Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 11/18/23
See below for an aviation forecast discussion for the 00Z TAFs.
&&
.SHORT TERM...(This Evening through Saturday Night)
Issued at 204 PM CST Fri Nov 17 2023
KEY MESSAGES:
- Winds to diminish overnight, but remain elevated across the
eastern slopes of the Sisseton Hills.
- Patchy fog possible over James River Valley Saturday morning.
- Dry and warmer than normal high temperatures through Saturday.
The surface map shows the weak trough across eastern ND and our
northern counties this afternoon, with the area of high pressure
over IA continuing to extend a ridge over the rest of SD.
Fog may develop with visibility falling 1-3SM from 11 to 15Z
Saturday. Most forecast solutions don`t have this potential, so at
this point the probability is low. As a result, kept visibility at
or above 3SM for now at ABR under the clear sky and light winds.
The HRRR is starting to point at the potential, with the NAM
indicating visibility falling below 1SM.
The surface ridge remaining in place Saturday will help keep winds
light at around 10kts or less. The ridge will exit east through the
day, as low pressure organizes to our west. Expect winds to slowly
increase out of the southeast Saturday night. They should still
remain below 15kts.
.LONG TERM...(Sunday through Friday)
Issued at 204 PM CST Fri Nov 17 2023
Key Messages:
- Light rainfall moving in by late in the weekend through Monday.
- Temperatures remaining above normal through Monday before falling
below average the rest of the period.
The main challenges in this period will revolve around precip
chances by late Sunday through Monday followed by the temperature
forecast for the latter half of the term. Starting things off
Sunday, models are in fairly decent agreement showing an upper
level low shifting eastward out into the Nation`s mid-section or
across the Central Plains. Associated sfc low pressure placement
amongst the deterministic and ensembles is well south of our area
and nearly co-located with the upper disturbance. An inverted sfc
trough extending north into our region will be the impetus for
increasing chances for precip by late in the day Sunday and Sunday
night in our southern zones initially before areas of showers
shift northward into more of our forecast area overnight through
Monday. Guidance also progs a cold front will enter our area from
the northwest by late Monday into early Tuesday. This front is
expected to sweep east by daybreak Tuesday shifting rain chances
eastward and out of our area.
Both deterministic and ensemble solutions remain in their varying
camps as to how much rainfall we can expect. The GFS is the drier
solutions for this CWA as a whole while the CMC/EC are arguably a
bit more wet. The EC/GEFS/GEPS ensemble probabilities for seeing at
least a tenth of an inch of rain remain highest basically along and
south of the US Highway 12 corridor. Probabilities of seeing a half
inch or more in the ensembles remain virtually south of most of
this CWA. So, we still anticipate this to be a lighter rainfall
event perhaps upwards of a few tenths of an inch or less.
After the fropa on Tuesday, cooler air does begin to settle in as
temperatures return closer to normal if not slightly below normal.
There still remains a spread(around 10 degrees) between the NBM 25th-
75th percentiles for high temperatures Tuesday and Wednesday,
indicating some uncertainty still as guidance remains up in the air
with respect to the strength of cooling we see through midweek.
Things come together more certain thereafter going into the
Thanksgiving holiday through the end of the period. There`s less of
a spread in those high temperature percentiles Thursday and Friday
indicating a bit higher confidence. We`ll see how things play out,
but it does appear that much colder temperatures will arrive in
time for the holiday as daytime readings fall below normal.
&&
.AVIATION...(For the 00Z TAFS through 00Z Saturday Evening)
Issued at 517 PM CST Fri Nov 17 2023
Terminals KABR,KATY,KPIR,KMBG
VFR ceilings and visibility are forecast for all four terminals,
presently, for the next 24 hours. Fog may develop with visibility
falling 1-3SM from 11 to 15Z Saturday in the Jame River valley (at
or near the KABR terminal). Most forecast solutions don`t have
this potential, so at this point the probability is low. As a
result, kept visibility VFR for now at ABR under the clear sky
and light winds, and will amend later on tonight if it starts to
look as though ground fog is developing.
&&
.ABR WATCHES/WARNINGS/ADVISORIES...
SD...None.
MN...None.
&&
$$
UPDATE...Dorn
SHORT TERM...KF
LONG TERM...Vipond
AVIATION...Dorn
Area Forecast Discussion
National Weather Service Corpus Christi TX
512 PM CST Fri Nov 17 2023
...New AVIATION...
.SHORT TERM...
(Tonight through Saturday night)
Issued at 243 PM CST Fri Nov 17 2023
Key Message:
- Weak cold front tonight
- Coastal Flood Advisory in effect this evening
Water vapor imagery this afternoon reveals the upper ridge in place
across the state being nudged south as a trough digs across the
Southern Plains. At the surface, light and variable winds are in
place under mostly clear skies. Temperatures have warmed up nicely
this afternoon with temps currently in the upper 70s to low 80s. A
weak cold front is currently progressing south across the state. The
boundary will near our northern tier of counties this evening and
offshore before sunrise. Ahead of this front, another round of
patchy to areas of fog are likely to develop. We should clear out
faster than we have the last couple of mornings as winds shift to
the north and increase slightly. Not expecting any precip along
the boundary due to the lack of moisture in place. However, did
include some silent POPs along the coast late Saturday morning
through the afternoon hours. Both the RAP and NAM12 slide a ribbon
of H85 vorticity through the region which may be enough to
trigger some showers as soundings so some moisture hanging around
between H92- H85. Otherwise, temperatures tomorrow will be a few
degrees cooler with highs in the low to mid 70s. Onshore flow
starts to return Saturday night so lows will only dip into upper
50s to low 60s.
Went ahead and issued a Coastal Flood Advisory for this evening`s
high tide cycle. Tide levels are currently running about 1ft above
normal with ~10s swells at buoy 19. Gerling-Hanson plots show 9-10s
swells persisting through this evening so felt confident enough to
issue the advisory.
&&
.LONG TERM...
(Sunday through next Thursday)
Issued at 243 PM CST Fri Nov 17 2023
Key Messages:
- Strong sustained winds of 20-25 mph Tuesday in wake of a cold
front passing through Monday night
- Low to medium (20-40%) chance of showers and thunderstorms
Monday night into early Tuesday morning
A cold front will push through Monday night bringing a low to medium
(20-40%) chance of showers and thunderstorms from the eastern Brush
COuntry to Victoria Crossroads along the front. A low chance of
showers and storms along the coast and over the waters early Tuesday
morning with drier air and conditions filtering in Tuesday
afternoon. Strong winds will follow in wake through the day on
Tuesday with sustained 20 to 25 mph and gusts around 30 mph.
Temperatures cool significantly with highs on Tuesday in the mid to
upper 60s and lows on Tuesday night in the mid to upper 40s.
Deterministic runs between the GFS and the ECMWF/CMC disagree
tremendously Wednesday into Thanksgiving; the GFS develops a strong
and amplified cut-off low over NE Mexico bringing favorable mid to
upper level dynamics and significant rain chances into South Texas
with the ECMWF/CMC containing a less amplified trough, drier
conditions, and no rainfall. Taking a deeper look, no other GFS
ensemble members show this wet scenario and therefore believe the
GFS deterministic to be an extreme outlier at this time. Only
contained very low silent PoPs (<14%) Wednesday night through
Thursday.
Cooler temperatures continue through Thursday with offshore flow
with highs in the low to mid 60s Wednesday and Thursday. The coldest
night looks to be Wednesday night with lows in the low to mid 40s.
&&
.AVIATION...
(00Z TAFS)
Issued at 506 PM CST Fri Nov 17 2023
Mainly leaning toward VFR conditions tonight, but there is
potential for some reduced visby ahead of a weak cold front that
will move through the area. Have backed off a bit on VIS
restrictions with probs only around 20-30% of any substantial vis
restrictions. The front is currently near SAT, and will continue
southward this evening reaching South Texas around or just after
midnight. This will limit the potential for the fog and low CIGS
to develop. Have kept an IFR condition for VCT where probs are
greater, but mainly VFR to MVFR elsewhere. Scattered clouds
around 3-3.5kft are expected tomorrow, but current thinking is
that any MVFR CIGS should be limited. Despite the cold front,
winds out of the north will remain at light levels.
&&
.MARINE...
Issued at 243 PM CST Fri Nov 17 2023
Light and variable winds will continue along the coast this
afternoon and evening. A weak cold front will move offshore
Saturday morning leading to a northerly wind shift. Winds will
begin to shift back to the east-southeast Saturday night into
Sunday morning. A cold front will push through the waters late
Monday night into Tuesday morning, bringing strong northerly winds
in its wake with gusts nearing gale. Small Craft Advisory
conditions are expected late Monday night through Wednesday
morning with a medium chance for gusts to gale. Scattered showers
and thunderstorms Monday night will decrease to isolated coverage
through the day on Tuesday.
&&
.PRELIMINARY POINT TEMPS/POPS...
Corpus Christi 59 75 62 79 / 0 0 0 0
Victoria 58 73 59 76 / 0 10 0 0
Laredo 61 76 61 81 / 0 0 0 0
Alice 57 75 60 80 / 0 0 0 0
Rockport 59 72 63 76 / 0 10 0 0
Cotulla 60 74 60 81 / 0 0 0 0
Kingsville 59 76 61 82 / 0 0 0 0
Navy Corpus 64 73 66 77 / 0 10 10 0
&&
.CRP WATCHES/WARNINGS/ADVISORIES...
TX...Coastal Flood Advisory until 3 AM CST Saturday for TXZ345-442-
443-447.
GM...None.
&&
$$
SHORT TERM...TC
LONG TERM....EMF
AVIATION...PH/83
Area Forecast Discussion...Updated
National Weather Service Lincoln IL
712 PM CST Fri Nov 17 2023
.SYNOPSIS...
Issued at 230 PM CST Fri Nov 17 2023
After a quiet and mild weekend weather-wise, a change in the
weather is expected for next week. A period of rain is expected
for Monday and Tuesday ahead of a cold front that will usher in
much below average temperatures for this time of year. After highs
in the mid to upper 50s on Sunday, expect highs in the mid 30s to
mid 40s for Wednesday through Friday of next week.
&&
.UPDATE...
Issued at 712 PM CST Fri Nov 17 2023
A narrow tongue of stratocumulus extends roughly along the I-57
corridor early this evening, which low level humidity plots from
the RAP suggest should diminish over the next couple hours.
Otherwise, clear skies will prevail through the night across
central Illinois. Temperatures have dropped into the 30s west of
I-55 where the driest dew points are, but more of a drying will
take place over eastern Illinois after midnight. This will allow
most areas to drop into the 20s overnight, perhaps staying just
above 30 south of I-70. Only minor changes needed to the forecast
at this time.
Geelhart
&&
.DISCUSSION...
Issued at 230 PM CST Fri Nov 17 2023
------------ ---------->>> KEY MESSAGES <<<---------- ------------
* Rain is expected Monday and Tuesday across central Illinois with
generally 0.25" to 0.75" of total rainfall expected.
* There is a 20-30% chance of storm total precip over 1.5" near
and southeast of I-55 for Monday and Tuesday.
* Cold temperatures are expected for Tuesday night through Friday
with highs in the mid 30s to mid 40s and lows in the 20s.
------------ -----------<<< DISCUSSION >>>----------- ------------
The area is in northwest flow aloft this afternoon with a cold
front pushing southeast across IN and southern IL. Expect clear
skies tonight with light winds as high pressure settles into the
region. High pressure will dominate through the weekend with
slightly above normal temperatures expected for Saturday along
with light winds. As an upper ridge moves into the area Sunday,
high clouds and warmer temperatures will be expected.
Sunday night, an upper wave from the southwest US will move
northeast into the area, thickening clouds, but most of the precip
will to the southwest still. By Monday morning, precip will move
into IL as a mid level trough rotates northward into the area
around the mid level low centered in KS/OK. The main upper low will
come through the area on Tuesday, bringing about 36 hours worth of
precipitation chances with the best chance south of I-70. The
latest ensemble of model data gives average forecast precipitation
of 0.25" in the northwestern counties (Galesburg) to 0.75" in the
southwestern counties (Lawrenceville) for the 36 hour period of
Monday morning through Tuesday afternoon. However, there is a
20-30% chance of storm total precip over 1.5" near and southeast
of I-55 through this period.
The upper low ejects northeast ahead of a deepening upper low over
western Ontario Tuesday night and Wednesday. The pressure gradient
behind the surface low will be somewhat tight Tuesday and
Wednesday, bringing northwest winds of 15-25 mph with gusts to
30-35 mph. The push of cold air behind the low will bring subzero
temps at 850 mb, which means highs in the upper 30s to mid 40s for
Wed-Fri. This cold air will be in place when the next upper low
moves in from the west-southwest Friday night. Rain or snow will
be possible with next weekend`s event. Currently, models support
rain more than snow, but there does exist a 25-50% chance of
0.1" of snow next Friday night/Saturday. There`s plenty of
uncertainty yet with this system, so stay tuned for updates.
Knutsvig
&&
.AVIATION... (For the 00z TAFs through 00z Saturday Evening)
Issued at 510 PM CST Fri Nov 17 2023
VFR conditions expected the next 24 hours. Mainly clear skies once
a few lingering clouds near KCMI exit over the next hour or two.
North winds diminish this evening and will gradually trend toward
the southwest early Saturday.
Geelhart
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
Area Forecast Discussion
National Weather Service North Platte NE
635 PM CST Fri Nov 17 2023
.KEY MESSAGES...
- Significant rainfall, greater than 1/4 inch, is likely across
north central Nebraska Sunday and Monday.
- Much below average temperatures, 20 degrees or so below
average, appear likely Friday.
- Light snow is possible Friday but forecast confidence is low
at this time because the storm track is uncertain.
&&
.SHORT TERM /TONIGHT THROUGH SATURDAY NIGHT/
Issued at 334 PM CST Fri Nov 17 2023
One more night of strong radiational cooling appears likely tonight
with weak sfc high pressure, light west winds and 850-300mb RH
around 25 percent insuring clear skies. The guidance blend plus bias
correction plus the NBM 10th percentile places lows in the 20s to
around 30. The HREF and NAMnest suggested valley fog in spots and
this is consistent with the radiational cooling predicted
overnight.
The temperature forecast Saturday opens up using the guidance blend
plus the NBM 90th percentile for highs well into the 60s. Full sun
is expected as a check on high cloud potential using the
RAP model indicated RH in the 500-200mb layer less than 20 percent.
And now a different temperature forecast approach is in place for
Saturday night as fairly strong moisture advection will commence
across scntl Nebraska. An increase in high cloudiness is indicated
in the models plus temperatures at h850 will peak around 10C before
a Pacific cold front pushes east into wrn Nebraska. All of this
supports a well mixed atmosphere for lows in the 30s using the short
term model blend plus bias correction.
Rain chances Saturday night have been nudged north and west a bit as
suggested by the SREF, WPC QPF and the very aggressive HRRR which
shows the low level flow backed toward the Sandhills. POPs get a
slight boost to 30-40 percent and the convective mode is showers. K
indices in the models in the 20s and the RAP soundings suggest lapse
rates would not support thunderstorms, yet.&&
&&
.LONG TERM /SATURDAY THROUGH FRIDAY/...
Issued at 334 PM CST Fri Nov 17 2023
The pivotal weather feature, make or break, for rain Sunday
appears to be the eastward progress of a Pacific cold front
forecast to move to near highway 61 by daylight Sunday and then
east to highway 83 during the morning hours. Thus, rain chances
are focused east of highway 83 where very strong 850-700mb
moisture transport is indicated in all models.
The models are now suggesting a period of wrap-around rain and snow
across most of wrn and ncntl Nebraska Monday. The moisture transport
is very modest and rain amounts will be light, less than 1/10 of an
inch in most areas. Its`s worth noting temperatures aloft in the NAM
and GFS, but not the ECM, will be cold enough for snow but near sfc
temperatures above freezing should prevent a changeover or
accumulations of snow in most areas.
Attention turns to the arrival of an arctic cold front Thursday,
followed by much below average temperatures and the prospect of snow
Friday. The deterministic ECM/GFS/ICON suggest the Rockies and
Colo/WY front ranges will be favored for the best snowfall. The
reason for this is the dynamics will take a southward track through
the mountains and then east through KS. Meanwhile, the ECM/GFS
ensemble means clearly favor WY and Nebraska. The reason for this is
uncertain, except to say the ensembles tend to have a northward bias
which would present the better eastward moving dynamics to Nebraska.
Snow chances across wrn and ncntl Nebraska for this forecast are in
the 20 to 40 percent range with the best chance across wrn Nebraska.
Otherwise, the forecast highs in the 20s to around 30 next Friday
are close to the climo for this type of cold air outbreak. The high
pressure will build in mostly from the North Pacific and small parts
of Siberia and the Arctic Ocean; not the coldest recipe. The ECM
even shows a two prong cold air spill with an initial surge Thursday
and Friday followed by a second stronger push later in the weekend.
The GFS and GFS/ECM ensembles shows just one large high pressure
system dropping down.
&&
.AVIATION /00Z TAFS THROUGH 00Z SUNDAY/...
Issued at 1105 AM CST Fri Nov 17 2023
VFR conditions will continue under clear skies across all of
western and north central Nebraska tonight into Saturday. Winds
will be light tonight then become south-southwest at 10 kts
Saturday afternoon.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SHORT TERM...CDC
LONG TERM...CDC
AVIATION...Taylor
Area Forecast Discussion
National Weather Service New York NY
1025 PM EST Fri Nov 17 2023
.SYNOPSIS...
A cold front approaching overnight will pass through during the
morning hours, while strengthening low pressure passes well
offshore. High pressure will then build from the west and
southwest for the weekend. Another cold front will move through
late Sunday, followed by Canadian high pressure moving overhead
on Monday. The high will move east on Tuesday as a frontal
system approaches from the west. Its associated warm front will
approach from the south Tuesday night, then a cold front will
move across on Wednesday. High pressure will follow for
Thanksgiving Day into Friday.
&&
.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
Latest surface analysis places the cold front from northern NY
state southwest into central PA. Much of the showers along and
ahead of the front remain unorganized with a only few those as
far east as the Lower Hudson Valley. Latest CAMs continue to
show mainly scattered coverage as the activity works in from the
west overnight, bypassing much of eastern LI and southeast CT
as jet dynamics lift to the north and west. Additionally, a
band of showers south and east of the area, in association with
weak instability and low-level WAA, is trending toward staying
east of the area. Latest HRRR still showing some cells
developing neat MTP the next few hours, but this seems to be
handled better by the more eastern solution of NAMNest.
Deepening low pressure east of the Mid Atlantic coast will
rapidly deepen and weaken any convergence ahead of the
approaching cold front. The heaviest rains stay well east of the
area. Overall, a very light event rain event.
Low temps will be unseasonably mild (15 degrees or so above
normal), near typical high temps for this this time of year.
&&
.SHORT TERM /6 AM SATURDAY MORNING THROUGH SUNDAY/...
Northern stream shortwave pivots east through the area on
Saturday with a longwave northern stream trough centered
around Hudson Bay polar low sinking into the NE US through
Sunday.
At the surface, weakening cold front passes east of the region
early Saturday morning, with offshore low pressure rapidly
deepening Sat into Sat night as it lifts north into the Canadian
maritimes.
Drying conditions on gusty NW flow Sat morning into afternoon in
wake of the cold front on gusty NW flow of 25-30 mph, with any
lingering post frontal showers coming to an end by midday. CAA
is weak, so temps will remain above seasonable in the mid to
upper 50s.
High pressure gradually builds to the south of the region
Saturday Night into Sunday, with a reinforcing cold front
passage Sun aft/eve and stronger caa on gusty NW flow late Sun
into Sun Night. Canadian high pressure builds in for early next
week.
High temps a few degrees above seasonable on Saturday, and near
seasonable on Sunday.
&&
.LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
At the start of the period, a 1030 mb high sliding SE from
Ontario into New England beneath strong mid level confluence
associated with a departing nrn stream trough moving across ern
Canada will lead to a cool Monday, with highs only in the 40s,
and lows Mon night from the mid 20s inland to the mid 30s in
NYC.
Longer term, siding mostly with the NBM which maintains fairly
good fcst continuity along with model ensemble means and also
the 12Z ECMWF regarding the frontal sys progged to affect the
area Tue-Wed. Model trend has been slower, with precip not
likely to arrive until late day Tue or Tue night. There is still
potential for strong winds gusting to 35-45 mph along the coast
and in the NYC metro area, and heavy rain throughout late Tue
night as a strong southerly LLJ passes overhead.
A cold front sweeping through on Wed will bring cool and brisk
conditions for Thanksgiving Day, with AM lows from the mid 20s
inland to lower 30s in NYC, and highs only in the upper 30s and
lower 40s. Similar low temps expected by sunrise Friday, with
less wind but high temps only a bit milder, lower/mid 40s.
&&
.AVIATION /03Z SATURDAY THROUGH WEDNESDAY/...
A cold front approaching tonight will pass through during the
morning hours, while strengthening low pressure passes well
offshore.
Rain showers develop ahead of the cold front and cigs potentially
lower to MVFR after 06Z. Low stratus may linger after the rain
through Saturday AM, then VFR.
S winds less than 10 kt this evening will gradually veer around
to the SW, and may even become light and variable for time
ahead of the front late tonight. Flow goes NNW behind front on
Saturday, with speeds increasing to around 15 kt G20-25 kt.
...NY Metro(KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...
Timing and duration of MVFR cigs may be off by a couple of
hours.
Isolated gusts to 30 kt possible Saturday afternoon.
OUTLOOK FOR 00Z SUNDAY THROUGH WEDNESDAY...
Saturday Night: VFR. NW G20-25kt early, then diminishing
through the night.
Sunday: VFR. W winds G20kt.
Monday: VFR.
Tuesday: MVFR/IFR or lower in rain, mainly late day and at
night. SE winds G20-30kt.
Wednesday: MVFR or lower in RA, becoming VFR. W winds G25-35kt.
Detailed information, including hourly TAF wind component forecasts,
can be found at: https:/www.weather.gov/zny/n90
&&
.MARINE...
Marginal SCA gusts expected to develop for all waters Sat AM in
wake of cold front and strengthening offshore low Sat AM.
Winds subside below SCA Sat evening, but SE swells from offshore
low pressure will maintain SCA ocean seas through the weekend,
gradually subsiding early next week.
Marginal SCA gusts are also possible on the ocean waters late
Sunday into early Monday in wake of a reinforcing cold front.
Residual 5-6 ft ocean seas likely to continue through the day
Monday as high pressure builds over the waters. Then sub-SCA
conds expected on all waters from Mon night into most of daytime
Tue.
A frontal system approaching Tue night and passing through Wed
AM should bring at least SCA conds to all waters Tue night
into Wed night. SE-S flow could gust to gale force late Tue
night into Wed AM especially on the ocean waters.
&&
.HYDROLOGY...
Heavy rain and minor flooding possible with a frontal system
Tuesday through early Wednesday. There is the potential for 1-2
inches of rain with locally higher amounts possible.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
NJ...None.
MARINE...Small Craft Advisory from 6 AM Saturday to midnight EST
Saturday night for ANZ331-332-335-338-340-345.
Small Craft Advisory from 6 AM Saturday to 7 PM EST Sunday for
ANZ350-353-355.
&&
$$
UPDATE...DW
Area Forecast Discussion
National Weather Service Blacksburg VA
1042 PM EST Fri Nov 17 2023
.SYNOPSIS...
A cold front crosses the area from west to east tonight bringing
showers to the mountains and followed by dry high pressure on
Saturday through Monday. A complex low pressure forming in the
Plains on Monday will track into southeast Canada by Friday.
This system will produce widespread rainfall in the Mid Atlantic
region Monday night through Tuesday night, then will lead in
dry, colder weather for Thanksgiving.
&&
.NEAR TERM /THROUGH SATURDAY/...
As of 1035 PM EST Friday...
Rain showers have been advancing through the area late this
evening and will continue to do so for the next several hours.
Coverage of these showers will continue to diminish, eventually
giving way to just some upslope showers in the far west.
Rain is progressing as expected, so not much change in the
previous forecast. Made some minor adjustments to the hourly
temperatures and dew points, but overall everything is remaining
on track.
As of 1226 PM EST Friday...
Key Messages:
- Cold front tonight brings showers mainly to the mountains
- Breezy and dry Saturday
Overall forecast has not changed as front located from the
easter Great Lakes to the lower Ohio Valley will swing across
our area tonight. Models are rather sparse with rainfall chances
east of the Blue Ridge and thanks to some downsloping, this
seems feasible. Rainfall chances will stay highest this evening
along/west of the WV/VA border where a third of an inch is
possible, dropping to a few hundredths along the Blue Ridge.
Rather brisk behind the front Saturday, but well under advisory
levels with gusts 20 to 30 mph possible especially along the
higher terrain. Sunshine starts the day east of the Blue Ridge
with upslope clouds eroding by early afternoon.
Lows tonight stay elevated with clouds and mixing, with around
50 east to lower 40s west. Saturday will be cooler especially
in the mountains, with mid to upper 40s, to mid 50s New River
Valley and milder in the mid to upper 60s east.
Forecast confidence is above average on cloud cover and winds,
and average on temperatures and rainfall chances.
&&
.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY NIGHT/...
As of 1230 PM EST Friday...
Key Messages:
1: Winds calm into Sunday
2: Seasonable temperatures before an early week front, dry conditions
By Saturday night high pressure will begin dominating the local
weather pattern, and as such the post-frontal pressure gradient will
weaken, leading to a slackening of surface winds. The cooler
continental air and clear skies will allow temperatures to drop to
freezing or the upper 20s Saturday night. Sunday`s conditions will
be dry with calm winds, with temperatures warming well into the 50s
and low 60s under the high pressure. The high continues to slide
east Monday, receding ahead of an approaching trough in the plains.
Monday morning will again be calm with dry conditions and
temperatures around normal for this time of year. A leading piece of
shortwave energy could enter our area by Monday afternoon, beginning
some light rain, but as the trend from run to run has continued to
slow this system, chances of measurable Monday rainfall become lower
and lower.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
As of 100 PM EST Friday...
With a well formed trough moving over the east coast, rain will fall
for most of Tuesday and last into Wednesday. As mentioned in the
short term portion of the discussion, this system has been slowing
run to run, so rain is likely to last into Wednesday afternoon. The
storm total looks to be in the 1 to 2 inch range, which would fall
over approximately 48 hours. Some periods will have heavier rain than
others, though given the extremely dry and even drought conditions
over most of the CWA, this will mostly be a beneficial rain rather
than one to cause flood concerns. Likely doubly beneficial, in fact,
as it seem unlikely given the current situation, that the Matt`s
Creek fire in Bedford County will be corralled and extinguished by
the middle of next week. So this prolonged period of wetting rain
will be helpful in the case that that fire is ongoing.
High pressure and dry weather returns for the end of the week, with
cooler than normal temperatures remaining.
&&
.AVIATION /04Z SATURDAY THROUGH WEDNESDAY/...
As of 645 PM EST Friday...
Mostly VFR conditions ongoing now, but expecting conditions to
deteriorate in the mountains over the next few hours. Sub-VFR is
expected, especially at LWB/BLF and perhaps periods of MVFR at
BCB. Upslope clouds will linger in the west, which may keep
periods of MVFR at LWB/BLF through noon. Otherwise, all other
TAF sites should be VFR after sunrise with improving conditions
areawide.
West to northwest winds pick up after 13z Saturday with gusts 15
to 25kt possible. Winds with lighten by Saturday
afternoon/evening.
Extended Aviation Discussion...
VFR continues into Monday and wind speeds will diminish.
Another system arrives late Monday for the mountains and
Tuesday for the foothills and piedmont. Much higher probability
of rain as well as MVFR or lower ceilings are expected in
Tuesday. Rain and snow showers may linger in the mountains on
Wednesday. Strong, gusty wind is also expected with this system.
&&
.FIRE WEATHER...
As of 1213 PM EST Friday...
Low Humidity and Gusty Wind on Saturday...
Per coordination with the Forestry Service and neighboring
weather offices, a fire weather watch has been issued for the
Virginia piedmont including Roanoke and Shenandoah Valleys for
Saturday.
Low humidity with gusty winds behind a front, combined with
already dry weather look to bring a surge in wildfire spread.
Later shifts will determine if a red flag is needed as we see
how much if any rain falls tonight.
The 16z/11M HRRR Smoke model keeps the smoke from the Matts
Creek fire near the source then northward across Rockbridge
County aligned along I-81 from Natural Bridge to Harrisonburg
into this evening, before inversion settles in and keeps it
closer to the source. As winds shift west overnight the smoke
plume will likely head toward Lynchburg and Buckingham areas.
Air quality alerts have been posted for Bedford, Amherst, and
Rockbridge Counties. Some areas of low visibility will also
occur.
Moisture is increasing today and minimum relative humidity
values will be in the 40 to 60 percent range. Cloud cover will
limit mixing heights and therefore smoke dispersion.
Burn bans or burn restrictions are in effect for many counties.
Consult your local Forest Service or Department of Forestry for
these guidelines.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...Fire Weather Watch from 7 AM EST Saturday through Saturday
afternoon for VAZ022>024-032>035-043>047-058-059.
NC...None.
WV...None.
&&
$$
SYNOPSIS...AMS/WP
NEAR TERM...BMG/WP
SHORT TERM...VFJ
LONG TERM...VFJ
AVIATION...BMG/WP
FIRE WEATHER...AMS/WP
Area Forecast Discussion
National Weather Service San Diego CA
139 PM PST Fri Nov 17 2023
.SYNOPSIS...
An area of low pressure will move inland over California through
Saturday. This will bring cloudier and wetter weather later this
evening into Saturday. Most areas will see light rainfall and even
a rumble of thunder for our northern locations. This system will
push out of the region on Sunday leading to cooler, but sunnier
conditions. Another trough of low pressure will descend into the
Great Basin by early next week, bringing warm and sunny skies with
gusty Santa Ana winds along and west of the mountains by Monday
and Tuesday. High pressure through the middle of the week will be
replaced by a weak troughing pattern, leading to slightly cooler
and dry conditions.
&&
.DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE...
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...
.SHORT TERM (Today through Sunday)...
Mostly clear skies are noticed across much of the forecast area
this afternoon, with fair weather cumulus developing across the
mountains and a patch of fog near La Jolla. Winds are beginning to
turn onshore and temperatures are warming up into the 70s and 80s
west of the mountains. Visible satellite depicts our area of low
pressure pushing northeast toward San Francisco. There is also a
distinct area of clouds and weak thunderstorms along the frontal
boundary extending southward moving toward the SoCal coast. This
feature will continue to weaken through the night and come into
our region tonight, bringing light showers and a small chance of
thunderstorms mainly across Orange County and the Inland Empire.
Prefrontal showers are not out of the question this evening near
the coast as well, per latest HRRR guidance, which has been noted
in previous cut off low events. A secondary boundary is expected
to move through Saturday afternoon and evening, bringing a shift
in stronger west winds and isolated showers. In total, amounts
will be light. Most lower elevations will see near one quarter of
an inch (locally near one inch across the SBD mtn slopes), and
minimal if any rain in the deserts.
Clouds and showers will make an exit by Sunday morning as a
shortwave protrudes into Northern California. Though skies will
begin to clear from north to south, winds will be on the increase
as the tight pressure gradient reaffirms its grip. Gusty west
winds will be evident across the mountains and deserts as the
shortwave passes to the north. Highest winds will be across the
high desert with a ~40% chance of seeing wind gusts over 40 MPH
in the Apple Valley / Victorville vicinity.
&&
.LONG TERM (Monday through End of Next Week)...
High pressure will begin to build off the coast Sunday, amplifying
significantly by Monday. As this system becomes stronger and the
shortwave dives southeast, pressure gradients will turn offshore,
prompting a time for gusty Santa Ana winds from the coastal
foothills westward toward the coastal valleys beginning Sunday
evening. Winds will be oriented most notably from the northeast,
so strongest winds will be felt north of SD County late Sunday
night into Monday morning, where areas near the passes and
foothills will see local gusts near 60 MPH, while lower elevations
can expect gusts 30-45 MPH. Winds will turn more easterly and
weaken as the high pressure moves into the region. Foothill areas
of SD County will see wind gusts near 35-45 MPH through the wind
event.
A weak region of high pressure will take hold for the middle of
the week with slightly cooler temperatures and dry weather.
Ensemble model clusters diverge slightly by Thanksgiving and
beyond. A trough may move in from the north by this time, which
could either lead to more Santa Ana winds or a cooler onshore wind
pattern. Nevertheless, mostly quiet weather should come into the
region by the long holiday weekend.
&&
.AVIATION...
172130Z...Coast/Valleys/Mountains...Low clouds based at 2500-3500
feet MSL will increase this afternoon, lowering to 1500-2500 feet
MSL after 02Z from coast to mountains. Isold -SHRA tonight with more
widespread and frequent -SHRA Saturday. Occasional cigs down to 800
feet MSL and vis reduced to 2-5SM in RA/BR with higher terrain
obscured between about 10-17Z.
Deserts...SCT clouds 3000-5000 feet MSL. Clouds and chances of
-SHRA increase after 05Z and continue Saturday. Bases would be
around 4000-6000 feet MSL.
&&
.MARINE...
A weak storm system will move through Southern California tonight
through Saturday night. There is a slight chance of thunderstorms
late tonight through Saturday morning over northern portions of the
coastal waters nearest to Catalina Island. Northwest winds will
increase mainly over the outer waters Saturday night through Sunday,
with some gusts reaching/exceeding 20 knots.
&&
.SKYWARN...
Skywarn activation is not requested. However weather spotters are
encouraged to report significant weather conditions.
&&
.SGX WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...None.
&&
$$
PUBLIC...APR
AVIATION/MARINE...MM