Area Forecast Discussion
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FXUS62 KRAH 261608
Area Forecast Discussion
National Weather Service Raleigh NC
1205 PM EDT WED OCT 26 2016
Cool high pressure will extend into our region from the north
through tonight, before shifting offshore early Thursday. A cold
front will move into the area from the northwest Thursday night.
.NEAR TERM /through Tonight/...
As of 1110 AM Wednesday...
Rest of today: Forecast trends are in line with observations this
morning. Skies are generally clear across the area and should remain
that way for the rest of the day, with little more than some high
cloudiness topping the weak shortwave ridge axis which will cross
the Southeast states this afternoon. The deep low- to mid-level
anticyclone noted from 850 to 700 mb will limit moisture influx and
resultantly will limit the amount of convective cloudiness over the
area this afternoon. Have nudged highs today upward slightly to the
mid 60s to around 70, given that temps are pacing a bit warmer than
hourly forecasts. -GIH
Previous discussion from 310 AM: An area of high pressure at the
surface coupled with a wly flow aloft will maintain dry and
seasonably cool conditions across central NC today. Low level
thicknesses average about 10m lower than normal, supportive of
afternoon temps 3-4 degrees cooler than normal. High temps generally
in the mid 60s north to upper 60s south. Aside from a few patches of
cirrus, expect sunny skies today.
Tonight, the area of high pressure drifts east, while aloft,
westerly flow begins to advect moisture ahead of a s/w crossing the
Great Lakes. This moisture aloft will be int he form of a cirrus
shield gradually spreading/thickening over central NC. Latest model
guidance suggest low level moisture advection will not become
significant until close to daybreak. Thus, not expecting much in the
way of low clouds and/or patchy fog until close to daybreak. The
moistening atmosphere will lead to mild overnight temps, mainly in
the mid-upper 40s. -WSS
.SHORT TERM /Thursday and Thursday night/...
As of 310 AM Wednesday...
Atmosphere will continue to moisten Thursday as southerly low level
flow continues to pull moisture into our region. While the bulk of
the energy associated with the s/w crosses well to our north, the
trailing end of the s/w and attendant sfc front will encounter a
moderately moist air mass. While instability will be lacking, still
cannot rule out a clap or two of thunder across the northern
Piedmont late in the day into the early evening hours when best
forcing noted in the lowest 15k ft.
Have scaled back timing of highest threat for measurable rain until
late in the afternoon into the evening. Still, expect rainfall
amounts to be light, on the order of less than a tenth of an inch.
In spite of extensive cloudiness, afternoon temps will be a few
degrees warmer than normal thanks to the low level warm air
advection. High temps Thursday 70-75, coolest northwest and warmest
far south. Expect the sfc cold front to drift east-se across central
NC, mainly during the overnight hours. Should see a gradual decrease
in cloudiness nw-se after 06Z. Min temps lower 50s nw to the
mid/upper 50s se.
.LONG TERM /Friday through Tuesday/...
As of 304 AM Wednesday...
Cold front will be near the NC coast by 12z Friday. Lack of CAA will
result in high temperatures on Friday similar to those on Thursday.
Transitory surface high pressure will build across the area in the
wake of the front Friday, before shifting south of the area
Saturday. Another cold front will move quickly through the region
Sunday. Dry westerly flow aloft with little moisture return will
result in a dry passage, followed by weak surface high pressure and
upper level ridging Monday and Tuesday. Temperatures will remain
above normal through the period, with highs in the 70s.
.AVIATION /18Z Wednesday through Monday/...
As of 1205 PM Wednesday...
Confidence is high that we`ll see VFR conditions continuing through
this evening, with high pressure nosing into the region from the
north and warm/stable air aloft. However, conditions are expected to
deteriorate overnight, starting after 06z in the southeast (FAY) and
after 08z elsewhere, as low level return flow brings increasing
moisture into the low level (under 3 000 ft AGL) surface-based
stable layer. A trend to MVFR or IFR cigs is likely late, lasting
through 13z, followed by a trend to low-end VFR through 16z, with
gusty winds from the southwest developing at all sites. Patchy
sprinkles are possible toward the end of the TAF valid period at
INT/GSO/RDU, but any sprinkles will be isolated and not impactful to
Looking beyond 18z Thu, a few showers with MVFR conditions are
possible in the west (INT/GSO) in the 21z Thu to 03z Fri time frame,
and in the 00z to 06z Fri time frame elsewhere (perhaps lasting
until 09z at FAY/RWI), but VFR conditions should remain dominant
with any sub-VFR conditions being very brief with only light precip
expected. Sub-VFR shallow ground fog is then possible late Thu night
into Fri morning (mainly 08z-13z). A weak cold front will drop
southward into the area Fri morning, with high pressure building in
behind it from the north. VFR conditions will return by mid morning
Fri, holding through the weekend and into early next week, although
sub-VFR fog/stratus is again possible early Sat morning and again
Mon morning as the high shifts to our southeast and another mostly
dry front approaches from the north. -GIH