think there will be a slightly better chance for showers/tstms
on Monday as ridging pattern begins to break down and troughing
approaches from the W/NW. Widespread activity not expected but
enough support for a 20-30 pop. Many locations will likely remain
dry though, and also expecting heat advisories for portions of the
Short term /Tuesday through Tuesday night/...
as of 300 am Sunday...the main focus will be on the significant mid level
trough and front moving across the area through the period. Made a
few changes here and there, mainly to increase pops incrementally
due to higher confidence as the guidance is consistent. A pre
frontal trough may bring some initial activity Monday night but the
atmosphere should reload Tuesday and have good coverage as the front
approaches and moves across late Tuesday into Wednesday morning. As
for severe chances, some action is possible as the shear is more
than adequate (somewhat unusual this time of year) while the
instability appears marginal. Storm Prediction Center has the area in a marginal
risk for day three.
Long term /Wednesday through Saturday/...
as of 300 am Sunday...walked back pops for Wednesday as guidance is
almost insistent the push with the strong mid level trough is
sufficient to move the front well offshore. I also trimmed back
pops for the subsequent days via this trend. The bigger story is
shifting to the cooler temperatures which should be a few
degrees below climatology but will seem even moreso citing the
current heat wave.
Aviation /13z Sunday through Thursday/...
as of 12z...VFR conditions will prevail under the influence of
ridging aloft and western periphery of the Bermuda high
pressure. A resultant sea breeze will create breezy conditions
along with a backing wind. Not much in the way of clouds today,
especially as water vapor imagery shows very dry air in place
across the coastal plains.
Extended outlook...VFR to dominate through Mon outside of
isolated tstms. Gusty SW winds will occur again Mon afternoon.
Better chances of flight restrictions later Tue into early Wed
as a front moves into and through the area with showers/tstms
likely. Improving conditions expected for the second half of the
as of 300 am Sunday...moderate to fresh SW winds will continue
Sunday and Monday between offshore high pressure and inland
troughing. The strongest winds will be near the coast in the
afternoon and evening hours with the sea breeze enhancement to
around 20kts. Associated short period seas will continue around
3-4ft while mixing with typical 1-2ft southeast swell at 7-9s. As a
result, mariners on smaller and especially Flat Bottom vessels
should expect somewhat uncomfortable boating conditions. Have
held off small craft advisories for now though since only brief
periods of 25kt gusts are expected during mainly the late
Guidance is fairly consistent with with southwest winds of
15-20 knots late Monday through most of the day Tuesday ahead of
what is a strong cold front this time of year. The front should
cross the waters early Wednesday with a brief west to northwest flow
developing. The remainder of the period should see a decent and
somewhat sustained northeast flow. There will be the embedded surges
in this flow but overall the synoptic speeds appear to be in a range
of 10-15 knots. Significant seas will waiver with the Ebb and flow
of the winds but the overall range of 2-4 feet remains intact.
SC...heat advisory until 8 PM EDT this evening for scz017-023-024-
NC...heat advisory until 8 PM EDT this evening for ncz087-096-099-