Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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FXUS62 KRAH 260216

Area Forecast Discussion
National Weather Service Raleigh NC
1016 PM EDT Tue Jul 25 2017

A cold front will settle south into SC tonight, stall there through
Wed, then retreat north through NC as a warm front Wed night and


As of 1015 PM Tuesday...

A positively-tilted upper level trough/shear axis evident in WV
satellite and 00Z upper air data, stretching from the New England
coast swwd through sern VA/west-central NC to srn TX, will settle
toward the NC coast tonight, while a trailing mid-upper level
perturbation now over swrn IL/sern MO will drift into the central
and srn Appalachians through the same time. A sharp deep layer
moisture gradient, characterized by 00Z/26th-observed precipitable
water values of an inch at GSO and two inches at MHX, accompanies
the lead trough axis.

At the surface, a frontal zone was analyzed at 02Z from near MRH to
RCZ to HKY, swwd through the TN Valley, then nwwd through the midle
MS Valley and to a 1009 mb surface wave over srn SD. Outflow from
earlier convection over ern NC has drifted wwd in an arc from near
RWI, to JNX, to CTZ.

A slight chance of a shower will linger for the next several hours
in the vicinity of the outflow and surface front, on the nwrn edge
of a weak, and further nocturnally-weakening instability axis along
and south of these features. It should otherwise be a dry night, as
the aforementioned upper level trough and following deep layer
dryness, settles through central NC.

Skies will be mainly clear, though with a persistence chance of
stratus in the vicinity of the surface front - from the srn Coastal
Plain to the srn/wrn Piedmont. Previously forecast lows mostly
within a few degrees either side of 70 need no adjustment.


As of 240 PM Tuesday...

The cold front should be positioned south of central NC on
Wednesday morning allowing high pressure to extend into the
region from the north. The front will begin lifting north on
later Wednesday as the surface flow veers to southeasterly and
southerly. This will allow an increase in moisture roughly in
the 925 to 850 hPa layer and promote an increase in cloud cover
and perhaps a shower or storm, generally in an arc from the
Coastal Plain west and northwest across the Sandhills and into
the Yadkin early in the day that will expand northward during
the afternoon and evening. Precipitation chances will be limited
to the slight chance range across most of the area, so all in
all it will be a much cooler and more tolerable day. Highs will
range in the upper 80s to near 90 with lows in the 68 to 74
range. -Blaes


As of 330 PM Tuesday...

Mid level ridging amplifying over the central CONUS will induce
corresponding deepening of east coast troffing and associated
northwest flow. Cooler air will be edging south out of the upper
Midwest and slowly spreading east and southeast, with the associated
cold front reaching the NC/VA border Thursday night. Thursday will
be dry with potential for some showers in the western Piedmont late
in the day. Highs will reach near 90 over the area with PoPs ramping
up to 30-40% by Friday morning as the front creeps in, with at least
50% chances on tap for Friday into Friday night. Strongest
convection is expected late Friday and through the overnight as
convergence along the h85 trof will provide the best lift, with
better shear profiles across the northern tier nearer the parent
surface low and triple point. Highs Friday will be a shade
cooler...mid 80s northwest to lower 90s east...mainly abetted by
heavier cloud coverage and rain, as the cooler air doesn`t make its
way into the area until Friday night.

Some showers may linger into Saturday morning in the east, otherwise
skies will be clearing with a noticeably cooler and drier airmass in
place through the weekend. Highs Saturday through Monday will top
out mostly in the mid 80s...3-5 degrees below normal, with morning
lows in the mid to upper 60s. The front, meanwhile, will be stalled
along the coast, with potential for development of a surface low
along the front that could pull moisture back into at least the
eastern sections of the state by midweek.


As of 800 PM Monday...

24-Hour TAF period: VFR conditions are expected to continue this
evening as a surface cold front settles to the south and west of the
region and stalls. We may see some low stratus (low end MVFR)
develop early Wednesday morning as at KFAY and KGSO/KINT (mostly
likely at KGSO/KINT). Any sub-VFR conditions are expected to lift by
late morning/early afternoon at the latest. Otherwise, VFR
conditions are expected to continue with dry conditions.

Outlook: The cold front to the south will lift north as a warm front
on Thursday before a stronger cold front moves through the area on
Friday and then stalls to our south over the weekend. Mainly VFR
conditions expected through much of the period with scattered mainly
afternoon and evening showers and thunderstorms and a chance of
morning fog and stratus. The greatest chance of adverse aviation
conditions in showers and storms will be Thursday night through
Friday night ahead of the approaching cold front. -Blaes


Technicians have completed the bulk of the first phase of the
Service Life Extension Project (SLEP) upgrade and the data
quality is sufficient for the radar to return to service.
Additional radar adjustments resulting in brief outages are
still possible during the next few days.

The temperature & dew point sensor at site KFAY, located at the
Fayetteville Regional Airport, is malfunctioning. NWS technicians
have turned the sensor off and ordered parts to repair it. At
this time, we expect the sensor to be returned to service early
next week.




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