Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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FXUS62 KRAH 241840
AFDRAH

Area Forecast Discussion
National Weather Service Raleigh NC
240 PM EDT Fri Mar 24 2017

.SYNOPSIS...
An area of high pressure anchored offshore will extend west into
central NC through Saturday. A weakening upper disturbance will
cross our region on Sunday.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 1025 AM Friday...

An area of high pressure at the surface through 850mb has drifted
offshore, resulting in a sw flow in its wake. This flow will advect
an increasingly moist and warm air mass into central NC. Aloft, an
area of high pressure centered over the northern Gulf will extend
newd into the Carolinas. Circulation around this feature will funnel
the deeper moisture west- northwest of our region through tonight.

The presence of the ridge aloft and the sw flow in the lower levels
of the atmosphere will yield partly cloudy skies and noticeably
warmer conditions. Afternoon temperatures in the upper 60s-lower 60s
will be common. ~WSS

Not as cool tonight, and with a chance of patchy radiation fog owing
to the aforementioned increase in low level moisture values, with
low temperatures mostly in the upper 40s (45-50) expected. ~MWS

&&

.SHORT TERM /SATURDAY THROUGH SATURDAY NIGHT/...
As of 355 AM Friday...

A mid-upper level trough axis extending south from a closed low now
over sern CO will migrate newd from the MS Valley early Sat to near
the srn Appalachians by Sun morning, as the parent upper low lifts
toward the Great Lakes. Associated mid level height falls on the
order of 20-30 meters will pivot NEwd across central and wrn NC Sat
and Sat night, but lingering influence of the preceding ridge axis
aloft/sub-tropical ridge will maintain a strong capping inversion
and dry air aloft. As such, precipitation chances will remain low
through Sat night, with perhaps just a slight chance of a shower
near the Yadkin River by 12Z Sun. Even then and there, however,
instability will be weak, shallow, and still capped by the
inversion, so the (relatively) better chances of any showers will
not occur until Sunday.

It will otherwise be warm Sat, with scattered to broken fair weather
cumulus, and mild Sat night with both thickening high level
cloudiness in Swly flow aloft, and a chance of stratus over the wrn
piedmont late. Highs in the lower to middle 70s, and lows in the
lower to middle 50s.

&&

.LONG TERM /SUNDAY THROUGH FRIDAY/...
As of 240 PM Friday...

A deep low pressure system will lift northeast into the Great Lakes
Sunday. Its associated cold front will be weakening and essentially
stalling as it edges up against the mountains Sunday and the parent
low moves further northeast. This will result in central NC being
nicked by only a glancing blow from the stronger dynamic regime
associated with the upper system. So, despite our increasingly warm
and moist airmass, convection will be favored northwest, with
progressively smaller chances heading southeast. Some areas east of
I95 may not see any activity at all. Will also maintain small
chances for thunder west during the afternoon as instability will be
modest and the east will be strongly capped in proximity to the
Bermuda high offshore. Highs will reach the low to mid 70s, but the
northeast may struggle to reach upper 60s due to heavier cloud
coverage and potential shower activity.

Warm and moist airmass remains in place in return flow around the
Bermuda high with isolated convection on Monday and highs mostly in
the upper 70s. A rather weak, but more southerly tracking short wave
will be approaching from the west on Tuesday to increase our chance
of convection somewhat due to its moving through during the heat of
the day. Not seeing forcing that would readily signal potentially
strong or well-organized convection, though, so will maintain 40-50
chance PoPs. Tuesdays highs will again climb way up into the 70s,
with some lower 80s likely across the southern tier. Highs will
again reach upper 70s Wednesday, but only isolated showers look
doable in weak westerly low level flow and upper ridging over the
area.

Cooler high pressure makes a surge down the Atlantic coast on
Thursday, with a backdoor cold front threatening to make it as far
south as central NC, but low confidence in picking a model solution
at this point. We will concurrently have a more southerly low
pressure system taking shape over the southern Midwest which would
feed moisture into the frontal zone and potentially give us a rain
period Thursday night and Friday.

&&

.AVIATION /18Z FRIDAY THROUGH WEDNESDAY/...
As of 100 PM Friday...

High pressure at the surface and aloft will gradually weaken and
drift east through Saturday night. This will allow an area of low
pressure to approach from the west Saturday night and Sunday. The
southerly flow ahead of the low will advect a moist air mass into
our region, leading to probabilities of MVFR conditions due to low
clouds and fog late tonight-early Saturday morning, and again
Saturday night into Sunday morning. The sub VFR parameters may
linger well into the morning hours before lifting into VFR criteria
during the afternoon. The threat for showers appear minimal through
Saturday, though the potential appears higher for late Saturday
night into Sunday.

Periods of MVFR/IFR ceilings and visibility due to fog appear
probable Sunday night through Wednesday. The highest threat for
scattered showers will be on Tuesday when another upper disturbance
passes primarily to our north.

&&

.RAH WATCHES/WARNINGS/ADVISORIES...
None.

&&

$$
SYNOPSIS...WSS
NEAR TERM...WSS/MWS
SHORT TERM...MWS
LONG TERM...mlm
AVIATION...WSS


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