Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 03/14/24
Area Forecast Discussion
National Weather Service La Crosse WI
943 PM CDT Wed Mar 13 2024
.KEY MESSAGES...
- Precipitation Chances Remain On Tap Late Tonight Through
Thursday, Limited To Rain With Limited To No Thunder Chances
- Highest Confidence For Near 0.5" Along & South Of Interstate
90 with 1"+ Totals Possible In Narrow Swaths
- Today Wraps Up The Highest Potential For The Record Breaking
Warmth As Highs Return Back To Normal For Thursday, Remain
Slightly Above Normal Into The Weekend, & Become Coldest
Sunday Night Into Monday With 5 to 10 Degrees Below Normal
Temperatures
&&
.DISCUSSION...
Issued at 142 PM CDT Wed Mar 13 2024
Initial Precipitation Chances Overnight Into Thursday Morning:
A multi-faceted forecast on tap for the Upper Mississippi River
Valley over the next 24 hours. Morning observations (GOES/METARs)
have exhibited the stationary moisture boundary that was south of
the forecast area earlier this morning slowly returning north with
diurnal heating. A near 90th percentile PWAT this morning at
DNV`s RAOB exemplified the strong moisture gradient with a
climatological mean PWAT at MPX (13.12Z) sounding. For the
anomalous warmth lovers, best warm air advection remains west
and south of the forecast area through today.
An upstream surface low undergoing cyclolysis while sagging
southeast through the Northern Plains early this morning will
advect the narrow filament of more anomalous temperatures
southwest of the local area. This trajectory will continue to
strengthen the theta e gradient along our southern periphery as
an appendage of the Canadian anticyclone behind this low`s
associated frontal boundary persists northeasterly flow from
central to northern Wisconsin. This theta e gradient expected to
zonally drape and bifurcate the forecast area through tonight.
Any leftover energy from this weakening low will be consumed
into the main surface low in the South-Central Plains into
Thursday.
Given the repeatedly mentioned drier air mass to the north,
precipitation onset continues to push back in time. Previous
high resolution model runs (Fv3,ARW,HRRR, RAP) exhibited a start
time near 9pm tonight, while most recent runs (13.12Z) are in
near 100% agreement with a later onset near 3am Thursday morning
as the initial, original deformation band remains to the
southwest from northern Iowa into eastern Nebraska. Not until
additional energy and increased troughing from the Northern
Plains surface low does confidence for saturation increase.
Lobes of mid level vorticity accompanying the mid level height
depression advect northeast through the area Thursday morning
as the exit and entrance regions of dual upper level jet streaks
provide optimal synoptic forcing.
Further Precipitation Timing Through Thursday:
Rain chances continue through much of Thursday as the elongated area
of lower surface pressure progresses just south of the forecast area
through eastern Iowa. Initial isentropic descent within the drier
air mass is overcome with meager upglide and enhanced low level
frontogenesis north of the surface low. Therefore, a band of higher
rainfall amounts expected to pivot across the Upper Mississippi
River Valley. Other than being directly dependent on saturation
location (i.e., 25th percentile remains 0.0"), HREF mean 1-hr
rainfall reaches 0.05" in this deformation band from 14.12Z -
14.14Z with highest confidence along the Iowa/Minnesota border
and points east in western Wisconsin. The same hourly, albeit
short lived, rainfall rates also concurrently graze far
southwest Wisconsin associated with the low center. The main
deformation band pivots cyclonically near the IA/MN/WI border
into the afternoon, eventually exiting east through the
afternoon hours.
Precipitation Amount, Type, & Impact:
While confidence in amounts has slightly increased, dependency on
the narrow band of frontogenetical forcing limits determining
the exact location of higher amounts. High resolution guidance
varies from a maximum 2+" within the NAM Nest from northeast
Iowa into southwest Wisconsin to near 1" within the most recent
HRRR (13.12Z). Although, this is twice as much as its previous
run (13.06Z), albeit not as widespread with the 1" isohyet as
the next previous run (13.00Z).
Have broad brushed near 0.5" storm rainfall totals as placing
tight, increased amounts would be misleading with current
forecast. These totals line up with the higher, albeit
moderate, confidence (60-80%) for the same amount in HREF and
same in long term global ensembles (60-100%). Most recent long
term global inter-model guidance has reached this same 100%
confidence threshold for 24-hour rainfall too. Although, the EPS
(13.12Z) exhibits this confidence in a very tight band from
northeast Iowa into southwest Wisconsin, similar to high
resolution guidance, while the GEFS (13.12Z) has broad brushed
100% to the southeast from eastern Iowa into northern Illinois.
Irregardless, given the the tight gradient, especially on the
northern periphery, expect sharp cutoffs between potentially
higher amounts.
A quicker solution for the subsequent upstream upper level trough,
over the Canadian Rockies at discussion issuance, resulting in a
quicker exit for precipitation and therefore removing frozen
precipitation chances locally. The colder airmass does
Temperatures Today Into Next Week:
Today appears to be the final day of record breaking warmth for
the Upper Mississippi River Valley as a general cooling trend is
expected through the weekend into early next week. Initial
temperatures today rebounded quicker than previous days, as the
colder, drier air mass remained shallow. The colder, sinking dry
air did limit valleys from bouncing back however. This, in
combination with the northern extent of the warmer air, has
resulted in Rochester breaking the high daytime temperature late
this morning while La Crosse has just recently tied its high
record near AFD issuance (2 pm CDT).
Temperatures remain throttled tomorrow as precipitation chances
through much of the day keep high temperatures near normal, in
the 40s for much of the area. A slight delay in the longer wave
cold tongue advecting farther south through the Upper
Mississippi River Valley keeps temperatures slightly above
normal, in the 50s, for Friday and Saturday. Long term global
ensemble confidence (80-100%) has remained persistent for this
cooling trend, bringing slightly below normal temperatures, 40
and below, for Sunday. The cold spell remains transient though,
coldest Sunday night with 5 to 10 below normal temperatures in
the teens to low 20s, remaining similar daytime highs into the
new week.
&&
.AVIATION /06Z TAFS THROUGH 06Z FRIDAY/...
Issued at 942 PM CDT Wed Mar 13 2024
Although a few light showers are possible late this evening,
more widespread showers will work north through Thursday before
diminishing by evening. There is still some uncertainty in the
northern extent of the more widespread rain band on Thursday
with higher chances south of I-90. If more southern solutions
pan out, KLSE/KRST may see little rain/predominantly VFR
conditions, while MVFR ceilings/visibility are more likely at
the TAF sites if the band does spread farther north through
I-90. For now, did not radically deviate from the prior
forecast, but did delay the arrival of any MVFR ceilings given
the dry air in place. However, some adjustments will be likely
as trends become more clear.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
IA...None.
&&
$$
DISCUSSION...JAR
AVIATION...JM
Area Forecast Discussion
National Weather Service Dodge City KS
625 PM CDT Wed Mar 13 2024
.KEY MESSAGES...
- Isolated supercell thunderstorm possible with very large hail
risk (10% chance of 2"+ diameter hail within 25 miles of a
point) this evening across I-70 corridor WaKeeney to Hays.
- Scattered showers/non-severe storms overnight as upper system
draws closer to western Kansas.
- Cooler air mass much of the Long Term period with Monday
morning the likely coldest morning, up to 70% chance of lows
28 degrees or colder Monday morning.
&&
.SHORT TERM /THROUGH THURSDAY/...
Issued at 152 PM CDT Wed Mar 13 2024
A significant, classic mid-latitude cyclone will develop and mature
through the Short Term period with only minimal impacts across our
west central, southwest, and south central Kansas counties of
responsibility. Early this afternoon, observations showed the
surface low centered along the OK-KS line south of Meade. Winds were
generally light and variable across much of our forecast area given
the low centered over our forecast area and negligible MSLP gradient
near the center of the low.
East and northeast of the surface low, low level moisture continued
to advect northward into central Kansas with mid 50s surface
dewpoints as far north as Great Bend-McPherson line. Much of the
moisture advection in the lower troposphere will be east of our
forecast area with warm frontogenesis from the surface to 850mb
focusing on north central and northeastern Kansas through this
evening. This will be the region of focus for organized severe local
storms, which is why SPC has Enhanced (Level 3 of 5) Risk covering
northeast Kansas (due to 30% Severe Hail Outlook with 10%
Significant "Hatched" Hail Outlook).
The updated 1630Z SPC Day One outlook maintains a 10% "Hatched"
outlook for severe hail due to the possibility of westernmost severe
storm as far west as our I-70 corridor (WaKeeney to Hays). That
said, most of the convective allowing models (CAMs) from the 12Z run
do not initiate robust severe local storms until around or shortly
after 00Z and mainly north of I-70. Even the most recent 16Z and 17Z
runs of the HRRR have delayed onset of warm front storms until 01Z
or so just north of I-70, however at least a couple of the most
recent HRRR runs have shown a formidable supercell signal given the
CAPE/Shear profile well into supercell range with the lower-mid 50s
dewpoints in vicinity. The slower and deeper cyclogenesis of the mid
level low will now favor the GCK to HYS corridor of overnight
showers and widely scattered thunderstorms 06Z or later, although
these western areas after midnight will not have near the low level
moisture access as the earlier evening warm front activity will, so
no severe is expected after midnight.
Low level cold advection will overspread western Kansas
overnight/early Thursday morning behind the low with widespread
stratus cloud development. Latest HREF Low Cloud product keeps 90-
100% probs of low cloud through much of the day Thursday, so the
lower end of guidance is the best forecast for temperatures on
Thursday (10th to 25th percentile NBM), especially out west closer
to the mid level deformation axis where some light precipitation may
be off and on through the day. For this reason, we will also carry
40-60 POPs from roughly Syracuse to Scott City, although QPF totals
will be on the light side with much of the forcing for ascent
confined to Colorado where major winter impacts are forecast toward
I-25.
&&
.LONG TERM /THURSDAY NIGHT THROUGH WEDNESDAY/...
Issued at 152 PM CDT Wed Mar 13 2024
For much of the Long Term period, a cutoff upper low will be the
prevailing meteorological feature across the southwestern CONUS.
Western Kansas will find itself between this cutoff low and the
north-northwesterly flow pattern from the highly amplified northern
branch of the westerlies. This blocked high-over-low hemispheric
pattern will keep western Kansas high and dry from a precipitation
standpoint given absence of baroclinicity and overall high pressure
in the lower troposphere. We will see a couple bouts of dry cold
front passages during this period, each of which resulting in cold
mornings with lows temperatures at or below 32F. Two mornings in
particular are Saturday and especially Monday morning. Latest NBM
has 40-70% probability of low temperature 28F or less across much of
southwest and west central Kansas as a surface ridge likely becomes
centered across southwest Kansas early Monday morning. Otherwise,
there is not much else to discuss in the Long Term as we remain in
this blocky pattern, which will really not lose its grip until early-
mid next week.
&&
.AVIATION /00Z TAFS THROUGH 00Z FRIDAY/...
Issued at 623 PM CDT Wed Mar 13 2024
There will be a 30-40% chance for thunderstorms in the Hays
area between 00z and 03z Thursday. A few of these storms over
the next few hours may be capable of producing locally heavy
rainfall along with hail larger than 2”. This will be the best
chance for severe weather across southwest Kansas but there will
be scattered convection ongoing through the overnight period,
mainly after midnight. Also cams are in good agreement with low
clouds spreading into southwest Kansas overnight behind a cold
front which will cross southwest Kansas between 00z and 06z
Thursday. Based on the HREF prob CEILHGT and BUFR soundings
ceilings will fall below 2000ft AGL after 06z with a 50-70%
chance for ceilings to drop below 1000ft AGL between 09z and 15z
Thursday. North winds will be at 10 to 15 knots overnight but
will increase to 15 to 20 knots between 15z and 18z.
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SHORT TERM...Umscheid
LONG TERM...Umscheid
AVIATION...Burgert
Area Forecast Discussion
National Weather Service Glasgow MT
536 PM MDT Wed Mar 13 2024
.DISCUSSION...
EVENING UPDATE:
Once again like yesterday we`re getting some surprise convection
with some low value CAPE over the area being touched off by this
Canadian Cold Front moving south. Only model that remotely handles
this well is the latest HRRR run so will be blending that in to
our POPs at least through 06Z to account for the showers now
showing up on radar.
-Bernhart
PREVIOUS DISCUSSION:
A cold front will move through late this afternoon with low
clouds coming south from Canada, expected to linger into Thursday.
This low stratus may lead to fog in elevated regions near the
Canadian border as well as the Little Rockies and Big Sheeps.
Ensembles show a warm up for Friday before the next cold front on
Saturday. Longer term, guidance indicates colder temperatures
toward next Thursday or Friday with an increasing chance for snow.
About a third of GFS ensemble members show snow advancing over the
region at that time and the NBM is increasing pops across our
western zones late in the forecast period.
&&
.AVIATION...
VFR conditions are expected this afternoon and evening with low
stratus moving in tonight with a cold front. MVFR to IFR ceilings
are likely with a few LIFR ceilings possible, especially in the
northeast. Right now there is about a 1 in 2 chance for ceilings
under 2000 feet and a 1 in 5 probability for ceilings below 1000
feet through Thursday.
&&
.GLASGOW WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
weather.gov/glasgow
Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
649 PM CDT Wed Mar 13 2024
.KEY MESSAGES...
-There is a 60 to 90 percent chance of showers and thunderstorms
mainly along and north of I-70 this evening. A few of these
thunderstorms could be strong to severe with the main hazards
being large hail and damaging winds.
-Additional thunderstorms are expected between Thursday afternoon and
night (60 to 80 percent chance) across much of the area. There
is a greater threat of these thunderstorms becoming strong to
severe than this evening with hazards of very large hail,
damaging winds, and a tornado or two possible.
&&
.SHORT TERM... (Through Late Thursday Night)
Issued at 347 PM CDT Wed Mar 13 2024
Latest RAP analysis is indicating that the main warm front
extends from northwestern Missouri into southeastern Iowa as of
18z. In the meantime, an axis of deeper moisture that extends from
just south of Kansas City east southeastward towards Rolla then
near Ste. Genevieve, MO has begun to interact with a shortwave
that is sliding east across the area. This will be the focus for
discrete thunderstorm development late this afternoon. The
combination of the shortwave, instability (ML CAPEs 1000-2000J/kg)
and deep-layer shear of 30 to 40 kt will support a few
thunderstorms becoming strong to severe. While the main threats
will be large hail and damaging winds, there is also a tornado
threat, though it is limited due to the lack of low-level
curvature in the latest forecast hodographs. Also, as the storms
track to the east and northeast they will be moving into an area
of lower instability. The best time for strong to severe storms
will be between 5 pm and 11 pm, especially over portions of
central/east central/northeast Missouri as well as west central
Illinois.
After sunset, a southerly LLJ (30-50kts) will develop which will
help to lift the storms northward into the northern portions of the
forecast area by late this evening. The majority of the latest CAMs
indicate that the storms will then congeal into a complex and slide
east along the warm front as the LLJ veers to the southwest
overnight. Then the complex will eventually sag to the southeast and
weakening around sunrise.
On Thursday, expect most of the day will be dry before the next
round develops during the afternoon hours. If clouds clear out
enough and the cold pool from the overnight activity weakens, expect
highs in the 70s to around 80 degrees. Otherwise there is the issue
of where an outflow from the complex lays out during the day on
Thursday, becoming the focus of new development before the cold
front moves through Thursday night. With dewpoints in the low to mid
60s in the warm sector ahead of the cold front, expect instability
will increase with MU CAPEs of 1500-2500 J/kg by midday. So the
instability combined with steep ML lapse rates will result in
moderate to strong buoyancy as heating destabilizes the air mass in
wake of the early morning clouds and convective activity. Latest
forecast soundings show a decent inversion, thus activity will be
suppressed initially. Once the capping inversion weakens by mid to
late afternoon expect thunderstorm development in the warm sector
ahead of the cold front. With deep-layer wind shear of 40 to 50 kt
and the aforementioned instability, there will be a more substantial
opportunity for strong to severe thunderstorms than this evening.
Initially development will be discrete with supercells, then
transition to a mixed mode of line segments and embedded supercells
through the evening as thunderstorm mergers take place. The main
threats will be large hail, possibly greater than golf ball size,
damaging winds and a tornado or two.
Byrd
&&
.LONG TERM... (Friday through Next Wednesday)
Issued at 347 PM CDT Wed Mar 13 2024
(Friday - Saturday Night)
Surface high pressure early Friday over the mid-Missouri Valley is
forecast to slide south/southeast. Decreasing cloudiness is expected
through the day, but low-level cold air advection continues well
behind Thursday night`s cold front. High temperatures generally in
the mid 50s to low 60s are likely, near to slightly above normals
for the date.
The surface anticyclone is forecast to weaken Friday night, with the
axis of the ridge quickly moving south through the bi-state area.
West/southwest return flow will begin in its wake, mainly preventing
a further temperature drop. Due to this return flow, lows are
forecast to be about 5 degrees above normal, generally in the mid
to upper 30s across the region.
A weak cold front is expected to move through the mid-Mississippi
Valley Saturday afternoon/evening, but is not expected to bring much
fanfare. 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. Temperatures should
climb on Saturday out ahead of the front, reaching into the low to
mid 60s for most locations.
(Sunday - Monday Night)
A secondary, and more substantial, cold front is expected late
Sunday associated with anomalously mid/upper level troughing
swinging through the Upper Midwest/Great Lakes. Very strong low-
level cold air advection moves into the CWA by Sunday evening, with
850-hPa temperatures dropping to near -10C by 1200 UTC Monday on the
GEFS/EPS. These values are pretty notable for mid March, generally
about 8 to 12C below normal. The surface high across the Plains is
also pretty notable (1030 hPa, near the 90th percentile of
climatology), illustrating this incoming air mass does have some
teeth for mid March. A hard freeze (<=28F) is more likely than not
across parts of the area both Sunday and Monday nights due to this
incoming air mass. For Sunday night, highest probabilities on the
LREF (50-70%) are in parts of northeast Missouri and west-central
Illinois. There is less certainty on Monday night due to a variety
of factors, including but not limited to: 1) potential for
increasing mid/upper level clouds and 2) timing of the surface ridge
axis across the area. If it stays clear and the surface high is in a
favorable position, a hard freeze likely would happen over most of
the area. However, due to some of these uncertainties mentioned
above, probabilities for a hard freeze Monday night are in the 30-
40% on the LREF at this time. This is a good reminder that it is
still mid March and hard freezes are pretty common this time of
year. Climatologically speaking, the last hard freeze typically
occurs between about March 20th and the first week of April. For
more detailed spring frost/freeze information for your location,
please visit our new web page at weather.gov/lsx/frostfreezepage .
High temperatures cool off on Sunday, but the coldest day should be
Monday areawide. Highs are only expected to climb into the 40s, or
about 10 degrees below normal.
(Tuesday - Next Wednesday)
This cool down late this weekend/early next week looks short lived
however. Return flow around the departing surface high is likely to
begin by Tuesday, with rising mid/upper level heights as well.
Temperatures will moderate heading into the middle of next week,
with at least slightly above normal values by Tuesday.
Gosselin
&&
.AVIATION... (For the 00z TAFs through 00z Thursday Evening)
Issued at 647 PM CDT Wed Mar 13 2024
Isolated storms have developed along the I-70 corridor early this
evening. Still expecting the storms will continue to develop and
lift northward this evening. Best time for storms at TAF sites
along I-70 will be between 00z and 03z Thursday. As for KUIN, the
storms will move in after 02z Thursday and persist through 15z
Thursday. As activity diminishes towards sunrise on Thursday, the
storms will sink back to the south, so have predominate showers
and storms at KCOU and KJEF between 09z and 17z Thursday.
Otherwise, as cold front begins to slide through will see another
round of showers and storms after 21z Thursday. Could see ceilings
and visibilities drop to MVFR briefly at all sites with the
heaviest storms.
As for winds, they will remain southeast to south before picking
up and veering to the southwest as the cold front approaches
Thursday afternoon. The front will move through KUIN by 22z
Thursday with winds veering to the north.
Byrd
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...None.
IL...None.
&&
$$
WFO LSX
Area Forecast Discussion
National Weather Service Nashville TN
938 PM CDT Wed Mar 13 2024
...New UPDATE...
.UPDATE...
Issued at 914 PM CDT Wed Mar 13 2024
Very nice and mild evening across the midstate with current
temperatures in the 50s/60s and comfortable dewpoints in the
40s/50s. LLJ strengthening to 30 knots by 12Z overnight will keep
temps from dropping much with lows only in the 50s to around 60.
Low and high level moisture will continue to increase tomorrow as
our next storm system approaches, and a line of strong to severe
thunderstorms still looks likely to move across the midstate
late Thursday evening into early Friday morning. Models are all
over the place with timing, but CAMs such as the HRRR continue to
trend faster and show storms moving into our northwest as early as
9-10pm on Thursday evening. Earlier timing would give storms more
instability to work with, and latest DESI mean CAPE ranges from
300 J/Kg near the Highway 231 corridor up to 800+ J/Kg near the
Tennessee River. With forecast soundings also showing strong low
level shear ahead of the storms with 0-1km up to 300 m2/s2, lots
of dry air aloft and low web bulb zero heights, conditions appear
to be favorable for damaging winds, hail, and even a few QLCS
tornadoes - especially along and west of I-65. Main uncertainties
regarding the svr wx potential continue to be the stout low level
inversion shown on forecast soundings and shear vectors generally
parallel to the line of storms, both of which could reduce the
threat - especially the tornado potential. Even with these
uncertainties, I would expect SPC to shift the risk areas further
east into our forecast area tonight. Stay tuned!
&&
.SHORT TERM...
(Rest of today through Thursday)
Issued at 1152 AM CDT Wed Mar 13 2024
Wow. What a day. The little showers in our northwest have all but
dried up, clouds are disappearing and the yellow orb is coming out
in all of its glory. Temps will climb into the 70s for almost
everyone and with a little breeze, it`s an amazing spring day out
there. Tomorrow will much of the same -- only warmer! Upper 70s
with a few 80s will be common.
&&
.LONG TERM...
(Thursday Night through next Wednesday)
Issued at 1152 AM CDT Wed Mar 13 2024
Today`s forecast package is going to revolve around one weather
system, one that is already trying to take shape back over the
OK/TX panhandles. This system will grow and intensify over the
next 24 hours, pulling more and more moisture into the mid-south
and TN valley. Initially, this could lead a brief passing shower
tomorrow afternoon, especially west of I-65, but the real show
looks like it`ll be Thursday night. With us getting into the time
range of our CAMs, the latest guidance is showing a much earlier
arrival time of convection to Middle TN that what our global
models have shown over the last several days. This is unfortunate
because as I mentioned yesterday, an earlier arrival would mean
the surface low is closer to us and therefore, more shear. Here`s
the other thing that is standing out with the 12Z CAMs:
instability is much higher across our western counties. Current
HREF probs are giving us 50% or better chances of seeing more than
400 J/Kg. Even the GFS, which we have been queuing from over the
last couple of days had 300-400 J/Kg after midnight. I will go
ahead and mention the outlier, which is the HRRR, coming in with
almost 2000 J/Kg ahead of a line of storms. It is a very sharp
outlier and I really hope it`s wrong, but even half of that is
going to cause some issues Thursday night. As I`m sitting here
writing this, I am also coordinating with SPC and they are going
to reintroduce severe probs back into our western counties for
tomorrow night (Day 2) based on everything I`ve previously
mentioned. At this point, I believe them to be running with a low-
end risk based on the fact this is the first time we`ve seen
these type parameters, but as you`ll see with the update this
afternoon, they have pulled things much further east than the
earlier Day 2 issuance. I always try to look for a limiting factor
when it comes to severe weather and right now, I think the main
one I`m seeing is the CIN values ahead of the line of storms. Mean
HREF values of almost -200 could lead to everything being
elevated and there not being a surface based wind threat. If
you`ve read the last couple overnight AFDs, this has been the
focus all along and the one main mitigating factor.
In the end, heavy rain, thunderstorms and gusty winds are likely to
affect all of Middle TN tomorrow night. 1 to 2 inches of rain still
seem to be a safe bet. This shouldn`t lead to any flooding issues
with our break in the rain over the last few days, but as far as the
severe threat, we`ll need to see the next couple of CAM runs to see
consistency and whether or not the suggested CIN values continue to
be shown. Please check back with us over the next 24 hours for
latest.
Outside the Thursday night/Friday rain and storms, we very well
could be dry for a week. Sunday`s rain chances have all but
evaporated, but we still should see some colder air return to the
area Monday night behind Sunday`s system. Frosty/freezing conditions
are likely.
&&
.AVIATION...
(00Z TAFS)
Issued at 625 PM CDT Wed Mar 13 2024
Diurnal cu will dissipate as the sun sets with just lingering mid
clouds through the night. Closer to 12Z some MVFR CIGS may be
possible, which should clear out by 18Z. South-southwesterly
winds will remain light through the night so no VIS reduction is
expected, then gusts to near 20kts possible during the day
tomorrow.
&&
.PRELIMINARY POINT TEMPS/POPS...
Nashville 56 81 61 71 / 0 10 80 90
Clarksville 56 79 60 67 / 0 20 90 80
Crossville 48 74 58 66 / 0 0 70 100
Columbia 54 80 61 70 / 0 10 80 100
Cookeville 53 77 60 67 / 0 0 70 100
Jamestown 49 76 58 66 / 0 0 70 100
Lawrenceburg 54 79 61 70 / 0 10 80 100
Murfreesboro 53 80 61 71 / 0 10 80 100
Waverly 57 79 60 67 / 0 20 90 80
&&
.OHX WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
UPDATE.......Shamburger
SHORT TERM...Unger
LONG TERM....Unger
AVIATION.....05
Area Forecast Discussion
National Weather Service Topeka KS
647 PM CDT Wed Mar 13 2024
.KEY MESSAGES...
- Thunderstorms remain likely (60-90%) across the area this evening.
- The main hazard with any thunderstorm is very large hail, though
damaging winds and a few tornadoes are also possible.
- Showers and storms become more isolated into Thursday,
followed by drier and cooler weather late this week into the
weekend.
&&
.UPDATE...
Issued at 548 PM CDT Wed Mar 13 2024
A Severe Thunderstorm and Tornado Watch have been issued through
1 AM CDT.
&&
.DISCUSSION...
Issued at 255 PM CDT Wed Mar 13 2024
19Z water vapor imagery shows a 500mb speed max rounding the base of
the upper trough as it crosses the Rockies. The associated sfc low
is centered in the TX/OK panhandles into far southwest KS with its
warm front stretched near the I-70 corridor early this afternoon.
Dew points in the warm sector in southeast and east central KS have
increased into the mid to upper 50s, with 60-degree readings still
mainly in OK outside of a few isolated locations in far eastern KS.
Of note is the fact that the low-level moisture appears to have
stalled somewhat behind the warm front, as dew points along I-70 are
still in the 40s.
For the rest of this afternoon into the evening, the focus for
convective initiation has been along the warm front with
thunderstorms quickly moving northeastward. However, subtle changes
in trends (such as that noted in the previous paragraph about
lagging moisture) lead to lingering questions on exactly how far
north or south storms will initiate and exactly what time. Most CAMs
continue to highlight supercells firing along the front around 01Z,
but some guidance has showed discrete cells developing as early as
22-23Z closer to the triple point towards central KS and that
possibility cannot be discounted. RAP/HRRR forecast soundings
indicate the cap should erode by 21-22Z, and sfc winds along the
warm front are forecast to back slightly between this time and 00Z.
This would act to increase low-level SRH with hodographs becoming
increasingly favorable to ingest streamwise vorticity. The better
upper-level support still looks to arrive as the 500mb jet streak
approaches with the area set in the exit region, and as the LLJ
strengthens after 00Z, which is likely the reason for higher storm
coverage by that time. It is also worth noting that while the RAP
has 0-1km SRH as high as 300-400 m2/s2 this evening, it is south of
the warm front and more associated with the LLJ. All of this is to
say, the time window for tornadoes remains quite narrow, but if a
discrete storm were to develop in the aforementioned
environment late this afternoon, it would become severe quickly.
The bigger concern with any storms throughout the afternoon or
evening is large or very large hail with instability, mid-level
lapse rates, and deep-layer shear well supportive of that
threat.
The severe weather threat should come to an end by midnight as
instability wanes and the majority of convection moves northeast
into NE. There looks to still be some isolated activity behind the
cold front associated with the sfc low, and that boundary is slow to
move across the area. It looks to potentially stall in central KS
overnight and slowly move across the area Thursday morning and
eventually exit by mid-afternoon.
Sfc high pressure builds in by Friday, with cooler and drier air
filtering in for the end of the week into the weekend. Highs in the
60s are forecast Friday and Saturday, then cooling into the 50s for
Sunday and Monday behind a secondary push of cooler air from
the northern stream trough while a cut-off low circulates over
the southwestern CONUS. A warm-up then looks to arrive by next
Tuesday.
&&
.AVIATION /00Z TAFS THROUGH 00Z FRIDAY/...
Issued at 636 PM CDT Wed Mar 13 2024
Storms continue to develop just south of the terminals. Should
lift north into the terminals over the next hour or two. May
need to adjust timing slightly earlier if progression is faster.
Coverage should increase so may be able to transition VCTS to
TSRA once a track to storms develop more into the terminals.
Expect the frontal system to and low center to transition
through the area over the next 6 hrs or so. This will cause and
abrupt change to the winds as the which will change to the NNW.
Winds increase into the morning and afternoon tomorrow. Stratus
deck through the morning and afternoon tomorrow expected to
remain within marginal VFR conditions.
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
UPDATE...Jones
DISCUSSION...Picha
AVIATION...Drake