Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 01/28/24
Area Forecast Discussion
National Weather Service Binghamton NY
1028 PM EST Sat Jan 27 2024
.SYNOPSIS...
A low pressure system tracking to our south will bring a mix of
rain and snow to the region tonight through the day Sunday.
Higher elevations will see mostly snow with several inches while
valleys will see mostly rain. Quiet and seasonable weather is
then expected through at least the middle of the week.
&&
.NEAR TERM /THROUGH SUNDAY NIGHT/...
1025 PM Update:
With the latest hi-res guidance, starting to see some
indications that higher snowfall amounts could occur with the
potential of a band setting up Sunday afternoon, which could
produce heavy snow. If this band sets up, colder temperatures
from aloft can be brought down to the surface, which could allow
for precipitation to be mainly snow (perhaps even in the
valleys). For now, bumped up forecast snow totals slightly and
left the Winter Weather Advisories as is, but will let the
upcoming midnight shift take a closer look at the full 00Z
guidance suite before making any potential wholesale changes.
Definitely a very tricky forecast; this system has the potential
to be an "overachiever" in some spots, especially at the higher
elevations above 1200 feet.
650 PM Update:
No changes were made with this update. Will be taking a closer
look at the near term guidance throughout this evening as the
forecast continues to be quite tricky for this upcoming system.
There is certainly a potential for this system to be an
"overachiever" in terms of snowfall, especially at the higher
elevations. But there is also an equal possibility this system
could underperform if there is just not enough cold air present.
The difference of a degree or two could be the determining
factor if this system could be mainly moderate to locally heavy
snow Sunday, or a rain/snow mix, with mainly rain in the
valleys.
300 PM Update...
A surface low will pass to our south tomorrow with
precipitation moving into the region from south to north
tonight. Looking at current observations and some of the
soundings launched this morning there is just not a lot of cold
air in place ahead of the system and wet bulb temperatures are
above freezing into Canada. The sounding from BUF and OKX this
morning had above freezing wet bulbs all the way up to near 850
mb. ALY was cooler but will need to see what the 0Z sounding
will look like. With winds at 850 E to SE with the precipitation
it looks like warm air will just be advected into the storm.
Given forecast soundings have marginal thermodynamic profiles
with a deep isothermal layer right around freezing trends in low
level temperature will be critical to what the precipitation
will be.
Given that most of the models have trended a little warmer with
recent runs and observed temperatures are all warm decided to
lower the snow probabilities for low elevations with ptypes
being mostly rain for elevations below 1000 feet in NEPA. Since
the thermodynamic profiles did have an isothermal layer near
freezing and easterly winds, there is a potential that adiabatic
cooling of the air being forced over the Poconos will drop
temperatures below freezing with rain so a winter weather
advisory was put out for Pike county with ice accumulations near
the crest of the Poconos approaching 0.10 inches of radial ice.
For the Southern Tier of NY and north, thermodynamic profiles
had more gradual cooling with height so rain or snow will be the
precip type depending on elevations. Most forecast soundings
had the wet bulb freezing elevation around 1500 to 2000 feet
with high chance of melting of the hydrometeors below 800 feet
as wet bulbs get above 35 degrees along with the heaviest
precipitation occurring during day light hours. Steuben, Yates,
and Schuyler were put under winter weather advisories as there
is plenty of higher elevation and there will be a quicker
transition to snow tomorrow once the center of the low moves off
the Mid Atlantic coast. Advisories were also issued for
Delaware and Otsego counties with the Catskills seeing mostly
accumulating snow with this event. Madison and southern Oneida
counties also have a high probability of seeing near 4 inches of
snow but the E to SE flow may lead to some downsloping so given
that the forecast error would be on the lower side decided to
hold off for those counties. Another wrench in the forecast was
snow banding, the WPC snow band probability tool did show quite
a few of the HREF members as well as the time lagged HRRR with a
snow band developing. If this does there could be enough
dynamic cooling to get snow levels to drop a bit but still would
be hard to get decent accumulations to valley locations.
Cold air advects in Monday night with precipitation becoming
showery and winding down. Forecast soundings dont show a great
profile for lake effect as 850 mb temperatures dont get quite
cold enough to get lake induced instability.
&&
.SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
215 PM update...
Low pressure system impacting the region on Sunday will
exit to the east on Monday. Northerly flow on the backside of
the low will push a cold Canadian airmass into the region. 850mb
temps of -7C to -9C moving over the relatively warm waters of
Lake Ontario and even the Finger Lakes should initiate some
lake induced snow showers through the day Monday. Accumulations
should be light, with up to 0.5in expected.
A narrow axis of high pressure in the mid levels combined with a
weak surface high will move into the area from the Great Lakes
Monday night. This ridge will shift winds to the SSW, dry the
atmosphere and bring an end to the lake snow process.
Temperatures are expected to drop into the upper teens and mid
20s Monday night.
The ridge axis continues to move across the region Tuesday,
keeping weather conditions quiet with cool but very seasonal
temperatures. High temperatures on Tuesday are expected to top
out in the mid to upper 30s, with some lower 30s in the higher
elevations that may have more of a snowpack. Lows Tuesday night
will be in the mid to upper 20s west of I-81 and upper teens to
low 20s east of I-81.
&&
.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
215 PM update...
Quiet weather conditions are expected Tuesday and Wednesday as a
trough digs SE through the Ohio Valley into the Carolinas. We
may get grazed with a little precipitation over our SW zones,
but most of it will miss us to the east.
The weather pattern for the back half of the week and the
weekend will be determined by an Omega block that is forecast
to set up over North America. Current ensemble guidance has the
block shifted a little farther west than runs earlier in the
week. This setup brings us cool, unsettled weather for the
weekend as the trough on the eastern side of the omega block
sits right over the NE US. If the block sets up farther east, we
should miss a lot of the unsettled weather and temperatures
should be warmer than average. Given the recent ensemble trends,
it is looking like the first scenario is more likely, which is
what was used for the forecast; warmer than average temperatures
Wed thru Fri, with cold and unsettled conditions Friday night
through the weekend.
&&
.AVIATION /03Z SUNDAY THROUGH THURSDAY/...
Expect IFR to continue at SYR/RME to continue through the night,
though the LIFR ceilings and mist should begin to lift as low
level winds shift. Elsewhere expect lowering ceilings,
especially after 06Z, with precipitation moving from S to N,
reaching AVP by 07Z, BGM/ELM around 12Z and SYR after 15Z, with
a couple hours of virga or VCSH possible at the outset.
Main concern is with precip type on Sunday. Surface temperatures
look favorable for mostly rain in the lower elevations,
especially at AVP, with mixing at times, but model soundings
suggest warm layer will be very shallow. Forecast confidence in
p-type (and vis) is very low, and carried PROB30s with SN at
various points. Best chance for snow will be at ITH and BGM
given elevations.
Outlook...
Sunday night...IFR to perhaps MVFR continues as another round
of rain and snow produces restrictions.
Monday...Restrictions possible with scattered snow showers.
Tuesday into Thursday...Low chance for restrictions from
rain/snow showers.
&&
.BGM WATCHES/WARNINGS/ADVISORIES...
PA...Winter Weather Advisory until 7 PM EST Sunday for PAZ048.
NY...Winter Weather Advisory from 7 AM Sunday to 4 AM EST Monday
for NYZ015-022-023.
Winter Weather Advisory from 7 AM Sunday to 6 AM EST Monday
for NYZ046-057.
&&
$$
SYNOPSIS...AJG/BJG
NEAR TERM...AJG/BJG
SHORT TERM...JTC
LONG TERM...JTC
AVIATION...AJG/MPH
Area Forecast Discussion
National Weather Service Dodge City KS
840 PM CST Sat Jan 27 2024
.KEY MESSAGES...
- Much less fog Saturday night and Sunday morning, compared to
previous nights.
- A long stretch of unseasonably mild and dry weather Sunday
through all of next week.
&&
.UPDATE...
Issued at 840 PM CST Sat Jan 27 2024
Infrared satellite imagery at 830 pm showed a completely clear
sky over SW KS and adjoining areas, in sharp contrast to
previous nights. Light, drier westerly flow will prevail
tonight, precluding fog in most areas. Stratus has retreated
well east of the Kansas turnpike this evening, and will have a
long ways to retreat westward to make it to our eastern zones
through morning. Kept patchy fog in the weather grids for the
eastern zones through sunrise Sunday, but indications are any
fog will be limited to none in SW KS. Temperatures will be
seasonably cold in the 20s at daybreak.
Models show a net warming of about +5C at 850 mb on Sunday, and
with full sunshine and gentle westerly downslope, the warmest
temperatures we have seen so far in January are expected.
Afternoon temperatures will range from the lower 50s on the
deepest old snowpack north, to the lower 60s adjacent to
Oklahoma. The high at DDC today was 52, which was the warmest
temperature since January 3, and Sunday`s forecast high of 59
will be the warmest we have seen in January.
&&
.SHORT TERM /THROUGH SUNDAY/...
Issued at 357 PM CST Sat Jan 27 2024
The beginning of our pattern shift to drier/warmer weather was
underway today. Water vapor loop and RAP analysis this afternoon
showed the large scale ridge axis across the Great Basin region,
extending out across the Rockies. Early morning low stratus cloud
and fog which lingered around Stafford-Pratt-Barber County dissolved
by midday.
A lot of melt was going on today in remaining large drifted areas
from our 8 January blizzard. Saturated grounds and still rather high
surface relative humidity, a weakening wind, and clear sky will
support development of at least some patchy ground fog early Sunday
morning, although redevelopment of widespread dense fog is not
expected given the continued downslope component to what little wind
we will have. In the Wx grids, we will carry Patchy/Areas Fog
generally east of U283 with greatest probability of 1/4 mile
visibility across Ellis, Rush, Pawnee, Stafford County. 12Z and 18Z
runs of the HREF bring 1/4 mile visibility probs up to as high as
70%.
Any ground fog Sunday morning will dissolve by mid morning as
boundary layer mixing commences due to insolation. Temperatures are
expected to warm fairly quickly from mid-morning through midday,
topping out in the mid to upper 50s as the lower troposphere
continues to warm due to classic downslope from Colorado-Wyoming in
the 850-700mb layer.
&&
.LONG TERM /SUNDAY NIGHT THROUGH SATURDAY/...
Issued at 357 PM CST Sat Jan 27 2024
A much-welcomed warm/dry pattern will be the theme much of the
upcoming week as a large scale ridge moves out of the Rockies and
across the Great Plains this week. Continued downslope component to
the lower-mid tropospheric flow field will support afternoon
temperatures well into the 50s and morning lows in the upper 20s to
lower 30s. A strong shortwave trough will move southeast across the
Upper Midwest/Great Lakes region on Tuesday, which will bear some
watching for a slight pullback in temperature, but this wave will
likely be too far removed from southwest Kansas to impact
temperatures much, if at all. The mild and dry weather is expected
through Thursday, but a major pattern change will be occurring over
the week.
Wet weather is likely to return as an impressive, southern branch of
the Pacific jet breaks through the central CONUS ridge Friday-
Saturday, leading to storm development across the Central/Southern
Great Plains. Global models and their associated ensemble systems
are in pretty good agreement through F+156 hours (valid 00Z Saturday
Feb 3) as a digging, cyclonically-curved jet digs into the Desert
Southwest/Northern Mexico region. This will favor significant lower
tropospheric development of a leeside trough and eventual
cyclogenesis, allowing for northward transport of Gulf of Mexico
moisture, which will eventually manifest as a large area of warm-
conveyor belt precipitation from Texas all the way into Kansas. All
models show some semblance of a large scale precipitation event,
with detail uncertainties, of course, in timing and areal
positioning of precip axes.
Another complicating factor will be just how much the northern
branch of the jet stream gets involved regarding how much (if
any) cold air can come south ahead of the precipitation
development. Latest ECMWF model is quite a bit colder than other
models now, with much of its precip in the form of snow over
the weekend (at least across western Kansas). That being said,
there is not much in the way of ensemble support for a major
snow storm, but there is for a formidable precipitation event...
i.e. latest Super Ensemble 25-75th percentile (half of the
100-member super ensemble) total precipitation for Dodge City in
the 0.40 to 1.20 inch range. So, this will be a storm system to
certainly watch, as there will most likely be quite a bit of
low level moisture infused into the system.
&&
.AVIATION /00Z TAFS THROUGH 00Z MONDAY/...
Issued at 438 PM CST Sat Jan 27 2024
Excellent flying weather has returned to the airports, and is
expected to continue at LBL/GCK/DDC through this TAF period,
with VFR/SKC and light winds. Light winds will maintain a
westerly component, but remain less than 10 kts. Satellite
imagery shows that stratus has cleared to roughly the Kansas
Turnpike as of 2230z. Consensus of short term models suggests
some stratus and/or reduced visibility will retreat westward to
possibly include HYS 06-12z Sun, and this possibility was
included in the TAF. Otherwise, VFR/SKC will continue through
Sunday.
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
UPDATE...Turner
SHORT TERM...Umscheid
LONG TERM...Umscheid
AVIATION...Turner
Area Forecast Discussion
National Weather Service Hastings NE
552 PM CST Sat Jan 27 2024
.KEY MESSAGES...
- The main story is that we`re entering a much sunnier, warmer, and
dry pattern for much of the next 7 days.
- Fog is possible once again tonight, but should remain more patchy
in nature compared to the last several days.
- Warmer temperatures and melting snow could result in POSSIBLE ice
jam-induced flooding along the Platte/Loup River systems over the
coming week, although uncertainty is high as this warm-up will be
fairly gradual.
- Dry weather remains in the forecast through the end of next
week, with a chance for rain returning next weekend.
&&
.DISCUSSION...
Issued at 325 PM CST Sat Jan 27 2024
The main potential forecast impact in the short term will be dense
fog. We`ve finally tapped into some westerly flow in the low levels,
which has scoured out the low clouds/fog earlier today. In it`s wake
we`re seeing full sunshine and mild temperatures above freezing,
even in areas N/E of the Tri-Cities, where snowpack is still deep -
around 6-12". Elsewhere, we`ve seen a gradual decline to few/several
inches, and areas W of Hwy 283 and down around Mitchell Co in KS
only have a T-2". These fringe areas will see significant melting
this aftn, and the concern is that this added boundary layer
moisture, when combined with fairly optimal radiational cooling
conditions (clear skies, light winds), will be enough for more
fog development late this evening and overnight. Furthermore,
dew points today have actually risen during the day today,
despite the drier W/NW wind, so crossover temps will be easily
met as lows should fall into the teens to low 20s. So there are
several factors that support fog again tonight, and this is
backed up by SREF progs showing generally 40-80 percent chance
for <1mi visibility from W to E. HREF is also similar.
Have increased the areal coverage of patchy fog to encompass roughly
areas with at least an inch or two of snowpack where diurnal
cooling should be most efficient. Have held off on getting too
aggressive, though, as the usually overdone HRRR has been
pretty limited in its depiction of fog tonight, and mostly
confined to areas SW of the Tri- Cities. Will continue mention
of fog in HWO, but no plans on another advisory at this time.
Will just have to monitor trends and nowcast as necessary.
The main story for next week will be the much warmer, sunnier, and
mainly dry pattern that will dominate not only the local weather
scene, but much of the central/northern Plains into S Canada.
Obviously, the warmup will be held back by the snowpack, but daily
highs well above freezing and overnight lows only near or slightly
below freezing will promote a very steady daily decline. This will
allow the warmer temps to gradually edge further across the region
such that by the end of the week even far E/EN zones should make a
run into the 50s. At the other end of the spectrum, areas W of
Holdrege are already mostly snow free, so by the end of the
week these areas could make a run at mid 60s at least once or
twice. A strong January thaw for sure!
Worth noting that with the warmer temps and melting snow pack will
come increasing risk for ice jams on the Platte and Loup Rivers. Ice
jams are notoriously difficult to predict, but in general, river ice
breakup due to warmth AND rising flow from melting snow tend to incr
the odds...especially for known trouble spots and near bridges.
Probably going to take another few days to get things moving, but
mid to especially late week will be the time to watch.
The latest forecast is dry until the very end, with the next decent
opportunity for moisture not coming until about day 7-8. With that
said, wouldn`t be surprised if some sprinkles or very light rain is
added to the forecast Mon eve/night for a weak front that skirts the
forecast area. In terms of the day 7-8 chances, the NBM suggests 50-
70 percent chances for rain, but the latest deterministic EC is
completely dry as it keeps all moisture S of I-70. This seems like
an outlier solution at this time as even its own ensemble gives most
of the area better than 50/50 chances. Still way out there with
plenty of time to work out the details. More confidently, though,
this system looks to bring an end to the string of mild weather.
&&
.AVIATION /00Z TAFS THROUGH 00Z MONDAY/...
Issued at 541 PM CST Sat Jan 27 2024
The wind will remain light and generally out of the northwest
this evening and then more southwesterly on Sunday. The main
concern will be fog and low ceiling potential again tonight.
However, MVFR and IFR ceilings and visibility are less likely
tonight and thus will keep IFR conditions out of the TAF for
now, although IFR conditions are still possible mainly after
midnight through a few hours after sunrise. The MVFR visibility
that we have in the TAF is low confidence, but again still
possible. With so many foggy nights in a row it is hard to
believe that we could be fog free tonight, but we do have more
of a westerly wind component tonight, which makes fog more
difficult.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...None.
KS...None.
&&
$$
DISCUSSION...Thies
AVIATION...Thies/Wesely
Area Forecast Discussion
National Weather Service Key West FL
1002 PM EST Sat Jan 27 2024
...New DISCUSSION, MARINE, AVIATION...
.DISCUSSION...
Issued at 1002 PM EST Sat Jan 27 2024
Skies were mostly to partly clear this evening as some moisture
trapped at 4000-5000 feet occasionally erupts into a high-based
stratocumulus with a few southeastward-propagating gravity waves
enhancing cloud cover from time to tome. Temperatures were in the
mid 70s with dewpoints in the lower 70s. Light southeast winds 5
mph or less were occurring over the Upper Keys and the Key West
area, however near-calm and even very light north northeast flow
had begun across the north side the middle and some lower Keys.
The evening Key West sounding indicated total column moisture
estimated right near the daily mean for a January 27th evening,
but slightly more stable than average owing to a weak inversion
near 850 mb. Unfortunately for the wintertime Keys airmass,
dewpoints seem to be running near the top 10% for the date.
Little has changed in the very short-range guidance including the
HRRR concerning the weak pooling of moisture and maintenance of
elevated dewpoints over relatively cooler sea surface
temperatures. Florida Bay, on the otherhand, warmed into the upper
70s to near 80F at several spots, thus will be monitoring mainly
the Gulf waters north of the Lower Keys for any fog and stratus
development. This could begin to happen over the next several
hours, although guidance insists the light southeast winds will
resume especially after 06Z as 850 mb heights fall with the
approach of the upper trough into the northern Gulf. The current
forecasts have fog indicated in our northern waters, but should
northerly flow induced by the near-surface density differences
last a bit longer, some low stratus and patchy fog could work into
portions of the Keys before morning.
&&
.MARINE...tonight
Issued at 1002 PM EST Sat Jan 27 2024
There are no watches, warnings, or advisories currently in effect
for the coastal waters of the Florida Keys. A Small Craft Advisory
likely will be required for all the Florida Keys Sunday night.
Light southeast breezes will veer to the southwest overnight. A
period of sea fog over the Gulf waters especially beyond 5 fathoms
to the north/northwest of Key West could develop during the early
morning hours Sunday. The next cold front will push through the
Florida Keys coastal waters late Sunday afternoon and Sunday
evening, with freshened northwest to north breezes expected in its
wake. Northerly breezes will diminish Monday afternoon through
Tuesday night. A reinforcing cold front will push through the Keys
Wednesday night, followed by a second period of diminishing
breezes Thursday and Thursday night.
&&
.AVIATION...
(00Z TAFS)
Issued at 1002 PM EST Sat Jan 27 2024
Light east to southeast winds this evening may become variable or
even calm through the late evening, before resuming near 5 knots
and veering from southeast to southwest by Sunday morning.
Currently there is a slight chance for some few to scattered stratus
with bases close to FL010 near or just north of the terminals
mainly in the 06Z to 12Z time period Sunday. Otherwise VFR
conditions are expected to prevail until a cold front moves
through the Keys 19Z-21Z time frame. A period of lower MVFR
ceilings is possible near and shortly after the frontal passage,
but there is higher confidence in increasing westerly winds
shifting out of the northwest near 15 knots with frequent gusts
over 20 knots early Sunday evening.
&&
.KEY WATCHES/WARNINGS/ADVISORIES...
FL...None.
GM...None.
&&
$$
Public/Marine/Fire...JR
Aviation/Nowcasts....JR
Data Acquisition.....DR
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Area Forecast Discussion
National Weather Service North Platte NE
523 PM CST Sat Jan 27 2024
.KEY MESSAGES...
- Mild conditions are likely Sunday through Friday.
- A significant storm system may begin to affect wrn and ncntl
Nebraska next Saturday. Depending on the storm track and
evolution, the impacts of the storm across wrn/ncntl Nebraska could
be excessive rainfall, ice-jam flooding, snowmelt and
overland flooding.
&&
.SHORT TERM /THROUGH SUNDAY NIGHT/...
Issued at 322 PM CST Sat Jan 27 2024
One more solid night of radiational cooling is expected tonight. The
h850-300mb RH will drop to around 20 percent with light winds and
modest warm air advection. The temperature forecast tonight uses the
guidance blend plus bias correction and this forecast is close to
NBM 25th percentile.
The forecast highs Sunday lean toward the warmer RAP model using the
bias corrected NAM, and the bias corrected short term model blend.
This forecast maintains highs around 40 across ncntl Nebraska to
upper 50s across wrn Nebraska. The forecast is slightly warmer than
the NBM 50th. Warm air advection will send h850mb temperatures to 6-
8C during the afternoon and the forecast wages h850mb will be the
afternoon mixing height. The RAP model shows the mid and high clouds
across the Pacific NW thinning out Sunday and the expected near-full-
sun conditions is the basis for the temperature mark-up.
The guidance blend plus bias correction suggested lows in the 20s to
around 30 Sunday night with the warmest lows across ncntl Nebraska.
The temperature forecast will require the atmosphere to remain
somewhat mixed. Temperatures at h850 will plateau at 7-9C overnight
and this is the mentality for the mild overnight lows.
&&
.LONG TERM /MONDAY THROUGH SATURDAY/...
Issued at 322 PM CST Sat Jan 27 2024
A blend of the NBM 50th plus the very warm bias corrected GFS plus
the previous forecast is in place for highs in the 50s to lower
60s Monday through Thursday. The BCGFS appears to do a
reasonable job keeping highs cooler across ncntl Nebraska. The
basis for the temperature markup is generally clear skies
suggested by h850-300mb RH of 40-50 percent Monday which falls
to 20-30 percent Tuesday through Thursday. There are also h850mb
temperatures warming to 8- 10C and this is the target mixing
height for this forecast.
Attention turns to the potential excessive rainfall, ice-jam
flooding, snowmelt and overland flooding event beginning Saturday.
The event may not mature until Saturday night and Sunday; beyond the
range of this forecast. Nonetheless, today`s ensemble men runs of
the GFS, ECM and CMC have the centroid of heaviest rainfall south
across either KS/Colo or swrn Nebraska- south of ncntl Nebraska
where deep snow cover and frozen ground are in place. Most of this
snow may melt but local research suggests frost could still be in
the ground across much of wrn and ncntl Nebraska next weekend.
POPs next Saturday get a boost to the likely category but this may
be partly the result of last night`s ECM and GFS which showed wrn
Nebraska with the best chance for significant rainfall. The morning
model runs have shifted this feature south. Meanwhile, the latest
WPC QPF forecast indicates significant rainfall for ncntl Nebraska.
A shift back to the north toward, or into ncntl Nebraska is
possible. Either way, this system will be closely monitored. The
180kt 300mb jet fueling the system has already produced impressive
weather events across the Pacific and ern Asia. The strength of the
winds aloft is causing jets to fly at supersonic speeds, an intense
blizzard occurred in the Sakhalin Oblast and a sneaker wave from
that storm flooded Roi-Namur in the Marshall islands.
&&
.AVIATION /00Z TAFS THROUGH 00Z MONDAY/...
Issued at 522 PM CST Sat Jan 27 2024
VFR conditions will prevail across western and north central
Nebraska tonight and tomorrow. Winds remain light and predominantly
out of the west. Given the very light nature of the wind, some
northwest to southwest fluctuations may be noticed, but expected to
remain under 4 knots. Skies will remain clear, outside of a few
passing high clouds tomorrow afternoon.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SHORT TERM...CDC
LONG TERM...CDC
AVIATION...Richie
Area Forecast Discussion
National Weather Service Memphis TN
851 PM CST Sat Jan 27 2024
...New UPDATE...
.UPDATE...
Issued at 850 PM CST Sat Jan 27 2024
GOES-16 Water vapor satellite trends depict an upper level low
centered just northwest of Evansville, Indiana. Regional WSR-88D
radar trends still show some light rain showers occurring across
portions of northwest Tennessee this evening. Temperatures across
the Mid-South as of 8 PM CST are in the 40s areawide.
Short-term model trends including CAM solutions indicate rain
showers will continue to decrease into early Sunday morning.
Adjustments were made to rain chances and winds to account for
short term trends. Otherwise, the remainder of the forecast is on
track at this time.
Updated grids will be available momentarily.
CJC
&&
.SYNOPSIS...
Issued at 217 PM CST Sat Jan 27 2024
Chilly conditions will exist on Sunday before a warming trend
begins early next week. Highs on Tuesday will be around 60 degrees
before a dry cold front brings slightly cooler air back to the
Mid-South. Rain chances will remain minimal through the end of the
work week.
&&
.DISCUSSION...
(This evening through next Friday)
Issued at 217 PM CST Sat Jan 27 2024
3PM surface observations depict gusty winds in place across the
Mid-South as an upper level low departs the region. Expect
elevated winds to continue through the evening with showers
tapering off to the north. Behind the aforementioned low,
temperatures will drop with Sunday afternoon highs in the mid to
upper 40s.
A gradual warming trend will begin on Monday as southeast winds
return. Conditions on Tuesday will be rather pleasant as
dewpoints stay in the 40s and afternoon temperatures rise to
around 60 degrees. By Tuesday evening, an upper level low will
dive across the Great Lakes Region and bring a dry cold front to
the Mid-South. As this system moves near the region, brief
instances of gusty winds will be possible. The rest of the work
week is forecast to be dry with highs in the 50s & 60s.
Long range models are hinting at a pattern change this upcoming
weekend as a weak Rex Block emerges over CONUS. Both the GFS and
ECMWF develop a low pressure system ejecting from the Rockies,
taking a southerly track across TX towards the Gulf of Mexico.
While it remains too soon for exact timing and impacts, this may
be the next shot of rainfall for the Mid-South.
ANS
&&
.AVIATION...
(00Z TAFS)
Issued at 538 PM CST Sat Jan 27 2024
KNQA radar shows -RA along and west of the MS River, upstream from
MEM. For the most part, MVFR CIGs prevailed over eastern AR, but
IFR was noted upstream over southern MO and northwest AR behind
the rain shield. MEM and JBR may drop to IFR for a few hours late
this evening, behind the exited rain.
Expect a slow improvement in CIGs Saturday afternoon. HRRR
soundings corroborate NBM and LAMP guidance prevailing MVFR.
PWB
&&
.MEG WATCHES/WARNINGS/ADVISORIES...
AR...None.
MO...None.
MS...None.
TN...None.
&&
$$
PUBLIC FORECAST...ANS
AVIATION...PWB
Area Forecast Discussion
National Weather Service Morristown TN
839 PM EST Sat Jan 27 2024
...New UPDATE...
.UPDATE...
Issued at 830 PM EST Sat Jan 27 2024
As referenced in the afternoon discussion, our line of showers and
storms are currently moving across the forecast area. At times,
there have been a few cells that have shown signs of weak
rotation across the southern TN valley. At the current hour,
instability is beginning to wane but there are still a few
hundred J/kg of SBCAPE across the southern TN Valley. Even with
the lower SBCAPE values, this is still enough instability to
allow for some weak rotation due to the shear that remains in
place. Overall, the threat for any strong to severe storms is very
low but remains in place over the next few hours. The main threat
continues to be isolated damaging wind gusts but an isolated weak
tornado is also still possible, albeit very low chances. Look for
westerly winds to become gusty behind this line of precipitation
with gusts from 20 to 30kts. These winds will last through the
night.
&&
.SHORT TERM...
(This evening through Sunday)
Issued at 258 PM EST Sat Jan 27 2024
Key Messages:
1. A convective line will cross the area this evening, with
thunderstorms potentially bringing strong to severe wind gusts, a
chance of hail, and a low risk of an isolated tornado.
2. Colder air builds into the area on Sunday, with a strong NW
flow persisting through Sunday night. Several inches of snow
accumulation are likely above 3000 feet, and a Winter Storm
Warning has been issued. Winds will also be strong and gusty
during this time.
Discussion:
Quite a complex forecast this period. First, the Flash Flood Watch
has been canceled due to precip tapering off in our western
sections. Observed rain amounts in SW sections have been between
05. to 1.25 inches, and while additional showers/storms are
expected, they should not produce significant rain amounts or pose
a flood threat.
Radar shows a line of storms in western AL to the West/Middle TN
border. Surface obs indicate that the surface warm front is
located from near Nashville to just south of Chattanooga. This
front is expected to continue to lift northward, putting our
southern and western sections in the warm sector by 00Z. SBCAPE in
the HRRR reaches to around 500 J/kg, and deep shear is quite
strong. As the convective line approaches, surface-based
instabilty and convergence near the front will aid storm
intensification. Deeper cells may bring the strong winds aloft to
the surface, and low WBZ heights may lead to some hail. Enhanced
backing of surface winds near the boundary may also pose a tornado
threat. These storms should exit the area around 06Z.
Cold advection increases Sunday morning as the low pressure system
tracks into the central Appalachians. From Sunday through Sunday
night, we will have abundant low level moisture wrapping around
the low, along with a 35-40 kt upslope flow. With the long
duration of these winds, several inches of snow are likely in the
mountains. Limiting factors in the snowfall are that the moisture
drops off near or just below the dendrite growth level in model
soundings, and lapse rates are not very steep. However, with
strong upslope winds, the moisture will likely be lofted higher
over the mountains, enough to lead to dendrite growth. The
emphasis for this snow event is that it will impact higher
elevations, mainly above 3000 ft. A Winter Storm Warning has been
issued for the mountains. Some higher peaks in SW VA may see a few
inches, such as High Knob, but due to the isolated nature of those
amounts, will hold off on any Advisory for that area at this
time.
&&
.LONG TERM...
(Sunday night through next Saturday)
Issued at 258 PM EST Sat Jan 27 2024
Key Messages:
1. Additional precipitation chances are expected Tuesday night
through Wednesday. Precipitation is expected to be light, and some
may fall as snow in the higher elevations of the East Tennessee
mountains. Only light accumulations expected.
2. Trending warmer and mostly dry late week into the weekend,
although, uncertainty exists about some additional light precip
chances.
Discussion:
Conditions will be trending drier by Monday as the primary upper
trough bringing the weekend weather is kicked further east by an
upper level shortwave ridge. Minor height rises and improving sky
conditions will allow for a slight warming trend through Tuesday. By
Tuesday night, a secondary upper-level low is expected to drop
through the Great Lakes and Ohio valley regions, increasing
precipitation chances once more.
While there are still discrepancies among model guidance about how
far west the trough will protrude, ensemble guidance suggest
precipitation will remain fairly light due to the progressive nature
and unfavorable upper level dynamics. Mean GFS and ECMWF
probabilities for 24-hour QPF GTE 0.1 inches reach the 60-70% range
across northeast Tennessee and southwest Virginia. Probability of 24-
hour QPF GTE 0.5 inches only reaches values of 10-20% for higher
elevations in the East Tennessee mountains.
For these higher elevations in the TN mountains, temperatures may be
favorable for this to fall as snowfall for a portion of the time.
Light snowfall accumulations are possible. Snowfall probabilities of
an inch or greater are generally 70% or greater for the highest
peaks, whereas, probability of 3+ inches tops out near 20%.
A quasi-similar pattern is expected to occur for the latter half the
the extended period. A warming trend late week will follow the
development of an upper low(potential to be closed off) over the
northeast into the weekend. Considerable differences between
deterministic models exist at this time and additional light precip
chances are uncertain. Currently, NBM has kept mentionable PoPs
omitted from the forecast. Have not deviated from it at this time.
If a pattern such as the Euro pans out, with a trough axis extending
further southwest towards the TN valley and the upper low becoming
closed off, precip chances may need to be introduced in future
&&
.AVIATION...
(00Z TAFS)
Issued at 634 PM EST Sat Jan 27 2024
TYS and CHA are LIFR as of the 23Z ob. LIFR CIGs should lift over
the next hour or so at CHA as a line of showers and storms
approaches and moves over the terminal. TYS will lift to MVFR for
this same reason but not until around 02Z. Winds will pick up from
out of the west-southwest with this line of precip and continuing
behind it, gusting to 20 to 30 kts. TRI should remain VFR until
this line of precip approaches later this evening, then MVFR
thereafter, along with gusty winds out of the west-southwest.
Then, winds remain gusty at all sties the rest of the night and
through the end of the period with MVFR CIGs in place.
&&
.PRELIMINARY POINT TEMPS/POPS...
Chattanooga Airport, TN 42 46 36 50 / 70 20 10 0
Knoxville McGhee Tyson Airport, TN 40 44 35 45 / 80 30 20 0
Oak Ridge, TN 39 42 33 47 / 90 40 20 0
Tri Cities Airport, TN 42 45 32 43 / 90 70 50 10
&&
.MRX WATCHES/WARNINGS/ADVISORIES...
NC...NONE.
TN...Winter Storm Warning from 7 AM Sunday to 1 PM EST Monday for
Blount Smoky Mountains-Cocke Smoky Mountains-Johnson-Sevier
Smoky Mountains-Southeast Carter-Southeast Greene-Unicoi.
Wind Advisory until 1 AM EST Sunday for Blount Smoky Mountains-
Cocke Smoky Mountains-Sevier Smoky Mountains-Southeast
Carter-Southeast Greene-Southeast Monroe-Unicoi.
VA...NONE.
&&
$$
SHORT TERM...
LONG TERM....KRS
AVIATION...
Area Forecast Discussion
National Weather Service Nashville TN
902 PM CST Sat Jan 27 2024
...New UPDATE...
.UPDATE...
Issued at 847 PM CST Sat Jan 27 2024
Cold front and associated line of thunderstorms that moved across
the area earlier this afternoon has pushed into East Tennessee,
with light wraparound showers and drizzle now rotating across the
midstate. Upper level low across Kentucky is forecast to move
eastward overnight into tomorrow, with winds aloft becoming more
northwesterly across our forecast area. This will bring in more
cold air at the surface and aloft, with temperatures dropping
into the 30s/40s by sunrise. Forecast soundings indicate snow
levels will drop low enough for the rain showers to mix with
light snow on the Plateau by 11Z Sunday morning, with the
rain/snow mix continuing throughout the day on Sunday despite
surface temperatures remaining above freezing. Even with the
above-freezing temperatures, favorable northwesterly upslope
winds could squeeze out a dusting up to a half inch of snow
accumulation in the typically favored areas around Monterey and
Bon Air Mountain. However, most of the Plateau will likely see
little or no snow accumulation due to the above-freezing
temperatures and light QPF. Nudged up snow amounts to around 0.5
inches on the west edge of the Plateau in line with recent model
guidance and CAMs. These amounts are above the low WPC numbers
but well below the very high NBM totals. Rest of forecast remains
on track and only made tweaks.
&&
.SHORT TERM...
(This afternoon and tonight)
Issued at 130 PM CST Sat Jan 27 2024
After an interesting morning, having to issue a High Wind Warning
due to a wake low on the back side of this morning`s rain shield,
we`ve moved on to the overall system itself. Most of this morning`s
rains have moved on. Some light rain is around, but the cold front
is now the focus. The HRRR seems to have won out this go-around,
(showing why we pay close attention to it regularly) depicting the
path of the surface low quite well. Currently in West TN, the
surface low is expected to take a track northeastward into the
Nashville Metro area. Radar is showing weak convection already
developing on the cold front itself. The HRRR, along with the RAP,
are showing further convective development as this line breaks into
Middle TN this afternoon. Severe weather parameters are pretty
decent. Shear is 70 kts, low-level helicities are 200 m^2/s^2 or
better and mid-level lapse rates ahead of the front are 7.0
degrees/km. Instability has always been the main limiting factor,
but if we`re going to follow the HRRR, we could get a ribbon of 400-
500 J/Kg into our southeast counties by mid-afternoon. The
combination of all of these would spell a damaging wind threat (this
is the main concern) and allow for these storms to rotate, opening
the door for a tornado or two to develop. Keep in mind, on the
whole, the threat of severe weather is low, but if you live/work
south of I-40/east of I-65, please remain weather aware between 2 pm
and 8 pm this evening. Storms should exit the Plateau early this
evening and while there could be some light rain around through the
night, the convective activity will come to an end.
&&
.LONG TERM...
(Sunday through next Saturday)
Issued at 130 PM CST Sat Jan 27 2024
There has been some discussion over the last couple of days about
the back side of this system and whether or not it`ll be cold enough
to snow -- and whether we`ll be saturated high enough in the
atmosphere to get ice nucleation. West of the Plateau? No. On both
accounts. But, the Plateau is it`s own beast in the winter. GFS
forecast soundings suggest saturation only to about -8 degrees C.
Here in Nashville (and in most places), that`s not high enough.
However, it`s really close on the Plateau. Plus, surface temps are
going to be just above freezing. Doesn`t mean it can`t snow, though.
Usually for the Plateau to get snow accumulation on the back side of
a system like this, they need an orographic assist with winds
solidly out of the northwest. They don`t quite get there until
Sunday afternoon. All of that to say, I think we`ll get a snow/rain
mix on the Plateau starting tomorrow morning, probably switch over
to all rain in the afternoon, then get some light snow in the
evening -- all with little to no accumulation before the moisture
can get out of Middle TN. WPC would concur with this assessment, but
a majority of HREF members would suggest a few spots could see up to
an inch. Right now, with the wet, warm ground, I find this unlikely.
Bottom line, keep the potential in mind if you`ll be travelling in
the Plateau vicinity tomorrow.
Beyond tomorrow, things FINALLY quiet down. We should be dry next
week and outside of a clipper Tue/Wed that should only cool us back
to seasonal temperatures, we`ll likely stay at or above normal
temperatures this week. Next shot of rain may be a week or more
away.
&&
.AVIATION...
(00Z TAFS)
Issued at 527 PM CST Sat Jan 27 2024
Poor flying conditions continue this taf cycle. Cigs as a whole
will stay down the whole period, mainly in the IFR category. A bit
of bouncing back and forth will happen over the next few hours as
the surface low moves NE of Tennessee. Tempos are in at CSV and
SRB for the line of storms to impact those terminals. Limited vsbys
and wind gusts between 30 to 35kts will be likely during storms.
Outside of storms, light showers will swing back through
overnight. Southerly winds within the storms will shift westerly
once the line clears the terminal. Sustained speeds will stay in
the 10-15kt range with gusts near 25kts the whole period.
&&
.PRELIMINARY POINT TEMPS/POPS...
Nashville 41 45 34 45 / 50 40 10 0
Clarksville 39 44 33 46 / 80 20 0 0
Crossville 35 38 32 42 / 90 70 40 0
Columbia 38 44 34 48 / 30 20 0 0
Cookeville 37 40 34 42 / 90 70 30 0
Jamestown 36 38 32 41 / 90 80 40 0
Lawrenceburg 39 44 34 47 / 20 10 0 0
Murfreesboro 39 44 34 46 / 50 40 10 0
Waverly 37 43 32 47 / 70 20 0 0
&&
.OHX WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
UPDATE.......Shamburger
SHORT TERM...Unger
LONG TERM....Unger
AVIATION.....Baggett