Area Forecast Discussion
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FXUS62 KILM 221031
Area Forecast Discussion
National Weather Service Wilmington NC
531 AM EST Sun Jan 22 2017
A complex and potent storm system will affect the Carolinas
today through Monday with potential for severe weather during
late this afternoon and evening. Total rainfall amounts through
Monday should amount to one to 2 inches. This storm system will
slowly depart through Monday leaving high pressure for Tuesday
and Wednesday. The next cold front will move across the area on
Thursday. Much colder weather will follow Friday and into next
.NEAR TERM /THROUGH TONIGHT/...
As of 345 AM Sunday...Two more rounds of pcpn will affect the
ILM CWA during the next 24 hrs. The 1st is currently pushing NE
from the Gulf Coast States with it`s northern periphery already
having reached the ILM SC portions of the CWA. Expect this pcpn
to continue its trek NE-ward this morning and encompassing the
majority of the ILM CWA by daybreak Sun. The pcpn from Sat
evening helped to stabilize the airmass across the FA prior to
this next pcpn area. The embedded thunderstorm activity over GA
and southern SC will fall apart by the time it reaches and moves
across the ILM CWA during this morning. QPF from this pcpn
round will run around one quarter of an inch for the ILM NC CWA
up to one half inch or slightly hier for the ILM SC CWA,, ie.
across the PEE DEE Region. Will see a brief reprieve from the
pcpn from midday thru mid- afternoon.
The next round of pcpn, and potentially the more potent, will
occur from late this afternoon through late this evening. The
pcpn will overspread the FA from SW to NE. A closed upper low
will move from the Gulf Coast States this morning to the western
Carolinas this aftn thru tonight. It`s accompanying sfc low will
quickly get captured by the upper closed low later today...and
become a somewhat stacked system by Mon daybreak. Plenty of
dynamics aloft and at the sfc will be in play with this next
round of pcpn. As for severe convection potential, the FA will
experience a High Wind Shear environment and a Low Cape,
instability environment. Do not need much instability when you
are dealing with plenty of atmospheric dynamics especially this
much low level wind shear. Thus, with plenty of twisting in the
low levels, rotating tornadic type thunderstorm activity is
possible beginning late this aftn thru this evening. Will
advertise the possible tornadic threat with damaging wind gusts
and hail also severe possibilities.
The low`s occlusion portion of it`s frontal system, will push
across the FA from west to east during the mid to late
evening hours. After pushing thru, the pcpn will come to an
abrupt end. A dry mid-level punch is the mechanism for pushing
this occluded front across the ILM CWA and likely where you will
find the most intense pcpn prior to it pushing thru. Will
indicate isolated showers after it`s passage for the remainder
of the overnight.
Temperatures will run up to 15 degrees above normal this period.
The CAA after the pcpn comes to an end will lag-some, with the
best of it occurring during the next period. As a result, do
not expect your normal diurnal temperature curve this period.
.SHORT TERM /MONDAY THROUGH MONDAY NIGHT/...
As of 430 AM Sunday...The Fa will be under the mid-level dry
air associated with the "dry punch" that pushed across Sunday
night. During Monday, expect the wraparound moisture to push
across the FA associated with the Closed Upper Low moving from
the western Carolina to only off the DELMARVA Coast by Tue
daybreak. Dynamics from weak mid-level vorts rotating around
the slowly lifting upper closed low will result in low topped
isolated to scattered showers across the FA, especially during
the daytime heating on Mon. This pcpn threat will diminish
quickly after nightfall Monday. However, low level clouds will
continue to persist thru Monday night. For Tuesday, the WNW-NW
downslope wind directions thru the atm column will scour out any
remaining moisture resulting in finally a Sunny sky for Tuesday
and a Clear Tue night. Temps thru the period will slightly
lower from each previous max and min temp occurrences. The
exception may be for Tue highs when a downslope trajectory may
add several degrees to Tueday`s highs. The CAA will end Tue
morning with various thickness schemes rising indicative of WAA
especially aloft. Overall, followed a consensus amongst the avbl
model Mos Guidance except for Tue highs where several degrees
were added due to ongoing WAA and the downslope trajectory thru
the atm column.
.LONG TERM /TUESDAY THROUGH SATURDAY/...
As of 3 AM Sunday...Period begins warm and dry with surface high off
the east coast and mid level ridge axis overhead. Ridging aloft
shifts off the coast during Wed but subsidence will continue
suppressing upward motion while pushing highs close to 70 degrees.
Cold front moves across the area Thu morning possibly accompanied by
isolated showers, however low level convergence is weak and the
front lacks strong dynamical support. Inherited low chc pop may be a
little generous but will not make any changes at this time.
Regardless of shower coverage any rainfall would be meager if
forecast soundings are correct in showing a brief 6 hour period of
precipitable water values over 1 inch. By Thu afternoon PWATs are
around 0.30 inch.
Following the cold front cooler air will start building into the
region, but its arrival is likely to be later Thu which will result
in one last day with temperatures above climo. 850 temps drop 5-10
degrees C between Thu morning and Fri morning and highs on Fri may
struggle to reach climo (mid 50s). Temperatures will trend even
cooler for the weekend with a reinforcing shot of cold air Sat
keeping highs around 50 with lows hover around freezing. Deep
westerly flow will keep skies mostly clear and prevent any
.AVIATION /10Z SUNDAY THROUGH THURSDAY/...
As of 06Z...With the exit of the 1st round of pcpn, the FA has
become more stable due to the subsidence in the wake of the pcpn
now exiting off the Outer Banks. Sfc SSW-SW winds will remain
active across the FA keeping dense fog development to a minimum
early this morning. As winds back to the SSW and S later this
morning, will have to keep an eye on any sea fog development and
any inland push to it.
The next round of pcpn is already making headway from the Gulf
Coast states as a warm front lifts northward early this morning.
This pcpn should be pushing across the FA from SW to NE, roughly
between 08Z thru 15z. The pcpn will be moving over an airmass
that has been stabilized and thus the thunderstorm activity, if
any, will be held to a minimum.
And finally, the final round of pcpn, with an increased
potential for severe Thunderstorms, will occur between 1/22 at
21Z thru 1/23 at 05Z. This will be associated with the
intensifying upper closed low and its accompanying sfc low, both
finally lifting NE from the Gulf Coast States to the western
Carolinas by 1/23 06Z. The dry punch in the mid-levels will
push across the area during the mid to late evening hours,
ending the pcpn after pushing across. Plenty of atmospheric
dynamics associated with this final round of pcpn along with a
meandering sfc boundary. Enough to warrant placing Gusts up to
45 kt during the convection this evening.
Extended outlook...Expect mainly VFR, except for possible
MVFR/IFR during Mon from clouds and reduced vsby from pcpn.
NEAR TERM /THROUGH TONIGHT/...
As of 400 AM Sunday...SCA all waters thru Tue afternoon.
Looking at S to SSW winds increasing to the 15 to 25 kt range
this aftn and evening. Some guidance indicates winds may
temporarily back to the SSE-SE prior to the pcpn ending. For
now, will hold onto the S-SSW directions. The cooler shelf
waters will help prevent the higher winds just off the deck from
reaching the sfc. The possible convection moving across the
area waters will have the capability to tap those stronger winds
aloft and bring them down to the ocean sfc. This will be
advertised in the Hazardous Weather Outlook.
Significant seas will build to 5 to 8 ft by late this aftn and
persist in the 6 to 9 foot range tonight. Wind driven waves at
4 to 7 second periods will dominate the significant seas. An
underlying 10 second period 1 to 2 foot easterly ground swell
will remain present.
SHORT TERM /Monday THROUGH TUESDAY NIGHT/...
As of 400 AM Sunday...SCA will be ongoing at the start of this
period and will extend thru 6 pm Tuesday.
Cyclonic flow aloft and at the sfc will dominate the local
waters thru Tuesday. This due to a closed low and it`s
accompanying sfc low, now stacked" moving from the Western
Carolinas to off the DELMARVA Coast Tue morning, and to off
Cape Cod by Wed morning. Sfc ridging from Florida will extend
northward across the local waters Tue night. A tightened sfc pg
will be ongoing at the start of this period and will very, very
slowly relax with time. Looking at SCA speeds Mon into Tue, with
SCEC speeds late Tue and Tue night. Directions will run SW
becoming WSW late Monday...and W to WNW during the day on
Tuesday. Decent CAA Mon into early Tue will help keep the winds
elevated. Significant seas thru Monday Night will run 4 to 7
ft, except up to 8 ft south of Cape Fear to Little River Inlet
during day Mon night due to the fetch associated with the
westerly wind direction. Seas will finally subside late Tue aftn
thru Tue night to a 2 to 4 foot range, except remaining
somewhat elevated across the waters south of cape fear to Little
river Inlet due to the fetch associated with westerly wind
LONG TERM /WEDNESDAY THROUGH
THURSDAY/... As of 3 AM Sunday...Southwest flow around western
side of high pressure will gradually increase Wed and Wed night
as gradient increases ahead of a cold front. Front moves across
the waters late Thu morning with offshore flow developing in the
afternoon. Ahead of the front southwest winds will peak around
20 kt Wed night and Thu morning. Winds veer to west-northwest
Thu afternoon with speeds remaining 15 to 20 kt into Fri
morning. Seas 2 to 3 ft at the start of the period will build to
3 to 5 ft later Wed and could exceed 6 ft in some areas late
Wed night. Cannot rule out short duration SCA just prior to the
front passing. Post front offshore flow will knock seas down,
from 3 to 5 ft Thu afternoon to 1 to 3 ft Fri morning.
MARINE...Small Craft Advisory until 6 PM EST Tuesday for AMZ250-252-254-