Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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FXUS62 KRAH 241849

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

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.


As of 250 PM Friday...

Air mass modification underway as sly low level flow has advected a
warmer and slightly wetter air mass into central NC. This is evident
by dewpoints currently in the 40s (versus the teens and 20s from
Thursday). Temperatures have rebounded into the 60s, near 70 over
the Sandhills. Extensive mid level cloudiness which covered much of
the western Piedmont this morning has thinned out, while scattered-
broken cu has developed, primarily south of highway 64. An area of
high pressure at the surface was anchored offshore. Circulation
around this feature was ushering the warm moist air into our region.
Aloft, an area of high pressure stretched from the northern Gulf
into the Carolinas.

These features will drift slowly east and weaken with time tonight
into Saturday. With the uptick in low level moisture, there is a
higher threat for patchy fog and/or low clouds late tonight into
early Saturday morning. The moist layer is relatively shallow and
the lift is very weak, so no precip should occur. Overnight
temperatures will be rather mild compared to recent nights. Lows
should be in the upper 40s to around 50.


As of 250 PM Friday...

Warming trend continues Saturday as the high continues to drift away
from our region, while an area of low pressure lifts from the
southern Plains into the mid MS Valley. The approach of this feature
will deepen our sw flow, increasing the moisture advection. This
will lead to increasing cloudiness. While the atmosphere moistens,
little if any lifting mechanisms noted to generate precip, aside
from afternoon heating, Saturday through Saturday evening. Still,
could see an isolated shower or two over the southern Piedmont but
probability and coverage is too remote at this time to mention in
the forecast. The warming air mass will translate to afternoon
temperatures in the 70-75 degree range.

Clouds will thicken and lower across the area Saturday night. This
blanket of clouds will trap the heat gained Saturday, resulting in
overnight temperatures in the 50s. A lead s/w ahead of the main low
pressure system over the mid MS Valley will support a band of
showers that will cross the mountains overnight, and may be in
vicinity of the Yadkin River just prior to daybreak. Will retain the
slight chance PoP over our western periphery late Saturday night.


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

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.


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.




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