Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 08/14/23
Area Forecast Discussion
National Weather Service Binghamton NY
956 PM EDT Sun Aug 13 2023
.SYNOPSIS...
High pressure will slowly build into the region tonight but
quickly give way to another low pressure system passing through
the region by Monday night. High pressure will again build into
the region for the middle part of the week.
&&
.NEAR TERM /THROUGH MONDAY NIGHT/...
955 pm update...
Fine tuned the hourly PoPs and weather grids based on the latest
blended hi-res guidance for Monday night time period. Forecast
remains on track with no other significant changes at this time.
715 pm update...
Cumulus clouds are now quickly dissipating as we lose the
daytime heating and instability. Removed any mention of showers
this evening as dew point depressions are high across the area
and our KBGM radar is not showing any activity developing at
this time. Otherwise, still looking quiet tonight under partly
cloudy skies with some patchy valley fog also likely forming.
Overnight lows dip down into the 50s and lower 60s tonight.
Monday is looking nice, with partly sunny skies after the fog
burns off in the morning. Highs will reach the upper 70s to
lower 80s (some mid-80s in Wyoming Valley). Still a bit of
uncertainty with the arrival time of the rain Monday evening,
with the HRRR being faster than the 3km NAM and RAP. Did not
make any changes to this portion of the near term forecast
considering the continuing model differences.
330 pm update...
High pressure will move southeast to be over our area Monday
morning. Monday night a strong surface low ahead of a strong
upper level trough moves through the area with periods of
heavy rain.
Today most of the showers are gone leaving a few sprinkles.
Heating has mixed out the limited moisture. Some models still
show showers developing in the northern Finger Lakes along a
convergence boundary. Towards sunset the possibility of light
showers will end. Skies should partially clear before stratus
forms late tonight. Due to the amount of low level moisture
valley fog is not expected to be widespread and dense. Low
temperatures will be from the mid 50s to around 60.
Monday during the day will be dry with increasing clouds. Highs
will be a little warmer with highs from the mid 70s to around
80. Dewpoints will rise into the mid and upper 60s making it
feel muggy.
Monday night rain moves in during the evening with most of the
rain from late evening into the overnight. The warm cloud
layer is deep approaching 15k ft. Precipitable water gets to 2
inches near daily records. The low level jet is strong replacing
the moisture being rained out. Training is likely bringing
localized rainfall amounts up to 2 inches. Many models show
stripes of higher rainfall across the CWA Monday night into
Tuesday. At this time little agreement on where the heaviest
rain will be. The area continues in mostly a marginal threat of
excessive rainfall. The chance of thunderstorms is low with
little instability with the warm air into the mid layers. The
shear is good though. Timing will be at night so daytime heating
will not be a factor. With the high dewpoints low will only
fall into the 60s.
&&
.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
315 PM Update...
Lingering showers from the early week system will be possible on
Tuesday, but there is quite a bit of uncertainty on coverage and
timing. The NAM has a stronger surface system to the south that is
quick to move through and is replaced by high pressure, leading to a
mostly dry day. Other model guidance shows southwest flow advecting
in a dry slot either into the region or just east of the region
early on Tuesday, which could also limit shower coverage. With this
uncertainty, National Blend of Models (NBM) was used for PoPs during
this period. This resulted in the highest chances in the afternoon
across CNY. With limited instability and strong shear, isolated
pulse thunderstorms cannot be ruled out. PWATs are forecasted to
decrease throughout the day, but are modeled to be over 1.7" early
on, so heavy rain showers may also be possible.
High pressure and drier air begin to build into the region overnight
and will remain over the region on Wednesday. Some deterministic
model guidance has some showers in the region as the lagging, upper-
level trough from the aforementioned system passes through. BUFKIT
soundings do show limited moisture near the surface in the morning
which could support some sprinkles or light showers, but the
profiles are quick to dry out and would not expect anything beyond
the morning hours. Even those models that want to bring in showers
on Wednesday show not much moisture present. For now, NBM guidance
and dry conditions are favored through Wednesday night.
Temperatures will vary little this period, though Wednesday may be a
couple degrees cooler. Still, highs will be in the 70s and low 80s.
Overnight temps will fall into the 50s and low 60s.
&&
.LONG TERM /THURSDAY THROUGH SUNDAY/...
315 PM Update...
A deepening upper-level trough will move across the Great Lakes
Thursday and into the Northeast late Thursday night, bringing the
next system to the region. Rain showers will be possible ahead of an
approaching frontal boundary Thursday night. The better chance for
widespread showers will be during the day on Friday as the surface
front moves through. Models are also have enough instability to
support thunderstorms as well. There does remain to be some timing
differences between guidance, so NBM and other ensemble guidance was
favored. This system will be through by Friday night and will be
replaced by a ridge of high pressure, leading to a dry weekend.
Mild temperatures will take a dip on Friday thanks to showers and
the FROPA, but will be quick to rebound with a warming trend
expected throughout the weekend.
&&
.AVIATION /02Z MONDAY THROUGH FRIDAY/...
Mainly VFR conditions are expected through the next 24 hours
(at least through 00Z Tuesday). However, there are a couple of
exceptions. KELM will likely see some valley fog late
tonight/early Monday morning, which is expected to bring
occasional IFR visby restrictions. However, there is a bit of
uncertainty associated with this, as clouds moving in may limit
fog formation. Also, MVFR ceilings are expected late tonight
into mid-Monday morning at KRME, before conditions return to
VFR.
Outlook...
Monday overnight through Tuesday...Restrictions likely in
showers and thunderstorms.
Wednesday through Thursday...Mainly VFR.
Thursday night through Friday...Occasional restrictions possible
in scattered showers and thunderstorms.
&&
.BGM WATCHES/WARNINGS/ADVISORIES...
PA...None.
NY...None.
&&
$$
SYNOPSIS...MWG/TAC
NEAR TERM...MJM/TAC
SHORT TERM...BTL
LONG TERM...BTL
AVIATION...BJG
Upcoming Work Week Forecast Discussion:
For the remainder of the week, an H5 ridge amplifies over the
western CONUS the current trough moving across the Great Lakes. This
leaves our region in predominantly mid-level northwesterly flow for
much of the week. For Monday and Tuesday, this will keep
temperatures cooler. By the middle of the week, the H5 ridge axis is
progged to shift further eastward that will bring height rises to
the lower Missouri River Valley and start to increase, and by Friday
could be back into the 90s. Ensemble output over the next week
maintains very low probabilities for precipitation, as well as the
NBM. Will need to monitor a few short-wave perturbations across the
top of the ridge, but as long as the ridge amplifies the forcing may
miss the area. The bulk of the work week currently holds dry
forecast with respect to POPs.
&&
.Aviation...(For the 00Z TAFS through 00Z Monday Evening)
Issued at 618 PM CDT SUN AUG 13 2023
An area of thunderstorms has developed northwest of the KC
terminals. This area will move southeast and affect the terminals
in the 00Z to 02Z time frame. Have extended the tempo group
through 02Z to capture this. While the surface analysis is very
complex, it looks like this area of storms formed as the cold
front was moving southward and as a result, has limited the
potential instability available to them, resulting in a lower potential
for large hail and damaging winds. The storms will produce locally
heavy rainfall which will likely result in brief IFR conditions at
the terminals. Behind the front, winds become northwesterly and
there will likely be a period of MVFR ceilings. Tomorrow morning,
winds become gusty from the northwest with gust around 25-30 kts
possible and ceilings improving to VFR.
&&
.EAX WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
MO...NONE.
&&
$$
Discussion...Krull
Aviation...CDB
Area Forecast Discussion
National Weather Service Flagstaff AZ
241 PM MST Sun Aug 13 2023
.SYNOPSIS...The Arizona monsoon continues with daily rain chances
forecast through the next week. Seasonable temperatures and light
winds will prevail outside of showers and thunderstorms.
&&
.DISCUSSION...There`s been a handful of showers and thunderstorms
so far this afternoon, primarily within Yavapai County. Storm
motion has been nearly stationary today, allowing a few localized
areas to see flash flooding. We could continue to see isolated to
scattered activity into the evening/overnight hours, but these
will likely be outflow driven storms.
Monday...The greater shower/thunderstorm coverage will flip to
the eastern side of our CWA for tomorrow. This will partially be
because of the shift in the trough to our west, creating more
synoptic forcing over eastern Arizona. There should also be decent
instability left over from the lack of storms produced in that
area of the state today.
Tuesday through Friday...Model guidance indicates showers and
thunderstorms becoming more widespread across our CWA. This
matches up nicely with the increase in PW values in both the GFS
and ECMWF ensemble members. We`ll start to see this increase in
moisture due to high- pressure beginning to set- up over the
Southwest and a trough off the coast of California allowing
moisture to funnel in from the south. During this timeframe,
overnight activity is being shown on the U of A 18Z HRRR WRF
run most nights. Pin-pointing the expected location of these
overnight storms will be tricky, since most storms will likely be
outflow driven during these nighttime hours.
Over the weekend...There is great uncertainty with the incoming
moisture expected for the upcoming weekend. Models are hinting at
a potential tropical system forming in the Eastern Pacific which
may increase our available moisture. Although models agree with
the formation of some type of disturbance, the trajectory has
little to no agreement. As we get closer to this timeframe, we`ll
have additional information and increased confidence on the
potential impacts.
&&
.AVIATION...For the 00Z TAF Package...VFR conditions are expected
through the TAF period outside of brief MVFR conditions due to
showers and thunderstorms. Winds will be light and variable
through 17Z, before E-SE winds of 10-15 kts begin. Storm
development is also looking to start after 18Z and continue
through the evening hours. Gusty outflow winds will be possible
throughout the forecast period. Aviation discussion not updated
for TAF amendments.
&&
.FIRE WEATHER...Monday and Tuesday...Showers and thunderstorms
will continue through the evening hours tonight and become more
active across eastern Arizona on Monday. By Tuesday, more
widespread showers/storms will be expected. Minimum RH values will
slowly increase each afternoon ranging from 20-50%.
Wednesday through Friday...Look for widespread showers and
thunderstorms each afternoon through the end of the week. Outside
of gusty/erratic outflow winds, winds will generally be out of the
south around 10 kts.
&&
.FGZ WATCHES/WARNINGS/ADVISORIES...None.
&&
$$
PUBLIC...Konieczny
AVIATION...Konieczny
FIRE WEATHER...Konieczny
For Northern Arizona weather information visit
weather.gov/flagstaff
AREA FORECAST DISCUSSION
National Weather Service Sioux Falls SD
638 PM CDT Sun Aug 13 2023
.SHORT TERM...(This Evening through Monday)
Issued at 227 PM CDT Sun Aug 13 2023
1. Scattered showers and thunderstorms will continue to develop
this afternoon and early evening, but severe weather risks remain
low.
2. Breezy and cooler temperatures for Monday with quite a few gusts
through the day.
3. Still quite a bit of uncertainty through next week regarding
precipitation risks. Latest trends continue to favor dry conditions
through the week.
4. Temperatures are expected to warm, with the greatest potential
for very warm temperatures beginning next weekend or more likely
after.
-----------------------------------------------------------------
THIS AFTERNOON: Surface low pressure continue to develop near
Huron this afternoon, with a cold front dropping southward through
Mitchell and O`Neill as of 2pm. Considerable cloud cover in the
pre- frontal environment has limited instability. HRRR instability
may be a bit low at 300 J/KG, but RAP/NAM is likely too high at
over 1000 J/KG. As dPVA spreads over the area this afternoon, and
mid- lvl jetlet arrives at the base of the upper trough, we should
begin to see scattered showers and pockets of convection form
along and ahead of the front through the afternoon. Tall skinny
CAPE profiles don`t necessarily suggest a great potential for
large hail, nor do the mostly saturated soundings suggest damaging
winds. The 0-1km CAPE remains low ahead of the boundary, and no
clear indication of increased stretching along the front from
model guidance, so feel a tornado risk remains low. However we
have had a couple reports of brief pencil funnels, so clearly some
potential does exist at updraft base, and this may be even more so
within a radius of the surface low.
THIS EVENING: The front is expected to pass quickly through the
CWA, moving east of the area by 9pm. With the surface low slowly
moving east and southeast, continued showers are expected around the
surface low north of I-90 into the early overnight hours.
Additionally, the increasing SPG may lead to some stronger gusts
over 30 knots into the early overnight hours through the James
River valley and eastward towards I-29.
TONIGHT: The surface low moves into southwest Minnesota by
midnight, with the upper low nearly vertically stacked at the same
time. Moisture advecting around the upper trough will keep
persistent area of showers or light rain drifting southeast
through daybreak across eastern South Dakota and Southwest
Minnesota. Gradient winds will also remain quite gusty into Monday
morning.
MONDAY: Generally a quiet day is expected as the upper low moves
eastward. Winds will stay gusty through at least early afternoon,
with a few 30 mph gusts possible. Rain will dissipate in the
morning, but watch out for some deep CU field development in the
afternoon leading to isolated showers or sprinkles at times along
and east of I-29. Highs climb into the 70s.
.LONG TERM...(Monday Night through Sunday)
Issued at 227 PM CDT Sun Aug 13 2023
TUESDAY- WEDNESDAY: As mid-lvl heights begin to build over the
Rockies and Four Corners region, a second upper trough will pass
across central and southern Canada into Wednesday. Broad warm
advection spreads across the Northern US on Tuesday, and as surface
winds turn more to the southwest, we should see highs climb into the
80s. A front is still expected to sweep through the region
Wednesday afternoon and evening, but the combination of capping and
poor moisture return may limit the risk for convection central
Minnesota and perhaps into southwest Minnesota into Wednesday night.
Highs Wednesday ahead of the front climb further into the 80s.
THURSDAY: Temperatures cool for Thursday as high pressure moves
through the region. As 850 mb temperatures fall into the lower
teens, highs may only rise into the 70s to lower 80s.
FRIDAY-SUNDAY: Medium range model spread grows for the end of next
week and into next weekend. This is largely due to both the
intensity and location of an upper ridge that is expected to build
across the central US. The GFS remains more amplified with the
ridge and spread the ridge further west. Given systematic warm bias
of the surface temperatures in the GFS, considerable caution needs
to be taken with both the GFS deterministic and ensemble
temperature output and there could be some feedback ongoing. The
GEM/ECMWF on the other hand remains more suppressed and further
east with the mid- lvl ridge, likely due to both deeper troughing
over the eastern Pacific and phasing with a trough crossing
southern Canada. If this solution verifies, we may end up on the
cooler side of a backdoor cold front through the weekend. What all
three models and their respective ensembles support is a
continued northward amplification of the ridge after next weekend,
with 60%+ probabilities of 90 or more degrees for the days
following.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday Evening)
Issued at 637 PM CDT Sun Aug 13 2023
Surface and upper low with associated cold front continue to move
southeast this period. Winds behind the system are gusting 25 to 30
kts. Expect gusts to slowly diminish from northwest to southeast
toward the end of the period.
A band of mildly convective precipitation along the front is
currently located in a rough line from Ivanhoe MN south to Moville
IA. This band will continue to move east through this afternoon and
evening. Lightning has been very infrequent with these showers and
with the general lack of instability have opted to leave thunder out
of this round of TAFs. Another round of wrap around showers will
form on the backside of the low pressure system early Monday
morning. Stratus will continue to hover between MVFR and IFR into
Monday morning.
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...None.
MN...None.
IA...None.
NE...None.
&&
$$
SHORT TERM...Dux
LONG TERM...Dux
AVIATION...AJP
AREA FORECAST DISCUSSION
National Weather Service Jackson KY
1118 PM EDT Sun Aug 13 2023
.UPDATE...
Issued at 1118 PM EDT SUN AUG 13 2023
The bulk of the forecast remains on track. A dying swath of
showers and storms is shifting southeast from Indiana into
Central Kentucky, but IR indicates warming cloud tops and
decreasing lightning. Additionally, CAMs have this generally fizzled
out by the time it reaches the western fringes of the CWA.
Nonetheless, do have a low end chance to account for isolated
showers before a better opportunity arrives into Monday morning.
Edits to sky grids to better reflect the on going trends through
the night were accounted for. Lastly, included some very minor
ridge/valley splits in the east. With higher clouds holding on the
longest there before low and mid level decks fill in from the
west through the night, feel eastern valleys fair the best chance
to see some values in the 60s. Outside of these changes, a load
and blend of the latest T/Td/Wind obs was done for consistency.
Updated grids have been sent to NDFD and Webfarms.
UPDATE Issued at 816 PM EDT SUN AUG 13 2023
This update primarily focused on tweaking PoPs through the evening
and overnight. Our first complex of showers and storms will
primarily stay south of the state, though scattered activity will
be possible along the border of Tennessee, as well as for a
cluster in and south of the Bluegrass. This should all weaken and
dissipate with time, setting up mostly cloudy skies tonight. CAMs
indicate a secondary and more widespread complex will approach
from the west late tonight into the morning hours of Monday -
again weakening with eastward progression. Have blended and
tweaked PoP grids based upon radar and CAM trends through this
time. A load and blend of the latest T/Td/Wind/Gust obs was also
done. Grids and a fresh set of zones with the mentioned edits have
been sent.
&&
.SHORT TERM...(This evening through Monday night)
Issued at 534 PM EDT SUN AUG 13 2023
Key Messages:
* Severe Weather will be possible Monday and Monday night.
* Strong to damaging wind gusts will be the primary threat;
however an isolated tornado, at least small hail, and isolated
flash flooding will also be possible.
The latest upper level map features ridging maintaining control
over the Gulf Coast States. A deeper cutoff low is spiraling over
the Dakotas, with seasonably faster west to east oriented flow
set up from the Plains through the Mid-Atlantic region. At the
surface, a remnant frontal boundary is aligned from Delmarva
through the central Appalachians and across the northern third of
the Commonwealth. An MCS is rolling through central Tennessee,
with the northern flank of complex showing some gradual
weakening, per the latest IR Satellite trends. Some isolated to
scattered convection fired up across eastern Kentucky this
afternoon, mainly along the instability gradient noted near and
just south of the frontal boundary.
The models have maintained good agreement aloft through the short
term. The Dakotas cutoff low will move into the Midwest tonight,
and then advance east towards the Illinois/Wisconsin border on
Monday, before moving across southern Michigan Monday night. At
the surface, low pressure will consolidate across the Midwest and
gradually deepen as it moves through the Ohio Valley/Great Lakes
region on Monday. The low will then reach the eastern Great Lakes
by early Tuesday morning. An attendant cold front will sweep
through eastern Kentucky by Monday night, with rounds of showers
and thunderstorms preceding the front.
Isolated to scattered convection will generally diminish through
this evening, although some additional development may sustain a
bit more across our southwest, as the upstream weakening MCS
grazes our counties bordering Tennessee through this evening.
Most of the CAM guidance then suggests another complex of
thunderstorms approaching from the west towards dawn ahead of an
increasing low level jet. The 12Z HRRR was more robust than the
other HREF guidance in maintaining this convection better;
however, the 18Z has since backed off this idea. Some patchy fog
will develop in the valleys tonight, especially at those locations
that can manage some rainfall. Lows will be near or a few degrees
on either side of 70.
The more widespread rains look to roll through our area between
12 and 18z Monday. The severe threat would be limited here, given
the time of day; however, as temperatures rebound in the
afternoon, effective shear values will be on the increase across our
area, as stronger mid-level winds advect in out ahead of the
approaching trough. This will support some supercells as well as
some smaller scale QLCSs. The 12Z HREF showed only a weak signal
across our southern counties in the afternoon/early evening for
more substantial updraft helicity swaths, so much will depend on
the amount of instability that can build back following the
morning convection. The best overall parameter space looks to be
south of the Hal Rogers Parkway and Highway 80, as well as along
and east of Highway 23. Damaging winds will be the primary threat,
with small hail and an isolated tornado also possible. Similar to
our previous event, any better tornado potential will likely be
more dependent on storm-scale boundary interaction. The convection
will likely be more scattered in nature preceding the front, with
storms becoming more consolidated off to our southeast with time
into Monday evening. Still, some training cells will be possible,
given that the approaching cold front will be more parallel with
the upper level flow, and with PWATs likely topping the 2 inch
mark at their peak. Highs on Monday will range from the mid to
upper 80s. Convection will gradually diminish from northwest to
southeast Monday night, as the cold front exits. Temperatures will
cool off to the mid and upper 60s.
.LONG TERM...(Tuesday through Sunday)
Issued at 318 PM EDT SUN AUG 13 2023
Key Concerns:
* Temperatures rising several degrees above normal levels next
weekend and beyond.
Analysis:
After a couple of days of September-like weather mid-week, much
warmer temperatures, among the hottest of the season, will build
into eastern Kentucky by the upcoming weekend and continue into
next week. The 13/12z model analysis beginning Tuesday morning
shows low pressure near/over Upstate New York with a cold front
extending down the eastern slopes of the Appalachians. The front
precedes a deep positively-tilted trough extending from its parent
~569 dam low spinning over Lower Michigan to over the Ark-La-Tex
region. Further west, an ~595 dam ridge extends from Texas to the
Columbia River Valley and then westward into the Pacific. Surface
high pressure is in place over much of the Plains.
The upper level trough axis will pivot across Kentucky on Tuesday
and Tuesday night. Expect fairly extensive post-frontal strato-cu
field to develop on Tuesday with daytime heating. A few of the most
robust updrafts may become deep enough to produce a shower,
particularly over the higher terrain further east (this potential is
covered by a 10 to 20 PoP at most locales). Otherwise, it will be
cool with more of an early autumn feel as temperatures peak in the
mid 70s to around 80. Any sprinkles or light showers come to an
end Tuesday evening with mostly clear skies prevailing. It will be
cooler with temperatures dipping into the mid to upper 50s for
many and to around 60 in the warmest spots.
Cool northerly breezes will continue on Wednesday as surface high
pressure builds eastward from the Central Plains/Ozarks. Once
that high crests over the Central Appalachians on Wednesday night,
low-level flow will turn southwestward and begin pumping
increasing warmth and humidity back into eastern Kentucky. Aloft,
500H heights will begin to rise steadily as the upper level
ridging consolidates and shifts northeastward to over the Ozarks
where the geopotential heights will near ~598 dam by next Sunday.
A shortwave trough does ride over the ridge early Friday, shunting
a cold front into the Ohio Valley, but that boundary`s southward
progress is in question as it will loses its upper level support.
Even if the front does reach our area, the potential for any
rainfall looks minimal to nil due to strong capping under the
strengthening ridge and any cooling of the air temperatures would
be inconsequential. Temperature-wise, after one more cool
afternoon on Wednesday (highs again in the middle to upper 70s),
a warming trend will begin Thursday and continue right through the
weekend. High temperatures in the lower 90s are likely by Sunday
at most locations. Meanwhile, nighttime lows will also moderate
from the middle 50s to lower 60s on Wednesday night to the middle
and upper 60s by Saturday night.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
ISSUED AT 816 PM EDT SUN AUG 13 2023
VFR conditions as of TAF issuance, which should generally prevail
for most sites through the period. The exceptions will be for
river valley fog development late tonight, which could impact JKL
and SME in the pre-dawn hours. Have included a brief window of
MVFR to account for rainfall seen at JKL this afternoon as well as
showers in the SW yesterday and again into this evening. Outside
of some visibility restrictions from fog, scattered showers or
storms are possible over the next few hours, but given the lack of
confidence in how well these will maintain eastward, have only
included VCTS at SYM. A more organized complex of convection will
perhaps threaten after 10z, but this should weakening with time.
The evolution of this activity will have some influence on how
convective trends play out through Monday afternoon and evening.
For now, activity is generally expected to increase through the
day. West southwest winds of around 5 kts or less are expected
overnight. Winds will then become southwesterly during the day on
Monday at around 10 kts.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...BB
SHORT TERM...GEOGERIAN
LONG TERM...GEERTSON
AVIATION...GEOGERIAN/BB
Area Forecast Discussion
National Weather Service Louisville KY
843 PM EDT Sun Aug 13 2023
.Forecast Update...
Issued at 842 PM EDT Sun Aug 13 2023
...Multiple Rounds of Convection Still To Go...
A nearly stationary frontal boundary remains draped along and just
north of I-64 at this hour. Convection that had developed just south
of this boundary has weakened and moved off to the east over the
past hour or two. In addition, the weak MCS across our southern
border has moved east of Clinton county. We did see some area across
central KY pick up 1 to 2.5" of rain with training/backbuilding
convection through the early evening, so will have to watch those
areas for the next two rounds of convection. Until then, we find
ourselves in a relative lull.
Have been watching a cluster of storms (with occasional supercell
characteristics) moving across southern IL over the past several
hours, and these storms will be our next focus as we head toward
Midnight EDT. Consistent indications from the HRRR, which has a
pretty decent handle on the current activity, is that this complex
will weaken as it approaches our NW CWA. Looking at current
mesoanalysis, would tend to agree with a slightly less favorable
environment the farther SE the complex works. That being said, there
may be just enough ingredients with moderate instability and modest
deep layer shear to sustain the storms a bit longer than the HRRR
suggests. Will have to keep a close eye on these storms as we near
Midnight.
Beyond that, expect to have sporadic coverage of showers and storms
through the overnight as the low level jet ever so slowly begins to
respond ahead of the approaching trough axis/mid and upper speed
max. The most likely area for new convective development will be
across our northern third of the CWA where that lingering boundary
will be slowly lifting northward. These showers and storms will be
capable of heavy rain given slower movement, perhaps some training,
and a high PWAT airmass.
Another complex which is already starting to develop over eastern
Kansas is expected to arrive across our western CWA toward
sunrise. This feature will have the potential for gusty or even
isolated damaging winds, as well as another round of briefly heavy
rainfall. This will likely be our best shot at severe weather,
and may result in a few instances of minor flooding, especially if
areas get repeated rainfall from the previous rounds of
convection. After this complex passes around mid to late morning,
the big question will be whether any new development can occur
before cold frontal passage later Monday afternoon/evening? This
will be when the deep layer shear is the strongest, and we may end
up with enough instability to still keep a lingering severe
threat until FROPA. Stay tuned. Busy 24 hours ahead. The good news
is that after tomorrow`s frontal passage, we could have a
prolonged dry period. The bad news is this could come with
increasingly hot temperatures by late week.
&&
.Short Term...(This evening through Monday)
Issued at 255 PM EDT Sun Aug 13 2023
...Strong Storms Possible Across Southern KY This Afternoon and
Evening...
...Widespread Strong to Severe Storms Possible Monday Morning...
Concern is growing this afternoon for strong storms to impact south-
central KY between 20-00z, mainly south of the Cumberland Parkway.
We continue to monitor a strong MCS pushing east across western
KY/TN. The downstream environment is increasingly unstable,
especially across Middle TN where 2000-3000 J/kg MLCAPE is noted.
MLCAPE approaches 2000 J/kg in southern KY (Logan, Warren counties,
etc.). Effective bulk shear is marginal at 25-30 kts, but a
developing MCV may boost mid-level winds locally and enhance storm
organization. This could support a localized damaging wind risk
across southern KY later this afternoon. Likewise, low-level shear
is quite weak. But given the approaching MCS, mesoscale effects make
it difficult to rule out a brief tornado where an otherwise weak low-
level shear vector is oriented perpendicular to the line.
Attention then turns upstream once again for round number two.
Showers and storms ongoing across northern and central Missouri will
continue to evolve eastward toward the Wabash Valley later this
evening. This activity could move across southern IN and portions of
north-central KY late tonight (after 01-02z). However, not confident
any scattered storms around that time will be particularly strong
given weak instability and stronger forcing still off to the west.
Moving into tomorrow morning, a sharp upper level trough will
continue to drop southeast over the Midwest. Strengthening WSW flow
aloft will spread south and east through the Mid-MS and Lower OH
Valleys. A strengthening 35-40 kt SW LLJ will fuel the development
of deep convection downstream of the cold front across portions of
Missouri overnight. Confidence has increased in a strong MCS then
moving east across central KY and southern IN during the early to
mid-morning hours. These storms will be associated with anomalous
low-level warm, moist air advection. The most likely time frame for
strong to severe storms is 6-11 AM EDT Monday.
This timing around the diurnal minimum may play a role in limiting
the severe wind potential at the surface. But depending on the exact
evolution overnight, certainly cannot rule out isolated damaging
winds and a few brief tornadoes with more favorable low-level shear.
PW values also rise above 2 inches, and any cell training could
result in a localized risk for flash flooding.
Convection clears the Bluegrass Region around midday, and we`ll see
a lull in activity Monday afternoon. However, the sfc cold front
will still remain off to the west. Breezy SW winds and partial
clearing will allow the airmass to destabilize ahead of the
approaching boundary. Temperatures are forecast to rebound into the
80s, with mid/upper 80s across central and southern KY. With
dewpoints still in the 70s, this will likely be a quite buoyant
airmass for the approaching upper level trough and sfc front to
interact with. Scattered strong to severe storms will be possible
along and ahead of the cold front late Monday afternoon and evening.
MLCAPE up to 1000-1500 J/kg looks possible late Monday afternoon,
with instability gradually waning through sunset. Deep-layer shear
of 40-45 kts will support robust updraft growth and maintenance (and
supercellular structure). The main concerns will be isolated
damaging winds and hail, with damaging winds a relatively greater
threat due to steep low-level lapse rates.
.Long Term...(Monday night through Sunday)
Issued at 305 PM EDT Sun Aug 13 2023
Could begin Monday evening with isolated to scattered thunderstorms
as a strong August cold front pushes across Kentucky, with a few
strong to severe storms still possible. Unseasonably mild weather
will follow Tuesday through Thursday. Warmer temperatures and higher
humidity will make a gradual return late in the week, but no
widespread precipitation is expected through next weekend.
The cold front will be near the Ohio River early Monday evening, and
push through fairly quickly given strong westerlies aloft. Modest
instability and up to 40-45 kt of deep-layer shear will support a
continued risk of severe weather, but it will be diminishing quickly
after sunset as the front clears the area and both instability and
moisture are lost.
Canadian high pressure will build in on Tuesday, bringing
unseasonably mild temperatures with most locations topping out in
the mid/upper 70s. Even though the days will feel like September
(still struggling to crack 80 on Wednesday), we`ll stay just muggy
enough to keep temps from bottoming out at night. Look for mins
in the lower/mid 60s, just a few degrees below normal, with
dewpoints in the upper 50s to near 60 through early Thursday.
Upper ridging starts to build from the Central Plains later in the
week, allowing a recovery in temps and, unfortunately, dewpoints.
This ridging is strong enough to shunt the stronger westerlies well
to our north, and while we can`t completely rule out precip chances
Thu night/Fri with a sharp upper wave cutting across the width of
Ontario, POPs will remain too low to mention. We`ll make another run
at 90 degree temps Sat-Sun as the ridging continues to build, and
keep the forecast dry as the Ring of Fire is pushed solidly to our
north and west.
&&
.Aviation...(00Z TAF Issuance)
Issued at 747 PM EDT Sun Aug 13 2023
An active period of weather for the TAF sites over the next 24 hours
or so as several rounds of showers and storms move through the area
ahead of a cold front. The TAF sites should start out dry, however a
few showers and storms could impact overnight. Tried to highlight
the best timeframe for each site. In addition, some MVFR ceilings
are possible across the northern sites through the early to late
morning time frame.
In addition to the low ceilings, a complex of showers and storms is
expected to quickly move west to east through the area from around
sunrise through the late morning hours. Thereafter, expecting
veering and increasing winds as the cold front approaches and
passes. Could see some W and WNW wind gusts up in the 20 to 25 mph
range. Ceilings will improve but a few lingering showers and storms
are possible into the early evening.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
IN...None.
KY...None.
&&
$$
Update...BJS
Short Term...EBW
Long Term...RAS
Aviation...BJS
Area Forecast Discussion
National Weather Service Marquette MI
628 PM EDT Sun Aug 13 2023
.SHORT TERM...(This afternoon through tonight)
Issued at 127 PM EDT SUN AUG 13 2023
Key messages:
-Impactful weather is not expected this afternoon and evening.
-Rain chances increase tonight as a system moves from the Northern
Plains into Wisconsin.
This morning, GOES 16 Water Vapor Imagery and RAP analysis
highlighted well a couple features, including an area of light rain
to our south, 2 clusters of thunderstorms further south, and an
upstream shortwave over the Dakotas. The first supported some
midlevel cloud cover at times near the Wisconsin/Michigan stateline
today while overnight lingering moisture and cyclonic flow supported
overcast low ceilings over the eastern half of the forecast area.
The mostly clear skies in the west has allowed daytime temps to
climb into the mid and upperer 60s under mostly northerly flow. The
cloud cover in the east delayed heating some, but we`ve still
observed temperatures mostly in the 60s. As we progress through the
remainder of the afternoon, expecting some additional heating and
off and on cloud cover, particularly in the east half this
afternoon.
The upstream shortwave is the main item of interest tonight. As it
progresses southeast, the surface high overhead will gradually
weaken, allowing precip to spread across Minnesota and Wisconsin.
There are still some questions about how far north the precip shield
will extend, but the best chances for light rain still appear near
the Wisconsin/Michigan stateline and south-central late tonight into
Monday. Some light rain or sprinkles may extend further north, but
the likelihood of persistent steady rain is low (<25%).
.LONG TERM...(Monday through Sunday)
Issued at 438 PM EDT SUN AUG 13 2023
Key Messages:
-A low passes south on Monday bringing rain to south half of the U.P.
-A quick shot of shower chances Tuesday evening, otherwise dry
-Next noteworthy system is expected late Wednesday to Thursday,
potential for thunderstorms and gusty winds mixing down
Starting 12z Monday, model guidance has come to fairly good
agreement about the track of the sfc low pressure bringing heavier
precip to the midwest, just not our CWA. A ~1008mb moves eastward,
deepening slightly along the southern edge of the Great Lakes Basin
before it moves northeast over New England and dissipates on
Tuesday. Acknowledging previous forecast packages, this system has
trended south, primarily out of our CWA with only the southern end
really seeing anything measurable from this system. GFS Ensemble
probability of 0.5 inches or more peaks in Menominee at around 50%;
lowering that to just 0.1 inches, Marquette only just falls into the
10% range with the Keweenaw staying completely dry. ECMWF ensemble
paint a similar picture, but with slightly lower probabilities. (An
even drier solution) That being said, up to 0.6 inches of rainfall
is possible in Menominee, with totals decreasing northward and the
northern half of the U.P. expected to stay dry.
Sfc high pressure originating over the Plains pushes east into the
Mississippi Valley in the wake of this system, providing a brief
break from the precip Monday night and Tuesday. A the high builds in
over the U.P. winds become light over the west Monday night. While
the NAM soundings show an impressive nocturnal layer developing,
neither the NAM or the GFS soundings show much saturation occuring.
Some patchy fog is possible interior west where we are able to
radiatively cool enough to saturate at the sfc, but I chose to leave
it out of the forecast at this time due to low confidence. A
shortwave brings some slight chances for light rain Tuesday evening,
however ensemble probabilities of 0.1 inches or greater are only 20-
30% at best in the Keweenaw and northern half of the Upper
Peninsula. Likely most will stay dry until our next system late week.
A 500mb cutoff low develops over northern Manitoba on Wednesday,
swinging east over Ontario through Thursday. There is still a bit of
spread in the sfc low track, but the general consensus is that it
follows a similar path through Ontario before heading northeast
toward Quebec/James Bay on Thursday. A low level jet begins to nose
in from the southwest Wednesday afternoon with winds at the 850mb
level up to 50 knots on GFS soundings. The low brings a cold front
west to east across the U.P. late Wednesday night into Thursday
morning bringing rain and thunderstorms chances. Bulk shear along
the cold front will build upwards of 40 knots with MLCAPE staying
below 1000 J/kg. Warmer midlevels and weaker mid-level lapse rates
will help work against storm potential, however an isolated stronger
storm is possible. The likely solution due to the lack of
instability will be scattered showers and rumbles of thunder.
What will be the bigger thing to watch out for is gustier winds
mixing down from this strong jet feature moving through. GFS and
ECMWF ensemble members indicate gusts between 30 to 40 mph could
mix down across the U.P. Wednesday night into Thursday.
PWATs show dry air intruding behind the frontal boundary yielding
dry weather into Friday and mostly dry weather the rest of the
weekend as sfc ridging briefly builds back over the region on
Friday. Saturday and Sunday could see another sfc trough pass
through the Great Lakes Basin, however guidance has a decent spread
on timing and track, so POP chances were kept slight at best.
Southerly winds Friday and Saturday will help provide a warmer
weekend with highs reaching back toward the 80s.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 628 PM EDT SUN AUG 13 2023
VFR conditions are expected to prevail at all TAF sites in this
forecast period.
&&
.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 438 PM EDT SUN AUG 13 2023
Northeasterly winds near 20 kts are expected on Monday as a sfc low
tracks eastward along the southern end of the Great Lakes Basin.
These will diminish Monday night as ridging builds in. Winds will
back southwest into Tuesday, building gusts up to 20 to 25 knots
over the west half of the lake as shortwave passes over the lake.
Southeast winds around or below 20 knots will continue over the lake
Tuesday night ahead of the next system bringing shower and
thunderstorm potential as well as gusty winds.
A low level jet builds in ahead of the next system from the west.
This coupled with some lake induced instability may support some
gusty winds between 20 and 30kts at times beginning Tuesday
afternoon. NBM probabilities of wind gusts exceeding 34 knots are
around 70-90% over much of the Lake Superior waters. That being
said, there is still some spread in the model guidance on where
exactly these stronger winds will mix down. These gusts should
persist into Wednesday as the system`s cold front moves through from
west to east Wednesday night into Thursday bringing scattered
showers and some non-severe thunderstorms. Lingering pressure rises
and an unstable airmass behind the front look to support winds near
25kts Thursday. Ridging briefly builds back in on Friday leaving
winds at or below 20 knots.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
None.
Lake Michigan...
None.
&&
$$
SHORT TERM...JTP
LONG TERM...Jablonski
AVIATION...07
MARINE...Jablonski
...Updated Aviation Forecast Discussion...
.DISCUSSION...
Issued at 218 PM CDT Sun Aug 13 2023
Key Messages:
- A few severe storms are possible (5-10% chance) south of Interstate
80 into this evening. Primary threats are damaging winds and
hail.
- Cooler and breezy start to the week with potential for
spotty showers on Monday.
- Overall warming trend and likely dry through the rest of the
week with potentially dangerous heat next weekend.
Here we go with a fairly messy, low confidence weather situation
for this afternoon and evening. While we saw widespread rainfall
and cloud cover overnight into this morning, much of southeast NE
and southwest IA saw clearing by mid morning. However, with
residual moisture lingering in the area, some lower clouds were
developing in said clearing early this afternoon. Still, plenty of
clearing remained and SPC mesoscale analysis showed 500 to 1000
J/kg of MUCAPE beginning to edge into the area, with the more
unstable air to the southwest. Guidance remains in decent
agreement that this more unstable plume should push into at least
far southeast NE through this afternoon (MLCAPE values approaching
1250 J/kg), ahead of the well-advertised cold front currently
stretching from northeast to southwest across NE. There were a
couple bands of spotty convection in vicinity of the front and
given the clearing and aforementioned instability to the south,
this convection should invigorate as the cold front continues to
advance southeastward. While shear also remains modest, there does
appear to be enough to yield some degree of storm organization,
so do think there is at least some low-end potential for severe
weather, generally near and south of I-80 where we saw the most
clearing. 12Z CAM solutions tend to agree that there could be some
stronger to severe storms, but it`s worth noting that most recent
HRRR guidance has trended toward nothing more than showers. So
bottom line, there`s probably a 5 to 10 percent chance we see
severe weather, with damaging winds and hail being the primary
threats.
While storms will exit this evening, some spotty precip could
linger through the day on Monday as the area remains under a
trough axis/cyclonic flow aloft. Model soundings also show some
decent moisture moving in along with a little instability in the
cloud layer. In addition, simulated reflectivity fields from
various CAMs show spotty light returns while many pieces of
guidance show at least some light QPF. Therefore, included some
low-end precip chances for much of the day, though drier air and
surface high pressure working in should limit what reaches the
ground, with anything that does likely being quite light.
Otherwise, north winds will be on the stronger side through the
day on Monday, with gusts of 30+ mph at times. This will lead to a
cool with widespread highs in the 70s.
We`ll generally see a warming trend with dry weather through the
remainder of the week into next weekend as upper level ridging
builds in and southerly low level flow returns behind the
departing high. Expect a return to the 80s for most areas Tuesday,
followed by 80s and 90s on Wednesday. Then guidance is in better
agreement regarding a shortwave trough digging into the northern
CONUS with an associated surface low in southern Canada dragging a
cold front through the area Wednesday night/Thursday. This will
lead to a brief pause in the warming trend, as temperatures hold
in the 80s on Thursday. A few various ensemble members suggest
potential for some light rain along the front, but the vast
majority of guidance keeps our area dry.
The warming trend returns Friday with mid 80s to mid 90s followed
by widespread 90s and possibly 100s for the weekend. For what
it`s worth this far out, NAEFS guidance does suggest 850 mb
temperatures in the 99th+ percentile of climatology by the
weekend, indicating at least some potential for heat advisory
criteria to be met. Obviously still a ways out and things can
change, but certainly something to keep an eye on in the coming
days.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 613 PM CDT Sun Aug 13 2023
Scattered showers will move through southeastern NE/southwestern
IA (including KLNK) until 0300 UTC. Moderate to heavy icing is
also possible across southeast NE/southwest IA between FL170 and
FL250 through 0400 UTC. Overnight tonight and through the day
tomorrow, strong gusty winds out of the northwest will impact the
region at all TAF sites. Winds could gust over 30 knots,
especially after 1200UTC. A brief period of MVFR ceilings is also
possible across northeastern NE and western IA between 1200 and
1800 UTC.
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...None.
IA...None.
&&
$$
DISCUSSION...CA
AVIATION...Nicolaisen
Area Forecast Discussion
National Weather Service Nashville TN
1053 PM CDT Sun Aug 13 2023
...New UPDATE...
.UPDATE...
Issued at 1046 PM CDT Sun Aug 13 2023
Earlier storms have already exited Middle Tennessee and thus we
await the next batch of cells, either later tonight or tomorrow
afternoon. The latest HRRR develops very little activity
overnight, but there is still some potential for at least
scattered convection toward sunrise. Model data coming in now
also suggests that the best storm chances will occur during the
afternoon with the expected fropa. We have added some patchy fog
overnight, mainly along the Cumberland Plateau and areas near the
Alabama state line. Existing clouds may limit the effects of
radiation cooling overnight, which is why we haven`t issued a
Dense Fog Advisory just yet.
&&
.SHORT TERM...
(This afternoon through Tuesday Night)
Issued at 213 PM CDT Sun Aug 13 2023
The active stormy pattern will continue for another 24 to 36 hours.
First off, the mcs to our west is on the move and will be moving
into the mid state this afternoon. The lightning is especially
impressive thus far and instability levels do support upcoming
strengthening. Straight line damaging winds and some heavy
rainfall with localized flooding will again be the primary
threats. A severe tstm watch has just been issued for the entire
mid state except for some of our Plateau counties. The watch will be
valid until 8 pm cdt. Look for this activity to exit our eastern
most counties early this evening. Following this, we will receive a
bit of a break for the overnight. However, conditions will become
active again for your Monday.
On Monday, we are expecting a cold frontal passage. There will be
some rather strong upper level support acting to strengthen the
boundary with time. Good n-s extension is indicated and this looks
especially pronounced for this time of year. The timing of the
frontal passage appears to be around midday into the afternoon
hours. Destabilization at the the time of the fropa will be greatest
across our eastern counties. It is for this reason that a slight
risk for severe is in effect for roughly our eastern third.
Straight line damaging winds is the primary threat with the window
of opportunity being the afternoon and early evening hours. There
is a smaller chance of hail and the risk of a tornado or two but
that threat is primarily east of the mid state. Note that some
early Monday morning convection will be possible as a bit of pre
frontal forcing could be in play. Storms at this time however
looks as though they will remain sub severe for the morning hours.
Monday night behind the fropa, we could see a few residual showers
as the upper level trough axis works its way through our area.
Much nicer weather on tap for your Tuesday.
For the near term temps, it will be quite warm through Monday. In
fact, areas in our south will easily be in that 100-105 degree heat
index range. Timing of the aforementioned convection will be key as
to how hot it will get as compressional pre frontal warming could
come into play. Otherwise, again, Tuesday appears to be the pick
of the week in terms of weather conditions. Looks like it will be
partly cloudy with highs in the lower 80s with lower humidity.
&&
.LONG TERM...
(Wednesday through next Sunday)
Issued at 213 PM CDT Sun Aug 13 2023
For the extended forecast, it`s been a while since we had an entire
pop free extended period. That said, for this round, no pops are
indicated. The surface high will be in control on Wednesday, with
pressure in the upper levels on the increase with time. This
equates to a definitive warming trend with highs reaching the
lower to mid 90s over the weekend. Humidity levels look close to
average with dewpoints in the 60s, reaching to near 70 by the tail
end.
Note that extended models do elude to a dry fropa around Thursday,
so will need to watch for the emergence of some low pops in future
model runs. The airmass looks quite dry, however, so we shall see.
Looking way ahead at the 6 to 14 day climate prediction, looks
like a very good chance of above normal temps and below normal
precip. Looks like an August heat wave could be on the way?
&&
.AVIATION...
(00Z TAFS)
Issued at 619 PM CDT Sun Aug 13 2023
Made some changes to the timing for storms expected into Middle TN
after 11Z and spreading across the area affecting all terminals
through the morning hours. Should come with lowered vis, but
uncertain about wind gusts attm. Wind gusts will pick up in the
afternoon behind fropa, along with wind shift to the northwest.
IFR to LIFR fog possible again after 06Z tonight for SRB and CSV.
Should return to VFR by 12Z.
&&
.PRELIMINARY POINT TEMPS/POPS...
Nashville 73 94 68 80 / 50 80 50 0
Clarksville 74 90 64 78 / 80 80 10 0
Crossville 69 87 63 74 / 90 70 60 10
Columbia 72 94 66 79 / 20 30 40 0
Cookeville 69 89 65 76 / 70 80 70 10
Jamestown 71 87 63 74 / 90 80 80 10
Lawrenceburg 70 93 66 79 / 20 30 50 0
Murfreesboro 73 95 67 81 / 30 60 60 10
Waverly 73 90 63 76 / 50 50 10 0
&&
.OHX WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
UPDATE.......Rose
SHORT TERM...21
LONG TERM....21
AVIATION.....Unger
Area Forecast Discussion
National Weather Service Tallahassee FL
1035 PM EDT Sun Aug 13 2023
...New UPDATE, MARINE...
.UPDATE...
Issued at 1035 PM EDT Sun Aug 13 2023
Did some minor first period updating to account for current radar
trends. Recent HRRR runs show the cluster of storms over southeast
Alabama falling apart in another 1-2 hours as they make inroads
into Florida. After that, a quiet overnight is expected.
We have upgraded Mondays Excessive Heat Watch to a Warning. The
east-west 500 mb ridge axis will remain squarely overhead while
starting to become more narrow, and 500 mb heights near 5940
meters will prevail. One more day of excessive heat is expected,
meaning heat index values maxing out at 113F or higher across a
fairly large area.
&&
.NEAR TERM...
(Through Monday)
Issued at 247 PM EDT Sun Aug 13 2023
Monday will bring much of the same in terms dangerous heat, and
chances for showers and thunderstorms. Unfortunately another day of
dangerous heat will be present across the region as the upper level
ridge slowly pushes east off the Atlantic coast of Florida on
Monday. This upper level ridge is being displaced by an upper level
trough currently progressing across the Great Lakes region, which
will bring ever so slightly lower 500mb heights into the region
Monday. This may lower expected high temperatures for the area into
the upper 90s, with a few locations still potentially reaching near
100; however, most folks across the area will remain below 100 for
their high temperature. On the downside, dewpoints will remain quite
high across the region in the mid to upper 70s, and in some cases
low 80s near the coast, which will once again push heat indices to
113 or higher over most of the region. Some areas across the Florida
Panhandle and Big Bend may reach heat index values near 120 once
again. Given these heat index values, an Excessive Heat Watch
remains in effect for Monday, and is expected to be upgraded to a
warning by this evening.
Isolated to Scattered showers and thunderstorms are again expected
Monday afternoon/evening. These storms will have some help
developing as the upper level ridge pushes east. This will allow
some diffluence aloft north of the region thanks to the
aforementioned upper level trough sliding east towards the Ohio
River valley. Storms may still have a later start given the
proximity of the upper level ridge to our area; however, with the
extra forcing for ascent present, storm activity may be slightly
more widespread, with 50-60% PoPs forecast over much of the area.
DCAPE values are once again forecast over 1000 J/Kg, which will
allow stronger thunderstorms that develop to produce strong gusty
winds.
&&
.SHORT TERM...
(Monday night through Tuesday night)
Issued at 247 PM EDT Sun Aug 13 2023
A compact upper level low is forecast to move over the Great
Lakes region during this period, which will shove upper level
ridging to our west. The upper level trough will then into the
eastern Great Lakes region leading to broad troughing setting up
over much of the east. Unfortunately, it looks like we`ll have
another hot day in store for us. Temperatures peak in the mid 90s
while the Heat Indices 107 to 117 degrees. It`s quite possible we
may additional heat products, but that could be dependent on when
the front associated with trough moves in. Models eventually bring
a front over the region potentially as early as late Tuesday into
Wednesday. Kept NBM pop in for Tuesday as timing is uncertain.
&&
.LONG TERM...
(Wednesday through Saturday)
Issued at 247 PM EDT Sun Aug 13 2023
Upper level trough sets up through Thursday, which combined with a
stalled frontal boundary, should lead to higher rain and
thunderstorm chances each day. Kept higher pops in through the
period, but this may be a bit over done as guidance continues to
favor a pattern change to upper level ridging towards the end of
the week or early weekend.
&&
.AVIATION...
(00Z TAFS)
Issued at 716 PM EDT Sun Aug 13 2023
Continued mention of VCTS at DHN, ECP, and TLH for the next couple
hours as outflow boundaries continue to produce isolated TSRA.
Gusty winds are possible if storms move over the terminals.
Otherwise, VFR conditions continue at all sites. Some patchy fog
is possible early Monday morning near DHN and VLD, possibly
bringing VSBYs down to MVFR. TSRA, perhaps greater coverage, will
develop after 19-20z across the area, and VCTS has been introduced
for all sites from 19-20z onward.
&&
.MARINE...
Issued at 1035 PM EDT Sun Aug 13 2023
High pressure centered over the northern and eastern Gulf will
only allow light to gentle breezes to prevail over the waters
through Tuesday. Breezes may briefly become moderate at times
starting Tuesday night as a trough of low pressure or perhaps a
weak cold front settles south to near the northern Gulf Coast.
This will also bring increased coverage of showers and
thunderstorms, bringing localized increases in wind and seas.
&&
.FIRE WEATHER...
Issued at 247 PM EDT Sun Aug 13 2023
Extreme heat and humidity will continue to be a large concern for
folks working outdoors for the start of the work week. Heat index
values will continue to surge to values of 110 degrees to 120
degrees across much of the region. Otherwise, the background flow
will remain rather light at around 10 mph or less out of the
southwest. Gusty and erratic winds will be possible each afternoon
during thunderstorms; however, and frequent lightning will also be
another concern. High dispersions also look to be a concern across
SW Georgia, with slightly stronger transport winds at around 10-15
mph out of the SW, coupled with mixing heights near 6000ft or
better.
&&
.HYDROLOGY...
Issued at 247 PM EDT Sun Aug 13 2023
Chances for rain increase as a frontal boundary is expected set up
around midweek and potentially stall over the region. Currently
WPC has a Marginal Risk (level 1 of 4) over us for Tuesday as well
as Wednesday and Thursday; however, the risk gets trimmed to the
southeast a bit each day. Widespread flooding is not a concern at
this time, but rather localized flooding may occur due to either
training or stalled storms.
&&
.SPOTTER INFORMATION STATEMENT...
Spotter activation is not requested. However, spotters are always
encouraged to safely report significant weather conditions when they
occur by calling the office or tweeting us @NWSTallahassee.
&&
.PRELIMINARY POINT TEMPS/POPS...
Tallahassee 78 98 77 95 / 20 60 10 70
Panama City 82 94 82 92 / 10 40 10 60
Dothan 77 98 76 95 / 40 50 10 70
Albany 78 98 77 95 / 10 50 10 70
Valdosta 78 98 76 95 / 10 60 10 70
Cross City 78 95 78 93 / 20 60 20 70
Apalachicola 82 92 81 91 / 10 50 20 60
&&
.TAE WATCHES/WARNINGS/ADVISORIES...
FL...Excessive Heat Warning from 10 AM EDT /9 AM CDT/ to 8 PM EDT /7
PM CDT/ Monday for FLZ007>019-026>029-034-108-112-114-115-
118-127-128-134.
GA...Excessive Heat Warning from 10 AM to 8 PM EDT Monday for
GAZ120>131-142>148-155>161.
AL...Excessive Heat Warning from 9 AM to 7 PM CDT Monday for
ALZ065>069.
GM...None.
&&
$$
NEAR TERM...Bunker
SHORT TERM...KR
LONG TERM....KR
AVIATION...Young
MARINE...Haner
FIRE WEATHER...Bunker
HYDROLOGY...KR
Area Forecast Discussion
National Weather Service Las Vegas NV
814 PM PDT Sun Aug 13 2023
.SYNOPSIS...Scattered thunderstorms are expected through this
evening as a low pressure system sits over southern California.
Drier conditions return tomorrow but will be short-lived as
monsoonal moisture will spill back into the eastern Mojave Desert
and eastern Great Basin Tuesday through the remainder of the week
with daily thunderstorm chances, especially in the higher terrain.
&&
.UPDATE...After an active afternoon and early evening, showers and
thunderstorms have really weakened. Likely see an isolated weak
shower or thunderstorm continue past midnight across Lincoln,
central Nye, Esmeralda and northern Inyo County in proximity to
easterly jet and axis of better moisture across central Nevada. With
the upper low over southern California shifting slightly further
west, offshore tomorrow the HRRR indicates less convective potential
across the region. Primarily focusing convection across central
Nevada and northwest Arizona. Forecast looks fine.
&&
.SHORT TERM...through Monday night.
Convection through early afternoon has begun to unfold about as
expected, with the greatest coverage focused across central Mohave
county into far southern Clark and northern San Bernardino
Counties. This particular zone is under an area of maximized
upper level divergence allowing for stronger ascent within a
marginally unstable environment of 500-1000 J/KG of CAPE. While
the instability is not particularly impressive, steep lapse rates
with H500 temps of -11C is promoting some pulse severe hail
signatures on radar and we have had a report of some dime sized
hail near Hualapai Mountain Park late this morning.
Expecting storms to persist in this general zone through early
evening and perhaps expand into the adjacent deserts through the
late afternoon on boundary collisions. Late afternoon and early
evening convection will likely shift into central and western San
Bernardino county later this evening as the best forcing shifts
southwestward. Main threats through this evening will be sporadic
strong updrafts capable of hail up to penny size, along with
strong wind gusts. Slow movement of storms and potential for
training also poses some potential for isolated flash flooding.
Outside of the storm risks, temperatures today will remain
slightly cooler than normal thanks to the cool thermal profile in
the vicinity of the nearby upper level low. The low will begin to
retrograde westward tomorrow and also advect some drier and more
stable air in from the south. This will tend to limit convective
coverage tomorrow to exclusively far eastern Mohave county, as
well as allow temperatures to climb closer to daily averages.
.LONG TERM...Tuesday through next Monday.
High pressure will build over the Four Corners states much of next
week allowing for a slow climb of temperatures to slightly above
normal along with an open door to increasing monsoonal moisture.
This will allow for daily chances of thunderstorm activity to
return Tuesday onward, particularly for the higher terrain of the
eastern Mojave Desert, Northwest Arizona, and Lincoln County. Day
to day variations in storm coverage and intensity can be expected,
but at least low-grade monsoon activity is anticipated each day.
Confidence in the forecast details decreases considerably by the
weekend onward. This is due to tropical activity and uncertainty
in the placement of the Monsoonal High versus an offshore low
pressure system. The way these features come together leads to an
assortment of possible weather outcomes, ranging from a return of
dry conditions within a southwesterly flow, or a very wet pattern
emerging as tropical moisture gets directed into the Southwestern
US. The NBM PoPs seem to have latched onto some of these wetter
outcomes with widespread PoPs of 30-60% advertised Sunday and
Monday across our eastern zones and a sharp cooling trend,
however, drier solutions remain possible as the ECMWF ensemble
envelope remains on the drier side of things.
&&
.AVIATION...For Harry Reid...Outside of any thunderstorm
influence, look for light to occasional northeast winds through the
afternoon. Speeds are generally expected to remain around 8 kts or
less. However, there will be thunderstorms developing around the Las
Vegas Valley through the afternoon and early evening that could
bring gusty and erratic outflow winds to the area. Although
unlikely, it is possible that a thunderstorm does develop in the
valley, but overall most of the storms will remain out of the
valley. Storm activity will wane this evening with a notable
decrease in storm coverage Monday. Look for light northeast to east
winds along with a FEW clouds around 12k feet.
For the rest of southern Nevada, northwest Arizona and southeast
California...Scattered showers and thunderstorms will develop across
much of the region this afternoon with the greatest likelihood of
impacts near KIFP, KEED, KDAG, and the Las Vegas Valley. Most of
these impact`s will be in the form of gusty thunderstorm outflow
winds, but it`s possible that a storm could directly form over and
near these TAF sites into early evening. Outside of any thunderstorm
influence, most areas will maintain a diurnal wind pattern.
Thunderstorm coverage on Monday is not expected and winds will
generally be less than 10 kts over most areas.
&&
.SPOTTER INFORMATION STATEMENT...Spotters are encouraged to report
any significant weather or impacts according to standard operating
procedures.
&&
$$
UPDATE...Pierce
DISCUSSION...Outler
AVIATION...Gorelow
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