Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 10/14/22
Area Forecast Discussion
National Weather Service Charleston SC
958 PM EDT Thu Oct 13 2022
High pressure will extend across the region through the
weekend. A strong cold front will push offshore Monday with
cold high pressure prevailing for much of next week.
.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
The 00Z sounding from KCHS reveals a dry atmosphere, especially
in the layer between 800 and 350 mb, where much of the RH is
less than 10%. PWat is just 1 inch, or around 70% of normal.
Surface analysis late Thursday is showing a cold front still
upstream from the local counties, mainly delineated by dew
points down in the 50s in its wake. Our region still has dew
points in the 60s, with the accompanied dew point depressions
mainly less than about 3 or 4F. Using a blend of the HRRR and
NAM yields a frontal passage between about 12 AM and 3 AM from
west to east. Other than few to scattered cirrus clouds skies
will be mostly clear, and cold advection will allow for min
temps to get down to mainly the lower and middle 50s. However,
some upper 40s can occur near and west of US-301, while places
at and near the coast will be in the upper 50s.
Prior to the cold front moving through, there will be a little
ground fog. But this will be short lived and there are no
significant visibility concerns.
.SHORT TERM /6 AM FRIDAY MORNING THROUGH SUNDAY/...
Longwave troughing will dominate the Eastern U.S. through the
period yielding mean temperatures a bit cooler than average.
Surface high pressure will extend across much of the Southeast
Friday through the weekend. Clear skies and light/calm winds within
a decoupled boundary layer will produce strong radiational cooling
regimes both Friday and Saturday nights away from warmer bodies of
water. Highs will warm into the mid-upper 70s Friday with upper
70s/lower 80s Saturday. Highs will peak Sunday in the lower-
mid 80s Sunday just ahead of a cold front. Lows Saturday morning
will drop into the mid-upper 40s well inland to the lower 60s at the
beaches and Downtown Charleston with upper 40s/lower 50s well
inland to the mid 60s at the beaches and Downtown Charleston for
Sunday morning. Rain-free weather will prevail.
.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
Quiet weather with below normal temperatures will prevail for much
of the extended period. A strong cold front will push through the
area Monday as the longwave trough over the Eastern CONUS deepens.
Moisture will increase ahead of the front with a ribbon of PWATs
potentially surging to near 1.50" by Monday afternoon. Despite this
increase in moisture, model RH/omega cross sections only show weak
deep-layered UVVs in place with the front, likely associated with
the left exit region of a subtropical jet streak. Slight chance pops
will be maintained based on this and the various model blends. This
is slightly above the 13/13z NBM which keeps pops below 20%. After a
warm start Monday, temperatures will run well below normal for much
of next week with a cP airmass dominating in the wake of the strong
cold front. Some areas inland could see lows dropping into the upper
30s both Tuesday and Wednesday nights.
.AVIATION /02Z FRIDAY THROUGH TUESDAY/...
Extended Aviation Outlook: Prevailing VFR.
Broad cyclonic flow around low pressure off the Delmarva will
give way to a cold front that moves into the waters during the
post midnight hours, then clears the entire marine area before 6
AM. SW and W winds at no more than 10 or 12 kt ahead of the
front will clock around to the NW and NW in its wake. Modest
cold advection behind the front will result in winds climbing to
15 or 20 kt. Seas will be held down by the offshore trajectories,
and generally just 2 or 3 feet.
Friday through Tuesday: There are no major concerns through the
period. A strong cold front will push offshore Monday. There will be
an increase on both winds and seas with the front, but current data
support conditions below Small Craft Advisory thresholds.
Area Forecast Discussion
National Weather Service Des Moines IA
618 PM CDT Thu Oct 13 2022
...Updated for the 00z Aviation Discussion...
.DISCUSSION.../Tonight through Thursday/
Issued at 343 PM CDT Thu Oct 13 2022
-- Very high fire danger into early evening, elevated concern Friday
-- Strong winds lessening into this evening, not as windy Friday
-- Less wind, dry and cool weather this weekend into next week
Details: GOES-East upper level water vapor imagery shows the broad
cyclonic flow from the Manitoba province to over the western Great
Lakes with several embedded shortwaves noted. Clouds have been
rotating over the northeastern third or so of the state with all of
Iowa experiencing strong, gusty winds from the northwest since mid-
morning. The airmass is rather parched with the surrounding 12z
RAOBs showing precipitable water values around or under a quarter
of an inch. Boundary layer mixing up to 2.5 to 3 km has resulted
in entrainment of the dry airmass with very low dewpoints and
relative humidities in the upper teens and 20s this afternoon.
This has yielded very high grassland fire danger over portions of
our area. There was at least one field fire today near Lynnville
in far southeast Jasper County as detected from the GOES-East fire
temperature, which was also seen on radar and confirmed listening
to Poweshiek County dispatch. More recently, an unknown type of
fire was near Bussey. These fire weather conditions will lessen
into this evening as the nocturnal inversion sets up and deeper
mixing ceases along with relative humidity recovery.
Into Friday, a potent shortwave trough in the vicinity of the
western shore of Hudson Bay as of this afternoon will pivot counter-
clockwise around the mean low into our area by later Friday
afternoon. Forecast BUFKIT soundings and model cross sections show a
fair amount of dry air below 800mb. However, as clouds move in
Friday morning into the afternoon and precipitation falls and
evaporates in this dry layer, it will aid to moisten the lower
atmosphere. NAM and GFS soundings would support a few hours at most
of light, spotty showers with the RAP staying on the drier side. The
most likely location based on saturation and omega along with QPF
placement in the models would be over southern Iowa at this point.
While Friday will not be as windy as today, it will still be a
blustery day with wind gusts generally not exceeding 40 mph.
Relative humidity also will not be as low and therefore do not see
anything worse than elevated fire weather concerns at this time.
Through the weekend into next week, the sprawling mid-level closed
low will drift east or southeastward before lifting northeastward
toward the northeastern Canadian provinces late next week. For Iowa,
this will mean cyclonic flow with shortwave ripples percolating
through this flow into early next week before the flow becomes more
northerly as the low`s influence diminishing toward mid to late
week. The forecast will favor dry conditions with only a few
ensemble members hinting at sporadic, light QPF and near to
generally below normal temperatures during this period. The
coolest days will be Monday and Tuesday with highs struggling to
reach 50 degrees as a zone of high pressure moves over the
region. Monday night into Tuesday morning will also likely have a
widespread freeze with temperatures below 30 degrees. However, no
further frost/freeze headlines will occur this fall with the
criteria for these headlines already met earlier this month.
.AVIATION.../For the 00Z TAFS through 00Z Friday evening/
Issued at 618 PM CDT Thu Oct 13 2022
VFR conditions will prevail through the period with gusty
northwest winds from this afternoon diminishing in the next hour
or so after sunset. Winds will increase again on Friday afternoon
at all sites, though lower than today with gusts of 25-35 kts
expected. Patchy sprinkles are possible on Friday as well, though
with little anticipated impact.
Red Flag Warning until 7 PM CDT this evening for IAZ004-015-023-
Area Forecast Discussion
National Weather Service Gray ME
1129 PM EDT Thu Oct 13 2022
A strong cold front will slowly cross through the area tonight
and tomorrow, bringing a period of heavy rainfall and strong
winds through Friday. A few thunderstorms are possible as well
tonight and Friday. The precipitation gradually pulls east
Friday night into Saturday morning. Skies clear up briefly
Saturday before unsettled conditions return next week.
.NEAR TERM /TONIGHT/...
1130 PM Update... Only minor changes to the forecast at this
point through the overnight period to pull in line with
observations. The forecast remains well on track otherwise.
Looking to regional radar and satellite... the atmospheric river
is evident out ahead of a cold front with convection firing east
of a coastal circulation off DELMARVA. This circulation is of
particular interest... with hires guidance hinting that the
mesoscale LLJ associated with this could pack a powerful punch
as it tracks up the coast Friday. I do think convective feedback
is leading so some exaggeration in these solutions, especially
given the statistical suite in general doesn`t support 50+ kt
gusts depicted here, but have nudged the wind forecast up a tad
owing to the presence of the low itself. Closer to home...
rainfall totals so far are generally 0.25-0.75 with small
pockets of higher and lower amounts. Latest HREF data has
highest rainfall rates mainly over the CT River Valley in the
coming hours, although a ribbon of higher rates is tracking up
through eastern Mass/RI ... flung north from the DELMARVA
circulation. I expect these higher rates to fill in over the
forecast area through the morning hours as the cold front pushes
into New England with maximum convergence into the mountains as
moist southeasterly flow increases.
645 PM Update... Have performed the usual round of tweaks to
T/Td to account for observed trends and blend in more raw model
guidance for overnight trends. Also reran through PoP to better
capture radar trends, boosting it up in many places... and
reduced sustained winds a bit per observations.
A strong cold front continues to slowly move east through NY
state and down through the Carolinas this afternoon with pre-
frontal showers developing across much of southern New England
and over NH and western ME. Satellite imagery and surface
observations indicate that an area of low pressure is beginning
to form along this front near Cape Hatteras, and this low is
expected to move northeastward through tonight before moving
overhead of our area by early tomorrow afternoon.
Scattered showers will continue through early this evening
before becoming more of a steady moderate to heavy rainfall
between 8pm-12am from west to east. Latest CAMs and global
guidance continues to indicate that the combination of strong
theta-e advection and PWATS of around +2 standard deviations
will allow for a fairly widespread heavy rainfall event across
the CWA with 1-3" expected for most locations but locally higher
amounts of 3-5" across south facing mountains. Due to this and
in collaboration with neighboring offices, the Flood Watch was
expanded to include southern NH except for Rockingham county
where amounts are expected to be lower. For more on flooding
concerns please see the hydrology section below.
The other forecast concern continues to be for the potential of
strong southeasterly winds late tonight through the first half
of Friday. The HRRR and NamNest indicates the potential for
up to 80kts of wind at 925mb, which translates to surface wind
gusts up to 45-50mph. The strongest winds look to occur just
before the frontal passage as the aforementioned coastal low
moves through. As a result, went ahead and issued a Wind
Advisory for the southern 2 forecast zone tiers that will run
from 3am to 3pm Friday. Some power outages are possible since
most trees still have a lot of leaves on them.
.SHORT TERM /6 AM FRIDAY MORNING THROUGH FRIDAY NIGHT/...
Moderate to heavy rain will continue through at least the first
half of Friday as the front and weak coastal low slowly moves
across the region. Given that soils will be primed by Friday
morning, any additional heavy rainfall will likely cause
flooding issues, especially across the higher terrain. There
could also be flooding in urban areas as fallen leaves clog
storm drains. Later in the afternoon and early evening drier air
aloft will begin to work in from west to east, which will help
to lighten up the rainfall across much of western NH.
Strong southeast winds will continue through Friday morning
with the peak winds likely occuring between roughly 8am to 12pm.
Later on in the day the core of the LLJ will move east of our
area, thus allowing for winds to slowly subside.
Saturday night will feature mainly cloudy skies with rain ending
from west to east, although a few lingering showers may persist
through daybreak on Saturday across eastern locations. Further
to the west, clearing skies will allow lows to fall back into
.LONG TERM /SATURDAY THROUGH THURSDAY/...
Overview: Troffing prevails thru the extended with temps
becoming colder as the trof axis approaches.
Impacts: Another slow moving storm system is possible
midweek...but at this time looks to be more progressive than
tonight/Fri and so QPF lower.
Forecast Details: With very active short term the extended
forecast is mostly a blend of the multi-model consensus.
Cyclonic flow prevails after the passage of the front but the
amplified nature of the pattern means more southerly flow than
westerly or northwesterly. For at least the weekend that should
keep things mostly dry. Gradually as the trof axis/upper low
approaches clouds and chance for showers will increase.
Early in the week it looks like a trailing S/WV trof will pass
thru the flow and bring a more widespread threat of rain. Based
on ensemble and extreme forecast index products there is at
least a subset of members that elongate the moisture transport
and produce another atmospheric river type event. Given that I
felt comfortable with the high PoP that the NBM has in the
midweek time period.
.AVIATION /03Z FRIDAY THROUGH TUESDAY/...
Short Term...A slow moving cold front will cross through the
area tonight through Friday, bringing widespread RA with pockets
of +RA and isolated -TSRA. Low ceilings and reduced visibilities
will lead to IFR/LIFR restrictions tonight through much of
Friday, and some patchy BR is also possible. In addition, LLWS
of WS020/17045 kts is likely across most terminals tonight
through about 16Z Friday. SE winds will gust up to 35-45kts
late tonight through early Friday afternoon, highest across
coastal TAF sites. Conditions will gradually improve from west
to east on Friday night, but FG may develop resulting in
Long Term...Generally VFR conditions expected this weekend
outside of some lingering upslope clouds around HIE that produce
local MVFR conditions. The next chance for widespread flight
category restrictions will be early next week with another slow
moving storm system.
Short Term...A slow moving cold front will cross tonight through
Friday, bringing strong gale to near storm force winds and seas
of 6-11 ft. Winds and seas will gradually begin to diminish late
Friday but SCA level seas will likely linger through Saturday.
Heavy rain is also expected tonight through Friday along with
Long Term...Winds and seas will gradually subside following the
passage of the cold front. Seas may linger above 5 ft outside of
the bays thru the weekend.
Soaking rain event on track for the region over the next 24
hours. Antecedent conditions with below normal soil moisture
support ample in-channel storage and infiltration capacity,
which will delay the runoff response until Friday. The rainfall
tonight will be sufficient to saturate the ground if exceeding 1
to 2 inches. Any convection or training heavy showers
thereafter could trigger flash flooding, particularly along
steep slopes and urban areas. Although widespread flooding is
not expected, locally high rainfall amounts of 3-5" in areas of
steep terrain are likely to produce flooding. Outside of the
mountains between 1-3" of rainfall is expected, with locally
higher amounts possible.
Riverine responses will be high flows and bankfull levels for some
headwaters and small streams/creeks, with isolated risk for minor
flooding. A significant concern will be the clogging of culverts and
other drains by leaf and other debris, which will worsen as winds
strip leaves throughout the event. Clogged drainage can lead to
water running over roads or even washouts, which is unpredictable
and require a lot less runoff to cause damages.
ME...Flood Watch through Saturday morning for MEZ007>009-012>014-
Wind Advisory from 3 AM to 3 PM EDT Friday for MEZ018>028.
NH...Flood Watch through Saturday morning for NHZ002>012-015.
Wind Advisory from 3 AM to 3 PM EDT Friday for NHZ010-013-014.
MARINE...Gale Warning until 2 PM EDT Friday for ANZ150>154.
Area Forecast Discussion
National Weather Service Melbourne FL
834 PM EDT Thu Oct 13 2022
...New UPDATE, MARINE, AVIATION...
Issued at 826 PM EDT Thu Oct 13 2022
Marginally unstable conds linger at the present hour, however
shower cvrg remains sparse ahead of the apchg sfc front. Recent
hourly HRRR runs have continued to back off on potential for any
development of pcpn ahd of the frontal psg tonight and thus short
term PoPs have been reduced from the earlier pkg. Considerable
clouds wl linger into the overnight with eventual wind shift early
Fri leading to a drying trend as anticipated.
Tonight...Drier air associated with an approaching cold front
will continue to work southward tonight and help to lower rain
chances from north to south. Activity will largely wind down after
9 PM, though lingering rain along the Treasure Coast is possible
through the early morning hours on Friday. As winds start to swing
around from the north overnight and sky conditions begin to
clear, temperatures will respond by falling into the low 70s and
Friday-Sunday (previous)...A large mid-upper level trough over
the western Great Lakes will drift slowly east through this
weekend. As this occurs, progressive/zonal flow aloft will veer
slightly from WSW to WNW. This will push the cool front from its
initial position near Lake Okeechobee early Fri morning across
SOFL and into the Straits on Sat. The boundary will become
stationary/diffuse as it gets bridged by onshore NE-E flow
associated with the post-frontal high pressure ridge centered from
southern GA to the Carolinas.
The drier ECM/CMC model runs from the past few days have trended
a little toward the GFS, showing a slightly slower, less "clean"
FROPA. This keeps the threat for showers in play from Osceola and
Brevard Cos southward Fri, along with a slight chance for TS along
the Treasure Coast. Lingering shallow moisture may keep a small
shower threat for the Lake O/Treasure Coast region Sat, before
drier air finally spreads across the southernmost CWA by Sun.
Max temps generally in the L-M80s through the period, except for
M-U80s across the interior south. L-M60s inland, and U60s closer
to the coast.
Issued at 250 PM EDT Thu Oct 13 2022
Tonight...Generally favorable boating conditions outside of isolated
rain and lightning storms, which are mainly expected from Sebastian
Inlet southward. A stronger storm or two may produce wind gusts
in excess of 35 kts over inland lakes and the Intracoastal/Atlantic
waters. A cold front bringing drier air will swing winds around
to the west tonight, becoming NNW overnight. Seas 2-3 ft with
occasional seas around 4 ft offshore and north of the Cape.
Friday-Monday (modified previous)...Surface cold front will
continue moving southward through the local waters south of
Sebastian Inlet by Fri afternoon. Model guidance has trended ever-
so-slightly weaker (closer to 15kt) with post-frontal winds, and
veers flow more quickly to onshore/NE-E. This limits the
magnitude/temporal extent of winds opposing the Gulf Stream, and
thus it looks less likely for seas there to have time to reach
6ft, lessening the confidence that an SCEC will be needed for this
event. Still, conditions will remain choppy with 4-5ft seas over
the offshore waters Fri- Sat, before winds/seas subside
10-15kt/3-4ft Sun and AOB 10kt/2-3ft Mon.
Issued at 826 PM EDT Thu Oct 13 2022
VCSH lingering at coastal terminals through about 03z then becoming
mostly dry overnight. Scattered showers Friday afternoon from MLB
south. VCSH around 18z along the Treasure Coast and 20z at MLB.
Light and variable winds overnight becoming northeasterly Friday.
.PRELIMINARY POINT TEMPS/POPS...
DAB 69 83 69 83 / 30 10 0 10
MCO 70 86 70 86 / 20 20 0 10
MLB 70 84 71 84 / 30 30 10 20
VRB 69 85 71 86 / 30 40 20 20
LEE 68 84 67 85 / 20 10 0 10
SFB 69 85 69 84 / 20 20 0 10
ORL 71 85 71 86 / 20 20 0 10
FPR 68 84 70 84 / 30 40 20 20
Area Forecast Discussion
National Weather Service Morristown TN
1019 PM EDT Thu Oct 13 2022
Issued at 1010 PM EDT Thu Oct 13 2022
No major changes to the immediate forecast. Blended observations
to the hourlies. Clear skies everywhere except scattered to
broken clouds in the far NE corner of TN and SW VA. Expect dry and
clear conditions to continue as surface high pressure builds over
(This evening through Friday)
Issued at 315 PM EDT Thu Oct 13 2022
1. Dry tonight and Friday with temperatures near to below normal.
2. Gusty southwest winds, and relative humidity will promote
elevated fire weather conditions Friday.
RAP upper analysis and GOES-16 imagery depict a deep upper level low
essentially situated from just south of Hudson Bay, extending into
the western Great Lakes. The local area remains on the southern
periphery of this low with WSW upper flow. Much drier air continues
to move into the area this afternoon with increasing surface
pressure. CAA this morning helped to keep low level stratus in
place, but subsidence and drier air moving in has won out, and skies
have began to clear out.
Tonight and Friday, the upper levels remain unchanged with a deep
upper low to the north keeping the local area within westerly flow
aloft. At the surface, generally high pressure will be located
across the southeast. Trended a bit lower than NBM guidance on
overnight lows. With how dry this airmass is, believe that if
winds relax as expected, temperatures should drop off fairly
quickly. As a result, have low temperatures in the upper 30`s to
mid 40`s. Dry weather will prevail through the short term period.
Guidance continues to favor strong mixing on Friday, with mixing
heights rising to near 5-7kft. The result will be low RH, and
gusty southwesterly winds on Friday. Followed the NBM 10th
percentile for dewpoints, which will bring RH values into the
20-30% range. Additionally, momentum transfer could bring wind
gusts between 10-20 kts to the surface tomorrow afternoon.
However, there has been a trend for lower wind gusts for Friday
in the models. The combination of low relative humidity, gusty
southwest winds, and dry conditions (especially with the gusty
winds already drying out what little rain we saw overnight) will
result in elevated fire weather conditions on Friday. Otherwise,
high temperatures should be similar to today with highs in the
60`s to lower 70`s. Locations across the southern valley could see
highs approach the mid 70`s given southwest flow.
(Friday night through next Thursday)
Issued at 315 PM EDT Thu Oct 13 2022
.LONG TERM...(Friday Night through Thursday)...
1. Dry, breezy and unseasonably warm conditions Saturday.
2. Scattered showers and possibly a thunderstorm for Sunday
afternoon and evening. Rainfall amounts will be limited.
3. Well below normal temperatures early/mid next week will bring
first widespread frost and freeze conditions. Highs will be 15
degrees or more below normal for Tuesday and Wednesday.
4. Moderation of temperatures and dry RH values for Thursday.
For Saturday, a short-wave upper trough moves across the northern
Great Lakes with the associated weak frontal boundary stretching
from the mid-Atlantic states into the lower Ohio and Tennessee
valleys. Boundary layer southwesterly jet of 20-25kts within a well
mixed environment. Trended toward slightly drier and stronger
southwesterly winds. Airmass is too dry for shower development
along this frontal boundary.
For Sunday and Sunday night, the frontal boundary stalls across the
Tennessee valley. Models show a short-wave rotating around the upper
low over the northern Great Lakes. This wave is associated with jet
streak of 120kts+ which will strengthening the frontal-genetic
forcing along this boundary. ECMWF showed cyclogenesis over
Latest deterministic run of the GFS shows elevated instability
with CAPES of around 500. Will continue with a chance of
thunderstorms as well for Sunday afternoon and evening.
GEFS and NBM probabilities keep show QPF amounts less than 0.25 inch
with this system which seem reasonable given the limited Gulf
moisture return. Some orographic showers expected across the far
east Tennessee and southwest Virginia mountains through Monday
For Monday through Wednesday, deep upper trough across the Great
Lakes, and Ohio and Tennessee valleys will bring unseasonably cold
temperatures into the southern Appalachians. The 850mb temperatures
drop to -5 to -8 degrees.
The Ensemble Situational Awareness Table and ECMWF Extreme Forecast
Index table show strong signals and anomaly cold air mass.
Temperatures will be some 15 degrees or more below normal.
Widespread freeze and frost conditions are expected across much of
the area, especially for Tuesday night/Wednesday morning.
For late Wednesday and Thursday, upper trough lifts northwest with
widespread warm air advection for the latter half of the week.
Moderation of temperatures are expected along with dry relative
Issued at 723 PM EDT Thu Oct 13 2022
The most notable key item for this TAF package is gusty SW winds.
Winds from this afternoon for the most part at all sites, have
stopped reporting gusts. Winds will continue to come down
overnight and be variable at times. SW winds will then increase
during the day Friday again with gusts between 15-20KT. Skies are
also clearing and will about to clear at TRI soon. Skies will
remain clear for much of Friday with maybe a FEW250 layer.
Otherwise, VFR conditions expected with no VIS or CIG restrictions
.PRELIMINARY POINT TEMPS/POPS...
Chattanooga Airport, TN 45 74 51 81 / 0 0 0 0
Knoxville McGhee Tyson Airport, TN 45 71 51 78 / 0 0 0 0
Oak Ridge, TN 42 71 48 78 / 0 0 0 0
Tri Cities Airport, TN 40 66 43 76 / 0 0 0 0
Area Forecast Discussion
National Weather Service Raleigh NC
915 PM EDT Thu Oct 13 2022
A cold front will pass through central NC tonight. Dry conditions
then return Friday and Saturday as high pressure settles into the
southeast. Another cold front approaches the area late Sunday.
.NEAR TERM /THROUGH TONIGHT/...
As of 915 PM Thursday...
The latest surface analysis shows that the cold front has just
passed Mt Airy and Statesville, and is approaching INT and CLT. Low
level moisture remains abundant ahead of the front, including
surface dewpoints still in the mid to upper 60s over much of central
NC, and this high RH combined with calm to nearly calm air has
contributed to pockets of fog over the forecast area. 00z soundings
at GSO and RNK show sufficiently steep low level lapse rates and low
dewpoint depressions below 700 mb for a lingering threat of showers
just ahead of the front as it progresses eastward through the rest
of the night. These same soundings, as well as RAP forecast
soundings, do show a couple hundred J/kg ahead of the front,
although little to none of this CAPE gets anywhere close to the
mixed phase depth aloft, with dry/stable air above 700 mb, resulting
in a very low risk of thunder. Any rainfall will be brief and fairly
light, given the fairly shallow moist depth. In addition to the
isolated to scattered showers crossing the area over the next
several hours, along with a brief period of overcast clouds, a
groundward surge in stronger WNW winds just aloft will culminate in
a couple hours of gusty winds with fropa, and these winds are
already evident just to our W in the higher terrain. Have held onto
this scenario from the earlier forecast with an upward bump to
gusts, which could reach 20-25 kts. Have made just minor tweaks to
lows, with a terrain-induced delay in noteworthy CAA, and expect
mostly upper 40s NW (with a few mid 40s) ranging to 50-56 along and
east of Hwy 1. -GIH
Earlier discussion from 300 PM: Latest surface analysis this
afternoon shows that the cold front has reached the high terrain of
the NC mountains. Ahead of the front, isolated showers have
developed primarily along and east of US-1 coincident with where dew
points and instability is highest. Given that the main axis of
anomalous PWAT has shifted offshore, available moisture and
instability (~250 J/kg) will be limited during the arrival of the
cold front. As such, still expecting just widely scattered showers
ahead of and during the passage of the front. Considerably drier air
will usher in quickly behind the front (PWAT has already dropped to
< 1 inch across the high terrain), spreading from west to east
through the overnight period. A brief burst of gusty northwesterly
winds is likely immediately behind the front as it pass through our
area. Otherwise, skies will clear overnight, with temperatures
dipping into the mid to upper 40s (NW) to lower 50s (SE).
.SHORT TERM /FRIDAY AND FRIDAY NIGHT/...
As of 300 PM Thursday...
Dry and cooler conditions are expected Friday as high pressure
settles in across the southeast. In absence of strong CAA,
developing southerly flow Friday afternoon will help to moderate
temperatures with highs in the upper 60s across the north to mid 70s
across the far south. Calm winds and clear skies Friday night will
allow temperatures to radiationally cool into the mid 40s area wide.
.LONG TERM /SATURDAY THROUGH THURSDAY/...
As of 250 PM Thursday...
In the upper-levels, a trough will swing across the Midwest on
Saturday, with southwest to zonal flow lingering across central NC.
Another deeper trough will traverse east across the Mid-Mississippi
River Valley Sunday, moving across central NC late Sunday into
Monday. The trough will tap into some moisture across the Deep
South, and increase precipitable water values across the region
ahead of the trough on Sunday. A deep low will then dive south out
of Canada, with a trough digging south from the low across central
NC on Wednesday. NW flow aloft will then set up for Thursday as the
trough ejects NE. At the surface, high pressure will linger across
the Carolinas for the weekend, then a cold front will push southeast
across the region on Monday. Cold high pressure will then dive south
out of Canada Monday into the Mississippi River Valley through mid-
Dry weather and slightly above normal temperatures will develop this
weekend under high pressure. Most areas will continue highs in the
70s, with some areas near the SC border rising to the low 80s.
Conditions will then deteriorate Sunday as an upper trough and cold
front approach the region. Some ensemble members develop rain
starting Sunday afternoon across western central NC, with the
majority of areas observing rain Sunday night into Monday. Colder
and very dry air will filter in behind the cold front as Canadian
high pressure builds in to our west, also keeping our weather dry
through the middle of the week. Dewpoint temps will lower into the
20s and 30s by Tuesday, and with thicknesses lowering to near 1310-
1315m, lows in the 30s are expected across most areas by Wednesday
and Thursday mornings. Frost will likely be an issue by Wednesday
morning, and could affect sensitive plants left outdoors.
.AVIATION /00Z FRIDAY THROUGH TUESDAY/...
As of 800 PM Thursday...
24-hour TAF period: The cold front is starting to make its way into
the far NW Piedmont (including INT) this evening. It will continue
to push SE and clear central NC by around 06z. The environment has
been too dry and stable for much shower activity with the front let
alone storms, so expecting a largely dry frontal passage. The main
impact to aviation will be potential for a burst of gusty
northwesterly surface winds that may occur for a few hours behind
the cold front tonight. Winds will then diminish before shifting to
the SW tomorrow afternoon, remaining light. Broken cloud ceilings
are expected along and for several hours behind the frontal passage,
but they should remain VFR. Skies will clear from west to east
overnight, remaining clear through the day tomorrow.
Looking beyond 00Z Saturday: Another cold front will approach the
area on Sunday which may induce sub-VFR conditions and showers
Sunday night into Monday. Dry and VFR conditions will return on