Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 05/08/23
Area Forecast Discussion
National Weather Service La Crosse WI
720 PM CDT Sun May 7 2023
.DISCUSSION...(This evening through Sunday)
Issued at 202 PM CDT Sun May 7 2023
Key Messages:
- A few showers, isolated storms this afternoon. Strong to severe
storm threat in the far south this evening.
- Potential for fog formation Monday night.
- Another round of showers and storms late in the week into next
weekend. Too early to discern if any storms will be severe.
* LIGHT SHOWERS, ISOLD STORMS FOR SOME THIS AFTERNOON. STRONG-SEVERE
THREAT IN FAR SOUTH THIS EVENING.
Ribbon of shortwave energy in the upper atmosphere was working on
some mid level moisture to produce a west-east running stretch of
light rain showers early this afternoon. RAP suggests there could be
enough instability a loft for an isolated storm, but awfully skinny
CAPE per soundings. No strong/severe threat if they would manifest.
In addition, a lot of dry air in the sub cloud layer, so any pcpn
would be challenged to make the surface. Could lead to a few wind
gusts up top 20 mph though.
Different story this evening as increasing low level jet impinges
into, northward of a west-east running warm front across southern
IA, tapping into a pool of warm, moist air with 3000+ J/kg of
SBCAPE. Storms will rapidly develop, with current set of CAMS
favoring roughly 22-23z. That said, its a messy atmosphere with
various sfc fronts, boundaries from previous convection, breaks in
cloud cover providing focuses for storms to fire from - and CAMS
aren`t necessarily going to pick up on these right away. Note the
convection that has fired over western IA, with a warning following
about 1/2 hour later. The same short term guidance drives the storms
east/northeast (which looks reasonable), eventually morphing into a
larger convective complex. Severe weather is expected with these
storms, so how far northward they extend is a key question for the
local area.
Medium and short term guidance has continued to keep the bulk of the
storms just south of the local forecast area tonight. Current
showers/isold storms moving west-east across the area (roughly
around and south of I-90) will reinforce this notion, cooling/
strengthen the already stable near sfc layer (and eating into the
instability a loft). Latest RAP and 12z HREF keeps the SBCAPE pool
across southern/central IA this evening, but still stretches upwards
1000 J/kg of MUCAPE across the local area. Storms look sfc based
across central IA, but soundings/thermodynamic profile suggest they
would be more elevated moving north of there. Not much for 0-1km
shear per the RAP locally - if it could even be tapped - but 1-7 km
is long (approx 60 kts of shear) and would aid storm development.
Threats transition from all types to mainly hail as this occurs.
Challenging scenario with the multitude of potential focusing
mechanisms and uncertainties with how these will interact.
Confidence on the higher end that the bulk of tonight`s severe
threat will hold just south, but its awfully close and there is
enough instability/shear to support strong to a few severe storms
across northeast IA/southwest WI in the current setup. Very close
attention will be paid to trends, both in boundary placement and
convective outflows/movement. Small changes could result in a
greater, or lesser, severe risk locally.
Monday night into Wednesday
Surface ridge builds into Minnesota/Wisconsin Monday night. With the
recent rainfall/light winds and potential for clear skies. Areas of
fog could form across parts of the forecast area. However...if skies
do not clear...confidence in fog formation is low. With the
uncertainty of skies clearing...will leave mention of fog out of
forecast for now.
Upper level ridge amplifies over the central United States Tuesday
into Wednesday. This should provide drier weather across the forecast
area both days and above normal temperatures. 925mb temperatures are
expected to be plus 15 degrees celsius across forecast area
Wednesday. With mostly sunny skies expected by Wednesday...high
temperatures will climb into the 70s Wednesday.
Wednesday night into Sunday
Main forecast concerns through the forecast period Wednesday night
through Sunday are shower/storm chances. Upper level ridge over the
Northern Plains/Upper Great Lakes region breaks down Friday into
next weekend. Western part of the forecast area is on the eastern
periphery of southerly moisture return Thursday. Weak impulse
tracking just to the west southwest of the forecast area will
produce showers/storms possibly across the wester forecast area
Thursday. With better moisture convergence/lift just west of
forecast and subsidence under upper level ridge will suppress any
convection development along/east of the Mississippi River. Upper
level trough over Central High Plains and associated impulses breaks
down upper level ridge and provide periodic shower/storm chances
Friday into next weekend. Temperatures will remain above normal
Thursday into Saturday...as NAEFS suggest plus 1 standard anomaly
over the forecast area. High temperatures will be mainly in the 70s
with a few locations in the lower 80s.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 720 PM CDT Sun May 7 2023
VFR conditions have prevailed at both TAF sites this early
evening. Guidance continues to suggest enough lower level
saturation to bring back MVFR/IFR ceilings, as well as some MVFR
fog development. With this, have continued the previous trend
for early Monday morning. Most current CAMS guidance still shows
convection developing across IA late this evening, although there
remains lower confidence in how far northward/north-westward any
showers and storms may reach. For now will keep the mention of
VCSH at KLSE and will monitor trends for any updates that may be
needed. Winds look to become generally more easterly, staying
around or less than 10 kts. Although, if any showers/storms do
make it farther north, some gusts will be possible.
&&
.HYDROLOGY...
Issued at 202 PM CDT Sun May 7 2023
Levels along the Mississippi River continue to fall and the periodic
rain tonight into Monday and late in the week is not expected to
be enough to prevent additional rising water levels. The latest
forecasts call for a few more sites to drop below flood stage
early this week.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
DISCUSSION...DTJ/Rieck
AVIATION...EMS
HYDROLOGY...DTJ
Area Forecast Discussion
National Weather Service Denver/Boulder CO
854 PM MDT Sun May 7 2023
.UPDATE...
Issued at 854 PM MDT Sun May 7 2023
Isolated showers/storms are still roaming across parts of the
northeast plains, as well as the northern mountains. Lingering
sprinkles have ended along the I-25 Corridor. The showers appear
to be getting some support from the left exit region of the upper
jet, but that feature is lifting northward overnight so we`ll see
drying and subsidence work in with clearing skies overnight.
For Monday, we`ll see some slight upper level ridging, but at the
same time we`ll be warming a few degrees and destabilizing just
the same as we did today. Limited instability will be present but
enough heating to produce another round of scattered
showers/sprinkles and an isolated storm or two. These will have
propensity to produce gusty outflow winds to 30-40 mph given
DCAPE around 800 J/kg. We did update the precip chances to at
least include a low threat of showers/isolated storm along the
I-25 Corridor, too.
&&
.SHORT TERM...(This evening through Monday)
Issued at 143 PM MDT Sun May 7 2023
The main area of deep convection this afternoon is moving across
Washington and Logan counties at this time. There is a marginal
risk of severe thunderstorms but that will likely disappear as
these storms make their way to the east. SPC analysis indicated
MLCAPEs up to 500 j/kg along the eastern border at this time. The
latest HRRR shows some additional development later this
afternoon and evening but will be weaker. Gusty winds will be the
main issue with the storms as the lower levels are pretty dry. The
showers and thunderstorms will die off by late evening with
clearing overnight. On Monday the flow aloft will remain
southwesterly, the upper level winds will still be fairly decent
with marginal instability in the afternoon. NAM12 forecast
soundings indicate 300-600 j/kg surface based CAPEs in the
afternoon, with DCAPEs 700-750 j/kg. Isolated to scattered
thunderstorm coverage with gusty outflow winds the main threat.
.LONG TERM...(Monday night through Sunday)
Issued at 143 PM MDT Sun May 7 2023
A few showers and thunderstorms will continue across the plains
Monday evening with marginal instability in place across the
plains. At this time it doesn`t appear that there would be much of
a severe threat with any convection Monday night, but some small
hail, gusty winds, and briefly heavy rain would still be possible.
Broad southwesterly flow will be in place on Tuesday as a broad
trough axis sits near the Pacific coast. Across the area, warm air
advection should be ongoing through the day, and we should see
highs in the mid to upper 70s. Isolated to widely scattered
thunderstorms are possible during the afternoon and evening across
the Front Range and urban corridor. There looks to be a
conditional threat of strong to severe storms, as steep mid-level
lapse rates, increasing deep layer shear, and a shallow inverted-V
moisture profile would favor the potential for both hail and
gusty winds. However, we`ll likely be dependent on terrain or any
remnant surface boundaries to initiate convection in the absence
of any deep layer forcing.
A fairly strong, negatively tilted trough axis will pivot across
the state Wednesday and Thursday, bringing more widespread chances
of showers/storms and some mountain snow to the region. Guidance
has struggled with both the timing and location of the "pivot" of
this trough axis. 12z Guidance has shifted the cutoff low and
associated lee cyclogenesis further south, with the 500/700mb lows
tracking almost directly across our plains. GEFS spaghetti plots
show a considerable spread among 500mb low tracks, and
unsurprisingly confidence in QPF/PoPs these days is low and is
heavily shifted towards the NBM. There would be a severe weather
threat somewhere near the area Wednesday or Thursday, though we`ll
hold off on discussing that for now.
A fairly unsettled pattern will continue into next weekend as the
aforementioned upper trough slows and weakens over the
Central/Northern plains, with a push of moisture potentially
coming in from the south as well. For now, continued chances of
showers/storms each afternoon is a safe bet, but any details
beyond that will have to wait.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 544 PM MDT Sun May 7 2023
Main challenges will surround variable and gusty wind potential
with relatively high based showers and thunderstorms. For this
evening, isolated showers around the TAF sites will linger to
around 02Z-03Z before completely dissipating, but some variable
gusts to 15-25 knots possible as evidenced by a few observations
sites in the area. Otherwise northeasterly winds will prevail,
gradually turning southeast 03Z-05Z this evening and then
returning to a light southwesterly flow overnight.
On Monday, winds are expected to become more southeast/easterly
16Z-22Z. However, scattered high based showers/isolated
thunderstorms are expected to develop toward 21Z. These will
likely produce gusty outflow winds to around 30-35 knots, again
due to the dry low levels and DCAPE. Thus, we`ll have TEMPO for
VRB G30kts in the TAF starting around 21Z. Cloud bases will
remain at/above 8,000 feet AGL/13,000 feet MSL.
&&
.HYDROLOGY...
Issued at 143 PM MDT Sun May 7 2023
Isolated to widely scattered thunderstorms are expected Monday and
Tuesday, but these should generally produce light precipitation.
A more organized threat of heavy rain will be possible during the
middle of the upcoming week as a storm system enters the region.
The overall storm track and moisture availability remains
uncertain, but guidance has started to indicate the potential for
moderate to heavy rain at times Wednesday or Thursday. The timing
and track of this system is still highly uncertain, but this will
be worth monitoring as we get closer to the event.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
UPDATE...Barjenbruch
SHORT TERM...Cooper
LONG TERM...Hiris
AVIATION...Barjenbruch
HYDROLOGY...Hiris
Area Forecast Discussion...UPDATED
National Weather Service Brownsville TX
639 PM CDT Sun May 7 2023
...New AVIATION...
.SHORT TERM...
(Tonight through Monday night)
Issued at 209 PM CDT Sun May 7 2023
Breezy conditions continue into this afternoon due to an increased
pressure gradient. Winds will decrease later this evening into
tonight. Breezy conditions are expected again Monday but should
remain below Wind Advisory criteria.
A shortwave moving over Deep South Texas could initiate some
showers and thunderstorms across Nuevo Leon this afternoon and
evening. This activity has a chance to hold together as it
advances eastward, potentially affecting Zapata, Starr, Jim Hogg,
Brooks counties counties this evening. While the HRRR continues to
show this activity weakening before crossing the Rio Grande
river, some other CAMS models show this activity holding together.
The SPC has expanded the area of Marginal Risk of severe weather
to include Zapata, Jim Hogg, northwestern Brooks and northwestern
Starr counties. The main threat with any activity that makes it
across the river would be large hail, but at this time confidence
remains low on this activity. Timing would be most likely between
6 pm and midnight if anything makes it across the river. Will
continue to monitor the situation closely.
Monday looks to remain dry for much of the day but as another
shortwave moves overhead Monday night into Tuesday, rain and
thunderstorm chances increase once again.
Temperatures will remain warm through the period with daytime highs
in the 90s and overnight lows in the 70s. Heat indices could reach
100 to 105 degrees across Zapata, Starr and western portions on
Hidalgo county on Monday.
&&
.LONG TERM...
(Tuesday through next Sunday)
Issued at 209 PM CDT Sun May 7 2023
The long term forecast continues to be active as the upper level
synoptic pattern will allow for a series of shortwaves to propagate
through Deep South Texas. As these shortwaves over the region during
the timeframe of Tuesday through next Sunday, surface winds will
continue to be out of the southeast allowing for more moisture to
move in the area. Some models show low-level moisture building up
close to 750 mb around late Tuesday into early Wednesday and PWATs
close to 1.5 inches as well. The moisture for showers and
thunderstorms appears to be there, and the shortwaves could help to
get the convection going. Models also show that there could be a
good environment to help produce strong to severe storms as well
throughout the long term period, as stated in previous discussions.
The greatest chance for rain in the long term forecasts appears to
be during the weekend particularly Saturday Night. As PoPs in in the
high 60s to low 70 percent. PWAT values are around 2 inches for the
weekend, so there will be plenty of moisture, and the train of
shortwaves will still be present as well. It is possible that these
storms could be strong to severe as well.
Outside of the rain activity in the long term forecast, the onshore
flow over Deep South Texas will also help bring in a bit of warmer
temperatures. High temperatures for most of the long term are in the
range of upper 80s along the coastline to 90s for the rest of Deep
South Texas. However, the exception to this is on Saturday and
Sunday as high temperatures are expected to be mostly in the 80s
with a few places, in Zapata and Starr, reaching triple digits. The
presences of storms expected those days will be cooling the area off
by preventing the sun from warming up the surface as much. Low
temperatures will stay in the range of the 70s for all of Deep South
Texas throughout the long term period.
&&
.AVIATION...
(00Z TAFS)
Issued at 635 PM CDT Sun May 7 2023
VFR to MVFR conditions are generally expected this evening through
tonight with increasing southeasterly winds once again into
Monday. A few gusts on Monday may approach 25 to 30 kts with VFR
ceilings. Severe thunderstorms west of MFE may work closer this
evening with tall CB and potentially destructive hail. At this
time, do not expect this activity to reach MFE, but worth noting
for anything west to southwest of that aerodrome over the next
few hours.
&&
.MARINE...
Issued at 209 PM CDT Sun May 7 2023
Now through Monday night...An enhanced pressure gradient will keep
winds elevated into this evening with Small Craft Caution on the
Laguna Madre and nearshore waters. Tonight, winds will decrease but
once again expect caution conditions on the Laguna Madre and
nearshore waters on Monday into the evening. Seas will remain at 3
to 5 feet. Monday night, showers and thunderstorms are possible on
the waters off the lower Texas coast that could lead to locally
enhanced winds and seas.
Tuesday through Next Sunday...An enhanced pressure gradient
will continue to affect the Lower Texas Coast, resulting in elevated
winds from the southeast and seas at times that will require Small
Craft Exercise Caution. Isolated to scattered showers and
thunderstorms are expected throughout the period and could result in
locally elevated winds and seas at times.
&&
.PRELIMINARY POINT TEMPS/POPS...
BROWNSVILLE 76 89 76 89 / 10 0 20 10
HARLINGEN 75 93 75 91 / 10 0 20 20
MCALLEN 76 94 76 91 / 30 10 20 30
RIO GRANDE CITY 75 96 74 93 / 20 10 20 30
SOUTH PADRE ISLAND 76 82 76 82 / 10 0 10 10
BAYVIEW/PORT ISABEL 75 88 75 87 / 10 0 20 20
&&
.BRO WATCHES/WARNINGS/ADVISORIES...
TX...None.
GM...None.
&&
$$
SHORT TERM...68
LONG TERM....64
AVIATION...56-Hallman
Area Forecast Discussion...UPDATED
National Weather Service Duluth MN
717 PM CDT Sun May 7 2023
.MESOSCALE UPDATE...
Issued at 712 PM CDT Sun May 7 2023
Weak surface convergence along a quasi-stationary front along and
near WI Highway 70 will persist over the next few hours. MLCAPE
values of 750 to 1100 J/kg remain in place over Burnett, Washburn,
and Sawyer counties. Effective shear of around 40 knots is in
place and will decrease over the next few hours.
There several thunderstorms developed over Washburn and Sawyer
counties in the past few hours. Of particular note is a left-
moving storm between Namekagon and Marengo as of 710 PM which
started out near Spooner around 5 PM. That storm has produced
several rounds of small hail up to one-half inch in diameter.
Several right-moving storms were located over north-central Sawyer
County at 710 PM and also have a history of hail up to one-half
inch in diameter.
These storms are expected to continue over the next hour or two
and additional development upstream is possible. Additional left
splits are possible with the southern cluster of storms. We expect
a general weakening trend after 9 PM, if not earlier, in response
to weakening deep layer shear and surface stabilization around
sunset.
MESOSCALE UPDATE Issued at 516 PM CDT Sun May 7 2023
A few storms have gone up in northwestern Wisconsin this
afternoon. Cumulus towers continue to go up in the greatest area
of instability, and more storms could develop this evening.
SPC Mesoanalysis indicates that around 1000 J/kg MLCAPE and wind
shear values at around 50 kts linger over parts of Burnett and
Washburn counties. With such high shear and modest MLCAPE, storms
will likely be short-lived, as seen with the couple of cells
developed so far, due to the top of the storm being blown out
ahead of the updraft fairly quickly. However, in the short time
these storms persist, small hail up to pea size remain possible.
MESOSCALE UPDATE Issued at 256 PM CDT Sun May 7 2023
Skies have cleared out across parts of east-central MN and
northwest Wisconsin, and the surface temperature has risen to 74
at Siren (though with a dew point of 50, while dew points are near
60 at Cumberland and Rice Lake to the south.) Cu have developing
to the south of the very clear area of Lake Superior influence to
the north (Solon Springs is at 55/54). Temps are currently a tad
warmer than recent HRRR runs, with SPC Mesoanalysis indicating
around 500 j/kg MLCAPE over parts of Burnett and Washburn
counties. One or two surface-based storms may develop in this area
in the next 1-2 hours. While mid-level lapse rates are just
modest (around 7 C/km), the effective shear in on the order of
nearly 50 knots. This environment may support a few short-lived
storms that produce small hail, with storm motions generally easterly
to east-southeasterly. Still not a guarantee that storms will
develop, but the surface heating observations and satellite trends
increase confidence of convection late this afternoon.
Near Lake Superior, dense fog persists. There have been periods of
improvement, and visibility at DLH has improved to a half mile,
but the widespread layer of dense fog impacting the areas near
the lake and confidence that fog will worsen this evening is
enough to keep the Dense Fog Advisory in place with no changes.
&&
.DISCUSSION...(This evening through Saturday)
Issued at 118 PM CDT Sun May 7 2023
Summary: Temperatures finally rise above normal this week, though
continued easterly flow off of Lake Superior will keep areas by the
lake cooler until mid-week with Wednesday looking like the nicest
day of the week. Precipitation chances exist nearly every day, but
are lowest Tuesday into Wednesday before a long period of off and on
showers and thunderstorms Thursday through Sunday.
On the synoptic scale the pattern across North America remains slow
to change like it has for the past week, with the omega block over
Manitoba/Ontario ever-so-slowly breaking down, but only for height
rises over the eastern CONUS and an approaching broad mid/upper
level longwave trough entering the southwest CONUS allowing for the
Upper Midwest to remain in an active weather pattern. At the surface
the broad area of high pressure over Manitoba and northern Ontario
gradually builds southeastward towards the Great Lakes early this
week, centered over Lake Michigan by mid-week and causing the
Northland to experience south-southwesterly low level flow, finally
allowing the north shore to experience warmer temperatures and
keeping the stronger Lake Superior influence at bay for a few days.
Precipitation chances and cloud cover persists early this week as a
series of weak mid-low level shortwave troughs lift east across the
Upper Midwest in the broad west-southwesterly flow aloft, with low
level moisture hanging around around causing continued low level
clouds, and fog near Lake Superior into Monday. Elevated instability
will lead to the chance for a few thunderstorms tonight through
Tuesday, but severe storms are not anticipated as the instability
will only be on the order of a few hundred j/kg MLCAPE at best,
though stronger winds aloft could lead to a marginal small hail
threat. Highs in the 60s, cooler near Lake Superior Monday and
Tuesday.
Wednesday will likely be the nicest day of the week, even with some
low precipitation chances (mainly some light/isolated showers) as
temperatures rise to the warmest temps since the mid-April warm
spell with highs in the 70s (60s along the Lake Superior shoreline)
and mostly sunny skies outside of the diurnally driven cumulus
clouds and a low possibility for a spotty shower.
Increasing clouds and precip chances late-week as temps remain
consistently in the upper 60s to low 70s for highs. It won`t be
raining the whole time, though, nor will every location see rain
every day, but there is a 40-50 percent chance of rain each day
until high pressure finally builds in Sunday into Monday leading to
drier conditions and briefly cooler temps. Severe thunderstorms are
unlikely with this late-week-into-next-weekend stretch of
precipitation due to limited instability advecting in aloft.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 712 PM CDT Sun May 7 2023
VFR conditions at BRD and HYR will continue into tonight. Expect
IFR conditions early Monday morning. Elsewhere IFR/LIFR conditions
will persist overnight and Monday. Ceilings may lift to MVFR at
BRD, INL, and HYR Monday morning and afternoon while IFR and LIFR
conditions persist at HIB and DLH. Drizzle and rain showers will
remain possible through tonight and early Monday morning. Isolated
to scattered showers are forecast at DLH, HIB, and INL for much of
Monday.
&&
.MARINE...
Issued at 118 PM CDT Sun May 7 2023
Easterly flow across western Lake Superior persists through Tuesday,
with a brief increase in winds to 20-25 knots in speed Monday
afternoon but otherwise around 10-15 knots. These winds will result
in continued waves around 3-5 feet through Monday evening. There
will also be dense fog across at least the head of the lake through
Monday morning, possibly lasting longer into the day Monday. Weak
winds Tuesday night through Thursday, then another round of
increasing easterly winds Friday through next weekend. Gale-force
gusts are not expected with either this early week period of higher
waves nor the late-week into next weekend round of increased winds
and waves.
&&
.PRELIMINARY POINT TEMPS/POPS...
DLH 42 51 40 59 / 60 60 30 20
INL 46 60 44 66 / 80 70 30 20
BRD 45 66 47 70 / 20 20 30 20
HYR 48 66 47 70 / 50 40 30 20
ASX 42 57 41 64 / 40 30 30 10
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...Dense Fog Advisory until 10 AM CDT Monday for MNZ020-037.
LS...Small Craft Advisory until 11 PM CDT Monday for LSZ140>147-150.
Dense Fog Advisory until 10 AM CDT Monday for LSZ142>146.
&&
$$
MESOSCALE UPDATE...Huyck
DISCUSSION...JJM
AVIATION...Huyck
MARINE...JJM
AREA FORECAST DISCUSSION
National Weather Service Kansas City/Pleasant Hill MO
659 PM CDT Sun May 7 2023
.Discussion...
Issued at 317 PM CDT SUN MAY 7 2023
Key Messages:
- Warm and Muggy Evening
- Linear Thunderstorm Complex Late Tonight and Overnight
- Warm with Isolated Showers/Storms Monday and Tuesday
Discussion:
The PV anomaly over the western CONUS continues to keep a troughing
pattern with the axis over the Intermountain West, setting up a
second day of active mid/upper-level southwesterly flow across the
forecast area. The first surface cyclone has lifted with the first
vorticity maximum into the Upper Mississippi River Valley. However,
additional surface cyclogenesis has been ongoing across the High and
Central Plains again in response to additional dCVA and WAA. The
convection from last evening aided in creating a differential
heating thermal boundary that started near Hwy. 36. Through this
morning and afternoon, the low-level meridional flow has pushed this
boundary northward, and this will continue to happen into the early
evening hours. Flow between 700mb and 600mb has remained
southwesterly coming from the desert southwest and Mexican Plateau.
As a result, we are still seeing signs of an EML in a few our RAOB
sites across the Central Plains, though not as prominent as it was
yesterday afternoon. The TOP and SGF RAOBs do not have the textbook
loaded gun sounding profile. However, the drier air in the 700mb and
600mb along with the weak subsidence this morning with a subtle
ridge axis moving through has cleared skies across most of the area,
and has even worked to clear skies in eastern Nebraska and southwest
Iowa. This will be important, because insolation will provide rapid
destabilization of the boundary layer across most of the warm sector
of this next approaching surface cyclone for nearly the entire
afternoon. Mid-level lapse rates are already between 8.0 to 8.5 C/km
from Central Kansas into northern Missouri. For our area, not seeing
a signal for much further cooling in the 700mb to 500mb layer, but
no substantial warming either, which indicates these mid-level lapse
rates will remain put in this range. With the clear skies, we are
already seeing stronger mixing in the near surface layer, with
temperatures in the mid 80s and dewpoints in the mid to upper 50s
across most of the forecast area as of 17z. Lapse rates within the
CBL steepened to nearly 9.0 C/km as of 20z this afternoon. For CAPE,
mixed-layer computations were already above 1000 J/kg by 17z, had
increased to nearly 2000 J/kg by 20z this afternoon. Instability
will not be an issue this later this evening.
H5 height falls will start in the 21-22z range this afternoon from
eastern Kansas into the middle Mississippi River Valley, and phases
the enhanced dCVA with the surface cyclone. With the center of the
cyclone over Central Kansas, surface winds will continue to back
toward the southeast most prominently for northern reaches of our
CWA, and will be more south to southwesterly in central and southern
portions. Hwy. 36 appears to be roughly the dividing line for backed
surface winds. This will increase moisture transport into central
and northern Missouri this afternoon and evening, though will have
to battle stronger mixing. As this cyclone deepens and southerly
flow picks up, the boundary is progged to push into central Iowa up
toward the Interstate 80 corridor, leaving our area fully in the
warm sector. The strongest portion of the H5 vorticity maximum will
also travel from Central Kansas into west-central Iowa. As a result,
the better convergence for lift will be displaced outside of our
forecast area during peak diurnal heating into the early evening.
This would be the lift needed to have an opportunity for surface
based discrete supercells. Currently, the discrete threat is focused
from eastern Nebraska into southwestern Iowa. The HRRR has continued
to placed a few discrete storms north of the area where this
convergence is stronger, but has kept our our counties in both
Kansas and Missouri dry until much later in the evening. Most of the
CAMs agree with a dry afternoon through middle evening for our
counties, including the typically robust Hi-Res FV3. Will quickly
point out though that mixing will erode the weak cap by late this
afternoon, and there will be decent deep layer shear throughout the
warm sector. Should the surface reach the convective temperature
(around 93-94F in our north) a supercellular mode could be
supported. Hodographs will have strong cyclonic shear in the first
1km and even first 500m. But, given the higher LCLs this afternoon
with the robust and stronger surface convergence being displaced
well to the north, this is a low probability outcome and as of this
afternoon will not be expecting supercells in our forecast area
tonight. What is anticipated, is for convection initialization in
eastern Nebraska later this afternoon, and as the low-level jet
kicks in, storms congeal into an MCS. Deep layer shear will remain
plentiful though on both sides of the cold front with this system. 0-
6km bulk shear values will be in the realm of 45 to 55 kts by that
time, and overall hodograph length and shapes (mostly straight above
3km) that support organization of the MCS into a linear storm mode.
Most of the CAMs are in agreement with this evolution, though differ
in the propagation speed and timing of the line moving through.
There is stronger consensus for the line to expand from Central Iowa
to about the Hwy. 36 corridor in Missouri. A few of the 12z CAM
solutions have thunderstorm activity forming along an outflow from
the MCS that goes as far south as the KC Metro and along Interstate
70. During the middle afternoon hours though, the HRRR has been
backing off on southward outflow boundary convection, keeping the
southern end of the line of storms to around STJ. Most of the line
will be capable of severe wind gusts late this evening and
overnight. The HRRR has persistently been depicting the line
evolving into a bow echo, with a strong bookend vortex moving across
south-central Iowa. This seems sensible, given that the better
kinematic field will be located up that way closer to the thermal
boundary. With that being said though, this does leave areas north
of Hwy. 36 in our forecast area in a position to be impacted by a
strong rear inflow jet into the system, and may even help promote
bowing segments in our area resulting in enhanced straight line
winds. The HRRR has been outputting wind gusts with convection
across northern Missouri between 50 and 60 kts. Meanwhile, the
experimental NCAR ensembles running this Spring Season have
increased probabilities across a similar area in our north for wind
gusts above 40 to 50 kts. Looking at the CAMs altogether via the
HREF, looking at mean wind gusts around 45 kts with maximums at 60
kts. Further south of Hwy. 36 including the KC Metro, wind
probabilities drop off quite a bit, but this largely is attributed
to less HREF members producing convection that far south. Overall,
the environment ahead of the cold front will support damaging winds,
just dependent on far south the line develops (and how rapidly an
outflow boundary is released). During the early afternoon, theta-e
deficits from the surface to the top of the CBL were already around
15K. Some RAP and HRRR soundings are indicating this may reach
between 20-25K even late into the evening across most of the warn
sector. Therefore, damaging winds will have two mechanisms in which
to develop with the line of storms. The first, with this kind of
thermodynamic profile will be very strong cold pools. The well mixed
boundary layer with nearly inverted-v soundings will support strong
negative buoyancy. Second, the potential for the development of a
strong rear inflow jet, especially if a bookend vortex develops
northward and provides additional acceleration and bowing segments.
The strengthening low-level jet could further augment this kind of
process. Again, this is greatly favored along and north of Hwy. 36,
and may be possible further south if an outflow boundary provides
additional convergence southward into the warm sector ahead of the
cold front.
With the robust thermodynamics and stronger shear, there is the
possibility of hail along the line. The steep mid-level lapse rates
will support locally stronger updrafts along the line. Would think
that the most favorable time for hail would be during the stage
while storms are congealing but before becoming and organized MCS.
Right now, this may occur outside of our forecast area. However, if
we do have a few discrete storms that go up this evening in our area
and realize the favorable wind shear, hail may be spotted with
those. As noted before though, discrete storms are not greatly
probable for our area unless we reach the convective temperature,
which most guidance keeps us about 3 to 4 degrees shy of. As for the
tornado threat, it is the same story with discrete potential. If we
see a discrete supercell, it will present a tornado threat with
moderately strong cyclonic curvature in the hodograph and about 150
m^2/s^2 SRH for the 0-1km layer. This outcome is more likely in
Iowa and Nebraska though, closer to the warm front and the better
convergence. What about QLCS tornado potential? The 0-3km shear will
be between 30 and 40 kts, and mostly parallel to the line. If a
bowing segment develops and orients a portion of the line
perpendicular, with strong 0-3km CAPE in place, may present
mesovortex generation potential. HREF members do simulate a few 2-
5km AGL Updraft Helicity Tracks within the line, but typically CAM
UH tracks with linear storm modes are not overly skilled at pointing
out mesovortex potential in the way they can be with supercells.
Additionally, if the cold front undercuts the updrafts and the
convection becomes post-frontal, this will wipe out a tornado
threat. Overall, the tornado potential is highly conditional and a
lower probability threat, and thus main focus should be on damaging
straight line winds and overall the evolution of the line.
The linear system should clear our eastern counties between 10-12z
Monday morning. You will note that there is a SWODY2 marginal risk
in our southeast (and a slight risk just outside our southeast).
This is mainly to reflect potential for initiation of a few more
cells along a remnant outflow boundary from the MCS (perhaps Bow
Echo) system that could result in gusty winds and some hail. The
Monday severe storm potential in our east and southeast is highly
dependent on how tonight`s system evolves. We may see some
additional shower activity on the backside of the cold front with
another vort max that ejects across the region. There is another
area of surface cyclogenesis across the Front Range and High Plains
that will maintain southerly flow up to about Interstate 70 in
forecast area. Thus the cold front from Sunday Night and early
Monday morning will not provide much relief with respect to
temperatures, as WAA brings the area back up into the mid 80s. By
Tuesday, the trough over the western CONUS wraps up around a few
simulated closed-lows that helps to amplify a ridge across the
Central CONUS. This will maintain warm temperatures through the rest
of this week. Will note though that there is potential for a few
short-wave perturbations to move through the flow even in the
overall ridge pattern, which will bring additional chances for rain
showers and thunderstorm activity. The Central to High Plains though
look to be the areas more favorable for stronger thunderstorm
activity in this set up though, so will hold off on more specific
details for the middle of this week until this system passes through
Monday morning.
&&
.Aviation...(For the 00Z TAFS through 00Z Monday Evening)
Issued at 659 PM CDT SUN MAY 7 2023
Gusty VFR conditions continue for the next few hours. A cold front
approaches the region overnight lowering CIGs and bringing chances
for TS across northern MO and NE KS. Confidence is fairly high in
TS north of I-70; however, some uncertainties remain if TS will
propagate south into the KC terminals. Winds remain southerly and
gusty ahead of the frontal passage; winds then become NW behind
the front. VFR conditions return afternoon.
&&
.EAX WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
MO...NONE.
&&
$$
Discussion...Krull
Aviation...Pesel
Area Forecast Discussion
National Weather Service Peachtree City GA
950 PM EDT Sun May 7 2023
.UPDATE...
Issued at 944 PM EDT Sun May 7 2023
High pressure in place across the northern GOMEX with slightly
northwest flow aloft. MCS/outflow boundary is approaching from the
NW. This convective system should dive SSE late this evening and
overnight, mainly impacting northern portions of the CWA. The
convective high res models are all handling this system a bit
differently. However, do think the system will have the potential
for producing some strong to an isolated severe storm(s) across
northern portions of the CWA overnight. The primary hazards would
gusty/damaging winds and with steep mid level lapse rates...some
hail.
The convective hi-res models are also bringing another round of
convection in from the north and west early this morning around
12Z. Have tried to get the best handle on pops, but the convective
forecast/coverage is confidence is low to med. Everything else is
on track.
&&
.SHORT TERM...
(This afternoon through Monday)
Issued at 259 PM EDT Sun May 7 2023
The mid-level pattern is in the process of devolving at the time of
writing of this AFD, with the weak ridge axis across the midsection
of the country flattening, giving way to quasi-zonal flow through
Tuesday. This coincides with the surface high sliding off of the
coast of the Eastern Seaboard, leaving behind a weakly forced
environment in its wake. As such, it will be very easy for any
passing upper disturbances to force periods of showers and
thunderstorms, but very difficult to time them out. Given the
pervasive cumulus across north and central Georgia presently and our
summerlike environment, very isolated pulse thunderstorms are
possible along and north of the Atlanta metro for the majority of
the afternoon. Our first *real* chances for precipitation hinge on
the progression of the ongoing MCS across the Ohio River Valley.
Within the 12Z run of the HREF, the HRW-ARW, HRW-NSSL, and HRRR have
had the best handle on actual intensity and location of convection.
These solutions prog a line/complex of showers (and the potential
for embedded thunderstorms) riding the edge of the residual outflow
to enter north Georgia between 3-4Z and continue their trek
southward toward the Metro area through daybreak before fizzling
out. Given lingering uncertainty, have translated this into the
grids via 20-40% chances of precipitation after 00Z tonight. Low,
but nonzero, potential for a few thunderstorms are included within
the aforementioned window -- with dewpoints in the 60s overnight and
ensemble forecast MUCAPE on the order of 500-1000 J/kg, would be
remiss to completely remove chances after dark. Our far northern
tier of counties are included in a Day 1 Marginal Risk for severe
weather (valid through 12Z/8AM tomorrow), primarily highlighting the
potential to see an isolated damaging wind gust from storms along
the leading edge of convection.
Any subsequent development will depend on how "worked over" the
environment becomes after the early morning round. HiRes guidance
begins to re-develop diurnally-driven isolated to scattered
thunderstorms tomorrow by 17-18Z. A handful of members of the HREF
show this activity filling in and becoming a loosely-organized
southeastward-moving band of convection through sunset. That said,
little true airmass changes are expected between today and tomorrow.
The 12Z sounding this morning showed a convective temperature of
84F. Much of the area will meet or exceed that value today, and
areas along and south of I-20 look to tomorrow. The entirety of the
CWA is enveloped within an area of general thunder on SPC`s Day 2
Convective Outlook to capture the widespread (but low) potential for
thunderstorms.
Aided by improving moisture under southwesterly flow, temperatures
will continue their slow climb into the low-to-mid 80s today and
tomorrow, and locations along and south of a line extending may
reach near 90 degrees on Monday. Lows will be in the 60s.
96
&&
.LONG TERM...
(Tuesday morning through next Saturday)
Issued at 259 PM EDT Sun May 7 2023
The long term forecast will be particularly active over the first
half of the long term period for parts of north and central Georgia.
As ridging at the surface establishes itself, shortwave impulses
embedded within the mid-level northwesterly flow will produce
several MCSs through the middle of the week. Discrepancies are
evident in model guidance solutions currently, so confidence in
onset and coverage of showers and thunderstorms is low over the
next several days. However, shower and thunderstorm activity does
appear to primarily be diurnally driven, so have maintained
chances for showers and thunderstorms primarily during the
afternoon/evening hours through midweek. Tuesday, the best chances
for precipitation will be across north Georgia, while Wednesday,
central Georgia will see the bulk of the activity. A weak wedge
and the eastward shift of the upper level ridge axis offers a
brief reprieve from precipitation as well as the heat on Wednesday
and Thursday where daytime max temperatures will moderate into
the upper 70s and mid 80s. As the surface high pressure moves over
the Atlantic and upper level ridge axis continues to progress
eastward by the weekend, slight chances of precipitation will be
possible with diurnally driven convection. Warm temperatures will
also return to the upper 80s and 90s over the weekend. QPF
guidance has much of the forecast area receiving a 0.25-0.75" of
rainfall throughout the long term forecast period.
KAL
&&
.AVIATION...
(00Z TAFS)
Issued at 727 PM EDT Sun May 7 2023
Convection timing will be rather tricky this TAF cycle. Outflow
boundary to the north skirt by just to the east this evening, but
do expect shra after 06Z tonight. Isold/sct aft convection will be
possible tomorrow. Winds will remain on the west side. Some sct025
possible with the overnight shra. Sct diurnal cu tomorrow
afternoon.
//ATL Confidence...00Z Update...
Low to med confidence convection timing. High confidence remaining
elements.
NListemaa
&&
.PRELIMINARY POINT TEMPS/POPS...
Athens 63 84 64 89 / 30 30 20 30
Atlanta 65 83 65 88 / 30 30 20 40
Blairsville 59 77 60 81 / 50 40 30 50
Cartersville 62 82 62 87 / 30 40 20 50
Columbus 64 86 66 90 / 10 30 10 20
Gainesville 64 82 64 87 / 30 30 20 40
Macon 64 87 66 90 / 10 20 10 20
Rome 63 83 64 87 / 50 40 30 50
Peachtree City 63 83 64 88 / 20 30 10 30
Vidalia 63 89 68 91 / 10 10 10 20
&&
.FFC WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SHORT TERM...NListemaa
LONG TERM....KAL
AVIATION...NListemaa
Area Forecast Discussion
National Weather Service Goodland KS
936 PM MDT Sun May 7 2023
.SHORT TERM...(This evening through Wednesday Morning)
Issued at 114 PM MDT Sun May 7 2023
The main focus for today will be the increasing severe threat this
afternoon and into the early evening. A boundary is situated through
Nebraska and into northeast Colorado where some cumulus has begun to
develop along with additional storms already developing in northern
Nebraska. Dew points have been fairly steady thus far with upper 50s
to low 50s into Nebraska and upper 40s to low 50s back into
northeast Colorado. Water vapor imagery shows a wave ejecting
onto the plains which will be the focus for storm initiation.
Current thinking for today will be a couple of supercells
developing across northeast Colorado into SW Nebraska. My highest
confidence in thunderstorms affecting the Tri-State area is along
and north of a Yuma to Norton line. RAP has been suggesting a 4mb
over 3 hours. MUCAPE is forecast to approach 1500 j/kg along with
0-6 wind shear 45-55 knots which would support supercells. Storms
are anticipated to develop into a cluster and move off to the
east ending the severe threat for the area around 02Z.
Expectations are hail up to 2 inches and wind gusts up to 70 mph
with the strongest storms. A tornado can`t be ruled out over
portions of Red Willow, Norton and Decatur county as the LLJ
increases this evening, but confidence in that is very low. A more
conditional threat for a supercell does lie along the I-70
corridor as some CAMS have been hinting at as well. Confidence
isn`t the highest in that occurring due to concerns about the
cirrus impact instability.
Overnight skies are anticipated to clear but will need to watch
for fog/stratus development due to the anticipated rainfall.
Monday looks to be fairly benign for the majority of the day was
temperatures again warm into the mid 70s to 80s across the area.
Winds will become easterly allowing moisture advection to work
into the area. A weak disturbance across the NW portion of the
area will allow a few showers and non severe storms to develop
during the evening and overnight hours. Some fog and low stratus
is possible into Tuesday morning as moisture increases.
Confidence is to low in coverage to introduce into the forecast
at this time.
Tuesday, another trough begins to develop across the western CONUS.
Moisture will be present ahead of it with a dryline setup near
the KS/CO border. A surface low will develop across southern
Colorado which lead to another afternoon and evening threat of
storms as some may be severe. A capping inversion, especially
across the east may help keep storms isolated in nature, but it
appears large hail and damaging winds will again be the primary
hazards.
.LONG TERM...(Wednesday through Sunday)
Issued at 100 PM MDT Sun May 7 2023
Wednesday...low pressure at the base of an upper level trough west
of the Continental Divide is forecast to become negatively tilted as
the base lifts northeast toward the four corners area by the end of
the day, continuing northeast toward the Palmer Divide/southeast
Colorado overnight. It appears that a weather disturbance lifts
northeast and into the area from northern Texas during the
afternoon, continuing northeast through the forecast area through
about midnight before exiting by 12z Thursday.
Plenty of moisture with PWAT values in the 1-1.25 inch range, lift
and instability to support a threat for strong to severe
thunderstorms. GFS hinting at a blowing dust threat per local
research findings with 0.5-1km wind speeds meeting roughly 45kt
criteria along the far southern zones with steep 0-2km lapse rates.
Otherwise, we`re looking at breezy to windy conditions as southeast
to southerly winds gust up to 45 mph during the day with gusts up to
35 mph during the night.
High temperatures are forecast to be in the upper 70s to lower 80s
with low temperatures in the upper 40s to middle 50s.
Thursday...todays model solutions suggest the upper low is to lift
northeast toward the Nebraska panhandle during the day then into
southwest South Dakota overnight. Southerly winds gusting 30 to 40
mph are expected during the day, shifting to the northwest overnight.
Another round of showers and thunderstorms will be possible as
disturbances eject from the approaching upper low, decreasing from
southwest to northeast overnight. Strong to severe thunderstorms
will be possible.
High temperatures are forecast to be in the lower 70s to around 80
with low temperatures in the lower 40s to lower 50s.
Friday...the upper low gradually weakens with the forecast area
under some weak upper troughing. It appears that per 850-500mb
relative humidity, another weather disturbance emerges off the front
range and into northwest half of the area during the afternoon and
overnight hours, supporting a slight chance for showers and
thunderstorms. High temperatures are forecast to be in the lower 70s
to lower 80s with low temperatures in the middle 40s to lower 50s.
Saturday...the 500mb pattern suggests a potential Omega block over
the area with low pressure over the southwest and upper ridging
centered north of Montana.
Todays GFS/GEM models show a large batch of moisture moving into the
area from the south after midnight with GFS precipitable water
values of 1 to 1.3 inches. This mornings NBM shows dry conditions
during the day with a slight chance to chance of showers and
thunderstorms during the night. High temperatures are forecast to be
in the upper 60s to lower 80s with low temperatures in the middle
40s to lower 50s.
Sunday...no change in the 500mb pattern when compared to Saturday.
The GFS maintains plenty of moisture over the area with PWAT values
of 1.1 to 1.3 inches. The ECMWF keeps the better moisture south of
the area. For now, wont make any changes to slight chance and low
chance pops. High temperatures are forecast to be in the middle 60s
to middle 70s.
&&
.AVIATION...(For the 06Z TAFS through 06Z Monday night)
Issued at 930 PM MDT Sun May 7 2023
VFR conditions are anticipated to prevail through the day on
Monday at both terminals. Thunderstorms cannot be ruled out at
either terminal Monday evening (00-06Z Tuesday). At this time, the
relative greatest potential appears to be at the GLD terminal..
though confidence in both thunderstorm development and location
are below average. N-NE winds at 10-15 knots will become light
and variable overnight.. any may remain light and variable
through the duration of the TAF period. Gusty/erratic winds can be
expected invof any thunderstorms.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
SHORT TERM...Trigg
LONG TERM...99
AVIATION...Vincent
Area Forecast Discussion
National Weather Service Green Bay WI
1036 PM CDT Sun May 7 2023
Updated aviation portion for 06Z TAF issuance
.DISCUSSION...
Issued at 310 PM CDT Sun May 7 2023
Key Messages:
- More thunderstorm/rain chances tonight and Monday.
- Patchy/Areas of fog likely again tonight and tomorrow night.
- Warmer and dry weather expected Tuesday through Thursday in
advance of rain chances towards this weekend.
-----------------------------------------------------------------
General Discussion:
Tonight and Monday rain chances...
Looking at several waves of precipitation tonight through Monday.
The first band is ongoing in SW Wisconsin. The HRRR seems to have
the best handle on this precipitation that is mainly being driven by
a weak PV anomaly aloft. Kinematics are awful with this first band,
so not expecting high-impact wx beyond a few rumbles of thunder with
this E-W oriented band that should encompass the area near Highway
29.
The second wave of precipitation is associated with the storms
expected to fire across Iowa this afternoon. Shortly after 06z Mon,
The nose of the LLJ that is transporting moisture ahead of the
accompanying low, should make its way into SW Wisconsin. Subsequent
response is realized in the 850mb moisture flux profile, with a
large swath of forcing that makes its way into east-central
Wisconsin. Models having a little challenge figuring out how far
north this will make it- something that is difficult to resolve
beyond 12-18 hours in a setup like this. But as of now, have precip
making it into Green Bay Monday. Will watch for trends. CAPE is
effectively nil, so have showers, with no thunder for Monday
afternoon/evening.
Tonight and Tomorrow night fog likely...
Patchy/Areas of fog likely once again both tonight and again
tomorrow night, especially across northeastern Wisconsin, including
the Fox Valley region tonight. As of now, expecting visibility to be
reduced to the 1 to 3 mile range. But will again monitor for the
potential for dense fog to creep in across northeast WI. By 8 to 9
am, expect visibility to improve.
Precipitation chances return towards next weekend...
Warm and dry weather expected Tuesday through Thursday. After
Monday`s rain keep temperatures in the 50s across our area, we
should rebound into the 60s and 70s for the rest of the week.
Long-range models have been trying to hint at a huge upper low
swinging through the Midwest- helping to bring the next round of
precipitation to our area towards the end of the week. Trends have
been slowing the arrival of said precip- which makes sense given
the magnitude of this low. As of now, it appears there is rather
decent anti-cyclonic flow from 850-300mb located over the Deep
South, which would help mitigate Gulf moisture from making it into
our area in advance of this system... ultimately helping to
mitigate severe weather potential. Will watch how this evolves, but
in future updates, we could see precip chances being lowered for
Thursday & Friday... and maybe Saturday as well.
&&
.AVIATION...for 06Z TAF Issuance
Issued at 1009 PM CDT Sun May 7 2023
Not expecting any precipitation early in the TAF period, but
showers should work their way into our southwest counties
overnight into early Monday as a short-wave trough arrives.
Light to moderate showers should expand north to at least highway
29 by midday, then gradually diminish from west to east later in
the afternoon and evening. The air mass will be fairly stable
across the region, so not planning to mention any thunderstorms
in this set of TAFs.
Low ceilings (MVFR/IFR) have rapidly expanded west across the
region this evening and should cover the entire region overnight
into Monday morning. Some fog has already been observed near Lake
Michigan and the bay, and this will likely work its way farther
onshore overnight, especially in eastern WI, and in the east wind
upslope areas of far NE WI. Not convinced that significant fog
will reach our western counties, but low ceilings will still drop
flight conditions to IFR there anyway.
Should see IFR/LIFR conditions overnight through Monday
morning, with some improvement occurring as the rain ends and
a ridge of high pressure builds in later Monday into Monday
night.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
DISCUSSION.....Kotenberg
AVIATION.......Kieckbusch
Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
1022 PM EDT Sun May 7 2023
.SYNOPSIS...
An active weather pattern will remain across the the area with
temperatures trending warmer and increasing chances for afternoon
showers and thunderstorms through the middle of the week. By
Wednesday, drier high pressure will move in from the north and
remain into the weekend.
&&
.NEAR TERM /THROUGH MONDAY/...
As of 1010 PM EDT Sunday: The passing MCS remnants are settling
south of the Interstate 85 corridor late this evening. The better
reflectivity on radar is now running well behind the gust front,
shear is diminishing, and lower Piedmont SBCAPE values continue to
dwindle ahead of the outflow. This indicates a downward trend
expected in the convective elements moving south. We turn our
attention back to the west where more MCS remnants are moving
eastward back into the eastern TN. However, most of eastern TN has
stabilized from the earlier round of activity and the most robust
convection should get driven southward west of the Smokies. Cannot
rule out some overnight upstream showers or isolated thunderstorms
brushing the spine of the mountains or northeast Georgia, but any
vigorous storms should be done for the night in our area. Debris
cloud cover will keep mild temperatures in the 50s across the
mountains and 60s over the foothills/Piedmont.
All of the recent and additional MCS activity will make profiles
hard to diagnose for Monday given the expected abundant debris
clouds. However, recent runs of the HRRR and other CAMS suggest that
another in the series of MCSs could make a run into the southern
Appalachians Monday evening. This looks quite uncertain at present,
so will continue to forego any HWO mention of strong to severe
storms for Monday until the next round comes better into focus.
Expect warmer temperatures in the lower to middle 80s for Monday
afternoon and upper 70s in the mountain valleys.
&&
.SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY/...
As of 205 pm Sunday: Upper troughs will steadily deepen along the
East and West Coasts during the short term, with a ridge building in
between across the Great Plains. Resultant mid/upper NW flow will
persist across the southern Appalachians and vicinity through the
period, with unseasonably warm and humid conditions expected to
continue into Tuesday. As such, mostly diurnal convection is
expected during the first half of the period, but with the NW flow
regime continuing, some potential for somewhat organized deep
convection originating from the vicinity of the Ohio Valley could
make a run at the CWA at just about any time. Some potential for
isolated severe convection will be possible, especially on Tue
afternoon, when short term guidance suggests instability will peak
in the vicinity of 2000 J/kg ahead of a frontal boundary sagging
south into the CWA. However, deep layer wind shear will remain
somewhat modest (generally 20-30 kts), so the severe storm threat is
expected to remain near the marginal end of the spectrum. Temps are
expected to be around 10 degrees above climo Min night/ Tue.
Frontal zone is expected to push south of the area for Wed, as
short wave trough digs off the Mid-Atlantic Coast. As a result, much
drier/more stable air will filter into the forecast area, bringing
temps closer to seasonal norms and putting the kibosh on any deep
convective chances.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
As of 220 pm Sunday: Heights will steadily rise through much of the
medium range, as an upper ridge slowly builds toward the East,
although the ridge may begin to break down by next weekend, as short
wave troughs accost it from the west and the east. In the interim,
the rising heights will allow for increasing humidity (albeit
slowly) and heat during the latter half of the week, with some
potential for diurnal convection steadily increasing each day. By
next weekend, temperatures are expected to return to levels around
10 degrees above climo. By Day 7/Monday, the global models are in
quite good agreement that a strong short wave will carve out a
rather deep upper trough across the East, with attendant frontal
zone expected to bring decent chances for convection
Sunday/Monday.
&&
.AVIATION /03Z MONDAY THROUGH FRIDAY/...
At KCLT and elsewhere: MCS outflow is impacting mainly KAND late
this evening, with thunder having passed at the other TAF sites.
Additional MCS activity back to the west over TN is largely expected
to miss the terminal forecast area to the west overnight. Cannot
rule out some brief MVFR visibility in fog in locations that
received heavy rainfall this evening. Otherwise, confidence on any
thunderstorms Monday is much lower as the MCS remnants and debris
clouds could play havoc with the returning instability. Still, a
PROB30 for TSRA will probably be warranted throughout. Expect mainly
SW winds on average, NW at KAVL, and then gusty winds near any
thunderstorms.
Outlook: Continued thunderstorms and associated restrictions are
possible through Tuesday. High pressure and drier conditions are
anticipated to move in by mid-week.
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...None.
NC...None.
SC...None.
&&
$$
SYNOPSIS...JDL
NEAR TERM...HG
SHORT TERM...JDL
LONG TERM...JDL
AVIATION...HG
Area Forecast Discussion...Updated
National Weather Service Lincoln IL
931 PM CDT Sun May 7 2023
.SYNOPSIS...
Issued at 931 PM CDT Sun May 7 2023
Thunderstorms, some potentially severe and capable of producing
heavy rain, are anticipated from this evening into Monday
morning. An additional, but weaker, round of storms may develop
south of I-70 Monday evening. Quieter weather is forecast for
Tuesday and Wednesday. Precipitation chances return from Thursday
into the weekend.
&&
.UPDATE...
Issued at 931 PM CDT Sun May 7 2023
Persistent thunderstorms continue along the residual outflow
boundary from this morning`s convection, stretching from Rushville,
curving around through Springfield and Taylorville. MRMS 1-hourly radar
precip accumulations are in the 1-2" range, with total precip
along this line since late this afternoon in the 2-5" range.
Latest HRRR indicates this precip continuing through the next 2-3
hours, however the backbuilding leading to this persistence may be
disrupted by the outflow-producing line coming in from the
southeast. At any rate, in addition to the continued threat for
severe wind gusts and isolated large hail, flash flooding will be
a concern. Flash flooding potential will need to be monitored
along the aforementioned line, as well as into the early morning
hours associated with a thunderstorm cluster from NE/IA. Current
thinking is that this early morning cluster will weaken as it
reaches central Illinois, but gusty winds may occur along the
leading edge. Also, any additional rain this cluster brings to
already near-saturated ground could be a flooding concern.
Severe watch 195 was locally extended through 11 pm, while our
other two severe watches in the northern part of our forecast area expire
at 12 am.
We raised precip chances along the remnant outflow boundary for
a few more hours this evening, as well as boosted chances in
northern portions of the ILX forecast area through early morning
in association with the next cluster. Winds/sky cover were updated
as well.
AAT
&&
.SHORT TERM... (Through Late Monday Night)
Issued at 218 PM CDT Sun May 7 2023
As warm and humid air advects into central Illinois from the
west, a remnant outflow boundary from morning convection has moved
to a position from just west of Peoria, to just west of
Springfield, passing just east of the St. Louis Metro and curving
toward Paducah KY. Expect this feature to the the focus for
convective initiation this afternoon/evening. With MLCAPE near
3000 J/kg in the vicinity of this boundary and cloud layer shear
in excess of 40 knots, both large hail and severe wind gusts will
be threats from these cells. As a short wave trough moving through
northern Arkansas approaches, additional forcing for ascent along
with some degree of mid-level cooling will likely lead to fairly
broad multicell storm coverage near the outflow boundary, though
even in this situation stronger updrafts may be capable of large
hail. The expected coverage will likely lead to a growing cold
pool and another southward push of the outflow boundary this
evening, with the severity of this round of thunderstorms waning
by around 8-9 pm.
CAMs depict a second round of convection during the early morning
hours on Monday, with an organized bowing complex of thunderstorms
approaching from southern IA/northern MO. The extent of
afternoon/evening convection across central Illinois will likely
play a large role in the evolution of this complex, with the most
likely outcome at this point being a weakening complex as it moves
into central Illinois after midnight, and/or the complex following
the instability gradient to the southeast with the wind threat
remaining farther west. Even so, the potential for strong to severe
wind gusts in association with this complex will need to be watched,
especially if little convection occurs with the first round across
northern parts of the ILX forecast area. In addition, there is
potential for flash flooding with both rounds of convection,
especially where training storms occur and/or where large amounts of
rain fell early this morning.
In the wake of the early morning convective activity, expect a
fairly quiet period for at least part of the late morning/early
afternoon on Monday before thunderstorms again develop on a cold
front/the remnant outflow boundary from morning convection. MLCAPE
will be closer to 1000 J/kg, with cloud layer shear decreasing to
around 25-30 kt. Though those values are less than today, there will
still be a risk of storms producing large hail and/or severe wind
gusts Monday afternoon/evening. Expect the storms to move out of the
southeast corner of the ILX forecast area by around 9-10pm with the
cold front, with light northeast winds and relatively quiet
conditions for the rest of the overnight hours.
AAT
.LONG TERM... (Tuesday through Next Sunday)
Issued at 218 PM CDT Sun May 7 2023
Key Messages:
1) Much quieter weather is forecast for Tuesday and Wednesday.
2) Precipitation chances increase once again from Thursday into the
weekend.
A mid-level ridge will amplify over the Midwest from Tuesday into
Wednesday, with minimal precipitation chances and high temperatures
falling back into the mid to upper 70s. Precipitation chances begin
to return on Thursday in association with a closed low moving from
the northern/central Rockies into the upper Midwest. Cluster
analysis shows ensemble member differences regarding the depth and
speed/track of this low, which will eventually affect where and how
much precipitation falls. Even so, this period doesn`t look terribly
high-impact at this point, with NBM probability of rainfall > 1" in
the entire Friday-Sunday period only in the 20-30% range. However,
we`ll need to keep an eye out for substantial rainfall accumulations
where soils are becoming more saturated. Additionally, the grand
ensemble (GEFS/EC/CMC) mean CAPE in the Fri/Sun period does poke up
between 500-1000 J/kg during the afternoons.
AAT
&&
.AVIATION... (For the 00z TAFs through 00z Monday Evening)
Issued at 644 PM CDT Sun May 7 2023
Thunderstorms this evening along a line from KMQB-KSPI-KTAZ are
forecast to gradually weaken over the next couple of hours, but
could bring brief MVFR ceilings or visibilities to KSPI and
points east such as KPIA as well. The next round of storms late
tonight into early Monday morning will bring a shot at variable
gusty winds, TSRA, and MVFR ceilings/visibility, with some
uncertainty regarding the exact track/evolution of a thunderstorm
complex coming from Iowa. Following exit of the early morning
activity, MVFR ceilings may occur into the morning, scattering out
by early afternoon. Redevelopment of TSRA along a cold
front/outflow boundary may occur prior to 00Z Monday evening, but
these cells will likely be southeast of TAF sites.
AAT
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
WFO ILX
AREA FORECAST DISCUSSION
National Weather Service Jackson KY
1111 PM EDT Sun May 7 2023
.UPDATE...
Issued at 1111 PM EDT SUN MAY 7 2023
The forecast remains largely on track as showers and a few
rumbles of thunder continue across the southwest near the
Tennessee border. Cloud cover has thinned a bit which has allowed
for a drop off in temps, mainly in lower valley locations. Have
lowered the lows a degree or two along with introducing a small
ridge to valley split, mainly for the eastern valleys.
UPDATE Issued at 625 PM EDT SUN MAY 7 2023
A few showers currently over the southwest counties will continue
to exit the area to the southeast. An area of showers and some
embedded convection is located upstream across the western portion
of the state and looks to be on an eastward trajectory. Recent
HRRR solutions have this area of precipitation breaking up as it
progresses into the central portion of the state while also
shifting to a more southeasterly trajectory. Given the trends and
observations, have kept the PoPs for the next 6-8 hours mostly
confined to the southwestern counties but will continue to monitor
how well the precip holds together for a later update. Hourly temp
and dew point grids have also been freshened up with the latest
observation trends. Ongoing showers have kept the southwestern
counties much cooler while Bluegrass counties rebounded back into
the low 70s.
&&
.SHORT TERM...(This evening through Monday night)
Issued at 300 PM EDT SUN MAY 7 2023
As of 15Z surface analysis, a center of high pressure is located off
to the southeast of the forecast area. However, a decaying MCS has
and is still slowly working through the CWA. The remnants of the
MCS are along the southern and eastern borders with the showers and
storms gradually exiting over the next couple of hours. CAM
solutions do suggest that a rebuilding of the storms is expected
this afternoon mainly for the southwestern portions of the CWA. This
is somewhat supported in the more medium range forecast model
solutions as well.
Synoptically, a subtle shortwave impulse moved southwest through the
ridging which supported and continues to support the MCS that moved
through the region. Also, with a surface low off to the west, warm
frontal boundary favored convection. That warm/stationary boundary
is largely expected to stall in the Ohio Valley overnight tonight.
This will keep chances of PoP in the forecast overnight tonight and
into the Monday. With the support of a frontal boundary in the
vicinity; as well as, potential outflow from overnight convection,
another stormy day is expected for Monday. All modes of severe
weather are possible with the best chances for hail and damaging
winds. However, can`t rule out a tornado for the Bluegrass counties
down to a line around London to the Mountain Parkway. With constant
shower activity and PWats around 1.30 inches, WPC has put the CWA in
a marginal ERO for today and Monday. With the slow approach of the
surface low late Monday into Tuesday, shower activity with continue
before the associated cold front crosses the region by late Tuesday
morning. Aside from all the showers and thunderstorms, temperatures
will remain on the warm side as highs are still forecast to be in
the 70s with overnight lows in the upper-50s to lower-60s.
.LONG TERM...(Tuesday through Sunday)
Issued at 318 PM EDT SUN MAY 7 2023
An upper disturbance moving southeast across the Midwest into the
Mid-Atlantic states will push remaining shower and thunderstorm
activity associated with a weak cold front through the area during
the late morning period Tuesday, with surface high pressure building
in from the north and northwest Tuesday into Wednesday and resulting
in clearing skies. With weak cold advection and radiational cooling
after recent rains, fog seems like a good bet in the mountain
valleys under mostly clear skies.
Drier and more stable conditions persist Tuesday afternoon into
Thursday morning, with warmer conditions developing Thursday into
Friday with low-level southeast winds off of the higher terrain
resulting in highs reaching into the 80s as upper ridging remains
just west of the area.
Late Thursday into Friday, models suggest this upper ridge may
weaken and allow a disturbance and associated increased west-
northwest flow to move into the region, which will result in
increased PoPs to around 20 to 40 percent for Friday afternoon and
continuing into next weekend.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
ISSUED AT 801 PM EDT SUN MAY 7 2023
Currently conditions across the area are VFR as showers and
storms have largely moved out of the area with the exception being
the far southwest near the Tennessee border. An area of showers
and storms will move through later this evening and early tonight
and may impact the SME and LOZ sites briefly. A resurgence in
precipitation is expected areawide Monday afternoon and may bring
visibility impacts with the heaviest cells. Patchy fog may
develop in areas that see a bit of clearing but impacts to TAF
sites are not expected. Winds will light at 5 knots or less
generally from the southwest an will increase to between 5-10
knots after dawn.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...BATZ
SHORT TERM...VORST
LONG TERM...CASSELL
AVIATION...BATZ
Area Forecast Discussion
National Weather Service Newport/Morehead City NC
1017 PM EDT Sun May 7 2023
.SYNOPSIS...
High pressure will continue to influence the weather tonight
while moving off of the coast. An initial wave with moisture
could impact the area tonight, with additional waves bringing
the potential for more unsettled weather through mid week. A
backdoor front will move through Tuesday night, with high
pressure building in from the north late next week.
&&
.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
As of 10:15 PM Sun...Radar shows light showers across our
northern CWA ahead of a line of convection traversing southeast
Virginia. The forecast remains on track with no changes in this
update.
&&
.SHORT TERM /6 AM MONDAY MORNING THROUGH 6 PM MONDAY/...
As of 405 PM Sun...Lower than average confidence in the forecast
tomorrow with a large spread in CAM guidance. The overall
environment tomorrow should be more supportive for thunderstorm
activity, as tonight`s shortwave will have significantly eroded
the mid-level ridge while low-level moisture continues to
build. The HREF ensemble suggests mean SBCAPE values of around
1000 J/kg, but this does not reflect the large spread among its
members from the NAM (pushing 2000 J/kg) and the HRRR
(suggesting no more than a couple hundred joules). Furthermore,
CAMs show high variation in possible storm evolution in the
afternoon.
The NSSL WRF and FV3 were discounted from the forecast for their
poor initialization of this morning and afternoon`s MCS activity
across the OH and TN Valleys. The HRRR, ARW, and 3km NAM were
better and leaned on them for tomorrow`s outlook, which favors
two zones for convective initiation - one along a trough inland
and a second, originating in VA as another shortwave impulse
races across the mid-Atlantic.
Given the uncertainty, opted for a fairly broad-brushed 40-50%
POP for tomorrow across most of the FA but favoring corridors of
higher QPF where reliable CAMs are in the best agreement. The
broader PoP also accounts for what should be a more favorable
environment for convective development, assuming more scattered
coverage than some CAMs suggest. Appreciable shear will be
displaced to our south and a severe risk appears minimal.
Outside of storms, a very warm and muggy day is expected with
highs well into the upper 80s and dew points in the low to mid
60s.
&&
.LONG TERM /MONDAY NIGHT THROUGH SUNDAY/...
As of 415 PM Sunday...The "Long Term" period will be dominated
by a NW flow pattern aloft and, initially, looks more
reminiscent of June than May. Within that flow, modified EML
plumes emanating off the Southern High Plains will overspread a
moistening airmass over the Carolinas/Mid-Atlantic, supporting
the development of plumes of moderate instability Tuesday.
Meanwhile, well upstream across the Mid-MS and OH Valleys, there
will be multiple convective complexes that will develop, with
multiple convectively- induced shortwaves eventually dropping
ESE across portions of the Mid- Atlantic and Carolinas. This is
a classic MCS pattern across the central and eastern US, and is
a pattern more commonly seen in June.
Locally, the above-mentioned shortwaves will each be accompanied by
at least some risk of convection as they cross the Mid-Atlantic
and the Carolinas. However, persistent MCS patterns like this
are often lower-confidence ones, as each day is highly dependent
on the previous days convection, the timing of various waves,
and how much instability can be realized prior to the arrival of
each wave.
From a probabilistic standpoint, the greatest chance of realizing
stronger instability and shear is on Tuesday. Consequently, Tuesday
also appears to have the best chance for a risk of strong to severe
thunderstorms.
Bottom line, multiple rounds of thunderstorms are through
Tuesday, with at least some potential for severe weather
(primarily in the form of damaging winds). In between each round
of convection, breaks in the clouds plus warm low-level
thicknesses will support above to well above normal
temperatures. Inland, a few 90s cannot be ruled out. With this
forecast update, temps were nudged warmer for both Monday and
Tuesday, but I held off on going with the highest available
guidance due to the potential impacts from convective cloud
debris and/or convection, itself.
Late Tuesday, the strongest shortwave of the week is forecast to
move across the Mid-Atlantic, sweeping out the moist and unstable
airmass, and replacing it with a cooler northeasterly low-level
flow. A few showers can`t be ruled out on Wednesday, but the general
theme mid-week is cooler and drier conditions. By the end of the
week and into next weekend, we may get back into a more active NW
flow pattern once again. Medium range guidance differ on how quickly
this pattern may redevelop, so for now we`ll keep with a mostly dry,
but warming, forecast during that time.
&&
.AVIATION /02Z MONDAY THROUGH FRIDAY/...
SHORT TERM /through 18Z Mon/...
As of 8:15 PM Sun...Continued high confidence in VFR conditions
through the period with the only mentionable nuisance being
scattered showers tomorrow afternoon near 18Z. Some thunder is
possible, but instability is lacking, so continued to hold off
on any VCTS mention for now.
LONG TERM /Monday night through Thursday/...
As of 140 PM Sunday...The potential exists for one, or more,
rounds of TSRA Monday evening and Tuesday, each with a risk of
sub- VFR conditions. Additionally, there will be a risk of
gusty/erratic winds and hail where TSRA occur. By mid-week, a
drier airmass will move in with a reduced risk of TSRA.
&&
.MARINE...
SHORT TERM /through tonight/...
As of 425 PM Sun...Southwesterly winds of around 10-15 kt in
place over the waters this afternoon as high pressure moves
offshore, while seas sit at around 3-4 feet. Winds are expected
to increase further tonight, peaking at around 20-30 kt over
portions of Raleigh and Onslow Bays tonight and 15-25 kt for the
northern waters and Pamlico Sound. Over the offshore waters,
this will help drive seas to a max of around 6-9 feet overnight,
especially for waters 15-20nm into Raleigh Bay. The wind surge
ebbs during the day tomorrow although southwesterly winds will
still be elevated, around 15 to 20 kt particularly for southern
and central waters. Seas here will continue to hover at around
4-5 feet late Monday and into Monday evening.
Current SCAs remain in place, although their expiration times
were moved up slightly based on latest 12z guidance showing
surge dropping off a bit more quickly. There may be some spotty
gusts to 25 kt across the northern sounds and the mouth of the
Neuse river, but occurrences are forecast to be too infrequent
to necessitate a headline. Similar logic applies for Gales for
outer central waters, where a brief period of 35 kt gusts is
possible early Monday morning.
Scattered thunderstorms are possible over area waters tomorrow
afternoon, with zones modestly more favored along the Crystal
Coast and the northern sounds and offshore waters.
LONG TERM /Monday through Thursday/...
As of 200 AM Sunday...A couple of surface lows will impact the
Eastern North Carolina waters early this week, each with the
potential to bring a risk of showers and thunderstorms, and higher
winds and seas. The timing of each low, and the magnitude of impact
from winds, seas, and thunderstorms is less certain, so stay tuned
for which periods have the greatest impact potential. By mid-week, a
decidedly northeasterly flow will develop across area waters, with
another risk of SCA conditions, especially across the central and
southern coastal waters closer to the Gulf Stream.
&&
.EQUIPMENT...
Beginning Monday, May 8th, the KMHX WSR-88D radar in Newport,
NC will be down for approximately two weeks for an important
upgrade. During the downtime, adjacent radars will be available,
including: KAKQ, KLTX, and KRAX.
&&
.MHX WATCHES/WARNINGS/ADVISORIES...
NC...Beach Hazards Statement from 8 AM EDT Monday through Monday
evening for NCZ196-204-205.
MARINE...Small Craft Advisory until 8 AM EDT Monday for AMZ135-150.
Small Craft Advisory until 8 PM EDT Monday for AMZ152-154-156-
158.
&&
$$
SYNOPSIS...MHX
NEAR TERM...OJC
SHORT TERM...MS
LONG TERM...RM
AVIATION...MS/OJC
MARINE...RM/MS
EQUIPMENT...MHX
Area Forecast Discussion
National Weather Service Morristown TN
1115 PM EDT Sun May 7 2023
...New UPDATE...
.UPDATE...
Issued at 1112 PM EDT Sun May 7 2023
Have updated hourly temperatures and expect temperatures to remain
nearly steady overnight. Convection will continue overnight along
the outflow boundary across SE TN and extending WNW along the
Interstate 24 corridor. Some localized flash flooding will be
possible if convection trains overnight with RAP PW values around
1.6 to 1.7 inches which is right at the max of climatology for
early May.
JB
&&
.SHORT TERM...
(This evening through Monday)
Issued at 251 PM EDT Sun May 7 2023
Key Messages:
1. Line of showers and thunderstorms this evening may produce
strong and gusty winds of 40-50 mph and hail up to 1/2 inch size.
Mainly along and north of interstate 40.
2. Another cluster of showers and storms overnight mainly along
and south of interstate 40. These storms may also produce winds up
to 40 mph and locally heavy rain.
Discussion:
Through this evening, a line of showers and storms will move
slowly southeast across southwest VA/northern half of east
Tennessee. Main forcing for this complex of storms is a wave/jet
streak riding the top of the ridge over Kentucky/northern
Tennessee valley.
Airmass along and ahead of this line will be marginally unstable
with MLCAPES of 500 (northeast) to 1,500 (Plateau) with mid-level
lapses of 6.5 to 6.8 degrees. Main concern is the area of mid-
level and sub-cloud layer initial dry air that produces DCAPE
values of 800 to 1000. This level of Downdraft CAPE may produce
isolated strong and gusty winds of 40-50 mph with main impact
being isolated down trees and localized power outages. Due to the
low Wet Bulb Zero around 9kft and decent mid-level lapse rates,
the strongest storms could produce small hail.
Latest HREF and HRRR shows this line of convection weakening once
it moves south of interstate 40.
For tonight, high-resolution CAMS shows another cluster of
convection moving southeast from middle Tennessee into the
southern half of east Tennessee and southwest North Carolina for
early Monday morning. Strongest storms will be along and south of
the outflow boundary from this evening`s convection (southeast
Tennessee). This complex of storms will move southeast of the
region soon after daybreak Monday.
For Monday, deterministic models and ensembles vary greatly on the
convective coverage and timing of next storm development. Trending
toward the latest HRRR model which only produces scattered storms.
This seems reasonable given the outflow boundary from the series
of convective will be well west and south of the region.
&&
.LONG TERM...
(Monday night through next Sunday)
Issued at 251 PM EDT Sun May 7 2023
Key Messages:
1. Additional showers/storms expected Monday night into Tuesday. Dry
mid week with low rain chances making a return Friday into the
weekend.
2. Above normal temperatures expected throughout the long-term
period.
Discussion:
The omega block pattern remains in place to start off the long term
portion of this forecast package. Ridging will gradually amplify
into the mid-week in response to shortwave activity deepening
troughing across the PNW. Monday night into Tuesday a surface
boundary will slowly shift southward through the forecast area and
act as a forcing point for additional showers and storms. NAM
soundings continue to show MLCAPEs at or in excess of 1000J/kg and
mid-level lapse rates in the 6.5-7.5C/km range. There will also be a
brief increase in amplitude of nwly flow aloft, leading to enhanced
but mostly unidirectional shear. For this reason, a few strong or
isolated severe storms will remain possible. Primary threat will be
damaging wind gusts with perhaps some hail as well. One thing
working against storm activity will be increasing subsidence aloft.
Additionally, PWATs hovering around 1.3 inches(which is between the
75th and 90th percentile according to SPC sounding climatology out
of BNA) could result in some isolated flooding concerns dependent on
antecedent rainfall over these next two days and whether or not
areas see repeated moderate/heavy downpours.
The increased ridging influence into the mid-week should keep the
forecast area mostly dry with continued above normal temperatures
expected. By the late week and into the weekend, surface high
pressure will transition east of the area with some extent of ridge
suppression that takes place due to increased troughing over the
northeastern CONUS and into Canada. Weaker subsidence will favor a
return of PoP chances. However, it looks to follow a more diurnal
trend at this time, with best chances in the afternoon/evening.
&&
.AVIATION...
(00Z TAFS)
Issued at 735 PM EDT Sun May 7 2023
Additional rounds of showers and thunderstorms are expected to
impact CHA and TYS overnight and again on Monday with periods of
MVFR and IFR conditions within heavier convection. This unsettled
pattern will continue through the entire forecast period as
showers and thunderstorms develop and move along a weak boundary
located across the region and in the vicinity of both CHA and
TYS. Winds will remain generally light and variable, but may gust
within areas of stronger convection.
&&
.PRELIMINARY POINT TEMPS/POPS...
Chattanooga Airport, TN 63 82 65 86 / 90 90 40 50
Knoxville McGhee Tyson Airport, TN 61 79 64 81 / 70 70 70 60
Oak Ridge, TN 61 79 63 83 / 80 70 70 50
Tri Cities Airport, TN 59 76 61 77 / 60 60 80 60
&&
.MRX WATCHES/WARNINGS/ADVISORIES...
NC...NONE.
TN...NONE.
VA...NONE.
&&
$$
SHORT TERM...DH
LONG TERM....KRS
AVIATION...JB
Area Forecast Discussion
National Weather Service Nashville TN
821 PM CDT Sun May 7 2023
...New UPDATE...
.UPDATE...
Issued at 812 PM CDT Sun May 7 2023
Widespread showers and thunderstorms continue to roll through
Middle Tennessee this evening, although there are no warnings
currently in effect. Still, some of these storms are capable of
producing non-severe hail, wind gusts to 40 mph, and considerable
lightning. In addition, instantaneous rainfall rates with the
heavier cells are such that brief, localized flooding of roads and
flashy creeks is something to watch for. While the original line
of storms that earlier came through Nashville Metro is now riding
up the Cumberland Plateau, another thunderstorm cluster is poised
to move across Nashville Metro with the hour. At this time, the
strongest of these next storms will likely go south of downtown.
The HRRR continues to show at least scattered cells persisting
for most of the overnight period, so we certainly haven`t seen the
last of the night`s activity. No forecast changes are planned for
now. The current forecast has this event nailed down quite well.
(Of note, the 00Z sounding at OHX was scrapped due to storms in
the area.)
&&
.SHORT TERM...
(This afternoon through Tuesday Night)
Issued at 213 PM CDT Sun May 7 2023
Current regional mosaic showing The large area of showers and storms
moving southward across KY. We also see a developing complex across
se MO and northern AR. NBS pop data has been ticking upward and the
latest Hrrr and nam nest data showing increasing confidence levels
as well. So, the showers and storms across KY will impact our area
beginning around 2 PM or so. The developing complex west of the MS
river will be gaining strength and will intensify the existing
complex as it reach our area this evening. Furthermore, latest
instability parameters showing the most favorable areas across
across western TN and extending into our western and northwestern
areas. The higher downdraft capes are situated along the TN River at
this time. The storms to our north do have an earlier history of
some low end wind damage across northern KY. SPC has recently
upgraded basically our entire western half from marginal to slight
risk of severe. Wind and hail still look to be the likely threat
beginning this afternoon and into this evening.
Additionally to all of this is the potential for some localized
flooding in our northwest this evening and overnight. This will
depend largely on the trajectory of the aforementioned complex to
our west. If this can slam into the western flank of the southward
moving system, rainfall amounts will likely be enhanced. As it
stands right now, 2 inches of rainfall could be rather common across
our northwest by sunrise Monday. Local amounts of 3 inches can not
be ruled out. Note that there is not enough confidence to hoist a
flood watch. Also, understand that the short term model qpf maximums
are rather isolated and across our northwest. There also appears to
be some uncertainty as to the arrival of the developing MCS to our
west.
Moving on, the mcs pattern will remain into Monday as another system
moves through. The airmass will need to refuel in order for a second
round of severe to be possible. This looks somewhat questionable.
We are in a marginal for now. The primary cold front should move
through on Tuesday. We are not outlooked at this time. Improving
conditions will begin Tuesday night.
For the near term temps, it will be rather soupy and warm for early
May. Lows in the 60s with highs lower to mid 80s.
&&
.LONG TERM...
(Wednesday through next Sunday)
Issued at 213 PM CDT Sun May 7 2023
In the extended forecast, models are a little more bullish with
leaning toward some upper ridging for our area. There is some
progressiveness and the ridge looks rather narrow in scope. That
said, some shortwave impacts cannot be ruled out for Thursday and
Friday. We will see our shower and tstm chances climb into the
chance category for that time frame. Otw, continued mild and soupy.
Lows 60 to 65 and highs 80 to 85.
&&
.AVIATION...
(00Z TAFS)
Issued at 607 PM CDT Sun May 7 2023
Radar trends indicate convection, some of which may be on the
strong side will impact BNA, MQY and CKV early in the TAF period,
with SRB and CSV seeing impacts a few hours later. Expect VIS
reduction to IFR/LIFR with possible MVFR CIGS with the storms.
Overnight some clearing is anticipated but showers and
thunderstorms may be in the area, with another round moving
through in the morning hours.
&&
.PRELIMINARY POINT TEMPS/POPS...
Nashville 66 85 67 83 / 70 60 50 70
Clarksville 64 85 65 80 / 80 70 40 40
Crossville 59 76 62 78 / 70 70 60 80
Columbia 64 83 65 84 / 70 50 40 60
Cookeville 62 78 63 79 / 70 70 60 80
Jamestown 59 77 61 78 / 70 70 70 70
Lawrenceburg 64 82 65 83 / 70 50 40 60
Murfreesboro 63 82 64 83 / 70 60 50 70
Waverly 63 83 64 81 / 70 50 40 40
&&
.OHX WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
UPDATE.......Rose
SHORT TERM...21
LONG TERM....21
AVIATION.....05
Area Forecast Discussion
National Weather Service Raleigh NC
1034 PM EDT Sun May 7 2023
.SYNOPSIS...
A warm southwest flow will hold over North Carolina through Tuesday,
as a series of disturbances aloft tracks over the region. A backdoor
front will drop through the state Tuesday night, ushering in surface
high pressure that will extend across the area Wednesday through
Friday, bringing dry weather and lower humidity.
&&
.NEAR TERM /THROUGH TONIGHT/...
As of 940 PM Sunday...
A largely dry night is ahead. What looked to be a decent chance of
convection as an MCS outflow tracked toward our area this afternoon
fell victim to a more hostile environment as compared to western
NC/SC westward into TN. This far east, despite good deep layer bulk
shear and sufficiently high dewpoints, the surface CAPE was marginal
as was the PW and lapse rates aloft, and this was followed quickly
by dwindling heating and CINH development toward sunset. The earlier
forecast update a few hours ago removed all but the smallest of rain
chances, holding onto isolated showers over the far SW Piedmont
through mid evening, a risk that is now gone for the rest of
tonight. Next up is the cluster of showers and isolated storms just
NE of Roanoke Rapids including one particularly robust cell, all
associated with a passing 850-700 mb shortwave trough. This, too,
appears poised to skirt just NE of the CWA, but will maintain a low
coverage pop there for another few hours, given how close it is to
the CWA border. Steering flow and propagation vectors suggest that
the MCS over SE TN will continue to track into NE AL, N GA, and far
SW NC over the next several hours, and additional MCS activity will
persist further upstream through IL overnight, however none of this
is expected to shift past the S Appalachians tonight, thus we should
stay dry overnight. The nocturnal temp dip thus far supports lows in
the low to mid 60s, so no noteworthy changes needed there. -GIH
Previous discussion from 220 PM: The afternoon surface analysis
shows that the MCS has certainly weakened. The eastern batch of
convection over eastern KY/WV and northwest VA has weakened in the
last few hours as it approaches the Appalachians. The more vigorous
convection is currently over south-central and southwest KY, in an
area of stronger moisture transport and instability. The outflow
boundary tied to the southward moving storms stretches roughly from
southern IL/KY into far western and VA and northern/northeast TN.
Some convective towers have developed along the lee trough in far
western NC/VA but activity currently appears relatively tame so far.
Dewpoints ahead of the southward moving MCS are not overly
impressive in the upper 50s to some low 60s. As such, current MLCAPE
based on the SPC meso page is less than 500 J/kg over western NC.
This instability is still progged to increase to 500 perhaps 1000
J/kg over the northwest Piedmont later this afternoon and evening in
a region of 30-35 kts of deep-layer shear. The 12Z HREF solutions
were in decent agreement on the weakened convection to our northwest
redeveloping over the northwest Piedmont by early evening as a
broken line of showers/storms. However, the NAM-NEST has continued
to be rather muted and the last few runs of the HRRR would tend to
agree. The latest 16-17Z HRRR shows any storms dying out over the
Triad owing to less instability. This has certainly lowered our
confidence on storm coverage over the region this evening. Our
latest thinking follows the 12Z HREF to a large degree, showing the
highest PoPs in the northwest Piedmont and lesser chances along/east
of US-1 as more stable air tied to the western extent of the ridge
will suppress development. Instability will be greatest over the
western Piedmont so any line that does form should be strongest west
of US-1 over the western/southern Piedmont. Damaging winds will be
possible with any stronger storms, where the marginal risk is in
place.
There could be a secondary chance of storms later tonight over the
eastern/northeast Piedmont and northern Coastal Plain, roughly from
the Triangle to Rocky Mount to Roanoke Rapids and just east of
Roxboro. The NAM-NEST and NSSL/NBM/GFS and somewhat the NAM show a
batch of showers and embedded storms tracking NW to SE over this
region later tonight into the early overnight hours, perhaps tied to
low-level moisture transport and a weak disturbance to our north
bringing a boundary southward into VA. MUCAPE upwards of 1000 J/kg
is forecast over this region. Confidence on this is low but have
kept a 20-30 percent chance of storms in this region to account for
the synoptic pattern. After that, convection is expected to wane
into the early morning hours of Mon with no real discernible
forcing, though cannot rule out a stray shower over the Coastal
Plain/Sandhills if any outflow exists. Lows to be in the low/mid 60s.
&&
.SHORT TERM /MONDAY AND MONDAY NIGHT/...
As of 220 PM Sunday...
The mid-level short wave through currently over the Mississippi
River Valley is progged to move east and cross central NC around mid-
day Monday. The combination of that disturbance, coupled with
lingering remnant outflow boundaries from the convection that is set
to move across central NC later today, should set the stage for
scattered afternoon and evening shower/tstm development. Our newest
grids show chance PoPs by 18Z Monday through late evening before
becoming slight chance during the late evening and overnight. Temps
on Monday will be similar or perhaps a couple degrees warmer than
today. Highs in the 80s and lows in the 60s.
&&
.LONG TERM /TUESDAY THROUGH SUNDAY/...
As of 220 PM Sunday...
A short wave trough currently over the northern Rockies is progged
to move east and cross the Great Lakes region early Tuesday. That
system will push a cold front and pre-frontal band of showers and
tstms across our area during the afternoon and evening Tuesday. The
combination of moderate instability along with bulk shear values in
the 40-50 kt range should support the potential for some storms
becoming severe. The main threat will be from damaging winds and
large hail. SWODY3 shows central NC in a marginal risk for severe
storms for Tuesday/Tuesday night.
Highs on Tuesday before the shower/tstm activity will climbs to the
upper 80s south and lower 80s north, but will be followed by cooler
highs on Wednesday in the wake of the aforementioned front (highs in
the 70s on Wednesday). Otherwise, it will be dry from early
Wednesday through Friday thanks to high pressure and drier airmass
over our area.
For this weekend, a weak backdoor front may result in widely
scattered mainly afternoon and evening showers/tstms. That front
won`t support much of an airmass change, so look for highs in the
80s next weekend.
&&
.AVIATION /0230Z MONDAY THROUGH FRIDAY/...
As of 1030 PM Sunday...
VWP data from KRAX, TRDU, KAKQ and KLTX have shown the LLJ at 2,000
has quickly strengthened to 40-45kts from RDU eastward. This gave
enough confidence to increase the strength of the LLWS at RDU, RWI,
and FAY through 6-9z with the 0226z TAF amendment. Previous
discussion follows.
As of 715 PM Sunday...
Coverage and intensity of the convective line has weakened
substantially as it moved toward the Triad terminals with a clear
split occurring around central NC. Thus, have removed the mention of
thunder at RDU through tonight. A cluster of showers may develop
over SE VA and NE NC tonight and may reach the vicinity of RWI
around 01-03z, although confidence in direct terminal restrictions
is low at this time. LLWS will likely be a concern at RDU/RWI as the
LLJ strengthens to 35-40kts, veering from 240 to 280 degrees by 09z
and then shifting offshore by daybreak.
VFR conditions will otherwise continue through tonight and a
majority of Monday with a chance for scattered airmass
showers/storms possible after 18z, with relatively equal chances (30-
40%) at all TAF sites through the remainder of the TAF period.
Looking beyond 00z Monday, sub-VFR conditions will be possible again
on Tuesday with a chance for afternoon showers/storms. A back door
cold front will promote drier conditions Wednesday through Friday.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SYNOPSIS...Hartfield
NEAR TERM...Hartfield/Kren
SHORT TERM...np
LONG TERM...np
AVIATION...Swiggett/Luchetti