Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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FXUS62 KRAH 210624

Area Forecast Discussion
National Weather Service Raleigh NC
124 AM EST Wed Feb 21 2018

High pressure at the surface and aloft will extend across the
Carolinas through Thursday, resulting in record warmth across the
region Wednesday and Thursday. A backdoor cold front will move
southward into the area Thursday evening into Thursday night but
lift back north as a warm front late Friday and Friday night.


As of 1015 PM Tuesday...

Aside from a tweaks to the hourly temperatures, little change
anticipated to the near term forecast.

Mild temperatures persisting this evening with mid evening
temperatures ranging from the upper 50s across the Triad region to
the upper 60s across the south. With low clouds and fog expected to
develop during the next hew hours, temperatures will likely hold
steady as the low clouds will trap the heat escaping from the
Earth`s surface.

Temperature/dewpoint spreads across portions of the Piedmont have
narrowed to 2 degrees or less. This will lead to the development of
patchy fog/low clouds. Expect this development to occur primarily
after midnight with areas of dense fog probable. This probability
appears highest over portions of the western and southern Piedmont,
though confidence not high enough to issue a dense fog advisory at
this time.

00Z upper air analysis depicts unseasonably strong anti-cyclone
positioned offshore of the Southeast U.S. Warming aloft associated
with this feature coupled with the warm sly flow in the lower levels
of the atmosphere will provide us with the record warmth the next
couple of days.


As of 316 PM Tuesday...

Very strong and near record strong upper level ridging will
be along the SE U.S. coast Wednesday and Wednesday night.
The flow around the high will continue to pump up the
dew points and low level moisture. Essentially, this will
be enough to create fog and stratus again tonight. However,
it is expected to be less widespread and time consuming.
Expect the stratus to burn off by mid morning, with partly
sunny skies the rest of the day. Highs are favored to warm into
the daily record territory. Readings in the mid 70s to near 80
are favored from NW to south, only tempered a bit by the
amount of moisture in the air with dew points in the 60s.

The warmest readings in the cool season (February in this
case) are typically associated with very dry, downslope
events characterized by dew points in the 20s/30s etc.

So this particular warm episode event will be accompanied
by record high low level moisture for February, leading to
record high minimums - not so much as hot daytime highs.

There should be an increase again of stratus late Wednesday
night and early Thursday morning. Otherwise, partly
cloudy with lows 60-65.


As of 229 PM Tuesday...

The last couple model runs have trended slower with the backdoor
cold front on Thursday, thus allowing for another very warm and
mostly dry day Thursday with highs from the mid 70s north to around
80 south. Latest guidance now suggest the boundary will move south
into our CWA Thursday evening, then stall along or just north of the
Hwy 64 corridor early Friday morning.  As such will continue to show
best chance for patchy light rain along and north of Hwy 64.

Friday now looks to be a bit warmer with the boundary farther north
and CAD airmass mainly across our northern Piedmont zones. As such,
will adjust temps up a few degrees, with the warmest readings (70s)
still expected across the southern half of our CWA, and 60s north
near the VA border. Otherwise, dry wx on Friday.

Saturday looks warm and dry now with SW flow increasing ahead of the
trough and cold front moving across the MS valley. Highs will climb
well into the 70s, with clouds gradually increasing from west to
east as the trough approaches.  It`s worth noting that the 00z ECMWF
tries to drop another backdoor front southward toward the NC/VA
border during the day Saturday, with rain chances across our
northern-most zones. However given the strength of the subtropical
ridge, for now the preference is to keep the backdoor front and its
wx farther north.

The next front moving in from the west is progged to cross our area
during the daytime Sunday, and will bring the chance for showers and
perhaps isold tstms with its passage.  Given that the best upper
energy is quickly lifting out and leaving broad SW flow in it`s
wake, the front may stall just to our east, prolonging the risk for
scattered showers, particularly across our eastern zones, into the
daytime Monday.  By Monday night however, the next short wave ridge
will move in from the west with a sfc high building to our north,
and that should clear out skies and bring a more seasonable airmass
for Monday night and Tuesday.


As of 120 AM Wednesday...

24 Hour TAF period: Some low ceilings starting to set in this
morning but they have been slower to develop than expected. Will
continue to monitor throughout the morning for any signs of dense
fog but expect a general lowering of aviation conditions through the
early morning hours and then improvement after sunrise. Some wind
gusts this afternoon up to 20 kts or so for a few hours before
sunset. Another lowering of ceilings can be expected after 00z.

Long term: A warm, moist weather pattern will promote chances for
fog and low stratus the next several mornings. A cold air damming
wedge could bring adverse conditions on Friday. A stronger cold
front will cross the area on Sunday and Sunday night.



RDU Records:

Date     |  High  Year  |  High Min  Year
02/20       75    1939        62     1939
02/21       76    2011        55     1939
02/22       75    1897        60     1897
02/23       79    1980        57     1962
02/24       81    1982        58     1985

GSO Records:

Date     |  High  Year  |  High Min  Year
02/20       74    1922        56     1939
02/21       74    2011        50     1954
02/22       74    1925        57     1980
02/23       74    2017        52     1922
02/24       79    1982        55     1985

FAY Records:

Date     |  High  Year  |  High Min  Year
02/20       82    2014        60     1939
02/21       80    1991        61     1953
02/22       77    2003        56     1989
02/23       80    1922        55     1922
02/24       83    1930        60     1975




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