Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 02/23/24
Area Forecast Discussion
National Weather Service Binghamton NY
1021 PM EST Thu Feb 22 2024
.SYNOPSIS...
A mix of rain and wet snow will continue overnight, before
ending early Friday morning. A strong cold front will follow
late Friday with some lake effect snow showers stretching into
Saturday. Saturday will be cold and blustery. A warming trend
follows on Sunday and especially into next week.
&&
.NEAR TERM /UNTIL 6 PM FRIDAY EVENING/...
1015 PM Update...
Valley rain and higher elevation wet snow continues over the
southeastern half of the forecast area late this evening. It
still seems like the snow level is around 1200-1400 feet or so
over the Twin Tiers, Catskills and NE PA at this time. There
have been isolated reports of up to 1 inch of snow over the
higher terrain in this area so far; here at the office at 1600
feet in elevation only a tenth or two of snow has accumulated so
far. The forecast remains on track though, with minimal changes
at this time (just tweaked PoPs, QPF and snow amounts based on
these latest trends and CAMs).
625 PM Update...
Temperatures were lowered by 1-3 degrees for this evening and
overnight based in the latest observations and trends. As the
precipitation overspread the area this evening, some wet bulb
cooling brought temperatures down into the 30s areawide...as
expected some snow and sleet is mixing in over the higher
elevations, perhaps as low as 1200 feet. Bumped up PoPs/QPF
slightly overnight based on the latest 18z 3km NAM and HRRR run,
and also snow amounts were raised for the highest elevations of
the Catskills, where temperatures will be at or just below
freezing overnight and 1-2" of snow looks to accumulate. Any,
very light (wet, and less than 1") snow accumulations look to be
confined to elevations above 1600-1800 feet overnight. Icing
does not look like much of a concern overnight, but with that
said, as temperatures aloft hover near 0C...it is still possible
some occasional, brief freezing rain could occur above 2000 feet
in the Catskills and Poconos. Overall, the near term forecast is
on track and no other significant changes were needed at this
time.
3 pm update...
Temperatures have now risen above freezing in Oneida County. An
area of rain will move into the Catskills and NEPA in the next
few hours. Rain will taper off further north in most of CNY at
the same time. Rain in NEPA will taper off late tonight and
Friday morning. As temperatures fall tonight snow will mix in,
along with possibly some freezing rain and sleet. The higher
terrain of the western Catskills could get an inch of snow
tonight. Low temperatures will be in the low and mid 30s. The
rain is forced by a cold front swinging through late tonight.
Despite this high temperatures will be from the mid 40s to
around 50 early afternoon with some sunshine and dry weather.
Cold air advection will continue all day Friday as a secondary
front drops southeast late Friday. The front will have some
showers with it. Cold enough air comes in to set off lake effect
snow showers. Most of CNY could get a coating of snow Friday
night into Saturday morning. The flow will be northwest setting
off multibands. There could be a connection to Lake Huron. 850mb
temperatures drop to -15C. Surface temperatures fall into the
teens. With winds picking up to 10 to 20 mph late Friday night,
wind chills will fall into the single digits.
&&
.SHORT TERM /6 PM FRIDAY EVENING THROUGH SUNDAY NIGHT/...
245 PM Update...
A quick shot of cold air moves through on Saturday as 850 mb
temperatures fall to around -13C to -17C across our area. With
the coldest air moving through mid-day, temperatures will
struggle to warm up. The upper level trough axis is through by
Saturday night with warming temperatures aloft. With surface
high pressure building in for Saturday night, it will likely be
cold with good radiational cooling.
Sunday will warm back up to above average as the surface high
propagates east and return flow sets up as upper level ridging
builds in. A weak cold front tries to drop in on Sunday night
though with limited moisture and not quite cold enough for lake
effect, chances of precipitation were limited to mainly along
the Thruway and north.
&&
.LONG TERM /MONDAY THROUGH WEDNESDAY/...
245 PM Update...
The long range is looking very warm with strong upper level
ridging building in along with strong SW flow. Models are in
good agreement that a deep area of low pressure forms in the
central US helping strengthen warm air advection for mid week
with high temperatures pushing into the upper 50s and low 60s.
Decided not to stray too far from the NBM mean due to
uncertainty with cloud cover and showers. NAFES tables are
already showing precipitable water values approaching 3 standard
deviations above average so it will be tough to get a lot of
sun. Despite the high amounts of water vapor, ensembles and
deterministic models bring the center of the low through the
Great Lakes into southern Canada so the best dynamics of the
system will likely miss us with low amounts of QPF for our area
but will need to be watched.
&&
.AVIATION /03Z FRIDAY THROUGH TUESDAY/...
Fuel alternate to IFR restrictions are expected overnight as
rain and low ceilings move through the area. Conditions start to
gradually improve from west to east after 12Z Friday, and
especially after 18Z as rain moves out of the area. Some
lingering MVFR restrictions will be possible at the Central NY
terminals (especially KSYR and KRME) due to lake effect clouds.
Outlook...
Friday night through Saturday evening...Scattered lake effect
snow showers with associated restrictions, mainly at the Central
NY terminals.
Late Saturday night through Sunday...Mainly VFR.
Sunday night through Monday morning...Potential restrictions
and chance of mixed rain-snow showers as a weak front passes.
Monday afternoon through Tuesday morning...mainly VFR.
Tuesday afternoon...restrictions due to rain.
&&
.BGM WATCHES/WARNINGS/ADVISORIES...
PA...None.
NY...None.
&&
$$
SYNOPSIS...MJM/TAC
NEAR TERM...MJM/TAC
SHORT TERM...AJG
LONG TERM...AJG
AVIATION...BJG
Area Forecast Discussion
National Weather Service Sioux Falls SD
943 PM CST Thu Feb 22 2024
.KEY MESSAGES...
- Above normal temperatures continue tomorrow, albeit only 10-15
degrees above normal, returning to be 20+ degrees above normal for
the weekend. Temperatures in the mid 60s to lower 70s expected for
Monday.
- A stronger cold front expected to move through on Tuesday bringing
chances (20-40%) for rain and snow, as well as breezy northwesterly
winds continuing into Wednesday.
- Brief cool-down Wednesday with slightly below normal
temperatures possible, warming back up by end of next week.
&&
.DISCUSSION...
Issued at 200 PM CST Thu Feb 22 2024
Early afternoon satellite imagery shows mostly clear skies, though
there remains some remnants of a stratus deck that dissipated before
reaching the area north of I-90. Surface temperatures as of 1 PM are
shown to be largely in the 50s, though areas along the highway 14
corridor remain in the 40s as they continue to melt their remaining
snowpack. Winds have come in a bit weaker than expected, though they
will remain breezy for a few more hours before weakening during the
evening hours as the inversion strengthens. Overnight, we`ll be
watching a cold front approach from the north, which will swing our
winds around briefly to be out of the west before switching back to
northwesterly by daybreak. Overall, quiet conditions are expected
with overnight lows in the mid 20s to mid 30s.
As the aforementioned cold front moves towards the area, the
tightened surface pressure gradient will again result in breezy
north-northwesterly winds by the afternoon hours. Strongest gusts
are expected west of I-29 with gusts into the 30s, while along and
east of I-29 gusts should remain in the 20s. With 850mb temperatures
cooling off towards zero by the end of the day as the cold front
moves through, temperatures on Friday will range from mid 30s across
SW Minnesota, and into the lower 50s across south-central South
Dakota where the front moves through last. Models are continuing to
suggest we could see light rain/snow showers after the front moves
through and a shortwaves moves across overhead, with the HRRR and
NAM-based models showing scattered chances. As probabilities for QPF
> 0.01" remain very low, have opted to include slight chances (20%)
for sprinkles/flurries as we`ll likely see precipitation though no
accumulations. Behind the cold front, overnight temperatures into
Saturday will drop into the lower to upper 20s.
Upper level ridging and southerly surface flow quickly brings us
back to well above normal temperatures on Saturday, with 850mb
temperatures again coming in between 3-5 deg C. This will result in
temperatures reaching up into the mid 50s and lower 60s, but
unfortunately breezy south-southwesterly winds are needed to bring
those warmer temperatures down to the surfaces. Expect winds to
become sustained in the teens and lower 20s by the afternoon hours,
with gusts in the 20s to 30s, highest for elevated areas. Sunday
will see slightly cooler temperatures as a weak front will have
moved through overnight, though we should still see temperatures in
the upper 40s to upper 50s as warm air remains aloft. One change for
Sunday is that a previously dry shortwave now looks to carry some
moisture along with it. While it doesn`t look to amount to much in
our area, portions of east-central South Dakota along and north of
highway 14 have a 20% chance for seeing light rain during the
morning hours.
Attention turns to a strengthening Alberta Clipper out ahead of a
strong trough moving onto the west coast overnight into Monday.
There remains considerable uncertainty on the strength of the
trough, whether it remains open or closed, as well as the phasing of
the trough, but there is good agreement that we`ll see warm
temperatures on Monday. This is because we remain in the developing
warm sector throughout the day, with 850mb temperatures above the
90th percentile per the most recent ensemble situational awareness
tables. The ECMWF Shift of Tails (SOT) has actually taken away the
contours for Monday, indicating the possibility of extreme
temperatures has decreased for Monday, but has instead shifted them
to be on Tuesday. The ECMWF Extreme Forecast Index (EFI) has also
decreased for Monday now showing values above 60% across the region,
still well above normal. Just as we saw with the SOT`s, the higher
EFI values are now expected for Tuesday.
However, comparing the EFI/SOT to other ensemble output, this shows
that there is still considerable uncertainty on the timing and
placement of the surface low on Monday, which would greatly impact
temperatures for Monday. If the further northern track is realized,
temperatures could be even warmer than expected, whereas a southern
shift would cool us off a bit as we can`t bring those warmer
temperatures northward. In addition, the timing of the cold frontal
passage is also not certain yet, opening up the possibility that we
may not see the front move through until the daytime hours on
Tuesday, which would again greatly increase our temperatures on
Tuesday. In the end, warm temperatures are expected on Monday, but
Tuesday is still up in the air. Precipitation chances behind the
front are of course tied to all of the aforementioned uncertainties,
so we`ll have to see how that progresses with additional model runs.
Lastly, there is decent agreement that we`ll see cooler (near-
normal) temperatures on Wednesday, with temperatures warming into
the end of the week.
&&
.AVIATION /00Z TAFS THROUGH 00Z SATURDAY/...
Issued at 941 PM CST Thu Feb 22 2024
While tonight will be quiet with VFR conditions Friday will see
northwest winds increase with a good chance for wind gusts
above 25 knots, especially along the Missouri River into parts
of northwest IA. There will also be a threat for some MVFR
ceilings and a few sprinkles or flurries with the better chances
east of the James River and especially over parts of southwest
MN.
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...None.
MN...None.
IA...None.
NE...None.
&&
$$
DISCUSSION...APT
AVIATION...08
Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
943 PM EST Thu Feb 22 2024
.SYNOPSIS...
A rainy cold front will cross the region tonight with a few
thunderstorms possible through Friday morning. A quick moving system
will bring a period of accumulating snow across the higher mountain
terrain Saturday, before dry weather returns on Sunday. A warming
trend begins Monday and highs will reach well above normal levels
through Wednesday.
&&
.NEAR TERM /THROUGH TONIGHT/...
As of 935 PM: Light showers continue across the tail end of the
Appalachians of SW NC and NE GA. The available surface obs indicate
measurable precip across much of Graham, Swain and Macon counties,
but not so much in other areas where radar returns have been
seen. The relatively persistent echoes in this western portion of
the CWA, with attendant moisture on GOES Channel 10 low-level water
vapor imagery, suggest mainly mechanical lift is responsible for the
precip so far. The main axis of rain/storms is oriented near I-40
in West/Middle TN and sinking southward. All indications are that
the overnight PoPs are on track in terms of coverage and timing,
along with the thunder mention revised at last update. Still
seeing signals for some elevated CAPE overnight in the SW CWA,
which expands into the NC Piedmont and eastern Upstate closer to
dawn, as lapse rates improve and lift occurs under the main slug
of DPVA. Still looking elevated, this suggests minimal severe risk;
overall lapse rates become favorable for updrafts but not especially
strongly. Locally heavy rainfall is a possibility along with brisk
25-30 kt gusts being brought down with some showers. Temps were
running warmer than forecast, and with CAA not likely to set in
until after daybreak and abundant cloud cover persisting until
then, went ahead and raised min temps a category or so degrees in
much of the CWA. Dewpoint depressions are large and some diabatic
cooling is expected after the onset of precip later tonight.
After daybreak, the bulk of the forcing and associated activity
will slide east of the forecast area and rain chances will
ramp back down. The actual cold front will push through during
the late morning and early afternoon hours, and as it does so,
there`s potential that another round of convective initiation may
spin up along it. Deep mixing is likely south of I-85 before the
surface front ever arrives, and ensemble guidance is in favor of
a plume of 300+ J/kg sbCAPE developing in these zones during the
late morning and early afternoon. z850 CAA analysis indicates
a possible elevated cold front, which depending on timing could
either smash any chance of destabilization altogether, or result
in convective initiation a little earlier than the arrival of the
actual surface boundary. If convection develops it`ll be doing so
in an environment rich in bulk shear (the HREF mean 0-3km shear is
in the vicinity of 60kts in the latest 12z cycle) so some manner
of organization would be likely. As for severe risk, neither hail
nor wind has much going for it, with only modest lapse rates and
skinny CAPE depicted in afternoon profiles, and little in the way
of dry air aloft to prompt strong downdrafts. Still, enough CAPE
and shear will be present that any developing columns will need
to be monitored. Machine learning guidance highlights an outside
risk of severe hail over the far southern, and successive runs of
the HRRR have depicted the development of supercellular convection
somewhere in the corridor from Laurens County up to Chester County.
Low-level shear will be paltry enough to make any tornadic threat
all but nonexistent, but if a supercell does develop, it would
enhance the hail threat.
Once the front clears the area by mid afternoon, dry air will
filter in on its backside. Gusty winds are expected across the
mountains in the ensuing 3-4mb pressure gradient, and as NW flow
picks up a few light upslope showers may pick up on favored western
slopes going into Friday evening.
&&
.SHORT TERM /FRIDAY THROUGH SUNDAY NIGHT/...
As of 105 PM Thursday...A rather strong clipper system will cross
the FA Sat and bring a good amt of moisture. The guidance has
trended a little drier than the previous couple runs, but still
expect this system to begin producing -snsh across the wrn NC mtns
arnd daybreak Sat and continue thru most of the day. With this
duration, snow will begin to accum decently with arnd 3-4 inches
possible across the Smokies and 1-2 inches over the other higher mtn
ridges. Likely sub-advisory level snow, but an elevated advisory may
be needed on the subsequent shift if snow totals trend upward. As
the system crosses the NC Piedmont, very good mlvl LRs are expected
which could aide in small scale convective elements and with a sub-
freezing cloud layer, a brief shot of snow pellets or graupel will
be possible. No sigfnt accums are expected with this scenario,
however. Cold air advection will increase and limit the diurnal temp
curve Sat, while stg gusts are also probable across the higher mtn
terrain into the evening. In general, expect max temps held a little
below normal across the mtn valleys and near normal levels east.
Very good cooling Sat night as the cP airmass continues to mix in
and lowers sfc td/s by abt 10 F. Drying sfc conds and limited sfc
moisture may lead to fire weather issues, mainly across NE GA during
the afternoon Sun. Lows will bottom out in the low to mid 20s across
the FA Sat night, which will lead to highs barely reaching normal
values on Sun.
&&
.LONG TERM /MONDAY THROUGH THURSDAY/...
As of 120 PM Thursday...Upper heights begin to rise Sun night and
turn into a flat ridging config thru Tue, before a trof deepens
across the MS Valley Wed. This will lead to a rather quiet pattern
with low-end -shra likely across the NC mtns/fthills Mon night into
Wed. Temperatures will also rise sigfnt/ly during the period as a
sfc high builds offshore and s/ly to sw/ly WAA flow commences thru
the period. Prefrontal showers may pick up in coverage Wed ahead of
a robust frontal system, but confidence is low as far as timing of
this system. In any case, Day 8 (Thu) may see an uptick in showers
and perhaps string thunderstorms with a FROPA possible. Highs will
warm nicely during the week with u60s to l70s outside the mtns and
reaching the m60s across the mtn valleys each day. Lows begin the
period Sun night arnd normal and rise 10-15 degrees thru Tue night.
&&
.AVIATION /03Z FRIDAY THROUGH TUESDAY/...
At KCLT and elsewhere: Low VFR clouds are just beginning to
reach the Appalachians as moisture advection occurs ahead of the
approaching shortwave trough and cold front. Some sprinkles are
a reasonable bet at KAVL by mid-evening and the Upstate sites by
midnight. Winds will remain SW and breezy at all sites tonight, with
some low-end gusts of 20 kt or less outside the mountains. Precip is
most likely between midnight and dawn with vort lobe preceding the
main front, and there is PROB30 to TEMPO potential for convection
producing SHRA with some embedded +TSRA. Such activity will be
capable of low MVFR to IFR vsby and cigs. Cigs may deteriorate
to IFR after the rain tapers off near daybreak or in the first
couple hours of the day, before cold front can induce mixing and
drying. All sites should be back to prevailing VFR in the 14-16z
timeframe. LCLs will still be fairly low at KCLT and can`t rule
out redevelopment of some -SHRA or even TSRA in the midday. As
winds turn NW behind the front, diurnally driven gusts of 15-20
kt will be possible at the terminals.
Outlook: Another quick shot of rain is possible on Saturday, but
with lower impact than the tonight/Friday system. Conditions will
dry out again Sunday and beyond.
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...None.
NC...None.
SC...None.
&&
$$
SYNOPSIS...SBK
NEAR TERM...MPR/Wimberley
SHORT TERM...SBK
LONG TERM...SBK
AVIATION...Wimberley
Area Forecast Discussion
National Weather Service Marquette MI
926 PM EST Thu Feb 22 2024
.KEY MESSAGES...
- A cold front will bring in a round of lake effect snow showers
beginning late tonight, as well as blustery conditions. Snow
accumulations will be light, generally 1-3 inches at most in
the north snow belts.
- A brief bout of colder weather (below normal temperatures)
Friday, then back to well above normal early next week.
- A more active period is likely next week with one or two low
pressure systems lifting northeast through the Mid and Upper
Mississippi Valley/Great Lakes region.
&&
.UPDATE...
Issued at 917 PM EST Thu Feb 22 2024
One of the updates I did this evening was to drop the mention
of snow showers over the western half of the U.P. earlier Friday
following the most recent CAMs guidance. That being said, some
scattered lake effect flurries look to continue across the
western U.P. until Friday evening. In addition, I`ve slightly
lowered the winds over the Great Lakes this evening through
Friday. This has lowered the projected wave heights as well as
the gales that are expected over Lake Superior tonight. It does
make me at least question whether the far eastern zones of the
lake need to have the Gale Warning dropped or not. Otherwise,
the only other thing I`ve altered all that much was the low
temperatures for tonight. Based off of the model consensus as
well as the 00z HRRR guidance, I`ve decided to bump up the lows
a few degrees across the area; it appears that the cold front
will be moving into and across our area slightly slower than
previously expected.
&&
.SHORT TERM /THROUGH TONIGHT/...
Issued at 251 PM EST Thu Feb 22 2024
Skies are clearing out across much of the UP this afternoon as a
weak shortwave exits eastward, with fairly dry midlevel air apparent
across the Great Lakes on water vapor imagery. Temperatures have been
able to quickly climb into the 40s where skies have turned sunny,
and areas closer to the WI border are even reaching into the lower
50s.
A surface low is currently analyzed just south of Hudson Bay, and
will continue to track eastward into Quebec tonight. As this
happens, a sharp cold front currently extending from western Ontario
into Manitoba will drop southward across Lake Superior the second
half of the night and through the UP Friday morning. Increasing
clouds and chances for flurries and snow showers (initially mixing
in with rain) spread across the area, then a transition entirely
over to lake effect snow is expected after 06Z, behind the cold
front. 850mb temperatures fall to as low as -20C by 12Z Friday, and
soundings are showing decent saturation through the DGZ. Towards
daybreak, however, drier air works in and inversion heights lower.
Unsurprisingly, then, href guidance shows our best snowfall rates of
around a quarter inch/hr across the NNW snowbelts, immediately
following FROPA. With blustery northerly flow developing behind the
front and a long fetch off of Superior, snow bands may extend
farther inland than usual. Thus, light snow totals below an inch are
possible across much of the UP, save the south-central areas, with
higher totals closer to Superior. Locally higher amounts of 1-2in
are possible by sunrise across the upslope enhanced areas of the
north-central and western UP.
Otherwise, expect temperatures to drop rapidly with the passing
front. Most of the area should be starting off in the teens by
Friday morning, though some of our typically cooler spots may flirt
with the single digits behind the cold front. Blustery NNW winds
will contribute to wind chills in the single digits across most of
the UP, and perhaps below 0F in the Keweenaw and the highlands of
Marquette and Baraga counties.
&&
.LONG TERM /FRIDAY THROUGH THURSDAY/...
Issued at 449 PM EST Thu Feb 22 2024
Beginning Fri, a vigorous northern stream shortwave now diving se
through northern Ontario today will support an associated sfc low
pres moving from northern Ontario today into Quebec tonight. The
associated cold front with the low will sweep s across Lake
Superior/Upper MI late tonight and ongoing CAA into Friday, will
send 850mb temps dropping rapidly from around -7C this evening to
near -20C by late morning Fri, leading to rapid LES development
under post-frontal low-level nnw flow. Despite the strong
instability, the rapidly lowering inversion to 4-5kft, sharp
transition to anticyclonic flow and quick influx of drier air will
hold LES in check. Only expect snow accumulations of 1-2 inches
tonight/Fri with maybe a few local amounts near 3 inches. The LES
will quickly diminish w to e on Fri, likely ending over the w by
late afternoon, and will end e around sunrise Sat. Weather on Fri
will be a huge change from today`s warmth as the surge of much
colder air results in daytime temps in the 10-15F range n and around
20F across the s central. Gusty north winds, especially in the
morning, will drive wind chills down the single digits above and blo
zero on Fri. So, it will feel 40-50 degrees colder on Fri compared
this afternoon. Passing sfc high pres ridge and a dry air mass Fri
night should allow temps to fall to a few degrees above and blo 0F
interior w half.
Over the weekend, the mid-upper level trough lifts into eastern
Canada and the eastern U.S. as ridging expands across the Upper
Great Lakes. In this transitioning flow, another fairly vigorous
shortwave will track ese from Saskatchewan/Manitoba Sat to northern
Ontario late Sat night/Sun. Strong waa in response to this wave
pushes into the area Sat aftn/night and may support a period of -sn
into the eastern fcst area late Sat night or Sun morning (only 20pct
chc for now), but better chc of pcpn will certainly pass by to the n
and ne, closer to track of shortwave and deeper into the retreating
cold air where saturation for pcpn production is more likely. As
this wave continues eastward, another push of caa occurs Sun, but
probably not quite cold enough to generate any LES except for
maybe some flurries into the Keweenaw and eastern fcst area.
On Mon, deepening mid-level trough over western N America will
quickly back flow to the sw into the Great Lakes, leading to
unseasonable warmth spreading out of the Plains to the Great Lakes
Mon/Tue. Strong waa/isentropic ascent lifting into the area late Sun
night/Mon morning suggests some potential of a light wintry mix
(less than 20pct maybe over the tip of the Keweenaw), but again,
better chc of pcpn will be n and ne of the area, deeper into the
retreating cold air. Ensembles, particularly the EPS and GEPS, show
increasing probability of max temps exceeding 50F Mon into Tue over
the west half, especially on Tue where probabilities rise into the
60-80 percent range.
As for pcpn Tue-Thu, models seem to moving toward some agreement on
how things will play out. Southern stream energy originating off of
CA seems unlikely to phase with the shortwave in the amplifying
northern stream. These lead waves would support some shra across
Upper MI as they lift thru the Upper Mississippi Valley/Great Lakes
on Tue. Might even be some thunder with indications of elevated
instability lifting into the area. The main shortwave will then
swing into our area Tue into Wed, leading to an organizing sfc low
along cold front that moves into the western Great Lakes Tue in
association with the lead energy. That low then deepens as it lifts
ne. Whether this low deepens rapidly to support a significant snow
for portions of Upper MI remains to be seen, but based on
deterministic runs and ensembles, that still seems unlikely.
However, the ensembles have increased the potential of at least some
accumulating snow across Upper MI for Wed into early Thu.
&&
.AVIATION /00Z TAFS THROUGH 00Z SATURDAY/...
Issued at 624 PM EST Thu Feb 22 2024
VFR conditions early this evening give way to MVFR cigs and
occasionally IFR vis from time-to-time as a cold front brings
blustery northerly winds and lake-effect snow showers across the TAF
sites late tonight into Friday (KIWD and possibly KSAW are more
likely to see IFR vis reductions last longer than KCMX). Also, NBM
guidance is bringing some LLWS over KSAW this evening for a couple
hours, with the gusty winds associated with the cold front making
its way over the terminal after midnight tonight. As the lake-effect
snow dissipates Friday, expect there to be a slow improvement across
the TAF sites, with KIWD improving to VFR by early afternoon and
KCMX and KSAW improving to VFR by late afternoon.
&&
.MARINE...
Issued at 449 PM EST Thu Feb 22 2024
Low pres tracking se into northern Ontario today will drive
associated cold front s across Lake Superior tonight. West winds
shift north and increase further tonight/early Fri after cold front
passes. Much colder air surging s into the area, leading to strong
overlake instability, combined with an incoming 4mb/3hr pres rise
will support 35-40kt nnw gales late this evening to early Fri
morning over central and eastern Lake Superior. Given how quickly
the cold air moves into the area and how strong the resulting
instability becomes over the water, winds may exceed all model
guidance. Although there are no indications for winds to exceed 40kt
in the model guidance, peak gusts to 40-45kt are a possibility in a
corridor from north of Copper Harbor down toward Marquette.
Combination of the much colder air and building waves/strong gusty
winds will lead to heavy freezing spray over all but western Lake
Superior late tonight thru Fri morning. Winds will then diminish as
high pres ridge arrives Fri night. Gusts will drop to blo 20kt from
w to e Fri aftn thru Fri night. As the ridge departs and the next
low pres tracks e toward far northern Ontario on Sat, sw winds will
increase, reaching 25-30kt late Sat aftn thru Sat night.
Probabilistic guidance indicates a 30-50pct chc of reaching low end
gales at this time. Winds will shift w to nw on Sun and diminish
just a little. After winds briefly fall off to under 20kt Sun night,
they will increase to 20-25kt on Mon.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
Small Craft Advisory until 5 PM EST /4 PM CST/ Friday for
LSZ240>242.
Heavy Freezing Spray Warning from 1 AM EST /midnight CST/ to 1
PM EST /noon CST/ Friday for LSZ240>251-263>267.
Gale Warning from 1 AM to 8 AM EST Friday for LSZ243>251-
264>267.
Small Craft Advisory from 8 AM to 5 PM EST Friday for LSZ243-
244-248>251.
Small Craft Advisory from 8 AM to 1 PM EST Friday for
LSZ245>247.
Lake Michigan...
None.
&&
$$
UPDATE...TAP
SHORT TERM...LC
LONG TERM...Voss
AVIATION...TAP
MARINE...Voss
Area Forecast Discussion
National Weather Service Nashville TN
818 PM CST Thu Feb 22 2024
...New UPDATE...
.UPDATE...
Issued at 809 PM CST Thu Feb 22 2024
Radar this evening shows rain and storms have congealed into a
solid line near and north of I-40, with activity expected to
continue southeastward through the rest of the evening before
moving out after midnight. Have not seen any strong activity due
to the near-zero MLCAPE and limited elevated CAPE, but there has
been plenty of lightning. Still cannot rule out a storm or two
with hail or gusty winds, mainly in our southwest counties where
MLCAPE could rise into the couple hundred J/Kg before the line
moves through. In addition, parts of our northern counties have
received quite the dousing of rain today with 1.6 inches reported
at the Cumberland River gauge in Dover. With line progressing
southeastward at a steady clip, not anticipating any flooding
issues but some road ponding or high water in low lying areas
could occur. Forecast already has all of this covered and only
made minor tweaks.
&&
.SHORT TERM...
(This afternoon through Friday Night)
Issued at 123 PM CST Thu Feb 22 2024
A cold front is currently pushing across the Great Plains with
the surface low located over Missouri. With the arrival of the
cold front will come the arrival of thunderstorms, starting across
our northwest. The HRRR continues to show initially unorganized
storms developing over our northwest and quickly filling in to
form a QLCS-type line that will push through all of Middle
Tennessee. So...What about severe potential? The threat for severe
weather is low. The greatest impacts today will be wind and
small/maybe medium-sized hail. The biggest limiting factor today,
though, is moisture. Dew points are expected to stay in the 50s,
MAYBE touch 60 degrees across our west for a short time, but these
values generally do not support a highly unstable environment and
thus limit instability overall. Surface-based CAPE continues to
be just marginal; on the order of 100-200 J/Kg.
Hail: Latest forecast soundings continue to feature steep mid-
level lapse rates between 6.0-6.5 C/km and decent mid-level
instability values between 300-400 J/Kg. As noted from the 12Z OHX
sounding this morning, the freezing level was quite high - over
10,000 ft. which means the majority of larger hail stones that
develop will mostly melt before reaching the surface. If mid-
level instability increases, though, this could help push out some
larger hail. Likely still below severe criteria, but maybe
nickel-sized. Pea-sized hail will be common with stronger storms,
though.
Wind: I`m sure you`ve noticed the breeze today. That is thanks to
the tight gradient surrounding the approaching surface low.
Within the storms, though, some higher gusts are possible as we
have sufficient shear in place this afternoon. The 12Z HREF
yields a few pockets of 40+ mph for the eastern-half of our CWA
ahead of the line. This could certainly happen with any heavier
downpours as it would help kick the wind up and out ahead of the
line.
QPF: This will be quick moving system, but as mentioned above, there
could be a few storms that produce locally heavy downpours. Models
show a PWAT around 0.9" which is in the 90th percentile for today.
DCAPE is also between 600-700 J/Kg - plenty enough for a healthy
downpour. QPF from this system ranges from 0.35" across the
northwest to 0.60" across the east.
Rain and storms will come to an end from NW to SE, completely
exiting the area overnight tonight.
Friday will kick off what will be a pretty fantastic weekend,
weather-wise. Highs on Friday will be in the 60s with overnight
lows near 40.
&&
.LONG TERM...
(Saturday through next Thursday)
Issued at 123 PM CST Thu Feb 22 2024
A dry cold front will push through the area Friday, making for a
cooler day Saturday with highs in the upper 40s to low 50s. Lows
will get below freezing on Saturday night for most everyone. The
cold won`t last for long, though, as models note ridging
developing over the Ohio Valley by Sunday. This will help squeeze
our temperatures back up into the 60s by Sunday. For the new
week, it`s really going to get warm with temperatures rising into
the 70s Monday-Wednesday. Models suggest an active pattern for
next week, but it`s way too early for specifics. Let`s just leave
it at we`ll be monitoring the situation as we draw nearer to next
week.
&&
.AVIATION...
(00Z TAFS)
Issued at 528 PM CST Thu Feb 22 2024
MVFR or lower conditions expected through at least 08Z as SHRA/TSRA
moves through the area. Tried to time down the heaviest line,
that will move through generally between 02Z to 07Z from NW to SE.
SHRA/TSRA will move out quickly, but low cigs will likely linger
especially along the Plateau. Entire area should return to VFR by
18Z. Current S/SW winds will shift to NE between now and 09Z
beginning with CKV and ending with CSV. Wind gusts up to 15 to 20
knots possible throughout much of the current TAF period.
&&
.PRELIMINARY POINT TEMPS/POPS...
Nashville 46 63 40 49 / 100 0 0 0
Clarksville 43 61 38 47 / 80 0 0 0
Crossville 44 57 34 44 / 100 10 20 20
Columbia 46 63 40 52 / 100 0 0 0
Cookeville 46 57 37 44 / 100 10 20 20
Jamestown 43 57 35 42 / 100 10 20 30
Lawrenceburg 47 63 40 52 / 100 0 0 0
Murfreesboro 46 63 39 49 / 100 0 10 10
Waverly 43 61 40 49 / 100 0 0 0
&&
.OHX WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
UPDATE.......Shamburger
SHORT TERM...Baggett
LONG TERM....Baggett
AVIATION.....Adcock
Area Forecast Discussion
National Weather Service Raleigh NC
930 PM EST Thu Feb 22 2024
.SYNOPSIS...
A storm system will cross the mid-Atlantic region tonight through
Friday. An upper level disturbance will pass over the Carolinas
Saturday, then high pressure will build over the Southeast states
Saturday night through Sunday.
&&
.NEAR TERM /THROUGH TONIGHT/...
As of 930 PM Thursday...
The latest available data showed a very dry sub-cloud layer east of
the mountains with PW values of only 0.43 at GSO and even Blacksburg
was 0.41. The SW wind aloft will increase later tonight to 35-45kt
transporting deeper moisture (note the 1.1 inch PW at Nashville) to
our west over the region. However, the latest hi-res guidance
including the HRRR are believable in allowing for a good portion of
the first round of showers now entering the NC mountains from the
west to dissipate over our NW Piedmont overnight into the early
morning hours. We will maintain the slight chance to chance POP in
the west and north beginning in a few hours to continue due to this
initial dry air that has to be moistened. Later tonight, the chances
should go up in most areas with several rounds of showers possible
Friday. See the short term discussion below. Temperatures tonight
will be well above normal-pre-frontal. Therefore, expect readings in
the 50s (upper 40s N-NE).
&&
.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
As of 300 PM Thursday...
There will be separate periods of showers as prefrontal convection
develops, and the aforementioned fronts move by. PW values will
increase to around 125% of normal, with only light to moderate
accumulations expected (around one-quarter inch to the north and one-
half of an inch across the south). Instability and shear will
increase across the region Friday, with isolated thunderstorms
possible across areas south and east of the Triangle Friday morning
and afternoon. Areas across SC are in a Marginal risk of severe
thunderstorms Friday, however severe storms look less likely across
our area. Breezy SW wind gusts to 20 mph will switch NWerly after
the cold front moves by Friday, then diminish overnight. Showers
should exit east out of the region by early Friday evening. Highs
will remain above normal, with most areas in the low to mid-60s.
The brief break in showers will only linger through Friday night as
the next cold front and upper wave quickly move SE across the
region. Isolated to scattered showers will begin to develop Sat
morning, with the greatest coverage Sat afternoon, and then showers
diminish early Sat evening. Accumulations will be light, mainly less
than one-tenth of an inch. Cold air advection and increased cloud
cover will help lower high temperatures compared to Friday, with
highs limited to the low 50s N to near 60 S.
Clouds will quickly clear Saturday night, and with good radiational
cooling and cold air advection in full swing, lows will dip to near
5 to 10 degrees below seasonal normals, with temps diving into the
mid-20s to low 30s.
&&
.LONG TERM /SUNDAY THROUGH THURSDAY/...
As of 232 PM Thursday...
...Significant increase in temperatures by mid week...
Sunday morning an upper level trough over SE Alaska and British
Columbia will begin its journey deepening across CONUS before moving
across NC next Thursday. Ahead of the this a few shortwaves will
move across the region late Monday and Tuesday with limited impacts
expected. At the surface, high pressure will linger over the region
Sunday before shifting offshore Monday morning. As mentioned before
a few upper level shortwaves will move just north of the region
Tuesday, which could result in a few isolated showers along the
northern Piedmont. For now, have slight chance of showers for areas
along and north of US 64 late Tuesday night into Wednesday morning.
Wednesday is slightly uncertain as models begin to differ on timing
and location of the next low pressure system moving across the
central plains. Euro has precipitation moving back in after a short
lull Wednesday morning where as the GFS has Wednesday completely
dry. Overall went with NBM guidance with low end slight chance of
rain (<20%) for Wednesday. With both models showing the upper level
trough moving across the region around Thursday, went with a
surface cold front moving across the region Thursday which will
bring the best chance of showers and the possibility of a few
stronger storms. Cold front is expect to clear the region by Friday
morning.
Temperatures will start off Sunday below average with highs in the
low to mid 50s and overnight lows in the 30s. After that, strong S
to SW flow will take over and temperatures will become 15 to 19
degrees above normal by wednesday with highs expected in the low 70s
NW to upper 70s SE. With the cold front moving in Thursday,
temperatures are expected to once again moderate with high in the
low 60s NW to upper 60s/low 70s SE.
&&
.AVIATION /23Z THURSDAY THROUGH TUESDAY/...
As of 610 PM Thursday...
TAF period: Flight conditions will begin as VFR at all sites with an
occasional gust up to 20 kt through the evening and low-level wind
shear initially at INT/GSO eventually spreading east to all
terminals. With the 00Z TAF package, delayed the arrival of showers
by 1-2 hours everywhere as well as delaying the arrival of MVFR and
eventually IFR ceilings. Cannot rule out gusts persisting through
the night in addition to the LLWS, but confidence in gusts is not
high enough to keep them going through the night. As a cold front
moves through late morning into the early afternoon, ceilings should
begin to lift along with wind veering to the west. When the front
continues to push farther east through the afternoon, showers should
decrease in coverage and northwest wind gusts to 20 kt will develop.
An isolated thunderstorm cannot be ruled out at RDU/RWI/FAY during
the afternoon, but confidence is too low to include in the TAF at
this time.
Outlook: Any lingering MVFR/IFR conditions will alleviate by sunset
Friday evening as the front pushes east of the area and drier air
filters in. A passing upper wave may bring sprinkles on Saturday,
but skies should remain VFR. VFR conditions will continue through
the rest of the outlook period.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SYNOPSIS...Hartfield
NEAR TERM...Badgett
SHORT TERM...Hartfield
LONG TERM...JJT
AVIATION...Green/Luchetti