-- Discussion containing changed information from previous version are highlighted. --
000
FXUS62 KILM 220547
AFDILM

Area Forecast Discussion
National Weather Service Wilmington NC
147 AM EDT Sat Jul 22 2017

.SYNOPSIS...
Hot and humid conditions will prevail today through the weekend
with only isolated rain chances. Storms will increase next week
as a series of weak fronts approach the coast, with near normal
temperatures for late July.

&&

.NEAR TERM /THROUGH TODAY/...
As of 915 PM Friday...Diurnally driven convection along the
Piedmont trof basically dissipated by and just after sunset. Do
not expect any convection this evening thru the overnight. Skies
basically clear except the far NW portions of the FA where
convective debris clouds will slowly scour out during late this
evening and overnight. Min temps will basically run in the mid
70s with upper 70s to near 80 along the immediate coast due to
a partially onshore SSW-SW flow having crossed adjacent SSTS
that are in the 80-85 degree.

Previous.......................................................
As of 645 PM Friday...Quick update issued to account for
isolated convection drifting into the NW portions of the ILM CWA
thru sunset.

Previous......................................................
As of 300 PM Friday...Steep low level lapse rates have combined
with just enough low level moisture to pop some cu throughout
the forecast area, especially along the sea breeze boundary
where moisture advecting in off the ocean provides a little more
fuel. However, it is very dry above 850 mb so still looks like
the remainder of today will be a dry one with only the odd spot
shower or thunderstorm possible. Best chances for anything look
to be well inland in closest vicinity to the persistent thermal
trough. As this is all diurnally-driven, expect overnight to be
clear and dry with lows in the mid 70s.

Similar story for Saturday, with diurnally-driven slight chance POPs
at best during the afternoon and early evening. It is possible that
a heat advisory may be required for heat index values of 105F or
higher, but confidence is not high enough at this time for issuance.
A consensus of guidance has actual temperatures for Saturday much
the same as today, with highs from around 90 near the coast to the
mid 90s inland.

&&

.SHORT TERM /TONIGHT THROUGH SUNDAY NIGHT/...
As of 330 PM Friday...Overall expect hot and humid weather with
heat advisory conditions over most of area on Saturday. A Broad
trough in the mid to upper levels extends just far enough south
into Carolinas as to prevent strong ridging to build in from
west or east to push temps high enough for any record heat, but
enough to produce temps a good 3 to 7 degrees above normal.
Temps should reach into the mid 90s over most of the area. Temps
overnight will remain well into the 70s most places. SW sfc
winds around Bermuda High will become quite gusty Sun aftn into
Sun eve as sea breeze and trough inland become more pronounced,
and should see winds increase further Sun night as trough pushes
east and tightens pressure gradient.

Both the Atlantic ridge and strong ridge over central CONUS
seem to exert enough influence with enough dry air and
subsidence to keep area mostly rain free, but with with
troughing inland and decent sea breeze on Sunday, can not rule
out an isolated shower Sat night into Sunday. By Sun night, the
mid to upper trough begins to dig a bit more south and a
shortwave rides by as well as a disturbance moving up the coast
from the south. This will all lead to better chc of shwrs/tstms
late Sun into Mon.

&&

.LONG TERM /MONDAY THROUGH FRIDAY/...
As of 300 PM Friday...A shortwave trough moving through New
England on Monday night, and a large upper low developing
across southern Quebec late in the week will help put a dent in
the heat. Falling upper level heights associated with these
systems will shift the core of the upper ridge (and its
associated heat) farther west into Texas and New Mexico. Don`t
expect a cleansing frontal passage by stretch, (06Z GFS ensemble
850 mb temps don`t fall below climatology next week) but at
least we should lose the 100+ heat indices for a few days.

Both the GFS and ECMWF show a cold front moving into northern
North Carolina on Tuesday. The GFS then sinks the boundary a
little farther south by Wednesday morning. There are enough GFS
ensemble members showing the front making it into South Carolina
that I`m leaning toward the GFS in this case. This front should
enhance the coverage of t-storms Tuesday night and Wednesday,
and I`ve placed my highest forecast PoPs (50-60 percent) of the
extended period during this period.

With a progressive upper level pattern to our north, surface
high pressure will push off New England and out into the
western Atlantic Thursday and Friday, probably with enough
southerly wind developing over the Carolinas to lift the front
or its remnants back to the north.

&&

.AVIATION /06Z SATURDAY THROUGH WEDNESDAY/...
-- Changed Discussion --
As of 06Z...VFR conditions will dominate the period with the
only hint of any restrictions at inland sites where patchy fog
could drop visibility to 5SM for short periods of time. Sea
breeze will again develop with onshore flow at coastal terminals
gusting around 20 kt at times. Only potential for afternoon
storms appears to be at inland sites late afternoon and evening
and even here chance is low. Have gone for VCTS at both FLO and
LBT. Realistically any storms that do develop are likely to be
farther to the west.

Extended Outlook...VFR through Sunday. Brief MVFR/IFR possible
in scattered showers and tstorms Mon and Tue due to a slowly
approaching cold front from the NW.
-- End Changed Discussion --

&&

.MARINE...
NEAR TERM /THROUGH SATURDAY/...
As of 915 PM Friday...Strong ridging from high pressure centered
well offshore and the Piedmont trof across the central Carolinas
will result with a slow tightening of the sfc pg tonight thru
Sat. Look for SSW-SW winds 10-15 kt g20 kt tonight that will
increase to 15 to 20 kt with g25 kt, especially near shore due
to a healthy inland progressing sea breeze. Significant seas
will run 2 to 4 ft tonight and build to 3 to 5 ft thruout by
late Sat thru Sat night. Power-wise, a 1 to 2 foot ESE ground
swell at 7 to 8 second periods will dominate over the wind
driven waves at 4 second periods. During Sat and Sat night, the
wind driven waves at 4 to 5 second periods will become more
dominant.

Previous.......................................................
As of 300 PM Friday...Circulation around high pressure over the
western Atlantic will keep winds from the SW, generally in the
10 to 15 kt range, through the period. Seas will likewise show
little variation, running right around 3 ft through Saturday.

SHORT TERM /SATURDAY NIGHT THROUGH SUNDAY NIGHT/...
As of 330 PM Friday...Precautionary headlines may be needed Sun
into early Mon as winds increase to 15 to 20 KT winds and seas
reach 4 feet offshore and possibly up to 5 ft. The afternoon sea
breeze circulation will keep winds gusty and seas choppy near
shore Sun afternoon to early evening. Very little TSTM activity
is expected until Sun night into early Mon when activity will
increase across the waters as trough shifts farther east toward
the coast.

LONG TERM /MONDAY THROUGH WEDNESDAY/...
As of 300 PM Friday...Bermuda High Pressure well offshore will
lose its influence on our weather by the middle of next week as
low pressure in the Canadian maritime provinces pushes a cold
front down the U.S. East Coast. This front is shown by the
latest GFS and ECMWF models to make it down to near Hatteras on
Tuesday. Models diverge slightly on Wednesday as the ECMWF keeps
the front stalled to our north and the GFS brings it down to
the Myrtle Beach vicinity Wednesday morning. Regardless of which
solution is correct, the frisky southwest winds of the weekend
should diminish by Tuesday within the weaker pressure gradient
near the front. Unfortunately thunderstorm potential should also
increase as the front approaches.

&&

.ILM WATCHES/WARNINGS/ADVISORIES...
-- Changed Discussion --
SC...None.
NC...None.
MARINE...None.
-- End Changed Discussion --

&&

$$
SYNOPSIS...RGZ
NEAR TERM...DCH/REK
SHORT TERM...RGZ
LONG TERM...TRA
AVIATION...III