Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 12/07/22
Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
635 PM EST Tue Dec 6 2022
.AVIATION...
Increasing upper level jet forcing across the central Great Lakes
region has led to a brief episode of elevated frontal forcing from
central Lake Huron southwestward to WI/IL border. As the forcing
passes to the east, a weak cold front will slip southward tonight
between 05-8Z. Onset of cold air advection will lead to increased
low level saturation, drizzle and potentially IFR cig heights. Have
refrained from going more aggressive with IFR for this taf issuance
but will monitor model/obs trends this evening. Lack of strong
gradient flow Wednesday with persistence of higher RH below 875mb
supports MVFR/VFR overcast for much of the day.
For DTW...
DTW THRESHOLD PROBABILITIES...
* High for ceilings at or below 5000 ft
* High for ptype as rain tonight.
&&
.PREV DISCUSSION...
Issued at 348 PM EST Tue Dec 6 2022
DISCUSSION...
Dry but cloudy mid to late afternoon conditions give way to another
round of banded precipitation inbound from the west this evening.
Patches of light rain and or drizzle are possible over the entire SE
Mi area as the surface front settles south of the IN/OH border while
the primary band of rain holds mainly north of I-69. Likely range
POPs remain warranted in that area as a textbook mid level frontal
circulation stays active while traversing central Lower Mi. A survey
of 12Z model analysis and cross section forecast fields indicate
strong fgen forcing associated with a 130+ kt upper jet that is
favorably aligned SW to NE over the mid level frontal zone. The
secondary circulation cycles through intensity variations in a
nearly unstable profile judging by the most recent RAP theta-e cross
sections through the 700-500 mb layer. This points to an even
stronger vertical motion response compared to the morning band with
perhaps a slightly farther north drift on the band location.
Afternoon surface observations also support model soundings that
indicate an all rain event across the area. RAP/HRRR/ARW soundings
all show freezing level holding well above 2500 ft with several
degrees of above freezing cushion on surface temperatures. HREF FRAM
output has just a few speckles of freezing rain possible in the
higher terrain north of Midland/Bay counties which is consistent with
the weak push of cold air in the diffuse large scale surface
pressure pattern. A push of slightly stronger gradient wind is
possible late tonight which carries temperatures down to near
freezing north of Flint but not before the rain band slides eastward
prior to sunrise.
Upper jet forcing shifts eastward and short wave forcing shifts
northward which allows the low level frontal zone to dissipate
during Wednesday. Surface high pressure then gains a foothold in the
Great Lakes by Wednesday night to reinforce a dry weather pattern
but struggles to dissipate clouds into Thursday. Any decrease in low
clouds early Thursday is quickly replaced by thickening high clouds
ahead of the next low pressure system.
Medium range projections in today`s 12Z model cycle maintain
solutions that bring today`s southern California low pressure system
into the Midwest by early Friday. There is reasonable agreement on
the track and strength of the short wave as it is kicked eastward by
next round of Pacific jet energy with the mid level circulation
reaching the south end of Lake Michigan by Friday afternoon. Model
variations are greater with the magnitude and placement of the QPF
axis which also feeds into precipitation type expectations. The
ECMWF is reasonable representation of consensus among the
deterministic solutions considering the short wave is forced to
shear eastward during the day Friday. Surface temperature guidance
is well above freezing during the day while NAM and GFS model
soundings are closer to a snow sounding. For now, a high POP
rain/snow mix with some light accumulation looks like a good start
while keeping a close eye on temperature trends. Strong surface high
pressure over northern Ontario and Quebec is poised to have a colder
influence on the low level thermal profile likely requiring
refinements to the proportions of rain and snow in upcoming
forecasts.
Additional short wave energy follows the Friday system into next
weekend, however the large scale upper jet pattern keeps any
substantially cold air confined to the north. A light rain/snow mix
is once again possible centered around Saturday night while
temperatures hover around normal values near 40 during the day and
near 30 at night.
MARINE...
A frontal boundary over the Central Great Lakes will wash out,
leading to light northerly winds through tomorrow. Strong high
pressure building into northern Ontario in the evening will likely
lead to a modest increase in winds over Lake Huron, but veering
around to the northeast and then east, with gusts up around 20 knots
by Friday morning. Low pressure coming out of the Midwest on Friday
will increase the pressure gradient further and easterly winds
gusting 25 to 30 knots should be no problem, along with rain and
snow overspreading the region during Friday. Sufficient cold air in
the low levels to support possible low end gales across the central
and norther sections of Lake Huron. As the low pressure systems
lifts north Friday evening, winds will diminish from south to north
Friday night into Saturday, Winds then increase for the second half
of the Weekend, as low pressure transfers to the East Coast, but it
appears winds should remain comfortably under 30 knots.
&&
.DTX WATCHES/WARNINGS/ADVISORIES...
MI...None.
Lake Huron...None.
Lake St Clair...None.
Michigan waters of Lake Erie...None.
&&
$$
AVIATION.....CB
DISCUSSION...BT
MARINE.......SF
You can obtain your latest National Weather Service forecasts online
at www.weather.gov/detroit.
Area Forecast Discussion
National Weather Service Quad Cities IA IL
904 PM CST Tue Dec 6 2022
.UPDATE...
Issued at 859 PM CST Tue Dec 6 2022
A problematic forecast is in place tonight, as the potential for
dense fog remains high in any clear area, which was expanding over
the area through 7 PM. However, despite the 00z DVN sounding
showing drying in the layer of the stratus, the patches that were
isolated at sunset, but now cover a growing percentage of the CWA,
and by 9 PM, we now are seeing the majority of the area covered by
stratus. While this is a problem for aviation, the stratus will
help abate any dense fog formation through the night. I`ll leave
the potential in the forecast through, as any hole will quickly
see dense fog formation through mid morning Wednesday.
&&
.SYNOPSIS...
Issued at 230 PM CST Tue Dec 6 2022
As of 2 PM, radar was showing a narrow band of mainly virga and
sprinkles along a line from Fairfield to Rockford. Some light
sprinkles were observed by a NWS employee just before 2 pm. The air
in place is dry with high cloud bases, but the HRRR has been
indicating some slight intensification of the band which may be
enough to squeeze out some more sprinkles or even some brief light
rain. This potential is expected to wane and move east of the CWA by
late afternoon or early this evening. Otherwise, mostly cloudy skies
were common with some clearing working into the western portions of
the CWA. Temperatures were in the upper 30s to mid 40s with dew
points in the upper 20s and 30s.
&&
.SHORT TERM...(This evening through Wednesday)
Issued at 230 PM CST Tue Dec 6 2022
Key message: Patchy fog possible late tonight into mid morning;
possibly resulting in slick roads
Tonight, high pressure will build into the area bringing decreasing
cloud coverage and nearly calm winds. Western areas will see mostly
clear skies while clouds may hold across areas along and east of the
MS River. Some patchy fog is possible after midnight tonight which
may linger through the Wednesday morning commute. Some locally
dense fog is possible, with visibility under a quarter mile. With
temperatures forecast to drop into the 20s to lower 30s, the
increased humidity levels and fog potential may result in slick
spots on roads; especially bridges and overpasses as they freeze up
faster. This will be something to watch this evening and tonight for
the possible need for an advisory headline.
Wednesday, the light and variable or calm winds will continue as the
high pressure remains over the region. Any fog is expected to
dissipate around mid morning, leaving a mix of sun and cloud cover.
Temperatures are forecast to reach the upper 30s and lower 40s north
with mid and upper 40s south. If any fog or low level clouds linger,
it may be cooler.
.LONG TERM...(Wednesday night through Tuesday)
Issued at 230 PM CST Tue Dec 6 2022
A late week storm system with minimal impacts. Temperatures
generally at or slightly above normal with a stronger storm system
around the middle of next week.
Wednesday night through Friday
Assessment...high confidence on a storm system. Medium confidence
regarding timing of precipitation.
The next storm system will move through the Midwest very late
Wednesday night through Friday morning.
Mainly dry conditions will be seen Wednesday night but some
sprinkles may develop in the pre-dawn hours across the far south.
On Thursday rain will overspread the area from south to north during
the day. The dry low level northeast flow could slow the northward
advancement of the rain but the strong push of moisture aloft will
eventually win out. Cooling of the atmosphere during the onset of
the rain may briefly result in a rain/snow mix but any accumulation
will melt on contact.
Thursday night is the main push of precipitation with the storm
system. Rain will be seen during the evening hours with a potential
rain/snow mix in the highway 20 corridor.
After midnight things get interesting. The rain will slowly cool the
atmosphere in the highway 20 corridor allowing the rain/snow mix to
`possibly` change over to all snow. Thermal profiles of the
atmosphere are marginal for this to occur but it cannot be ruled out.
If a change-over to all snow occurs any accumulations would be north
of highway 20 and probably a dusting at best. A possible inch of
accumulation `may` occur along a Fairbank, IA to Balltown, IA line.
A very tight gradient is expected on the southern edge of the snow.
North of a Fairbank, IA to Warren, IL line accumulation amounts will
quickly ramp up over the short distance of 10-20 miles.
On Friday a lingering rain or rain/snow mix will end from west to
east during the morning followed by dry condition in the afternoon.
Friday night through Sunday
Assessment...high confidence
Quiet and dry conditions will be seen across the area as high
pressure moves through the Midwest and into the eastern Great Lakes.
Temperatures are expected to be around or slightly above normal.
Sunday night through Tuesday
Assessment...high confidence on a storm system in the mid-CONUS.
Low to medium confidence on timing and potential impacts.
All global models develop a strong storm system next week. As
expected there are differences (some significant) regarding storm
evolution and timing.
The deterministic ECMWF keeps the area dry through Monday night with
rain moving into the area on Tuesday. The system tracks from
northeast Colorado into the Dakotas before occluding and then moving
east.
The EPS has very light precipitation as soon as late Saturday night
and continuing through Tuesday. The better rain chances are favored
Monday night/Tuesday.
The deterministic GFS has a dry Sunday night with precipitation
developing Monday into Tuesday. The system tracks from western
Kansas into Western Minnesota.
The GEFS develops precipitation Saturday night with it continuing
through Tuesday. However the better precipitation chances favor
Monday into Tuesday.
The deterministic CMC global is dry Sunday night through Monday
night with precipitation developing Tuesday. The system is
slower but tracks through central Iowa and into Wisconsin.
The CMCE develops precipitation Sunday night and continues through
Tuesday. The better rain chances are favored Monday afternoon into
Tuesday.
Given the differences between the models and their respective
ensembles, they do agree on two things: 1) there will be a strong
system system developing and 2) it will generally track west of the
area.
The model consensus has chance pops Sunday night, chance to likely
pops Monday followed by likely pops Monday night and Tuesday.
&&
.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 516 PM CST Tue Dec 6 2022
While conditions at 00z will be mainly VFR, there is some MVFR
stratus in patches over the area, and these could be in place,
especially near CID into the evening. Otherwise, the light wind
flow, and moist low levels will allow for fog potential to grow
through the night, with possible LIFR dense fog at all sites from
09z through 15Z...which may linger a long time into Wednesday
given the light winds. Expect potentially a prolonged poor flying
weather forecast into late Wednesday should the dense fog develop.
ERVIN
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
UPDATE...Ervin
SYNOPSIS...14
SHORT TERM...14
LONG TERM...08
AVIATION...Ervin
Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
957 PM EST Tue Dec 6 2022
.SYNOPSIS...
Periods of rain continues mainly over the mountains and foothills
through Friday. A cold front crosses our area to start the weekend
with drier conditions behind the front and temperatures returning to
near normal for this time of year. A strong cold front may approach
from the west early next week.
&&
.NEAR TERM /THROUGH WEDNESDAY/...
As of 950 pm EST Tuesday: Visibilities continue to bounce around
across the forecast area late this evening, but with the Dense Fog
Advisory area across the foothills/Piedmont still generally well-
placed with observations reporting 1/4 to 1/2-mile visibilities at
times. The mountains remain even more variable, with visibiities
ranging from 3/4 mile to 5+ miles. Will continue to ride on the
existing SPS across the mountain counties until any clearer trends
for overnight fog/visibility develop. The general approach is to
prefer low stratus with patchy dense fog over the high terrain and
areas of dense fog east of the mountains.
Regional radars are starting to show a modest uptick in light
precipitation coverage late this evening in and near the southwest
mountains where improving low-level south to southwest flow is
producing more upglide. Expect coverage to continue to increase from
the west overnight and through Wednesday morning as 500 mb vorticity
lobes bring better DPVA. Will feature the highest PoPs over the
mountains and stretch out improved light rain chances along and
north of I-40 early Wednesday. Lows tonight will be some 15-20
degrees above normal, with most locations seeing an evening low with
hourly temperatures then rising a bit overnight.
Short term guidance continues to predict slow erosion of the wedge
through Wednesday, with NAM and RAP profiles featuring a significant
low-level inversion even as late as early afternoon. Isentropic
ascent should weaken, but CAD erosion is often slower than forecast
so will hedge a bit cloudier and toward cooler temps than guidance.
Assuming erosion does occur at some point, Wednesday`s highs should
reach 10 to 12 degrees above normal.
&&
.SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY NIGHT/...
As of 205 pm Tuesday: Much of the forecast area is expected to
become solidly warm-sectored during mid-week, as a cyclone lifts
from the lee of the Rockies into the upper Miss Valley by Fri
morning. The leading edge of a baroclinic zone will nevertheless
loiter near the periphery of the CWA through the period, warranting
an extended period of mostly chance PoPs in/near those areas. By the
end of the period, the model guidance is in generally good agreement
in sending the boundary back into the area through the back door, as
low level high pressure is reinforced over the northeast Conus in
the wake of a short wave trough. Meanwhile, another section of the
front will approach the region from the TN Valley as aforementioned
cyclone (in a weakening phase by that point) moves into the Ohio
Valley. This warrants an increase of PoPs to the likely range,
mainly across western and northern areas by the end of the day
Friday. Temps will generally be well above normal through the
period, except perhaps across northern areas Friday, where fropa may
occur early enough to yield near-normal maxes.
&&
.LONG TERM /SATURDAY THROUGH TUESDAY/...
As of 215 pm Tuesday: Global model guidance is in generally good
agreement that cold air damming will develop across much of the area
over the weekend in the wake of short term back door cold front.
There`s little signal for an organized precip through at least early
next week...certainly not on a model consensus basis. However,
moisture within a general weak upglide regime associated with the
CAD regime...followed by an eventual return to warm sector
conditions as the CAD weakens, and a major cyclone develops over the
Great Plains, justifies some PoP mention through the period. The
moist CAD regime will generally support max temps near to slightly
above normal, and min temps a category or two above climo through
much of the extended.
&&
.AVIATION /03Z WEDNESDAY THROUGH SUNDAY/...
At KCLT and elsewhere: LIFR to VLIFR conditions should be fairly
persistent at all sites except perhaps KAVL overnight into Wednesday
morning. Periods of dense fog and cigs down near airfield minimums
are quite possible at times given the slowly shallowing cold wedge
in place atop the region. Will also feature slower than guidance
improvement in conditions through Wednesday given the typical
difficulties we have in scouring shallow damming without a decent
downslope flow. A brief window of lower MVFR late tomorrow is
probably the best we can hope for at most TAF sites. Will feature
mainly drizzle and light rain through the period to go with the
periods of fog, with the best chances overnight through Wednesday
morning. Light winds will be calm to variable tonight but see a
steadily increasing S to SW flow through Wednesday with the slow CAD
erosion.
Outlook: Unsettled weather and associated flight restrictions will
continue on and off through Friday. Temperatures will mostly be
above normal, so no wintry precip is expected at any of the
terminals during this time. The trend becomes drier on Saturday, but
uncertainty remains in the weekend forecast.
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...Dense Fog Advisory until 10 AM EST Wednesday for GAZ017-018-
026-028-029.
NC...Dense Fog Advisory until 10 AM EST Wednesday for NCZ035>037-
056-057-068>072-082-502-504-506>510.
SC...Dense Fog Advisory until 10 AM EST Wednesday for SCZ008>014-
019-101>109.
&&
$$
SYNOPSIS...DEO
NEAR TERM...HG
SHORT TERM...JDL
LONG TERM...JDL
AVIATION...HG
Area Forecast Discussion
National Weather Service Gray ME
1053 PM EST Tue Dec 6 2022
.SYNOPSIS...
Rain will continue to spread east tonight with the precipitation
continuing on Wednesday as a weak area of low pressure crosses
New England. Canadian high pressure builds into New England to
end the work week. A mix of rain and snow showers then return
for the weekend, as low pressure develops off the Mid Atlantic
coastline.
&&
.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
1050 PM Update...Waves of rain will traverse the forecast area
from southwest to northeast overnight and PoPs are in good
shape. Overall, forecast hasn`t needed much change, just a few
minor adjustments here and there. Winds will be gusty on the
W/NW slopes of the Whites as the southeasterly LLJ downslopes.
Previously...
6pm Update...Mostly a discussion update as forecast changes were
small. SE flow continues over the ME/NH seacoast. Temps are
holding fairly steady amid this warm/moist flow. Did increase
winds a bit over the western higher terrain as obs sites
occasionally gust over 20 mph and higher peaks likely in a more
breezy layer than the lowlands. MRMS RALA cuts away a lot of the
elevated shower returns in the area, and hones in on a few
patches of rain now moving across southern NH and from the
foothills to coastal ME. A lot of the continuous rain has been
mainly north of the international border. HRRR and NAMnest runs
both agree with these rain shower continuing intermittently
through much of the evening and overnight, with a more
concentrated plume of rain moving through the area come early
Wed AM.
A weak area of low pressure will approach from the west tonight.
This will spread precipitation across the region from west to
east. The ptype will mainly be rain, however some mixed
precipitation is possible across the highest peaks. Eastern
portions of the forecast area will remain relatively dry for
much of the night as the precipitation encounters dry air per
latest observed and forecast atmospheric soundings.
A southeasterly flow and plenty of cloud cover will keep
temperatures relatively mild overnight. Readings will also be
relatively uniform across the region with most areas in the
upper 30s to mid 40s.
&&
.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH WEDNESDAY NIGHT/...
12Z guidance remains in relatively good agreement bringing the
weak surface system and upper level trough through the region on
Wednesday. Rain and patchy fog will continue. Rainfall totals
will reach a half inch to an inch in most areas with a few
locations possibly topping out just over an inch.
Cyclogenesis will occur as the system exits to the east and into
the Gulf of Maine. This will allow winds to switch to the
northwest, bringing drier air into the region as Canadian high
pressure builds into Maine and New Hampshire. The rain will
taper to scattered showers with any chance of precipitation
shifting to northern and eastern areas.
&&
.LONG TERM /THURSDAY THROUGH TUESDAY/...
A drier airmass will be moving into the region as low pressure
continue to slowly scoot off to the east on Thursday and Friday
while broad high pressure becomes centered across Ontario/James
Bay/Quebec. Other than some lingering upslope rain or snow
showers across the mountains on Thursday, this will give us a
couple of mostly dry days with well above normal temps again
Thursday with highs around 50 degrees south of the mountains,
but Friday will see highs back down to around 40 degrees.
As we go from later in the day on Friday and through the weekend,
the high pressure will slide east and strengthen over Quebec or the
Maritimes, forcing the previously mentioned low pressure back
to the south and west. Increasing northeasterly flow with a
tightening gradient between these two features will send higher
moisture back our way, with mostly cloudy conditions and
increasing shower or snow shower chances, especially closer to
the coast. However, Ptype along the coast is expected to be
mostly rain. Wind gusts will also be highest along the immediate
coast from Friday into the weekend, where 25 to 35 mph look
possible, while inland areas could see gusts to around 25 mph.
The forecast has gone more pessimistic on the cloud cover for
Saturday and Sunday, and with more cloud cover expected, have
also gone on the cooler side of guidance.
For next week, the weather looks to remain somewhat unsettled with
the GFS and ECWMF showing a disturbance heading in our general
direction while a ridge builds across the center CONUS. The ECMWF
has the same high pressure holding fairly strong over Quebec
(and even building slightly farther south) which would send the
wave more to our south while the GFS has the high weakening,
which would allow the wave to move across our area and bring
increasing precip chances. With such big discrepancies in the
upper air pattern amongst the global models, don`t see any
reason to deviate from the low-end PoPs from the NBM.
&&
.AVIATION /04Z WEDNESDAY THROUGH SUNDAY/...
Short Term...Mainly IFR and LIFR conditions tonight through
Wednesday in low clouds and rain. Some brief periods of mixed
precipitation possible in the far north. Patchy fog developing
as well during the overnight hours. This precipitation will
taper off Wednesday night as winds shift to the northwest and
drier air enter the region.
Long Term...VFR conditions are expected on Thursday/Friday with
high pressure building in, except a few snow showers and MVFR
ceilings could last into Thurs afternoon at HIE. From Friday
evening into the weekend, increasing moisture and northeast winds
will bring increasing chances for rain or snow showers as well as
MVFR ceilings, especially along the coast.
&&
.MARINE...
Short Term...An area of low pressure slowly tracks towards the
Gulf of Maine Wednesday with winds diminishing to light and
variable...but seas increasing to around SCA thresholds. SCA
seas persist into Wednesday night as low pressure departs east
and winds pull around to the northwest.
Long Term...SCA conditions look to continue through the upcoming
weekend and into early next week with seas remaining elevated. North
to northeast winds will also stay brisk across the waters being
between an area of low pressure to the east and a strong high
pressure to the north. Wind gusts will be around 30 kt from
Thursday night through the weekend but could approach or even
exceed Gale force at times during this period. Winds may
diminish somewhat early next week.
&&
.GYX WATCHES/WARNINGS/ADVISORIES...
ME...None.
NH...None.
MARINE...Small Craft Advisory until 8 PM EST Wednesday for ANZ152-154.
&&
$$
NEAR TERM...Ekster
SHORT TERM...Cannon
LONG TERM...Combs
AREA FORECAST DISCUSSION
National Weather Service Wilmington OH
914 PM EST Tue Dec 6 2022
.SYNOPSIS...
Occasional showers can be expected at times through the work
week as a series of low pressure systems move through the
region.
&&
.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
The 00Z KILN sounding captured a sharp inversion at about 850mb,
with a very stable (and very moist) boundary layer underneath.
Above the inversion, lapse rates are actually somewhat steep. As
some marginal elevated instability has been able to develop,
some embedded thunderstorms have formed within the wider area of
precipitation. With the steep lapse rates and somewhat cool
profile (freezing level at about 10kft, -20C at about 20kft)
some small hail could form in the stronger cores.
Although visibilities have improved slightly where rain has
fallen, parts of the northern / northeastern ILN CWA remained in
a more favorable environment for very thick/low stratus and fog
development. There have been widespread 1/2SM observations, with
a few 1/4SM readings on occasion. With very light surface flow,
HRRR visibility projections suggest at least a risk of patchy
dense fog continuing through the overnight, though it is unclear
if the truly dense fog will become persistent/concentrated
enough for an advisory.
Previous discussion >
A weak boundary remains stalled out southwest to northeast
across our area this afternoon. A wave of low pressure will
ride northeast along it tonight and ahead of the low, a 30 to
40 knot 850 mb jet will shift east across the upper Ohio Valley.
This will lead to an increase in shower activity through this
evening with categorical pops overspreading much of our area.
Will hang on to a mention of thunder across our southeast as
some elevated instabilities work up from the south overnight.
Meanwhile, areas of fog are persisting across our area this
afternoon and vsbys will likely begin to drop off again this
evening into the overnight hours. Temperatures will remain
fairly steady overnight, generally ranging from the mid to upper
40s in the northwest to the mid to upper 50s in the southeast.
&&
.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH WEDNESDAY NIGHT/...
The boundary will shift slightly off to our southeast Wednesday
morning as the surface low lifts off to the northeast. A few
showers may linger early across our far southeast, but otherwise
expect mainly dry conditions. Lingering areas of fog in the
morning should also dissipate, but clouds will hang around
through the day and likely into Wednesday night as a fair amount
of moisture will remain in the lower levels. Temperatures will
only rise a few degrees on Wednesday with afternoon readings
ranging from near 50 degrees in the northwest to the upper 50s
in the far southeast. Lows Wednesday night will be in the upper
30s to mid 40s.
&&
.LONG TERM /THURSDAY THROUGH TUESDAY/...
Active weather pattern with temperatures generally above normal
through the long term forecast period.
Model solutions consistent and therefore forecast confidence is high
for Thursday/Thursday night with a mid level shortwave and
associated surface low tracking through the Ohio Valley. This will
offer an enhanced chance for rain, with the best chance for pcpn
focused across ILN/s southern counties. Main mid level shortwave to
pass through the Great Lakes on Friday leading to a continued chance
for rain.
Mid level ridging to bring dry weather Friday night into Saturday.
Model solution spread and therefore uncertainty increases later
Saturday into Sunday with some solutions offering light QPF with
ILN/s area in a weakly forced area between systems. Have limited
any pops to slight chance mainly east during this time frame.
Mid level flow amplifies with ridge building into the area Monday
ahead of closed low moving into the plains. Have trended drier than
the NBM with main pcpn holding off until Monday night/Tuesday as the
ridge axis shifts east and moisture overspreads the area.
Above normal temperatures forecast for Thursday and Friday.
Temperatures closer to normal this weekend before warming above
normal next week.
&&
.AVIATION /02Z WEDNESDAY THROUGH SUNDAY/...
Significantly reduced aviation conditions are expected through
the next 12-18 hours. The region is covered in widespread LIFR
ceilings, with a few IFR or even MVFR breaks. However, these
breaks should fill in over the next couple hours, leaving
prevailing LIFR ceilings through the overnight hours.
Visibilities range from LIFR to MVFR, but are also expected to
settle into the LIFR/IFR categories overnight. There is
certainly a chance of some dense fog (1/4SM) and this may need
to be included in the TAFs as the timing and location becomes
more certain. In addition to the above, rain is also moving into
the area. This rain is not likely to result in any further
reductions to aviation conditions, which are already quite low,
but there will be a chance of thunder (placed in a TEMPO group)
for Cincinnati.
Conditions are expected to very gradually improve tomorrow, with
IFR ceilings lasting until early to mid afternoon, and IFR
visibilities lasting until late morning. VFR conditions are
expected very late in the TAF period or closer to 00Z.
Winds will be light through the period with no significant
impacts expected.
OUTLOOK...Episodic periods of MVFR/IFR conditions possible
through Saturday.
&&
.ILN WATCHES/WARNINGS/ADVISORIES...
OH...None.
KY...None.
IN...None.
&&
$$
SYNOPSIS...JGL
NEAR TERM...Hatzos/JGL
SHORT TERM...JGL
LONG TERM...AR
AVIATION...Hatzos
Area Forecast Discussion
National Weather Service Louisville KY
805 PM EST Tue Dec 6 2022
.Mesoscale Update...
Issued at 802 PM EST Tue Nov 29 2022
Sfc low pressure is analyzed near Paducah this evening, with the
warm front draped northeastward into central KY. Numerous showers
and a handful of elevated storms have developed west of I-65, where
a 30+ kt low-level jet has contributed to robust low-level moisture
transport. Available instability is weak and largely elevated. The
southern half of central KY will have the best chance at storms
becoming marginally sfc-based tonight, but even BWG soundings show
marginal low-level lapse rates. The 00z BNA sounding shows stronger
instability, including around 500 J/kg SBCAPE with a mid 60s sfc
dewpoint. Instability will likely remain weaker further north in
south-central KY, but will need to keep an eye on any storms in that
area with such strong low-level shear in place. A brief tornado is
still not out of the question.
Otherwise, small hail looks likely from any stronger storms that
develop. Some areas south of the Cumberland Pkwy have already seen
more than 1.50 inches of rainfall, so minor flooding issues could
develop on Wednesday in southern KY. The area of showers ongoing now
may tend to re-orient slightly more WSW to ENE over southern KY
Wednesday morning.
&&
.Short Term...(This evening through Wednesday)
Issued at 330 PM EST Tue Dec 6 2022
Latest water vapor imagery and RAP analysis showed a steady stream
of moisture from Arkansas back to west Texas along a southwest wind
aloft that will continue to advect a good amount of moisture into
the Ohio Valley over the next 24 to 30 hours. Surface obs showed
surface relative humidity values between 80 and 90 percent with some
lingering reduced visibility due to some light fog, drizzle or light
rain in the region. Radar returns during the early afternoon were
mainly confined to the KY parkways and south.
Model forecasts continue to hint at a low level jet max over mainly
Kentucky along and south of the Kentucky Parkway system, and along
with a steady influx of water vapor based on satellite imagery,
areawide rain is a certainty at this point tonight. Precipitable
water amounts are at or above 90th percentile for climatology, also
indicative of a good supportive atmosphere for overcast conditions
and rain. Model soundings in the southwest corner of the forecast
area (west of I-65, South of western KY parkway) show decent lapse
rates with good bulk shear and effective inflow values, which
could be indicative of some severe weather chances this evening.
While probabilities will be low, there could be a chance for a
brief tornado or damaging wind gusts from a strong developing
thunderstorm.
Rain tapers off to the KY parkways and southward for light
precipitation through Wednesday. Through Wednesday, anywhere from
0.25" to 0.50" of rain along and south of the KY Parkways is
possible, which falls roughly between the 25th and 50th NBM
percentiles. 10th percentile probabilities have rain areawide
between roughly 0.05" to 0.30" of rain, where 90th percentile
rain amounts are anywhere from 0.50" to 1.30" (reasonable highest
case scenario).
.Long Term...(Wednesday night through Tuesday)
Issued at 320 PM EST Tue Dec 6 2022
Highlights:
- Wet and mild weather through the end of the week with best rain
chances Thursday into Friday morning
- Rainfall amounts range from 0.50" to 1.00" across central KY with
less than an inch in southern IN through Friday morning
- Slight break from the rain over the weekend
- More rain chances early next week
Our stagnant mild weather pattern will continue through the end of
the week as the upper flow becomes more zonal across the Ohio Valley
with a quasi-stationary sfc boundary remaining draped across
southern KY and northern TN. Embedded upper shortwave trough will
eject out of the Four Corners Thursday into Friday. At the surface,
a weak system will work eastward out of the central Plains into the
Ohio Valley by Friday morning. Ahead of this system a strong LLJ
will work into KY during the day Thursday as the aforementioned sfc
boundary lifts slightly northward into central KY. Rain will
increase over the area from the west-southwest during the day thanks
to the added lift from the sfc boundary and LLJ. Model soundings
show very little in the way of instability but with the lift and
model soundings showing some 0-3km shear, not going to rule out the
possibility thunder Thursday night early Friday morning. Rainfall
totals look to be around 0.50" to 0.75" with some localized areas
approaching 1.00". Temperatures will remain mild with highs in the
mid/upper 50s with the exception of south-central KY towards the TN
border behind the sfc boundary where afternoon temperatures could
climb into the low/mid 60s.
Sfc low and associated cold front will sweep through the Ohio Valley
during the day Friday as slight ridging builds in over the Ohio
Valley behind the departing shortwave trough. Rain chances will
decrease from the west to the east but wrap around moisture behind
the departing system could keep some clouds lingering across north-
central KY and southern IN during the day. Temperatures will warm to
the low/mid 60s on the day which is 10-15 degrees warmer than climo
norms.
Bulk of the weekend continues to look mainly dry but with another
quasi-zonal flow setting up over the Ohio Valley. Another embedded
shortwave looks to work through the region Saturday into Sunday.
This could bring a slight chance of PoPs, mainly across the southern
portion of our CWA through the weekend. For now, going to stay with
the NBM which keeps slight chance PoPs from the parkways southward
through the weekend. Highs will be closer seasonal levels with
highs in the upper 40s/low 50s and lows in the upper 30s/low 40s.
Deterministic models are starting to show the development of an
amplified weather pattern across the CONUS for the middle of next
week. With a deepening trough across the western US and ridging
building across the Plains and Midwest. Both the Euro and GFS
develop the western trough into a closed low over the central plains
and Upper Midwest Tuesday into Wednesday with a sfc low and a strong
associated cold front at the sfc. Concern in this kind of pattern
and setup would be the potential for strong to severe storms
somewhere across the Plains and Midwest by the middle of the week.
&&
.Aviation...(00Z TAF Issuance)
Issued at 650 PM EST Tue Dec 6 2022
Confidence is high on IFR and LIFR ceilings lingering overnight and
into Wednesday morning. Periods of SHRA are forecast tonight into
early Wednesday as low pressure lifts northeast near the Ohio River.
VCTS is certainly possible, though confidence is only medium in
exact timing of TSRA. The bulk of the showers should push south of
the northern terminals (HNB/SDF/LEX) during the early morning hours
of Wednesday, while it will take longer for BWG to dry out.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
IN...None.
KY...None.
&&
$$
Mesoscale...EBW
Short Term...MCK
Long Term...BTN
Aviation...EBW
Area Forecast Discussion
National Weather Service Midland/Odessa TX
523 PM CST Tue Dec 6 2022
...New AVIATION...
.SHORT TERM...
(This afternoon through Wednesday night)
Issued at 150 PM CST Tue Dec 6 2022
Per latest water vapor imagery and RAP 500mb analysis, southwest
flow has commenced over the region, evidenced by increasing clouds
region-wide today. A few transient showers have been observed across
portions of the Trans Pecos and Permian Basin, though most locations
will stay dry, at least until later this afternoon into this
evening. A positively-tilted trough remains entrenched between a
broad trough along the US/Canada border and a broad ridge over the
southeastern CONUS, and as this trough translates eastward, its
attendant jet as well as a series of shortwaves embedded in the
southwesterly flow aloft will yield increasing rain chances across
much of the region through Wednesday night. As ascent increases this
afternoon, precipitation will begin to overspread the area from
southwest to northeast, expanding in coverage overnight through
Wednesday. Despite somewhat limited instability and marginal lapse
rates, thunderstorms will be possible, though are not expected to be
severe. The best chance for thunderstorms will be Wednesday
afternoon into Wednesday evening, and storms could produce localized
enhancements to rainfall received. Overall, however, rainfall
amounts will generally remain on the light side, under 0.50" for the
duration of the event. Rainfall will diminish rather quickly
overnight Wednesday night as the jet progresses northeast of the
region, and the aforementioned trough moves across the Rockies,
sending an attendant Pacific front eastward through the area.
Temperatures, despite the expected rainfall, will remain on the mild
side. As a matter of fact, Midland set a record warm low both Monday
morning and this morning and another record warm low is expected
Wednesday morning. The current forecast low tonight is 58 degrees,
which would easily beat the standing record of 51 degrees, set on
December 7, 1980. Highs Wednesday afternoon will be several degrees
cooler than today, though will remain well above normal, in the
middle 60s to lower 70s for most. Wednesday night, as the Pacific
front sweeps across the area, portions of Southeast New Mexico south
to the Davis Mountains will see temperatures fall into the 40s,
though lows in the 50s to around 60 degrees are expected elsewhere.
&&
.LONG TERM...
(Thursday through Monday)
Issued at 150 PM CST Tue Dec 6 2022
West Texas and Southeast New Mexico remains nestled between a broad
ridge over the Gulf of Mexico and a trough over the Pacific
Northwest. The ridge keeps temperatures into the 60s and 70s for the
end of the week before it flattens out over the weekend and
temperatures fall back towards average. A weak disturbance looks to
skirt just north of the area and will bring the chance for some
showers to the northeast Permian Basin Saturday afternoon.
Indications are that rain amounts stay low, but given drought
conditions, any rain is a welcomed sight.
The beginning of the next week features a longer wave trough moving
out of the Pacific Northwest and rolling across the northern Plains.
For now, it does not appear to be a threat precipitation wise, but
the forecast area could see fairly breezy conditions as the southern
edge of this system moves overhead. With the trough nearby during
the Monday to Wednesday timeframe next week, temperatures will dip
back towards near or below average.
&&
.AVIATION...
(00Z TAFS)
Issued at 515 PM CST Tue Dec 6 2022
Winds are generally light and southerly with a broken cloud deck
around 10k feet. Showers are developing and impacting FST. These
will slowly spread north and east this evening and overnight.
Ceilings should gradually fall as these showers spread. Many
terminals will fall to MVFR early tomorrow morning with lowered
ceilings and reduced visibility in heavier showers.
&&
.PRELIMINARY POINT TEMPS/POPS...
Big Spring 59 71 58 72 / 50 40 50 0
Carlsbad 53 66 47 66 / 30 40 30 0
Dryden 59 71 59 74 / 20 0 0 0
Fort Stockton 57 76 54 71 / 50 10 20 0
Guadalupe Pass 51 59 44 59 / 30 50 30 0
Hobbs 53 64 49 65 / 40 50 50 0
Marfa 46 71 41 68 / 50 10 10 0
Midland Intl Airport 58 72 56 71 / 50 30 40 0
Odessa 58 71 56 70 / 50 30 40 0
Wink 55 70 50 70 / 40 30 40 0
&&
.MAF WATCHES/WARNINGS/ADVISORIES...
TX...None.
NM...None.
&&
$$
SHORT TERM...84
LONG TERM....93
AVIATION...91
Area Forecast Discussion...UPDATED
National Weather Service Memphis TN
600 PM CST Tue Dec 6 2022
...New AVIATION...
.DISCUSSION...
(This evening through next Monday)
Issued at 334 PM CST Tue Dec 6 2022
We`re currently in a bit of a precipitation lull, but widespread
showers, and a few thunderstorms, will affect the Mid-South late
tonight through Thursday. Locally heavy rainfall will be the
primary concern though there is a potential for a few strong
storms. Expect above normal temperatures through the remainder of
the work week.
A classic split-flow pattern continues over the CONUS this
afternoon with a closed shortwave trough moving slowly southeast
along the CA coast. Strong southwest flow aloft downstream of
this trough has tapped into a subtropical air mass, advecting deep
moisture across the Southern Plains and into the Lower MS Valley.
Precipitable water (PWAT) is slightly lower than 24 hours ago in
the wake of yesterday`s trough but we`ll see additional moistening
through tonight as PWATs climb to near 1.75". As stated yesterday,
these PWATs are is in the 99th percentile of climatology for early
December, indicating highly anomalous moisture throughout the
column.
A warm front continues to lift poleward slowly this afternoon and
is located near the northern reaches of the CWA along the MO and
KY state lines. Just north of this front, dense fog resulted in
visibility below 1/2 mile through mid-afternoon but these
conditions have largely improved. Another area of large-scale
ascent can be inferred from the water vapor loop and this will
overspread the area this evening and and overnight. The
aforementioned warm front is expected to stall and eventually
slide back to the south late tonight. Warm advection over the top
of this boundary will enhance frontogenesis from 850 mb up
through 500 mb, enhancing the thermally direct circulation and
providing ascent in the vicinity of the boundary.
CAPE will be somewhat limited, but shear is sufficient to warrant
a marginal risk for severe thunderstorms, mainly north of I-40.
Effective bulk shear near 40 kts is supportive of organized
convection and there is enough curvature in the hodograph to at
least note the possibility of a few supercells. Low-level shear is
supportive of minimal tornado mention. This conditional severe
weather threat is low confidence, but will be watched closely
throughout the evening.
QPF progs continue to indicate widespread rainfall in the 1-2"
range with localized higher amounts through Thursday night. The
greatest totals will occur in areas where banded precipitation is
favored and/or precipitation echoes train but that will depend on
exactly where the front sets up. This front will remain in the
vicinity throughout Thursday and into Thursday night, maintaining
high PoPs, especially along and north of the front with
temperatures remaining well above normal. Areas in the far
southeast portion of the CWA will see much lighter precipitation
through this time frame.
The cold front will swing through the area early Friday as an
occluding trough lifts northeast across the Midwest. A few
thunderstorms will be possible ahead of the front, but nothing
significant is anticipated at this time. Cooler and drier air will
move into the area behind this front with with PWATs briefly
dropping below 0.50" by Friday afternoon. This will result in
temperatures returning to near climatology Saturday with highs
mainly in the 50s and lows in the 40s. This respite from the
rain looks to be short-lived as moisture quickly returns and rain
chances re-enter the forecast for Saturday.
Much of the ensemble uncertainty by late weekend exists in the
evolution of the trough off the West Coast. A majority of the
NAEFS and EPS members favor a weaker trough with more quasi-
zonal flow aloft over the southern tier of the CONUS to begin the
week. However, a few do feature a deeper, slower trough. This
particular system will bear watching as it moves onshore and
approaches the Mid-South toward midweek as it could offer another
potential for significant weather impacts. In the meantime, the
period from late weekend into early next week looks to be
highlighted by continued rain chances with temperatures climbing
back above normal.
MJ
&&
.AVIATION...
(00Z TAFS)
Issued at 539 PM CST Tue Dec 6 2022
00Z surface analysis showed a cold front extending from ARG-SIK-
PAH line. IFR/LIFR prevailed the north of the front, with
VFR/occasional MVFR to the south.
The cold front will drop south through the night, stalling over
the far southern MEM TRACON by 15Z. In the interim, a weak passing
disturbance will support isolated TSRA along the front, perhaps
within the 25SM norheast of MEM. 00Z TAF followed HRRR guidance
frontal timing, showing passage through MEM during the early
outbound push.
With the front stalling between MEM and TUP, expect little flight
category improvement Wednesday, as occasional showers reinforce
the most frontal inversion. In the warm sector, TUP should
prevail at MVFR with VFR potential limited by SHRA.
PWB
&&
.MEG WATCHES/WARNINGS/ADVISORIES...
AR...None.
MO...None.
MS...None.
TN...None.
&&
$$
PUBLIC FORECAST...MJ
AVIATION...PWB
Area Forecast Discussion
National Weather Service Shreveport LA
1002 PM CST Tue Dec 6 2022
...New UPDATE...
.UPDATE...
Issued at 934 PM CST Tue Dec 6 2022
Updates this evening remain minor as only a few adjustments were
made to the present forecast. Decided to adjust overnight lows by
1-2 degrees across NW zones based on present sfc analysis and the
latest 00z guidance. Sfc theta-e in both the NAM and HRRR show a
very slow SE progression of the cold front that is currently located
to the NW of the Idabel,OK obs site as of 9:30 PM CST. Sfc analysis
this evening also showcased some fog developing just south of the
boundary in De Queen. Based on this and the idea that other sites
may see a similar theme under a rather moist environment ahead of
the boundary, brief patchy fog has been added through midnight for
sites north of I-30. Given increased coverage of shower activity
overnight, and into the early morning, the idea of fog past midnight
remains low at this time. The final adjustment was to remove low
end odds of thunder along the I-20 corridor to fit in line with
the SPC general thunderstorm outlook.
Rain coverage will continue to develop across northern zones,
mainly I-20 and north over the next couple of hours, heading into
Wednesday morning. Based on the confidence and placement of this,
POPs have not been adjusted during this update.
/53/
&&
.SHORT TERM...
(This evening through Wednesday Night)
Issued at 239 PM CST Tue Dec 6 2022
A frontal boundary across eastern Oklahoma into Arkansas will be
the main driver of the weather pattern through the short-term
period. The front is forecast to remain in place through Wednesday
before gradually lifting north on Wednesday night. Low-level
instability associated with the front combined with moist west to
southwest flow aloft will maintain mostly cloudy skies through the
period across the entire ArkLaTex. Rain chances will gradually
increase tonight through Wednesday along the frontal boundary as
instability increases in response to an upper-trough kicking out
of the Rockies and moving east into the Great Plains. However,
forcing across the ArkLaTex will be relatively weak, allowing for
mainly widespread showers tonight, mainly in the vicinity of the
front across Arkansas and Oklahoma, with the addition of isolated
thunderstorms on Wednesday into Wednesday night. Otherwise, expect
warm temperatures across the region with highs on Wednesday
approaching 80 degrees across much of east Texas and north
Louisiana with slightly cooler temperatures across the I-30
corridor where rain chances will be higher. Overnight lows both
tonight and Wednesday night will be in the 60s. /05/
&&
.LONG TERM...
(Wednesday Night through Tuesday)
Issued at 239 PM CST Tue Dec 6 2022
The recent long term forecast story, featuring waves of moisture
riding on southwesterly flow on the northwest side of a stubborn
ridge over the Gulf, will change little this week. Said area of
ridging established over the Gulf of Mexico by mid week will remain
firmly in place through the end of the workweek and into the
weekend. Late in the weekend, this long lived pattern will start to
come to an end, as the upper level high breaks down and the ridge
broadens and begins to drift east, making way for the next large
scale feature of note. A pronounced trough will dig south from
Canada, deep into the Rockies before ejecting east over the Great
Plains early next week, characterized by a tight gradient of 500mb
heights on its leading edge, extending from the Great Lakes south
and west into west Texas and northern Mexico. This trough looks to
bring with it a potent cold front, which when introduced to the
warmer, very moist environment across the southeast, may set the
stage for another round of unsettled weather.
It remains far too early to deal in speculation of precise
specifics, but it bears mentioning that the latest SPC severe
weather outlook highlights the ArkLaTex in a slight risk (15%) for
Day 7 (Monday, December 12th). There is still plenty of time for
this forecast to drift in both time and space, but based on previous
performance of Day 7 SWOs highlighting the ArkLaTex this season,
this feature will be closely monitored in the coming days.
Rainfall will progress south and east into the ArkLaTex Thursday,
lingering overnight before clearing the region Friday afternoon. The
next wave will be hot on its heels, with rain chances returning to
our northern and western zones shortly after sunset, overtaking the
region and remaining areawide through Tuesday, not departing
entirely until overnight into Wednesday.
Above average temperatures late this week (mid to upper 70s) will
begin to fall over the weekend (upper 50s to lower 70s) before
rebounding slightly early next week in advance of the frontally-
driven cool down. Lows will drift accordingly, from 50s to 60s late
this week, followed by a round of 40s to 50s, and a return of 30s
mid next week. /26/
&&
.AVIATION...
(00Z TAFS)
Issued at 536 PM CST Tue Dec 6 2022
Mainly OVC skies will prevail across all terminals through the
00z TAF cycle as a warm front continues to advance north of the
airspace. As a boundary sets into place, this will help to generate
-RA, increasing in coverage by 07/11z, with possibly even -SHRA
across extreme northern terminals by 07/15z. The general theme is
for VFR conditions to prevail through the early stages of the
period ahead of MVFR with lowering CIGs. Some brief IFR conditions
may be possible across terminals by mid to late morning. Continue
to expect south to southwest winds to average between 5 to 10
knots through the period, with an occasional gust not out of the
question.
/53/
&&
.PRELIMINARY POINT TEMPS/POPS...
SHV 67 80 65 77 / 30 20 10 10
MLU 66 80 64 79 / 20 20 10 10
DEQ 59 70 60 73 / 70 90 70 60
TXK 64 76 64 76 / 70 70 40 40
ELD 63 76 61 75 / 60 60 30 20
TYR 66 78 66 77 / 40 20 10 30
GGG 67 79 65 77 / 30 20 10 20
LFK 66 81 65 79 / 10 10 0 10
&&
.SHV WATCHES/WARNINGS/ADVISORIES...
AR...None.
LA...None.
OK...None.
TX...None.
&&
$$
SHORT TERM...05
LONG TERM....26
AVIATION...53
Area Forecast Discussion
National Weather Service Las Vegas NV
647 PM PST Tue Dec 6 2022
.SYNOPSIS...Wintry weather moves into our northwestern areas this
evening, sliding east through Lincoln County tomorrow afternoon.
For the rest of the area, seasonal temperatures and dry conditions
persist before a more potent system approaches over the weekend.
&&
.UPDATE...Continuing to track the incoming upper level low
as it pivots into to region tonight. Satellite imagery through the
early evening would have the center of the the low finally moving
ashore along the central California coast. An obvious area of decent
forcing and upward motion was present out ahead of the main system
based on 500mb analysis as strong potential vorticity wrapped itself
around the low. Even away from the low itself there was at least
some forcing evident as clouds increased and cooled over Inyo,
Esmeralda, and central Nye County. While observations are few and
far between in that area and radar returns have been limited, based
on the satellite trends in the past hour and surface temperatures
being below freezing, it likely has just started snowing under these
better organized cloud signatures. Elsewhere, it remains dry under
partly to mostly cloud skies.
The forecast for overnight remains about the same with the only
changes being made to precipitation chances based on the latest hi-
res short term models. The main uncertainty overnight will be how
far south and east precipitation will be able to blossom. Each run
of the HRRR keeps areas like Lincoln County dry through the night
which would match up with the slower progression of the system
moving east. If the system gets any slower, there will be concerns
for cold core showers in eastern Nye and Lincoln County Wednesday
afternoon. Based on the latest forecast and trends, there is no need
to make any changes to the Winter Weather Advisory.
-Nickerson-
&&
.PREVIOUS DISCUSSION...112 PM PST Tue Dec 6 2022
.SHORT TERM...Today and Wednesday.
The low that has been lingering along the West Coast finally swings
through tonight and tomorrow. As it does so, positive differential
vorticity advection and diffluence aloft will produce ascent over
the northern half of the CWA. Precipitation s expected to begin
around 5PM in Esmeralda, northern Inyo, and central Nye Counties.
Ascent and the cold core of the low will produce relatively-steep
lapse rates, possibly enough to yield some low-end CAPE (100 J/kg or
less). With this in mind, can`t rule out convective enhancement of
precipitation, and possibly a few flashes of lightning. Outside of
the Owens Valley, snow levels will be around 5000-5500 feet at
precip onset, but fall to 4000-4500 feet overnight. In the Owens
Valley, snow levels may support a brief window of rain initially,
but precip will be primarily snow. Accumulations in Inyo County
come to an end early tomorrow morning, lingering until lunchtime
in Esmeralda and Nye Counties. Amounts? Well, it`s a little
tricky. Highest totals will be in the higher terrain (above 5000
feet), where 3-5 inches are possible. Places of most concern are
along US- 95 near Goldfield and Highway-266 near Lida Summit.
Confidence in impactful accumulations is less in northern Inyo
County, though if any occur, Highway-168 through Westgard Pass
will likely see them. Below 5000 feet, anything from just rain to
2" of snow is generally expected. The caveat in this forecast
extends from the potential for convection and precipitation
banding, which could produce locally-higher amounts and periods of
low visibility. With all this in mind, opted to issue a Winter
Weather Advisory for Esmeralda and central Nye Counties for
tonight and tomorrow morning.
Farther east in Lincoln County, snow amounts have trended downward
slightly. Current forecast has 2" or less for the US-93 corridor
between Alamo and the White Pine border. South of Alamo, precip will
be mostly rain except on the high terrain. Thus, opted to leave
Lincoln County out of the advisory, but minor impacts will be
possible. Snowfall should begin after midnight, and come to an end
tomorrow afternoon. Light snowfall is also expected in the Spring
and Sheep ranges, as well as the high terrain of northern Mohave
County, but impacts are not anticipated.
For the rest of the area, dry conditions and seasonal temperatures
prevail. Highs are forecast to be in the 50s and low 60s as clouds
hang around.
.LONG TERM...Thursday through Monday.
As the aforementioned system exits our area, a series of weaker
shortwaves move through. These won`t do much other than keep
temperatures slightly below normal and bring periods of cloud cover.
A more robust system takes aim at the region over the weekend.
Southwest breezes begin to increase on Saturday, becoming gusty on
Sunday. The ECMWF EFI is already beginning to highlight Sunday for
the potential of strong winds. The bigger question with this
system is the precip potential for the Mojave Desert, which
hinges on the depth of the trough. Ensemble guidance shows some
variability in timing and depth, so uncertainty remains in this
regard. However, with a modest atmospheric river forecast,
confidence is fairly high in accumulating snow for the southern
Sierra during this time. As the weekend draws closer, details will
become more clear, so stay tuned! &&
.AVIATION...For Harry Reid...Light and mainly diurnally driven
winds through Thursday morning. A more persistent southwest wind at
10-15 kts will develop Thursday afternoon but weaken to a more
diurnal flow in the evening. A few clouds are possible around 8k
feet but otherwise any CIGs should be AOA 15k feet.
For the rest of southern Nevada, northwest Arizona and southeast
California...Isolated areas of SCT-BKN040-060 today otherwise
SCT-BKN AOA 15k feet. Precipitation will move into Inyo, Esmeralda
and Nye during the evening hours with CIGs lower to BKN020-050
with isolated lower CIGs and mountain obscurations. The majority
of precip will fall as snow and limit VSBYs to under a mile at
times. Elsewhere, mainly light diurnally driven winds through
Wednesday morning then southwest winds of 10-20 kts mainly at
locations south of I-15. &&
.SPOTTER INFORMATION STATEMENT...Spotters are encouraged to report
any significant weather or impacts according to standard operating
procedures.
&&
$$
DISCUSSION...Woods
AVIATION...Czyzyk
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