Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 03/15/24
Area Forecast Discussion...UPDATED
National Weather Service Brownsville TX
1054 PM CDT Thu Mar 14 2024
...New UPDATE...
.UPDATE...
Issued at 1047 PM CDT Thu Mar 14 2024
Been keenly watching the incoming Convectively-Allowing Models
(CAMs) and the NAM-12 that have come in over the past few hours.
All are now advertising some degree of convection to blossom
around or after midnight, generally along the Rio Grande between
southwest Hidalgo and southern Zapata, before quickly scooting
east/northeast across much of the region. Of course, the devil is
in the details and the models differ...from the more explosive
HRRR and WRF-ARW (which imply a reasonable worst-case scenario for
hailstorms) to the weaker HRW-FV3 and incoming NAM-12.
A quick glance at the 01Z NBM QPF matches up (somewhat) with
consensus...and a quick update to the NBM rain chances is somewhat
in the ball park.
The big question? Are we unstable enough west of IH-69C to allow
quick convective development ahead of the weak (and small scale)
short wave that these models are keying on? The answer may be yes,
as point-soundings show less of a cap and plenty of CAPE to make
the case.
Bottom line? Preferred to jump on a mention of isolated to
scattered showers/thunderstorms after midnight through daybreak
(12Z...7 AM) rather than leave a general cloudy sky.
Forecast updates have been sent.
&&
.SHORT TERM...
(Tonight through Friday night)
Issued at 216 PM CDT Thu Mar 14 2024
The short term forecast period for the most part is rain free until
Friday night as a cold front moves through Deep South Texas and the
Rio Grande Valley. This front will bring enough instability and lift
to help showers and thunderstorm develop along the front. Due to the
southeasterly flow, plenty of moisture will move into the region
that will help provide fuel for these developing showers and
thunderstorms. SPC also has Deep South Texas and the Rio Grande
Valley in a general thunderstorm area for the duration of the short
term forecast period. The activity for showers and thunderstorms are
expected to start out towards the west around Zapata and Starr on
Friday and then the rain chances will spread from there during
Friday night.
Moving into the temperatures for the short term forecast period. The
low temperatures for tonight are expected to be mostly in the 70s,
while a few locations along the coast could be in the upper 60s.
Then the high temperatures for tomorrow could be mostly in the low
to mid 90s, while the highs along the coast are expected to be in
the 80s. Finally, the low temperatures for Friday night, are
expected to be in the range of upper 60s to low 70s.
On the beaches, a moderate risk of south to north longshore
currents is expected to continue through tomorrow due to
persistent south-southeast moderate swell. Surf height stays
around the range of 2 to 4 or 5 feet...even as southeast winds
remain generally around 10 to 15 mph by morning and 10 mph in the
afternoon.
&&
.LONG TERM...
(Saturday through next Thursday)
Issued at 216 PM CDT Thu Mar 14 2024
As was mentioned over the past several days, an unsettled synoptic
weather pattern is in store for much of the extended forecast
period across our CWA. A Rex Block pattern situated across most
of the Western US and portions of Western Canada will persist
through next Tue. The net result will be little movement of the
main synoptic features one of which being the mid/upper closed
low pressure area located across the Desert Southwest and Great
Basin. This closed low will maintain an unstable southwest flow
aloft across our CWA through most of the period.
The best chances for strong to possibly severe convection will
occur during the weekend. Moderate instability, a weakening cap,
an approaching cold front, and several shortwaves impacting the
CWA within the southwesterly flow aloft will be some of the main
ingredients in place this weekend. There is some indication from
the HRRR that a potential MCS may pass just to our north on Sat
morning, leaving a potential outflow boundary across our area. The
better chances for convection are expected for Sat night into Sun
as a potent shortwave interacts with the southward-sagging
frontal boundary. Another potential MCS, this time tracking
further south across portions of our CWA, may impact the area from
west to east overnight Sat into Sun. Initially, this convection
will be enhanced by upslope flow into the Sierra Madre. A
Marginal SPC risk lines up well with this potential scenario. The
main threats would be large hail and wind, mainly across the Rio
Grande Plains and Upper Valley. Although conditions are expected
to be not quite as unstable, another round of convection will be
possible Sun night into Mon as additional shortwave energy
interacts with the frontal boundary lying across the CWA.
A lull in the activity may occur by Mon afternoon into Mon night
as low level divergent flow and shortwave ridging aloft prevail.
This will help to drive the surface high pressure area behind the
front further southward across the CWA. The coolest period is
expected to be from Mon night into Tue night as a result. Most of
the guidance indicates that any lull will be short-lived with rain
generally expected to return on Tue. This will be generally due to
additional shortwave energy aiding coastal trough development by
Tue into Wed. As a result, will shift the highest POPs over the
waters and coastal counties with this coastal trough scenario.
Warmer conditions are expected on Thu as the main closed low
finally opens up and begins accelerating eastward across the
Plains. Residual moisture should maintain at least isolated POPs
on Thu.
Rainfall amounts through the period will generally by around 1-1.5
inches. However, the 95th percentile storm total QPF values
indicate that 2-3 inches will be possible, especially if short-
lived training occurs with any potential MCS.
Minor tidal run-up will be possible on Mon-Wed as persistent
moderate to strong E/NE flow prevails across the W Gulf.
&&
.AVIATION...
(00Z TAFS)
Issued at 640 PM CDT Thu Mar 14 2024
Another warm and muggy night (for mid March) across the RGV, which
sets up nicely for a quick return to MVFR, than IFR, ceilings
spreading from Brownsville to Harlingen then ultimately McAllen
as the night progresses. IFR should be the rule between 1-3 AM and
9-10 AM, before a slow, then more rapid, mix-out arrives by early
afternoon. Unlike today, when multi-layer clouds across the lower
Valley terminals hemmed in the MVFR ceilings, drier air arriving
above the mixing height should scour our the
stratus/stratocumulus, latest (once again) at Brownsville.
Continued soupiness of the air and diminishing winds overnight
should return MVFR visibility (3 to 5 statute miles) in haze a
few hours after sunset for Brownsville and Harlingen. As for
winds...effects of 30 knots low level jet (around 2K feet early
this evening) will continue a couple hours of 20+ knot gusts
through 9 PM before gusts should subside...then winds themselves,
dropping below 10 knots between 2 and 3 AM and continuing through
mid morning. Lessening gradient and much weaker low level wind
fields will hold speeds below 15 knots Friday afternoon...though a
few gusts could reach 20 knots given the afternoon clearing.
&&
.MARINE...
Issued at 459 PM CDT Thu Mar 14 2024
Updated through Tonight...
Marine layer of much cooler nearshore waters vs. the sensible air
mass above them has sharply reduced wind speeds at the beach, and
by extrapolation out to 15-20 nautical miles, there as well. Model
blends continue to struggle with wind speeds in the nearshore
waters in such cases, and were more than 20 knots above observed
as of 3-4 pm.
For Laguna Madre, cloud cover and some minor marine layer
influences nipped the winds a bit as well, with speeds in Small
Craft Exercise Caution (15 to 20 knots and gusty) rather than
full-blown advisory conditions (20 knots and gusty) by mid
afternoon.
For each reason...the Small Craft Advisory was cancelled prior to
issuing the forecasts...and gridded winds were dropped
considerably to match the current observations.
Remainder of the discussion remains as is.
Tonight through Friday Night...Favorable conditions return
tonight with pressure gradient slackening steadily. Onshore flow
is expected to be light to moderate with low to moderate seas,
which is expected to persist through Friday night.
Saturday through Thursday...Convective chances will increase
through the weekend across the coastal waters given the many
factors referenced above. The actual cold front will slowly push
through the waters by Sunday night into Monday. Small craft
advisory conditions will then persist behind the front through
Tuesday night. Rain chances will persist Monday through Thursday
as shortwave energy interacts with an adequate moisture profile
and coastal troughing. The rain chances may be ending by late
Thursday as the main low finally begins to move past the area.
&&
.PRELIMINARY POINT TEMPS/POPS...
BROWNSVILLE 72 86 71 84 / 20 10 10 10
HARLINGEN 70 90 69 87 / 20 10 10 10
MCALLEN 73 92 72 89 / 20 10 20 20
RIO GRANDE CITY 71 94 71 87 / 30 20 30 30
SOUTH PADRE ISLAND 69 76 69 75 / 20 10 10 10
BAYVIEW/PORT ISABEL 69 83 68 81 / 20 10 10 10
&&
.BRO WATCHES/WARNINGS/ADVISORIES...
TX...None.
GM...None.
&&
$$
SHORT TERM Update...52-Goldsmith
Area Forecast Discussion
National Weather Service Charleston SC
853 PM EDT Thu Mar 14 2024
.SYNOPSIS...
High pressure will prevail through tonight. Upper disturbances
will move through Friday night and Sunday night, then high
pressure will rebuild next week.
&&
.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
No major changes were made for the late evening update. Still a
bit of uncertainity with respect to fog development overnight.
Near term guidance has backed off a bit on both its coverage
and density along the Georgia and far southern South Caorlina
coast. No changes were made as a result.
Visible satellite imagery show quite a bit of elevated smoke
impacting much of southern South Carolina with hazy conditions
early this evening. So far, air quality values have stayed
above Air Quality Alert Levels across the Lowcountry. RAP
vertically integrated smoke products show the smoke/haze
clearing by midnight. Haze was included in the forecast this
evening given current trends. Otherwise, a dry and somewhat warm
night is in store. Some guidance is hitting the fog, possibly
sea fog, along the Georgia and far southern South Carolina
coasts, but most of these models have already initialized poorly
over the coastal waters based on satellite and webcam
observations. Given marginal 1000 hPa condensation pressure
deficits progged, most of the fog should remain patchy with
maybe a little more concentration along parts of the Georgia
coast where dewpoints will be higher. "Patchy" to "areas of fog"
were maintained, but the overall area was reduced somewhat.
Lows from the lower-mid 50s inland to the upper 50s/near 60 at
the coast and Downtown Charleston look on track.
&&
.SHORT TERM /6 AM FRIDAY MORNING THROUGH SUNDAY/...
Another unseasonably warm day expected Friday as southerly flow
persists on the western periphery of Atlantic high pressure.
Upper shortwaves will move in from the west late in the day,
then move offshore by daybreak Saturday. A weak cold front will
sag through the area during this time. Scattered showers
and isolated thunderstorms expected, with the greatest QPF
across southeast GA. Things should dry out Saturday morning due
to NVA and downslope flow. Highs will remain fairly warm due to
adiabatic warming, with highs in the lower 80s. Another round of
shortwave energy will move in Sunday afternoon, likely bringing
scattered to numerous showers and tstms.
&&
.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
Scattered showers and tstms will move through Sunday night,
followed by dry high pressure. A reinforcing cold front will
bring a brief period of cooler temperatures on Tuesday, then
temps quickly warm back up by mid week as the surface high
shifts offshore.
&&
.AVIATION /01Z FRIDAY THROUGH TUESDAY/...
15/00z TAF Discussion:
KCHS/KJZI/KSAV: VFR will prevail for much of the period at all
three terminals. Guidance looks a bit aggressive bringing
widespread fog into the KSAV terminal later this evening from
off the Atlantic. Guidance has initialized poorly in this area
overall. For now, shallow ground fog with vsbys around 6SM were
maintained until confidence increases in anything lower. A
weakening area of showers/tstms could approach KSAV mid
afternoon. 18z data are showing varying arrival times at the
terminal. VCSH was introduced at 20z to trend.
Extended Aviation Outlook: Brief flight restrictions possible
Friday night and again Sunday night as scattered showers and
tstms move through the area.
&&
.MARINE...
Tonight: High pressure across the western Atlantic will remain the
dominant weather feature across local waters, favoring another night
of light winds. In general, south/southeast winds will be no higher
than 5-10 kt. Seas will range between 1-2 ft. The main issue will
come late, as light southerly winds become more parallel to the
coast and slowly advect sfc dewpts ranging in the upper 50s/around
60 across slightly cooler Georgia waters. Some guidance insists that
sea fog develops a few hours prior to daybreak across Georgia
waters. At this time, patchy fog remains in the coastal waters
forecast for Georgia waters, and slowly expands north across
southern South Carolina waters into daybreak.
Warm southerly flow will persist on Friday, with lower 60s
dewpoints moving over the nearshore waters. Sea fog development
remains possible so we maintained patchy fog over the waters on
Friday. Winds will turn SW and eventually W over the weekend as
several weak fronts moves through. A more pronounced wind surge
is anticipated Monday night behind a reinforcing cold front.
Small Craft Advisory gusts are possible over most of the marine
area, though conditions should improve on Tuesday.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...None.
SC...None.
MARINE...None.
&&
$$
Area Forecast Discussion
National Weather Service Louisville KY
955 PM EDT Thu Mar 14 2024
.KEY MESSAGES...
* Slight to marginal risk for severe storms again overnight. Timing
looks to be between 03z to 10z as a west to east oriented line of
strong to severe storms works from the northwest to the southeast
across southern IN through central KY.
* Potential impacts include damaging wind gusts, large hail, and an
isolated spin-up tornado.
* Unseasonably cool Monday through Wednesday, with subfreezing
temperatures possible each morning.
&&
.UPDATE...
Issued at 955 PM EDT Thu Mar 14 2024
Sfc analysis this evening reveals the sfc cold front boundary
stretching from northern Texas to Lake Erie, with plenty of deep
moisture convergence ahead of it. This broken QLCS is responsible
for warnings from Texas to Pennsylvania. Ahead of that line, the
warm sector is characterized by sfc dewpoints near 60F, and sfc
temperatures near 70F. SPC RAP Mesoanalysis depicts roughly 2000
J/kg of MLCAPE in far western KY, and tapering off to 500 J/kg over
the Bluegrass. With a gradual eastward progression of the frontal
boundary and associated convection, expect this line to approach our
NW forecast areas within the next 1-2 hours. We are beginning to see
some isolated WAA radar echoes popping up ahead of the line within
the unstable warm sector, which was suggested by earlier runs of the
HRRR. This could help eat away at that low level inversion, setting
up a better sfc-based environment across central KY and southern IN.
With the loss of daytime heating though, do expect to see MLCAPE
slowly weaken through the rest of tonight. Model soundings, and SPC
Mesoanalysis, are picking up on a shallow cap near the sfc, with
SBCIN values around -150 J/kg. However, this line appears to
continue to move through a highly favorable environment, with strong
DCAPE values over 1000 J/kg across central Kentucky. Shear values
remain strong as well, with approximately 50 kts of effective bulk
shear across our northern CWA. It`s also worth noting that
convection is not as discrete as in the prior hours, most notable
with the cluster that is moving into southwest Indiana. Expect
damaging wind gusts to be our primary threat going forward, but with
WoFs suggesting we`ll see an increase in low level shear as the line
approaches, can`t rule out brief spin-up tornadoes within the line
either. With convection becoming more linear, not expecting large
hail to be a primary threat at this time. Convection should be out
of our CWA by 07-08z tonight.
&&
.SHORT TERM /THROUGH FRIDAY/...
Issued at 350 PM EDT Thu Mar 14 2024
Another round of potentially strong to severe storms are possible
overnight into early tomorrow morning. Current satellite and radar
imagery show quiet conditions over central KY and southern IN and
that should remain through the rest of the afternoon into the early
evening. While not ruling out an isolated storm, ACARs as well as
model sounding show a capping inversion in place over most of the
area which looks to hold until the arrival of the next wave of
showers and storms.
Quasi-stationary boundary extends from along the IN/MI border
through northern IL and back over northern MO into central OK. A
weak sfc low was centered over northeast IL just south of Chicago.
This will slowly work east along the mid-level jet and drag the
boundary towards the Ohio Valley as a cold front. Convective
clusters will begin to develop just ahead of the approaching
boundary across central IN and along the boundary into southern IL
towards southern and southeastern MO. This activity will continue
work into southern IN from the north and central KY from the west-
northwest. By the time it reaches our CWA, the activity should be in
the form of a broken QLCS oriented more west to east. Timing for
this activity appears to be from around 03-04z into southern IN and
northern KY, central KY between 05-06z and then across southern and
southeastern KY between 07-08z.
Instability will be weaker than earlier today due to the loss of
diurnal heating but 500-1000 J/kg CAPE will be enough to get
scattered strong to severe storms embedded in the line. Main threat
with this round will be damaging winds and large hail but there
should be enough deep-layer shear to support a brief spin-up
tornado. The SPC continues to have the northern and western part of
our CWA in a Slight Risk for severe storms.
The bulk of the storm activity should start to exit our area between
10-12z. Sfc cold front will be oriented along the Ohio River around
12z tomorrow and slowly work across Common Wealth from north to
south during the day. Colder air will filter in behind the front
with a few lingering showers, embedded rumbles of thunder and
pockets of drizzle. Temperatures will start off mild near 60 but as
the front moves across the state, temperatures will fall from the
north to the south. With temperatures in the mid/upper 50s north of
the parkways with 60s for most of the day to the south and into the
Lake Cumberland region.
&&
.LONG TERM /FRIDAY NIGHT THROUGH THURSDAY/...
Issued at 350 PM EDT Thu Mar 14 2024
Through the weekend and into much of next week, the upper levels
will feature a Rex Block pattern over the western CONUS, which will
result in persistent troughing across the eastern CONUS. Within the
large scale eastern CONUS troughing, we`ll see a couple of embedded
shortwave troughs and surface cold fronts slice into the Ohio and
Tennessee Valleys. The most prominent one will arrive late Sunday
into Monday, bringing much colder conditions into the region and
perhaps some light rain/sprinkles in our northern/eastern zones.
Highs Monday afternoon will struggle to get into the mid/upper 40s,
and lows Tuesday morning will fall into the mid/upper 20s.
The Rex Block looks to break down by midweek and we should see a
gradual warming trend as upper flow shifts to quasi-zonal. A cut-off
low over the Desert Southwest may approach the region by
Thursday/Friday as an embedded shortwave trough and could bring
showers to the area.
&&
.AVIATION /00Z TAFS THROUGH 06Z SATURDAY/...
Issued at 730 PM EDT Thu Mar 14 2024
VFR conditions are observed at all terminals this evening, but the
main focus for the period continues to be the increasing potential
for strong to severe storms to sweep through the region. Timing for
these impactful storms will be between 03-08z tonight. For SDF, the
expected window for TS is from 03-06z.
After the line of TS pushes through, light rain and/or drizzle will
linger well into the morning hours. Ceilings will also lower to MVFR
and eventually IFR. Expect these restricted flight cats to prevail
through the end of the period, except for SDF, which for their 30-
hour period we could see ceilings begin to improve by 16/00z.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
KY...None.
IN...None.
&&
$$
UPDATE...CJP
SHORT TERM...BTN
LONG TERM...DM
AVIATION...CJP
Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
632 PM CDT Thu Mar 14 2024
.KEY MESSAGES...
-Thunderstorms are expected through this evening (60 to 80 percent
chance) across much of the area. There is a threat that some of these
thunderstorms will become strong to severe with hazards of very
large hail, damaging winds, and a tornado or two possible.
-Expect near or slightly above normal temperatures Friday and
Saturday, then a cool down on Sunday and Monday after a dry cold
front moves through Saturday night.
&&
.SHORT TERM... (Through Late Friday Night)
Issued at 302 PM CDT Thu Mar 14 2024
The atmosphere ahead of the cold front has destabilized once
again with activity beginning to develop in the warm sector as of
19z. The latest surface analysis shows the outflow boundary
beginning to retreat back to the north, and currently extends from
surface low near MCI southeastward to near Jefferson City, then
eastward to the southern sections of the St. Louis metro area.
Latest RAP analysis is showing MLCAPEs near 2000 J/kg with no cap
left underneath a right entrance region of an upper level jet
streak. This instability combined with deep 0 to 6km bulk shear of
50-60kts, as well as 0-3km SRH around 200 to 250, indicates that
storm development will initially start off as supercellular.
Currently thunderstorms that are developing in southwestern MO
will race off to the northeast into central/east central/southeast
Missouri this afternoon. As some of the storms approach the
outflow boundary, winds are backed to the southeast on the north
side of it, thus this will increase the "spin" in the lowest
levels of the atmosphere and increase the likelihood of
tornadogenesis with any supercell that crosses it. Along with the
tornado threat, very large hail, baseball size or larger, and
damaging winds will also be likely with any severe thunderstorm.
By late this afternoon and evening, the shear vector will become
aligned with the boundary, thus will likely see a quick transition
to a mixed mode. The latest HRRR run continues to show the storms
will become more numerous along the I-70 corridor in IL and I-44
corridor in MO by 00z Friday and slide south, exiting the region
between 03z and 06z Friday.
Dry and near normal temperatures are expected on Friday as a surface
ridge builds into the region. Despite decreasing clouds, the colder
northerly winds will keep temperatures in the mid 50s to low 60s for
highs.
Even though the surface ridge will weaken Friday night with surface
flow backing to the west to southwest once again, lows will still
drop off into the upper 30s to low 40s, but still a bit above normal
for this time of year.
Byrd
&&
.LONG TERM... (Saturday through Next Thursday)
Issued at 302 PM CDT Thu Mar 14 2024
A strong area of low pressure will drop southeastward out of
western Canada into the Great Lakes region by this weekend. It
will drag a cold front into the area by Saturday night. This
boundary should pass through dry, with very weak low-level
convergence along it and the better mid/upper level forcing for
ascent residing across the Great Lakes. In the meantime,
temperatures will warm up on Saturday with highs in the 60s.
As decent CAA moves in Saturday night, temperatures will be below
normal for the last half of the weekend and into early next week.
Highs on Sunday will be in the upper 40s to upper 50s, while highs
on Monday will be in the 40s. Expect below freezing temperatures
area wide Sunday night and Monday night with lows in the 20s.
Temperatures will warm back above normal by the middle next week
with the next chance of rain holding off until Wednesday night and
Thursday.
Byrd
&&
.AVIATION... (For the 00z TAFs through 00z Friday Evening)
Issued at 631 PM CDT Thu Mar 14 2024
Cold front has moved south of KUIN and has just moved through
KCOU as of 23z Thursday. The front will move through KJEF by 00z
Friday, while it will move through St. Louis metro area between
03z-04z Friday. As the front moves through winds will veer to the
north. Otherwise, lingering showers and storms through 04z Friday
for TAF sites along I-70. Then MVFR ceilings which have moved into
KUIN, will continue to sink south into remainder of TAF sites by
03z-04z Friday.
As surface ridge builds in, ceilings will lift and scatter out
from north to south during the day on Friday, by 11z at KUIN and
by 16z-17z Friday at remainder of TAF sites.
Byrd
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...None.
IL...None.
&&
$$
WFO LSX
Area Forecast Discussion
National Weather Service Marquette MI
732 PM EDT Thu Mar 14 2024
.KEY MESSAGES...
- Dry weather and above normal temps expected through Friday.
- A strong weekend storm system brings light rain/snow mix and
blustery conditions Fri night into Saturday.
- Below-normal temperatures, continued blustery conditions into
early next week and accumulating lake effect snow potential
Saturday night into Monday night.
- High-end northerly gales possible over north central and east half
portions of Lake Superior Sat night into Sunday.
&&
.SHORT TERM /THROUGH FRIDAY/...
Issued at 404 PM EDT Thu Mar 14 2024
Current RAP analysis and GOES WV imagery show a mid level shortwave
over southern WI and an associated sfc low over northern IL which is
lighting up the radar mosaic in IA, southern WI, lower MI, and OH.
While this feature continues eastward along the southern end of the
Great Lakes Basin today into tonight, precip remains south of our
CWA as sfc ridging extending over Upper MI holds steadily overhead.
While high level clouds streaming over the east half of the U.P.
continue eastward with the low pressure system, a batch of low level
clouds that settled south across Lake Superior this morning
continues to cover the Keweenaw and north central. These will linger
into the evening hours supported by upslope flow before scattering
out tonight. Aided by cool northerly flow off Lake Superior, these
clouds will hold temps in the 30s the rest of the day along the
lakeshores. A few spots in the southern half of the U.P. may warm up
to near 50, otherwise where obs are currently at in the mid to upper
40s will be the peak temps for today.
The mid level shortwave/sfc low progress east over the Great Lakes
Basin tonight and a mid level trough begins settling south over Lake
Superior. Some low level clouds may linger early on over the west,
otherwise mostly clear skies return as weak sfc ridging also settles
south across the Upper Great Lakes. With CAA, lows will settle into
the 20s with warmer temps near the lakeshores. That being said, some
interior spots that get good clearing overnight could dip into the
teens. Northerly winds gusting up to 15-20mph early on this evening,
strongest winds over the east half of the U.P., will gradually
diminish tonight; some variable winds over the far west are likely
by late tonight.
Although the mid level shortwave drops south on Friday, the
weakening sfc ridge overhead and dry profile noted in the model
soundings will prevent any precip. That said, cloud cover will
increase from the northwest Friday morning primarily over the west
half of the U.P. Warmer than normal temps are expected with highs
mainly in the 40s with some low 50s possible along the WI/MI state
line. Model soundings indicate mixing up to 3-5kft on Friday,
keeping dew point temps down in the low to mid 20s. This results in
min RHs in the low to mid 30s. Luckily, wind gusts are not expected
to exceed 20 mph until later in the evening when RHs begin to
recover. Thus, elevated wildfire conditions are not forecast at this
time. Will monitor for any changes in potential wildfire risk.
&&
.LONG TERM /FRIDAY NIGHT THROUGH THURSDAY/...
Issued at 420 PM EDT Thu Mar 14 2024
A developing rex block building over the West Coast will result in
500mb positive height anomalies in British Columbia approaching 340m
(+3 st devs) this weekend. This blocking ridge forces a deepening
trough downstream across eastern North America Friday night through
Tuesday that provides most of the noteworthy weather during this
forecast period. The most impactful hazards appear to be gusty west
winds Saturday into Sunday followed by a period of accumulating lake
effect snow Saturday night into Monday night. Meanwhile, behind a
cold front moving through on Saturday daily temperatures will trend
blo normal for late weekend into early next week.
The primary weather maker approaches the region Friday night. The
event begins with a 55-60 kt westerly low level jet resulting in
WAA, isentropic ascent, and perhaps some weak frontogenesis as well.
Operational models have ~9 hour period of deep moisture aloft, but
the antecedent air mass is quite dry so this will likely keep any
rain/snow mix amounts light Fri night into Saturday. Northern and
eastern portions of the area are most likely to get precipitation in
the warm sector of this clipper, but precip amounts appear light
with minimal impacts expected. The other thing to watch for on
Saturday is the potential for gusty west to northwest winds in the
wake of the clipper system`s cold front. Models are advertising
fairly deep mixing/destabilization behind the cold front with fcst
soundings indicating a potential for advisory wind gusts of 45 or
higher mixing down to the sfc across a good portion of the west half
of the U.P. with the highest gusts likely over the Copper Country
per EPS mean gust data.
Continued cold air advection increases lake effect snow potential
Saturday night as a secondary shortwave digs into the base of the
trough. This shortwave should enhance any ongoing LES while also
sending a reinforcing cold front that should cool temperatures below
normal for the first time since Feb 29th. With lake average
temperatures around 2-3C, the critical 850 mb temp threshold for
pure lake effect is around -11C. The grand ensemble mean cools 850mb
temps below that threshold Saturday night and doesn`t warm temps
back above that threshold until sometime on Tuesday with the coldest
850 mb temps likely occurring late Sunday night into Monday morning
when most ensemble means have temps as cold as -16C. Model soundings
advertise synoptic moisture up to 15-25 kft with the convective
boundary layer extending to around 5 kft and cooling into the DGZ
later Sunday into Sunday night which should boost SLRs closer to
20:1. However, sfc-850 mb flow is becoming increasingly anticyclonic
with time as upstream ridging approaches the lake with an increasing
inverted-v signal Sunday night into Monday. All told, Grand Ensemble
means indicates 2 to 3 with locally 4 inches of 10:1 snowfall for
the 36 hour period between 8 PM Sat night and 8 AM Monday. If SLRs
end up closer to 20:1 then snowfall amounts may locally approach
advisory criteria when combined with the blustery NW to N winds and
some blowing snow potential. However, the current lack of snow cover
should limit blowing snow impacts.
Overall, expect N-NW flow LES to taper off quickly from west to east
late on Monday as the surface ridge axis and associated subsidence
build in from the west and 850 mb temperatures moderate. Forecaster
confidence diminishes by Tuesday when another clipper may track into
the area, but considerable differences exist between models.
Ensemble means are in good agreement with temperatures warming above
normal ahead of the clipper disturbance, but cooler conditions may
return by mid to late next week.
&&
.AVIATION /00Z TAFS THROUGH 00Z SATURDAY/...
Issued at 732 PM EDT Thu Mar 14 2024
Dry air mass associated with passing high pres ridge tonight will
allow VFR to continue at IWD/CMX. Meanwhile, at SAW, IFR cigs that
developed earlier today will be departing in the next 1-2hrs as
satellite imagery shows a steady southward progression of clearing
across s central Lake Superior. Clearing is nearly to the lakeshore
as of 2330z. VFR will then prevail at SAW thru the night. On the
backside of the ridge, guidance is in good agreement that stratocu
in the 3500-5000ft range will spread across w and central Upper MI
Fri morning into aftn. Winds at IWD/CMX will become gusting to
around 20-25kt in the aftn as pres gradient tightens btwn the
departing ridge and low pres dropping se toward northern Ontario.
&&
.MARINE...
Issued at 420 PM EDT Thu Mar 14 2024
A weak low pressure system tracks east across the Lower Great Lakes
tonight as a high pressure ridge settles across Lake Superior with
light north winds below 20 kts. Looking ahead, southwesterly winds
increase to gales up to 40 kts across western and north-central
portions of the lake Friday night as a low-level jet moves over the
area. There is a high probability (50-80 pct) of gales between Isle
Royale and the Keweenaw late Fri night, justifying issuance of a
gale watch. As colder and more unstable conditions move in behind
the clippers on Saturday, winds veer from SWerly to NWerly. Ensemble
probabilities indicate northwesterly gales are nearly certain (70 to
near 100 pct chance) across north central and the east half portions
late Sat through Sunday where a gale watch was also issued.
Winds come down quickly blo gales late Sun night into Monday as a
high pressure ridge begins to build in from the west. Unstable
conditions remain into the early part of next week, but winds should
diminish to 20 kts or less for Tuesday and Wednesday as high
pressure and warmer conditions move over the area.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
Gale Watch from Friday evening through late Saturday night for
LSZ162-240>244-263-264.
Gale Watch from Saturday morning through Sunday evening for
LSZ245>251-265>267.
Lake Michigan...
None.
&&
$$
SHORT TERM...Jablonski
LONG TERM...EK
AVIATION...Rolfson
MARINE...EK
Area Forecast Discussion
National Weather Service Norman OK
1052 PM CDT Thu Mar 14 2024
...New AVIATION...
.SHORT TERM...
(This evening through Friday)
Issued at 319 PM CDT Thu Mar 14 2024
We will see a brief lull in the convection across our area as the
severe storms have moved into eastern Oklahoma. The cold
front/dryline surface boundary has moved through the OKC area and
just east of the H.E. Bailey Turnpike in southcentral Oklahoma.
Severe thunderstorms expected to redevelop in the moist warm
unstable sector ahead of the surface boundary in the next couple of
hours with the risk area this evening across southeast Oklahoma.
Moderate surface-based instability and strong deep-layer shear
within the warm sector could maintain organized severe thunderstorms
with supercells capable of producing large damaging hail (up to
baseballs), damaging downburst wind gusts (up to 80 mph) and a few
tornados. An additional flood risk will also persist as heavy rain
could result in some localized flooding. The cold front may not
make it through our southeast CWA until midnight when the severe
risk shifts east and entirely out of our southeastern counties.
A cut-off low system stalled over the Southwestern U.S. will start
expelling a series of shortwave disturbances downstream over the
Southern Plains bringing periods of rain to a few elevated storms
back into our area Friday and early into the long-term period. Will
have rain POPs (20-40%) in place near the Red River for Friday
afternoon as well as our western north Texas counties in fairly
stable air. Another shortwave will be expelled over the Southern
High Plains. Although deterministic models & NBM keep our west dry
as well as very low probabilities with the ensembles, several HRRR
runs paint rain across our west with a moist forecast sounding, so
will add very low rain POPs across southwest Oklahoma. The remainder
of our area should stay dry although cooler and cloudy with
northeast winds as temperatures return to more seasonably average.
Did go slightly cooler than NBM with Fridays MaxT using the CONSMOS
guidance.
&&
.LONG TERM...
(Friday night through next Wednesday)
Issued at 319 PM CDT Thu Mar 14 2024
The cut-off system never gets recaptured by the main westerly polar
flow and continues to spin over Southwestern U.S. and gradually
weaken until dissipating by the middle of next week. However before
weakening, it will continue expelling shortwaves over the Southern
Plains with rain & elevated storm chances for Saturday across all of
western through southcentral Oklahoma and western north Texas. Will
include a mention of thunder due weak instability/MUCAPE values over
northern Texas. Although moisture will be saturated at the mid-
levels, not entirely confident when lower levels will moisten up
based on model forecast soundings so will keep Saturday rain POPs
around 50% with very low POPs (20%) for Sunday restricted across far
southwest Oklahoma and adjacent northern Texas. A large open trough
in the polar jet flow digging through the eastern half of the
country will push a cold front across the Central Plains. Sundays
cold front could push partially across our forecast area reinforcing
our northerly winds with an additional shot of Canadian-based air
resulting in a colder Sunday night while maintaining seasonably
average temperatures on Monday. High surface pressure settles
through Monday night with a warming trend starting Tuesday as winds
shift out of the southwest under a building upper ridge in the
weaker southerly subtropical jet flow.
As the aforementioned cut-off low dissipates Wednesday, both GFS &
ECMWF develop an open trough over the Southwestern U.S. where the
pressure heights had fallen, with that trough digging through the
Southern Plains during the latter half of next week. Strong
southerly flow starting Wednesday could bring a return of low-level
moisture transport coming up from the gulf and perhaps forming a
dryline across the Southern High Plains through western Texas. With
our forecast area in the warm moist unstable sector with surface
boundaries to our west and north and an upper disturbance
approaching, will see thunderstorm chances return during the latter
half of next week. We may not see the cold front from this system
push through until late Friday.
&&
.AVIATION...
(06Z TAFS)
Issued at 1050 PM CDT Thu Mar 14 2024
Only VCTS is now expected over DUA through 07Z. The thunderstorms
have cleared the rest of the terminals. Northerly wind gusts
around 20-25 kt can be expected behind a cold front through most
of Friday. Speeds and gusts will decrease after sunset Friday.
MVFR cigs will follow the front by 3 hours or so, impacting most
of the terminals until 18-21Z. High clouds will then move over.
&&
.PRELIMINARY POINT TEMPS/POPS...
Oklahoma City OK 45 62 42 66 / 0 0 0 10
Hobart OK 44 61 41 62 / 0 20 10 30
Wichita Falls TX 48 63 46 64 / 0 20 10 40
Gage OK 39 57 35 64 / 0 10 0 20
Ponca City OK 44 64 40 68 / 0 0 0 0
Durant OK 52 64 48 68 / 90 10 10 30
&&
.OUN WATCHES/WARNINGS/ADVISORIES...
OK...None.
TX...None.
&&
$$
SHORT TERM...68
LONG TERM....68
AVIATION...03
Area Forecast Discussion
National Weather Service Raleigh NC
944 PM EDT Thu Mar 14 2024
.SYNOPSIS...
A weak cold front will cross the region Friday night and then stall
out along the coastline during the weekend. A stronger cold front
moving through the area Sunday will bring noticeably cooler air for
the beginning of next week, bringing frost and freeze potential
Monday night.
&&
.NEAR TERM /TONIGHT/...
As of 940 PM Thursday...
WV imagery and regional radar show an expansive area of storms
extending from Ohio to Indiana then pivoting SW through southwestern
Oklahoma, with the upper level convective debris resulting in
increasing, albeit thin, cirrus beginning to filter into the Mid-
Atlantic. Point soundings from the RAP show the overall opaqueness
of the high level moisture will remain very thin across the area
until early Friday morning. The pressure gradient is tighter across
the area tonight thanks to an area of low pressure currently making
its way into the Great Lakes region combined with the anchored
surface high in the western Atlantic between the Bahamas and Bermuda.
Surface bservations across central NC have mostly remained
relatively stirred due to this tighter pressure gradient across the
area, but some locations in the typical cool spots have managed to
briefly go calm at times. As such, have lowered lows in these areas,
but overall the general flavor remains the same for tonight. Lows
will bottom out in the mid 50s for most, and upper 40s to low 50s
for few.
&&
.SHORT TERM /FRIDAY AND FRIDAY NIGHT/...
As of 320 PM Thursday...
As the New England low pressure system moves over the Atlantic
Ocean, the cold front will shift to the east. While the synoptic
models show precipitation continuing along the front as it crosses
the Appalachians, CAMs show a substantial decrease in shower
coverage as the front moves east. Did not change the forecast too
much from what was inherited, generally keeping chance pops west of
I-95 during the day and slight chance pops by late afternoon east of
I-95. Highs will likely be slightly cooler Friday than today due to
the additional cloud cover, and will range from the mid 70s in the
Triad to the lower 80s in the east.
The cold front will likely be bisecting the forecast area from
northeast to southwest at sunset. The trend of the synoptic models
showing much more precipitation than the high resolution models
continues into the overnight hours, and have gone with chance pops
decreasing from west to east overnight instead of bumping up pops to
likely. Despite the front moving through Friday night, it will take
some time for colder air to move into the region, and after another
warm day on Friday, Friday night`s lows should be similar to
tonight`s values or even a touch warmer, ranging from the mid 50s to
the lower 60s.
&&
.LONG TERM /SATURDAY THROUGH THURSDAY/...
As of 300 PM Thursday...
Zonal flow will result aloft across central NC Saturday, with
ridging along the PAC NW, a cut off low across the Desert Southwest
and a broad trough stretching from the Midwest to the Northeast. A
stalled front near the NC/SC border will keep chances for showers
elevated Saturday across the southern half of the region before the
front washes out. Isolated to scattered showers are possible during
the day, with light accumulations less than one-tenth of an inch
expected. Northwesterly surface flow will quickly switch back
southerly, helping highs to range from the upper 60s N to mid-70s S.
A cold front will dig southeast across the region on Sunday, but
with limited moisture available (PWs around 0.50"), only isolated
showers are possible in the afternoon across most areas and across
the Coastal Plain in the evening. Temperatures ahead of the front
will remain mild, with highs still in the low to upper 70s Sunday.
The cooler air will arrive Monday behind the front and ahead of a
deep upper trough digging across the Mid-Atlantic late Monday. Dry
weather is expected with the passage of the trough due to limiting
moisture, however windy conditions may develop. Northwesterly wind
gusts of 20 to 25 mph are possible late Monday through Tuesday.
These winds, combined with low relative humidity from 20-30 percent,
could generate elevated fire weather conditions on Tuesday.
The ridge across the West will begin to relax by the middle of next
week, and with the departing upper trough, mostly zonal flow will
develop across the region, yet again. Surface high pressure building
into the Southeast will develop west to southwesterly flow through
mid-week, helping highs in the 50s on Tuesday to rebound into the
60s by Wednesday. Sub-freezing temps are also expected across many
areas Tue morning, and with the frost/freeze program beginning
across portions of the south/east on Match 17th, a frost advisory or
freeze warning may be needed for some areas. Lows will rise slightly
Wednesday morning, but could remain frosty through Thursday morning.
&&
.AVIATION /00Z FRIDAY THROUGH TUESDAY/...
As of 810 PM Thursday...
TAF period: Skies will stay mostly clear across central NC through
late tonight, with only a few passing high clouds. The only aviation
concern overnight will be the threat for low-level wind shear, as a
35-40 kt southwesterly low-level jet develops. However, it should be
marginal given there will likely be some continued light winds (~5-8
kts) at the surface. The best chance is across the northern sites,
though it can`t be entirely ruled out at FAY either. Any threat of
shear will end after sunrise and these winds start to mix to the
surface, with gusts of 15-25 kts possible during the day. Meanwhile,
mid and high level cloud ceilings will begin to move in from NW to
SE during the morning and afternoon. As a cold front approaches, a
line of showers and isolated storms may move through from west to
east from early afternoon into the early evening. High-res models
show it diminishing as it heads east, so the best chance for a
period of sub-VFR conditions is around INT and GSO.
Outlook: Scattered showers and isolated thunderstorms may persist on
Friday night, with a better chance of sub-VFR conditions at all TAF
sites. A slight chance of showers will continue at FAY Saturday, and
again at RDU/FAY/RWI Sunday afternoon/evening. The rest of the
outlook period should be dry. Winds could gust to 30 mph Monday.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SYNOPSIS...Green
NEAR TERM...Swiggett
SHORT TERM...Green
LONG TERM...JJT
AVIATION...Danco/Green
Area Forecast Discussion
National Weather Service Blacksburg VA
858 PM EDT Thu Mar 14 2024
.SYNOPSIS...
A cold front will cross the area on Friday with associated
showers and a few thunderstorms. Disturbances will progress
through the Great Lakes region Sunday into Monday with mainly
gusty and colder conditions the impact on our region.
&&
.NEAR TERM /THROUGH FRIDAY/...
As of 845 PM EDT Thursday...
Key Messages:
1. Severe storms to our north will approach overnight, but
weaken (considerably).
2. Showers and storms get started again in the morning, with
moderate confidence in LOW measurable rainfall outside the
western mountains.
Line of convection severe/tornadic storms stretched from near
Pittsburgh to Dallas tonight and were moving slowly east. Skies
are mostly clear here with some cirrus beginning to move into
SW WV. CAMs have this activity making it to SE WV around 1-2 AM,
but falling apart as it outruns the upper level energy. Flat
westerly flow does not help things, and it appears we will have
to wait until late morning into the afternoon hours tomorrow for
the next short wave kicker to move things into the southern and
central Appalachians. Seeing varying signals as to the coverage
of not only thunderstorms but measurable QPF, which looks to
struggle with the terrain and drier air in place.
For this update adjusted temperatures and tonight`s PoPs over SE
WV.
As of 150 PM EDT Thursday...
Key Messages:
1. Continued dry through this evening.
2. Cold front to cross the area Friday with the greatest
potential for showers across western areas.
3. Isolated thunderstorms will also be possible.
High pressure was centered over the Southwest Atlantic. A
series of low pressure systems were over the mid-Mississippi
Valley with an associated cold front extending southwest into
Oklahoma. Plenty of sunshine across our region and generally dry
lower atmosphere was allow for above normal temperature across
the region. As we head into the evening, a 25 to 40 deg F dew
point depression will allow for a quick cool down into the 50s
and 60s by the late evening. Advancing high level cloud cover
from upstream convection over the Ohio Valley will help limit
the cooling process after midnight. Low temperatures tonight
will still be on the mild side of normal.
We have been seeing the NAMNST and to a greater extent the HRRR
simulated reflectivity offer a band of showers crossing PA/WV
late this afternoon and early evening. The southern extent of
this feature may clip western Greenbrier County for an hour or
two right around sunset. Otherwise, dry conditions are expected
this evening across area.
Showers will be on the increase starting late tonight across
Southeast West Virginia in advance of the approaching cold front.
Through the day Friday, the cold front will cross our region.
Confidence is decreasing though on its wetting impact on our
region. The latest CAM solutions are hinting that the best
convection will remain south of our region, with eastern
portions of our area receiving limited amounts of showers. Given
this trend, have toned down the precipitation chances in the
east, while keeping them moderately high across western areas. A
look at the latest SREF output places MUCAPE across the area on
Friday around or a little over 500 J/kg across the area.
Likewise, effective bulk shear is expected to be within the 30
to 40 kt range nearly orthogonal to the cold front. Given these
parameters, we will continue with the mention of a slight chance
of thunderstorms on Friday. The best chances should be south of
our region. Temperatures will continue to be milder than
average, but slightly cooler than today in the west thanks to
better coverage of cloud cover and precipitation for this
region.
Confidence in the above weather scenario is moderate to high.
&&
.SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY NIGHT/...
As of 140 PM EDT Thursday...
1. Rain diminishes by Saturday morning, then mainly dry through
Sunday night.
2. Above normal temperatures through the weekend, but closer to
normal overnight lows Sunday night.
A cold front exits the area Friday night with rain showers
coming to an end by early Saturday morning. Isolated
thunderstorms are possible Friday evening. Saturday will be dry
and warmer than normal, though a few degrees cooler than Friday.
By the end of the weekend, a surface low tracks across southern
Canada and the Great Lakes, with a trailing cold front progged
to cross the eastern US, while a southern stream frontal system
develops over the southern US. The deeper moisture continues to
look to stay south of our area, and further to the northeast for
the system to the north. Therefore, thinking precipitation
coverage over the area will be limited and trending mainly dry.
Highs on Sunday will be mild, since the frontal passage looks to
be later Sunday night, but behind that, overnight lows will
drop back towards freezing in the mountains.
&&
.LONG TERM /MONDAY THROUGH THURSDAY/...
As of 140 PM EDT Thursday...
Key Messages:
1. Colder temperatures and gusty winds to start the work week.
2. Mostly dry weather expected through midweek, with a few
upslope snow showers.
The work week will start with a fairly amplified upper level
pattern, with a deep trough over the eastern US and a closed
upper low situated over the southwest US. A much colder
airmass will fill into the region behind the frontal passage
Sunday night. Strong cold air advection and pressure rises
through Tuesday will lead to gusty northwest winds for the
beginning of the work week. This northwest flow may bring enough
moisture from the Great Lakes for some upslope rain and snow
showers, mainly over southeast West Virginia, Monday and
possibly Tuesday, but any precipitation will be likely be light.
Surface high pressure will develop over the central US and
expand towards the east coast by Tuesday, then become more
centered over the southeast by midweek. The high will keep
weather dry and quiet for most of the area, outside of those
light mountain showers. Monday night will be the coldest night
of the period, with lows dropping back below freezing, with 20s
for most. Tuesday will start a warming trend, with temperatures
warming back towards seasonal normals. By Thursday, southwest
flow increases on the backside of the high bringing temperatures
around 5 degrees above normal in the mid 50s to near 60
mountains to mid 60s southside VA into the NC Piedmont.
&&
.AVIATION /01Z FRIDAY THROUGH TUESDAY/...
As of 840 PM EDT Thursday...
VFR conditions are expected through 06Z/2AM Friday. After
this time, look for ceilings to trend lower from northwest to
southeast across the region. By the conclusion of the valid TAF
period at 18Z/2PM Friday, VFR conditions will still be expected
at KROA, KLYH, and KDAN. KBCB, KLWB, and KBLF will see a mix of
IFR and MVFR ceilings with pockets of rain showers moving into
the region. Isolated thunderstorms will also be possible.
Visibilities for the most part are expected to remain VFR
through Friday. Winds will trend slightly stronger through the
afternoon hours with many experiencing a south or southwest wind
of 7 to 10 kts with some gusts in the mountains of 15 to 20
kts. Through the night, there will a slight, but gradual,
increase in wind speed, and stronger gusts at the ridge tops are
expected. On Friday, winds will veer more southwest to west with
both sustained winds and gusts slightly higher than those
expected tonight.
Confidence in the above aviation scenario is high.
EXTENDED AVIATION OUTLOOK...
Friday into Friday night, eastern portions of the area are
expected to remain generally VFR, but the mountains will see
continued sub-VFR conditions and lingering isolated to scattered
rain showers.
Saturday through Saturday night, VFR conditions will prevail.
Sunday into Monday, increasing and gusty northwest winds will
bring a return of some sub-VFR clouds to the Southeast West
Virginia mountains, along with isolated to scattered rain/snow
showers.
Confidence in the above aviation scenario is moderate.
&&
.FIRE WEATHER...
As of 205 PM EDT Thursday...
After today, relative humidities will be much higher thanks to
the approach and passage of a cold front on Friday. However,
we will continue to see relative humidities in the 25 to 30
percent range across the Piedmont this afternoon with a mix of
low to mid 30s percent for the mountains.
With the passage of the front on Friday, we are starting to see
evidence of less organized coverage of showers and storms then
earlier advertised. This may mean the bulk of the showers will
be across the mountains, with less showers activity translated
east of the crest of the Blue Ridge. Rainfall on Friday is
expected to average a few hundredths across the Piedmont and one
to three tenths of an inch across the mountains. Isolated
thunderstorms will also be possible.
Looking ahead, two northern branch systems will move across the
Great Lakes region Sunday into Monday. Northwest winds behind
these system will increase and remain gusty through this period
of the forecast. This could be a fire weather concern,
especially if rainfall amounts on Friday are limited.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...None.
NC...None.
WV...None.
&&
$$
SYNOPSIS...DS
NEAR TERM...DS/SH
SHORT TERM...WP/AS
LONG TERM...WP/AS
AVIATION...DS/SH
FIRE WEATHER...DS
Area Forecast Discussion
National Weather Service Shreveport LA
908 PM CDT Thu Mar 14 2024
...New UPDATE...
.UPDATE...
Issued at 853 PM CDT Thu Mar 14 2024
Tornado Watch #45 remains in effect until Midnight and through
that time, it appears that only our far northwest counties in
Northeast Texas, McCurtain County in Southeast Oklahoma and the
adjacent counties in Southwest Arkansas will see that large hail,
damaging wind and isolated tornado threat through watch expiration
time. For the update, we are following the HRRR output which has
really handled the isolated to scattered nature of the evening
convection north and west of the I-30 Corridor well thus far.
Having said that, storm mode after midnight should become more
linear in nature with embedded supercell thunderstorms as the
storms get closer to the I-30 Corridor and eventually towards the
I-20 Corridor of NE TX into far NW LA in the 09z-12z timeframe.
Will continue to mention the severe threat near and north of the
I-20 Corridor in NE TX and N LA through the remainder of the night
but did delay the expansion of higher pops from northwest to
southeast through the remainder of the night given the slow timing
to get the convection south and east thus far.
Believe the greatest tornado threat will remain across our far
northern zones through the duration of the overnight hours or
where Tornado Watch #45 continues through midnight. Further south
of the Tornado Watch which encompasses the I-20 Corridors of NE
TX and NW LA, the threat will be more of a damaging wind and large
hail threat. Obviously, the heavy rainfall threat will increase
overnight once the convection takes on more of a linear mode,
especially if we see any training after midnight.
Updated zones have been sent...13.
&&
.SHORT TERM...
(This evening through Friday Night)
Issued at 153 PM CDT Thu Mar 14 2024
By this evening, thunderstorms will be expand north of I-30, as
the main show for severe weather begins to get underway. An
enhanced risk for severe weather still remains in place, with a
slight risk extending down to the I-20 corridor. Not much has
changed with the overall thinking regarding this severe event.
Clusters of severe storms will meander along the front, before it
begins to move to the SE overnight. These clusters of storms will
be capable of producing damaging winds and very large hail, with
damaging winds becoming the primary threat once these storms form
into a line.
It also remains worth mentioning that the tornado threat continues
to appear "secondary" in nature, but that doesn`t mean a tornado
or two won`t occur. The last few days, it`s appeared as if the
SFC-1km shear would really be lacking in the areas with the best
forcing, but morning observations had some pockets of better shear
farther north than expected. Now, it still looks like the truly
better shear values will remain south, but any local storm merger
or influence could be enough to get a storm over that hump.
From a flooding standpoint, it still looks like locally heavy
rainfall is possible in these same areas, as training
thunderstorms are possible during these same timeframe. The flash
flooding threat continues to look highly conditional, as multiple
rounds of heavy thunderstorms would have to occur in a short
window.
With all that being said, once the cold front begins to shift
south, severe weather chances will begin to wane into the early
morning hours Friday. This is not to say they will disappear
altogether, but chances will greatly begin to decrease the farther
south these storms get. A good chunk of the region will likely be
waking up to rain and thunder to start their day, with general
thunderstorm chances continuing into the afternoon hours,
particularly along and south of I-20.
/44/
&&
.LONG TERM...
(Saturday through next Wednesday)
Issued at 153 PM CDT Thu Mar 14 2024
With the surface front having moved through the region, the 850mb
front remains just north of the area. By Saturday, another
shortwave disturbance will part from the closed low continuing to
spin near California. This disturbance will ride the 850mb front,
allowing for another round of heavy showers and thunderstorms to
develop Saturday evening, and into the overnight hours. At this
time, no additional severe weather is anticipated, but a strong
storm during this timeframe is not out of the question. This will
be the last good soaking in the long-term, with half an inch to an
inch of rain possible in some areas during this time. The
elevated front will finally push through the region into Sunday,
which will allow for below average temperatures to return to the
forecast to start the new workweek. However, temperatures will
begin to rebound into the weekend, as flow across the region
begins to turn back towards the SW.
/44/
&&
.AVIATION...
(00Z TAFS)
Issued at 1245 PM CDT Thu Mar 14 2024
Widespread MVFR ceilings will eventually prevail overnight in
advance of convection that is expected to move south and east
through all but the LFK and MLU terminals through 12z Fri. Did
account for strong and gusts winds with convection and the
possibility of IFR ceilings with the convection through sunrise
and a little later in the mid to late morning hours in some
locations before we see ceiling improvement by late afternoon.
13
&&
.PRELIMINARY POINT TEMPS/POPS...
SHV 66 75 58 72 / 90 70 20 20
MLU 67 75 56 71 / 70 80 20 10
DEQ 59 69 48 71 / 90 20 10 10
TXK 63 70 52 70 / 90 30 20 10
ELD 63 71 51 71 / 90 50 10 10
TYR 65 71 58 70 / 90 30 20 30
GGG 65 73 58 71 / 90 40 20 20
LFK 68 78 62 74 / 60 90 30 40
&&
.SHV WATCHES/WARNINGS/ADVISORIES...
AR...None.
LA...None.
OK...None.
TX...None.
&&
$$
SHORT TERM...44
LONG TERM....44
AVIATION...20
Area Forecast Discussion
National Weather Service Las Vegas NV
816 PM PDT Thu Mar 14 2024
.SYNOPSIS...A strong low pressure system will bring gusty northerly
winds to the forecast area through Friday morning. This system will
also bring increased chances for isolated showers and thunderstorms
through Saturday. Temperatures will drop to 10 to 15 degrees cooler
than normal by Friday before gradually warming back up through the
weekend.
&&
.UPDATE...Satellite and radar imagery continued to show an upper
level low swirling in place, centered over Southern California.
Radar returns, while more widespread than this afternoon, remain
light and unimpressive. Surface observations conquer with this
assessment as gage reports have been 0.10 inch or less over the past
6 hours. No additional snowfall has been reported since this morning
in the Spring Mountain SNOTELs and webcams on Mount Charleston
showed only light flurries. Much of the precipitation so far has
been virga as dewpoint depressions near the surface have remain
around 30 to 40 degrees. Overall, low impact precipitation so far
this evening.
North to northeast winds remained elevated through the evening.
Widespread gusts over 30 MPH were reported in many locations through
southern Nevada into California in conjunction with the best
pressure gradient and northerly flow aloft. Further east, the
center of the low and saggy isobars resulted in lower winds.
Overall, no changes were needed for the overnight forecast as the
upper level low continues to spin and remains nearly stationary
through the night. Continued gusty north to northeast winds are
expected north of the I-15 through the night with lower winds
further southeast where the pressure gradient is lower. A Wind
Advisory remains in effect through the areas where the highest risk
for impacts from gusty north winds to around 40 MPH are possible.
Southern portions of the wind advisory may be able to be cancelled
early as high-res models suggest winds will decrease quickly after
midnight. In addition to the winds, models continue to show the
precipitation band currently rotating through northwest Arizona and
southern Nevada increasing in coverage and intensity late tonight
into early Friday morning. The latest HRRR shows an uptick in hourly
precipitation totals after 1AM in Mohave County through Clark
County. Still not expecting high impact precipitation at any point.
The best chance for precipitation impacts will be in the Spring
Mountains and Sheep range where upslope flow may enhance
precipitation rates and moderate impacts may be possible. A Winter
Weather Advisory is in effect for the Spring Mountains that goes
into Friday to capture these potential impacts.
Temperatures tonight actually run a few degrees warmer than last
night as cloud cover and winds keep the area from efficiently
cooling off tonight.
-Nickerson-
&&
.PREVIOUS DISCUSSION...215 PM PDT Thu Mar 14 2024.
.SHORT TERM...through Saturday.
A cut-off low-pressure system is currently churning over southern
Nevada, southeastern California, and northwestern Arizona. This
system will continue to dig south before retrograding slightly as it
settles over the region. As this low settles over the region, the
Eastern Pacific Ridge will wrap around into the Pacific Northwest,
resulting in a Rex Block over the Western US, that will persist into
next week.
Gusty northerly winds will continue across much of the area through
tomorrow morning as this low pressure system continues its
southwesterly trek before it parking itself/stalls over the area.
Valleys and lower elevations can expect wind gusts up to 40-50 mph
with 60+ mph wind gusts possible for higher elevations. Outside of
gusty northerly winds, this system will also bring cooler
temperatures to the Desert Southwest. Temperatures today may be
limited by overhead cloud cover, especially for the Las Vegas
Valley. Currently temperatures in the Vegas area are running 10
degrees below where they were at this time yesterday. Should the
cloud cover from this morning linger through the afternoon we will
find ourselves struggling to hit 60 degrees. Friday will be the
coldest day, with high temperatures around 10 to 15 degrees below
normal for mid-March.
Isolated showers and thunderstorms will be possible each afternoon
as we head into the weekend, as anomalous moisture lingers over the
area along with the low pressure system. Currently we can see a line
of showers developing over central Mohave County, which finds itself
under the northeastern quadrant of the low pressure circulation.
These showers will continue to push west while slowly rotating with
the low pressure system. The best chances for precipitation will
begin during the evening hours, continuing through Friday afternoon.
Widespread 30% to 50+% precipitation chances will spread from
southeast to northwest as the center of the low drops to our
southwest. Precipitation totals will be highest in the mountains
where liquid totals will range from 0.75" up to 1.00" at the
mountain peaks. For lower elevations and valleys, precipitation
totals will range from 0.01" of rain up to 0.25". Higher
precipitation totals are expected in the eastern portions of our
forecast area, with totals decreasing as you move northwest. Another
round of isolated showers will be possible on Saturday afternoon.
Precipitation totals on Saturday will be lighter with showers being
more isolated in nature compared to Friday.
.LONG TERM...Sunday through Wednesday.
A Rex Block pattern will remain in place through early next week
with strong high pressure to our north and lingering troughing
across the Southwest Deserts. Little to no precipitation is forecast
in this period with weakening low pressure over the Southwest. No
significant winds are forecast although there will be some breezy
winds at times, especially early in the extended along the Colorado
River Valley. A warming trend is forecast with temperatures back to
seasonal by Monday and above normal Tuesday and Wednesday.
&&
.AVIATION...For Harry Reid...Gusty north-northeast winds to 30kts
will continue into this evening. Speeds will decrease overnight,
but directions will continue to favor a northeast direction through
Friday afternoon. Scattered showers will be possible at times
through the period, with the best chances occurring 23Z to 02Z today
and after 12Z on Friday. CIGs away from shower activity should be
AOA 8kft but will fall to 4-6kft in and near shower activity. A few
isolated thundershowers are also possible on Friday afternoon.
For the rest of southern Nevada, northwest Arizona and southeast
California...Gusty north-to-east winds will continue across much of
the region through this evening. Scattered showers and a few
embedded thundershowers are likely over northwest Arizona and
southern Nevada through the evening, generally along and south of I-
15. Winds will decrease overnight into Friday, but areas of
scattered showers and isolated thundershowers will continue through
Friday afternoon, with the precipitation spreading further to the
north by afternoon. CIGs away from shower activity should be AOA
8kft but will fall to 4-6kft in and near shower activity.
&&
.SPOTTER INFORMATION STATEMENT...Spotters are encouraged to report
any significant weather or impacts according to standard operating
procedures.
&&
$$
SHORT TERM...Varian
LONG TERM...Salmen
AVIATION...Planz
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https://weather.gov/lasvegas or follow us on Facebook and Twitter