Forecast Discussions mentioning any of "ACARS" "MDCRS" "AIRCRAFT" "TAMDAR" "AMDAR" "WVSS" received at GSD on 04/17/20

AREA FORECAST DISCUSSION

National Weather Service Raleigh NC

 855 PM EDT Thu Apr 16 2020

.SYNOPSIS...
Canadian high pressure will settle over the Carolinas and Virginia
through tonight. This high will slide offshore Friday as a warm
front advances northeastward through the area. A cold front and
upper level disturbance will cross the region Saturday morning, then
settle just to our south, as high pressure builds briefly over the
Mid Atlantic region late Saturday through Saturday night.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 855 PM Thursday...

The risk for frost tonight is starting to look more doubtful than it
did earlier today, at least in some areas. Subtle but important low
level moisture pooling over the eastern and far southern CWA, ahead
of the incoming weak/dry trough, has pushed dewpoints up into the
mid to upper 30s in spots, and current temps, while falling steadily
from today`s highs, are still running 5-10 degrees above this time
last night. And the ground heat flux is probably contributing to
this modest temp drop thus far. All hope is not lost, however: The
current dewpoints across most of the Piedmont are trending 5-10
degrees cooler than 24 hours ago, and with clear skies and winds
already going calm over much of the forecast area, we should
continue to see a steady drop in temps over the next several hours.
With the surface trough likely to push further southeast overnight
as the high builds overhead, dewpoints should drop back a few
degrees in the east, making frost once again possible in outlying
areas of the Coastal Plain. Will keep the frost advisory as is, as
the rural and low locations still have a good chance of seeing
frost, especially in the Piedmont. Lows in the 30s. -GIH

Earlier discussion from 250 PM: Another frost advisory has been
issued for tonight. Quiet weather is expected with generally clear
skies through tonight (apart from a few mid clouds upstream drifting
across the N late) and a dry column. High pressure from the surface
up through 850 mb will settle over the region, bringing
light/variable winds after sunset and, given the current dewpoints
in the 20s to around 30 areawide and clear skies fostering good
radiational cooling, we should see temps plummet again tonight.
Statistical guidance was too warm last night and I expect the same
for tonight, so have gone below guidance, particularly in the
outlying areas. In fact, there is likely to be a wide range of low
temps even within small areas, with the cities and towns likely to
bottom out in the mid-upper 30s while suburbs and other areas just
outside the towns drop into the lower 30s. The frost advisory will
cover all of central NC, with a more widespread frost threat in the
outlying/rural areas, from 2 am to 8 am. -GIH

&&

.SHORT TERM /FRIDAY AND FRIDAY NIGHT/...
As of 305 PM Thursday...

The current fast zonal flow across the southern half of the CONUS
will buckle a bit as a shortwave trough now over the intermountain
West tracks E and digs through the Midwest and Ohio Valley toward
the Appalachians through Fri night. Surface high pressure overhead
late tonight will shift offshore Fri morning, allowing the warm
frontal zone to progress NE through the area. We`ll see good deep
mixing Fri but the mid levels will remain dry and stable with
surface dewpoints taking awhile to recover, and as such, we should
still see quite a bit of sunshine for much of the day. Morning
thicknesses should be below normal but rebound nicely through the
day, yielding near normal highs in the low-mid 70s. Clouds will move
in quickly overnight associated with the fast-moving shortwave
trough, with lowering bases through the mid levels in tandem with
lower stratocu with strengthening low level WAA ahead of the
approaching surface low and cold front. Latest model output
indicates showers moving into the NW forecast area late, after 3 am,
as it should take that long to moisten the column. Will bring in 20-
50% pops mainly across the NW Piedmont. In stark contrast to
tonight`s lows, expect lows Fri night in the mid-upper 50s. -GIH

&&

.LONG TERM /SATURDAY THROUGH THURSDAY/...
As of 235 PM Thursday...

Three distinct systems should impact the region during the long term
portion of the forecast. The first system will be a cold front
beginning to cross the region late Friday and completing the passage
on Saturday. With the associated low pressure system passing through
the New York City metro area, dynamics will not be as strong this
far south and have continued with likely wording for showers.
Considering the time of year, cannot rule out an isolated
strong/severe storm, primarily to the north and east of Raleigh. All
locations should be dry by sunset. Temperatures will be slightly
above normal.

Dry weather will not last very long with another low pressure system
forming in the central Plains Saturday into Sunday and moving east-
northeast. The 12Z GFS came in with a slightly farther storm track
compared to the 06Z GFS, which keeps the low moving across our
southern counties Monday morning around sunrise. With our region
staying in the cold sector, this should strongly prevent, if not
eliminate, the chance for thunderstorms Sunday night into Monday.
While the inherited forecast had a slight chance of thunderstorms
across southern counties, have removed the slight chance from the
forecast. Even without the chance for thunder, this storm could
still bring one to two inches of rainfall to some locations. Once
again, all locations should be dry by sunset. Temperatures will be
slightly above normal Sunday, but cool down on Monday.

After Monday`s low pressure system moves through, high pressure will
move into the eastern United States for Tuesday and Wednesday,
allowing for a couple days of dry weather. The ECMWF and GFS then
show another system moving into the eastern United States for the
second half of the week, but with major differences in track. The
12Z GFS shows a low pressure system over Detroit by Thursday
evening, while the 00Z ECMWF shows a low over Arkansas. Even with
the models showing the low pressure center several hundred miles
apart, both models still show a wide swath of rain across the
eastern half of the United States. There will be plenty of time for
the models to come into better agreement with this system.
Temperatures will be above normal through the time period, with
Wednesday the warmest day.

&&

.AVIATION /00Z FRIDAY THROUGH TUESDAY/...
As of 710 PM Thursday...

24 hour TAF period: High confidence VFR conditions will prevail
through the TAF period, with winds abating around sunset and
increasing again Friday morning. Skies should remain largely clear
through tonight, with some high clouds starting to overspread the
area during the day. Southwesterly winds will will be strong and
gusty through the aft/eve Friday, with sustained winds around 10 kts
and gusts to around 20 kts. -KC

Looking ahead: A warm front will lift through the area from SW to NE
Friday night, increasing chances for sub-VFR cigs after midnight Fri
night, lasting through early afternoon Sat, with a good chance of
showers areawide and perhaps a storm near FAY. Winds will be strong
and gusty Fri night/Sat morning, increasing with height, leading to
potential difficulties with aircraft handling. VFR conditions will
return by mid afternoon Sat, with decreasing winds. But sub-VFR
conditions, with showers/storms and strong/shifting winds, are
expected to return late Sun and last through much of Mon as a
powerful storm system crosses the region. Improvement is expected
Mon evening with VFR conditions likely Mon night/Tue beneath high
pressure. -GIH/KC

&&

.RAH WATCHES/WARNINGS/ADVISORIES...
Frost Advisory from 2 AM to 8 AM EDT Friday for NCZ007>011-021>028-
038>043-073>078-083>086-088-089.

&&

$$
SYNOPSIS...Hartfield
NEAR TERM...Hartfield
SHORT TERM...Hartfield
LONG TERM...Green
AVIATION...KC/Hartfield