Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 05/09/23
Area Forecast Discussion
National Weather Service La Crosse WI
1059 PM CDT Mon May 8 2023
.DISCUSSION...(This evening through Monday)
Issued at 150 PM CDT Mon May 8 2023
Key Messages:
- Conditional Strong to Severe Storm Threat Today and Tuesday
- Warmer Temperatures Through Midweek Across The Area
- Active Pattern Continues Latter Half of the Week Into The
Weekend
Storm Threat Setup This Morning:
Conditional storm threat has increased over previous forecasts
later this afternoon and into the evening. Upper level ice
nucleated clouds overhead earlier this morning were associated
with the convection farther south into central IL and have
continued east, evident in recent satellite upper level water
vapor imagery loops. Derived GOES upper level winds suggest
associated perturbation quickly advecting downstream to the Great
Lakes. Upstream, the quasi-zonal jet streak core expected to
bifurcate the forecast area this afternoon, placing a thermally
indirect transverse ageostrophic circulation for parts of the
forecast area this afternoon. This is evident in forecasted
isentropic analysis pushing 5 ubar/s of upglide at 295 K.
Conditional Storm Threat Later This Afternoon & Evening:
Weak surface boundary earlier this morning from east-central
Minnesota into western Iowa exhibits meager dewpoint differential of
10 degrees per 100 miles. A thick, low level stratus deck early this
morning ahead of this moisture gradient has muddled surface
temperature differential across the surface front. Forecast cross
section analysts show the ageostrophic influence and
frontogenetical response expected later this afternoon with 5-10
ubar/s of omega. RAP/HRRR (08.15/12Z) build MLCAPE pool through
central Iowa into central Minnesota later this afternoon, pushing
500 J/kg later this afternoon. Associated model soundings show
MUCAPE reaching 1000 J/kg, weak low level shear profiles, and
straight line hodographs. Tying it all together, early this
afternoon the initial inhibitive stratus deck has been clearing,
increasing mixing. While, as previously mentioned, low level shear
is nearly naught, mid to upper level speed shear should sustain
storms and severity, 60 kts from 3-8km, showing straight line
hodographs, and RAP soundings suggesting 10km storm tops. In
summary, severe hail will be a conditional concern late this
afternoon into the early evening from southeast Minnesota into
northeast Iowa. Given the nearly non-existent low level shear,
surface based storms will be limited, however still possible. Main
driving mechanism would be ingestion of the nebulous surface
boundary into a splitting discrete supercell storm, resulting in
isolated, limited tornado threat. Very low confidence (<20%) and
spatial extent.
Tonight:
This afternoon storm threat and exit behavior of clouds will
determine surface cooling overnight and increasing fog potential.
Surface dewpoints expected to remain near 50 degrees, suggesting
enough moisture should skies clear and surface cooling increases.
Conditional Storm Threat Tuesday:
While mid and upper level heights build early Tuesday morning,
slight ridge running perturbations continue precipitation and storm
chances primarily along our western periphery. Lobes of passing
mid level positive vorticity advection concurrent with lobes of
increased low level theta e are expected to primarily impact our
western counties in northeast Iowa and southeast Minnesota into
the late afternoon-evening. A quasi-stationary boundary appears
to be the initial forcing mechanism exhibiting meager surface
convergence. Initial storm motion may lie along and quasi-
parallel this quasi stationary surface boundary. Current high
resolution forecast models drape this surface boundary from
central Minnesota to western Wisconsin; west to just northwest of
the local forecast area. Similar to today, best shear expected to
be elevated, however more directional shear in the midlevels
resulting in clockwise turning hodographs increasing helicity
above 250 m2/s2 for an extremely short window into the early
evening. While low level shear is limited, again, ingesting of any
surface vorticity along the boundary, depending on where it sets
up, could result in the potential for an isolated tornado threat.
RAP/HRRR build 1000/1500 J/kg ML/MUCAPE through the late
afternoon along our western periphery with long and skinny CAPE
profiles, limiting initial development and vertical velocity as
well as perhaps other severe threat types. Overall, extremely
conditional threat given the current forecast hour limiting the
number of high resolution models. Also, many different storm
dependencies, including cloud and fog deck(s) tonight, exact
placement of surface boundary during the day, and timing of best
instability concurrent with peak diurnal influence. Given these
dependencies and model differences, lot to work out yet and need a
lot of ingredients to come together; will be something to keep an
eye on.
Midweek Into the Weekend:
Through midweek, heights again try to build with potential ridge
running perturbations and positive lobes of mid level vorticity
advection. Low level moisture transport and resultant increased
theta e peak off to our west through Wednesday afternoon, with
forecast concern becoming maximum daytime high temperatures. Most
confidence (>70%) for maximum daytime temperatures in the 70s for
much of the area. Progressive pattern continues through the
latter half of the week with increased low level theta e passing
over the forecast area Thursday. Increased low level moisture
transport backs to our west, keeping more moist air there. Storm
and severe chances continue Thursday night into the weekend with
disagreement on eastward extent of Central Plains upper level
positively tilted trough becoming closed as it attempts to advect
northeast. Again, something to keep an eye on for Friday into the
weekend.
&&
.AVIATION...(For the 06Z TAFS through 06Z Tuesday night)
Issued at 1054 PM CDT Mon May 8 2023
Upcoming TAFS at 06Z will be challenging with various weather
situations across the airfields. Clearing at KRST will provide
conditions preferable for fog formation by morning, possible LIFR.
Recent rains have only added to the confidence and increased the
probability. At KLSE, a band of showers will move through around
05Z and set the stage similar to KRST for fog. However, IFR
clouds are about 2 counties east of the airfield and with
inversion conditions overnight, that deck will expand west into
KLSE. IFR is expected but confidence is slightly lower on
visibility.
Conditions will improve through the morning on Tuesday.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
DISCUSSION...JAR
AVIATION...Baumgardt
Area Forecast Discussion...UPDATED
National Weather Service Corpus Christi TX
956 PM CDT Mon May 8 2023
...New UPDATE...
.UPDATE...
Issued at 948 PM CDT Mon May 8 2023
Convection over northeast Mexico has struggled to maintain
organization as activity approached the Rio Grande. Even though
there is plenty of instability and shear is adequate, it appears
the convective inhibition is winning out. Adjusted PoPs down
slightly for the coastal plains. Latest HRRR shows redevelopment
overnight around a forming mid level low.
&&
.SHORT TERM...
(Tonight through Tuesday night)
Issued at 345 PM CDT Mon May 8 2023
A mid-level trough over the Rio Grande will push a cluster of
showers and thunderstorms from Mexico into the Rio Grande Plains and
Brush Country tonight. This trough is progged to develop a closed
low over Central Texas tonight into Tuesday. Latest CAM guidance
shows a bow-like feature move west to east through the CWA from
around 7PM through 3AM. Have 40-50% PoPs tonight following this
event.
Afterwards, the forecast is tricky with global models and NBM
indicating higher QPF and rain chances compared to latest CAM
showing only a few showers and storms on Tuesday. A surface meso-low
is shown to the develop in the CAMs from the storms moving into the
coastal waters, progressing parallel northward along the Texas
Coast, putting South Texas in the unfavorable drier air
entrainment part of the low. Still believe scattered showers and
thunderstorms could develop Tuesday and Tuesday night with at
least 75th percentile PWATs and bands of positive vorticity aloft
associated with the mid-level trough.
Mostly cloudy to overcast skies with rainfall will "cool"
temperatures down to highs from the low 80s to low 90s east to west
respectively. Lows will stay in the mid 70s.
&&
.LONG TERM...
(Wednesday through next Sunday)
Issued at 345 PM CDT Mon May 8 2023
Key Messages:
- Potential for heavy rain, especially Friday through Sunday.
Very messy forecast from the middle of this week through the
weekend. The overall pattern remains wet with multiple mid-level
disturbances interacting with well above normal moisture levels.
We`ll break it down here as best we can, but the smaller scale
features and timing/placement of the period of heavy rain are still
unclear.
In the long term period the first feature we`re looking at is a mid-
level low that should be exiting the region at the beginning of the
period. Depending on the speed of this feature and it`s surface
reflection, currently expect a pretty wet Wednesday morning into the
afternoon before a drier period Wednesday evening/night. Central to
eastern portions of the area will have the best rain chances
Wednesday and could see a couple of inches. We are in a slight risk
of excessive rainfall for that period.
By Thursday morning a weak shortwave will be approaching to bring
another shot at showers and thunderstorms during the day. This
period looks less organized, but PWAT values remain elevated, so any
showers and storms that do develop could bring locally heavy rains.
The most concerning period comes Friday afternoon through the weekend
as a deeper mid-level trough and closed low develop and approach the
area. There are still substantial differences in model guidance
which leads to the low confidence in the finer details of this
event, but there is pretty high confidence in at least portions of
the area getting a few inches of rain through the weekend.
Probabilities of 3" or more made out around 50-60% in the NBM in
central and eastern parts of the area, but looking at ensembles,
ECMWF is indicating 70% chance of 2" for Saturday alone. GEFS
ensemble is significantly lower than this. Thus the lower
confidence. That said...with current QPF expectations, we will
likely have concerns of flash flooding and river flooding for this
weeekend. We`ll just have to see how things evolve over the next few
days and hope that guidance can settle in on something to improve
confidence moving forward.
Outside of the thunderstorms/rainfall concerns, there`s not too much
else to discuss for the long term period. Temperatures will be
seasonal through the end of the week, but likely a bit below normal
for the weekend if the widespread rain pans out.
&&
.AVIATION...
(00Z TAFS)
Issued at 654 PM CDT Mon May 8 2023
Strong convection continues to organize over the higher terrain of
northeast Mexico to the west-southwest of Laredo as the mid level
short wave trough moves in from the west. Strongly unstable air
mass resides along the Rio Grande into the Brush Country with
MLCAPE values up to 4000 J/kg. The 0-6 km shear vectors are from
the west around 35 knots. Expect activity will continue to advance
toward the Rio Grande and affect the Brush Country this evening.
Latest HRRR forecast (21Z) does not add confidence in this
scenario, showing the complex moving east-southeast toward the Rio
Grande valley. But will base forecast on the HREF with the
ensembles showing storms moving into the western areas. Will be
cautious with bringing activity all the way toward the coast as
mid level inversion could inhibit the storms. Will bring the
convection to ALI later this evening but only show VCSH for CRP at
this time. MVFR ceilings along the coast will move inland this
evening with IFR ceilings and MVFR vsbys possible for the coastal
plains during the overnight period. A mid level low is expected to
form over the Mid-Coast region Tuesday morning. This system will
interact with deep moisture in place to produce scattered
convection from the Coastal Bend to the Victoria Crossroads from
late morning through most of the afternoon. Will show MVFR
ceilings prevalent over the coastal plains through the afternoon
while VFR ceilings occur over the Brush Country.
&&
.MARINE...
Issued at 345 PM CDT Mon May 8 2023
Generally moderate flow is expected across the local waters
through this weekend. Daily showers and thunderstorms are
expected each day this week with Friday through Sunday being the
most active. Any thunderstorms that develops will have the
potential to produce gusty winds and frequent lightning.
&&
.PRELIMINARY POINT TEMPS/POPS...
Corpus Christi 74 85 74 82 / 40 50 40 40
Victoria 73 83 71 82 / 30 60 40 50
Laredo 73 92 74 90 / 60 30 30 30
Alice 71 87 71 86 / 50 50 30 40
Rockport 74 81 75 84 / 40 50 40 40
Cotulla 73 92 74 91 / 40 30 30 40
Kingsville 74 87 73 84 / 50 50 30 40
Navy Corpus 76 82 76 84 / 40 50 40 40
&&
.CRP WATCHES/WARNINGS/ADVISORIES...
TX...None.
GM...None.
&&
$$
SHORT TERM...TMT/89
LONG TERM....PH
AVIATION...TMT
Area Forecast Discussion
National Weather Service Cheyenne WY
525 PM MDT Mon May 8 2023
.SHORT TERM...(This evening through Tuesday)
Issued at 400 PM MDT Mon May 8 2023
Active weather pattern will begin over the next 24 to 36 hours
with several potential hazards to discuss. Overall, confidence is
increasing with the vigorous Pacific storm system forecast to
begin pushing into the Rocky Mountain Region on Wednesday.
Deterministic models are in much better agreement with this system
compared to 2 days ago with solutions favoring a southward track.
This storm system is expected to bring widespread low elevation
rainfall...heavy at times, severe thunderstorms, some fog, and the
potential for significant mountain snow after Wednesday.
For today, showers and thunderstorms developed a few hours earlier
than expected with a quick 0.05 to 0.10 inch of rain near the I-80
Corridor. Further north, clouds are struggling to develop in an
area of broad midlevel subsidence. Expect this to change this
evening as the next shortwave disturbance/vorticity maximum enters
the region from the west. Expect another round of widely scattered
thunderstorms to develop and push east across the high plains late
this evening and possibly continuing overnight. Kept the highest
POP (30 to 50 percent) after 9 PM as this shortwave trough enters
the region. Another jet streak is forecast to push east creating
a weak jet couplet and enhanced diffluence aloft. Some of these
thunderstorms may contain some gusty winds with high res guidance
showing some cold pool activity just behind the bands of showers
and thunderstorms. This makes sense given current observed
surface dewpoints and inverted V soundings across the northern
portion of the area towards Converse County eastward into the
northern Nebraska Panhandle. In addition, the Low Level Jet is
still forecast to strengthen with gusty south to southeast winds
east of the I-25 corridor. This may enhance convection even
further with decent low level moisture advection even further
south towards the southern panhandle. With convection around the
area, not expecting fog to form, but low clouds and overcast skies
may be pretty widespread by sunrise Tuesday.
For Tuesday, SPC Marginal Risk for strong to severe storms remains
over portions of the forecast area, mainly areas along and east of
I-25. Still a tricky thunderstorm forecast for afternoon and
evening hours since models are still showing the upper level flow
backing into the south ahead of the Pacific storm system. A
shortwave ridge axis is expected to build ahead of this storm into
Kansas, Nebraska, and eastern Wyoming during the day, but models
struggling to resolved the position and movement of the next
disturbance/weak vort max aloft. HRRR and current NAM are not
showing too much activity Tuesday afternoon and evening with only
a few thunderstorms developing just east of the Laramie Range and
quickly pushing east into the western Nebraska Panhandle. Still
expect some thunderstorm activity to develop as winds across the
high plains shift into the southeast...resulting in the typical
convergence boundary along/near the Laramie Range. However, the
timing is highly uncertain. Models are showing higher confidence
with a developing storm complex in northeast Colorado and western
Nebraska overnight which looks like an MCS moving east south east.
Increased POP between 40 to 70 percent east of I-25 late Tuesday
night. Tuesday should be the warmest day of the week with highs in
the upper 60s to mid 70s, but Wednesday might be a little warmer
if the system slows down during the day.
Wednesday morning should be deceptively quiet across the area just
ahead of the strong Pacific storm, which will be tracking into the
Four Corners Region during the day. With a surface low developing
and track eastward into Utah and western Colorado, surface winds
will likely shift into the east and southeast Tuesday night
through Wednesday morning. Expect low clouds and fog to develop as
surface moisture advection increasing towards the 80th to 90th
percentile, and even higher during the day on Wednesday based on
the NAEFS. Added fog mainly to the Pine Ridge and Cheyenne Ridge
including the I-80 Summit for now, but may need to extend this
across the eastern plains. This will set the stage for a
potentially active Wednesday afternoon and evening with ample low
level moisture between the 90th to 99th percentile versus
climatological averages. Model soundings and convective parameters
are favorable for severe weather, and models have trended further
west with the favorable shear and 0-3km instability. 12z NAM and
NAMnest continue to show EHI`s between 2 to 4, with earlier runs
as high as 5 across Albany county and stretching east across most
of the eastern plains. 18z run is not quite as aggressive, but
still pretty impressive. Soundings continue to show impressive low
level wind shear as cyclogenesis gets going somewhere between
Albany County, Platte County, and further south along northeast
Colorado. With MLCAPE values between 1500 to 2500 j/kg with an
impressive cap inversion just below 700mb, which erodes as the
potent dynamic forcing ahead of the main storm system tracks north
into the region. Started wording the forecast for severe
thunderstorms Wednesday afternoon and evening as SPC shows a
Day 3 slight risk for severe weather. Expect this area to increase
in coverage and can not rule out an Enhanced Risk sometime in the
future. Damaging winds, large hail, brief very heavy rainfall,
and even a few isolated tornadoes are possible with this set up.
However, will have to watch how long the low stratus and fog
linger over the area, which may result in considerable CIN
through the day. Also, the Pacific storm may be so dynamic, that
most of the convection becomes organized (squall lines) too early
in the evolution...which will result in more of a straight line
wind threat and very heavy rainfall. Residents and travelers are
urged to closely monitor this potential severe weather event on
Wednesday.
But wait, there`s more...snowlevels ahead of this storm will
likely be close to 12000 to 13000 feet at the onset Wednesday
afternoon. With mositure and warm air advecting into Albany
county and the adjacent mountains, will have to closely monitor
river and stream levels particularly in the Snowy Range and the
surrounding areas for heavy rain on a solid snowpack up around
8000 to 10000 feet. Thought about an Areal Flood Watch, but will
let the next shift(s) take another look at it before we commit.
.LONG TERM...(Tuesday night through Monday)
Issued at 400 PM MDT Mon May 8 2023
Active weather is likely to continue through the end of the week and
into the weekend under the influence of a soggy, slow-moving low
pressure system meanders its way through the area. The main impacts
concern continuing severe thunderstorms, flooding potential due to
rain-on-snow in some areas, and heavy mountain snowfall.
Starting off Wednesday evening, we will have a strong upper level
low located near or just south of the Four Corners encroaching on a
strong ridge located over the Plains and Midwest. The severe
thunderstorm threat described in the short term period will carry
over into Wednesday evening, with profiles remaining conducive.
Please see above for details on this threat since the following
discussion will mainly focus on the transition to the cool sector of
the system and heavy rainfall threat continuing after the severe
threat. Veering shear profiles and steep lapse rates continue
through much of the overnight hours so scattered severe
thunderstorms may continue. By Thursday morning, models show the
upper level low moving out into eastern Colorado and becoming
negatively tilted against the amplifying downstream ridge. This will
lead to winds aloft turning more southeasterly. More vertically
stacked wind profiles and less steep lapse rates Thursday will
likely change the precipitation characteristics. We will still have
isentropic lift and deep orographic flow with easterly winds up to
nearly the tropopause. The atmosphere will remain extremely moist.
Ensemble mean PW values exceed the 90th percentile of climatology,
and the ECMWF ensemble mean PW exceeds the 99th percentile.
Widespread showers with scattered embedded thunderstorms are likely
through the day on Thursday. The severe potential is a little
uncertain with instability more limited than Wednesday and weaker
shear owing to the vertically stacked profile. However, a slightly
more northward track in the upper level low could easily push more
potent profiles into the area, particularly the southern Nebraska
panhandle. We will need to watch for this potential, and breaks in
cloud cover that could enhance instability. Overall though, the main
impact after Thursday morning looks to be more on the
rainfall/flooding side of things.
There is some concern with heavy rainfall and rain-on-snow
especially during the early part of the event Wednesday night
through Thursday. Rain could be falling as high as 10kft Wednesday
evening with very warm 700-mb temperatures in the +5 to +7C range.
Cooler air will work in Wednesday night, pushing 700-mb temperatures
to around 0C to +2C over the higher terrain by 12z Thursday. This
should bring snow down to around 8500 to 9kft. Substantial snowpack
still remains in the 7500 to 9000 ft range that could continue to
see rain through the daytime hours on Thursday. We will need to
monitor small streams and possibly some rivers for rises due to the
combination of heavy rainfall and rain-on-snow through Thursday.
Heading into Thursday night, snow levels drop further, such that
snowflakes mixing in for the city of Laramie can`t be ruled out
early Friday morning.
Looking at total QPF estimations, the GFS and GEFS have trended
slightly towards the ECMWF over the last 24 hours, while the
latter has held fairly steady. The ECMWF solution is a slower,
more southerly track of the upper level low that ejects off to the
east later, resulting in a longer period of deep upslope flow and
favorable dynamics and heavy precipitation. All ECMWF ensemble
members now have a surface low developing over Colorado and
ejecting eastward from there. There is still roughly one third of
the GEFS members that show the surface low quickly moving
northward into Nebraska or South Dakota during the day on
Thursday, but there are fewer than at this time yesterday.
Ensemble QPF remains substantial. The ECMWF ensemble mean
continues to show around 1.75" or more liquid precipitation
falling by Saturday for almost the entire area from the Snowy
Range eastward. The ECMWF ensemble minimum is a fairly eye
catching 1.0" liquid at KCYS. The GEFS remains more modest, but
has come up a little since yesterday. This ensemble mean still
shows 1 to 1.75" for the majority of the area, with higher amounts
in Converse county. For the official forecast, kept QPF generally
in between the two ensemble means, but will note that with
convective nature, some areas are likely to see much more, while
others may see much less. Finally, the precipitation will be
falling as largely snow in the highest elevations, and could be
enough to lead to Warning level accumulations particularly in the
Snowy range.
Models continue to diverge Friday onward, but there is enough
confidence in unsettled and generally cool weather to continue. The
GFS pushes the upper level low further north, while the ECMWF holds
it further south. The main difference would be additional rainfall
in the slower scenario Friday into Saturday, whereas the GFS
scenario is still cool and somewhat cloudy but a little drier.
Models are showing a highly unusual synoptic weather pattern for the
weekend. There is fairly good agreement now on an extremely strong
ridge developing over the Pacific northwest and southwest Canada.
200-mb and 500-mb heights to our north will be well above the
climatological maximum. Over our area and further southwestward,
models show a messy signal with weak vort maxes retrograding and
meandering around the southwest under very weak flow aloft. Most of
this unsettled weather may stick to our southwest, but could see
daily shower and thunderstorm chances continuing Sunday and Monday
beyond the end of the main system.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 516 PM MDT Mon May 8 2023
A weak disturbance will be moving through the area through 12Z
Tuesday. VCSH and VCTS will be present for most of the terminals
between 0Z and 12Z. WY terminals could see localized fluctuations
to MVFR if -SHRA occurs during the VCTS events overnight. VRB
winds are anticipated for the NE Panhandle terminals, with weak
upslope flow taking over between 9Z-13Z. This will create MVFR/IFR
CIGs, with MIFG being present at times. Wind gusts should pick up
to 15-25 knots by mid-day Tuesday for terminals.
&&
.FIRE WEATHER...
Issued at 400 PM MDT Mon May 8 2023
No fire weather concerns this week due to an unsettled and wet
weather pattern. Today will be the driest day with relative
humidities down to around 20 percent with a few places near 15 to
18 percent. This will be short-lived with increasing moisture
tonight ahead of a strong Pacific storm forecast to impact the
area with widespread rain, mountain snow, and scattered to
numerous thunderstorms through the end of the week. Forecast
rainfall amounts are trending higher compared to a few days ago
with most places between a half an inch to one inch of liquid by
Friday.
&&
.HYDROLOGY...
Issued at 400 PM MDT Mon May 8 2023
River levels will continue to trend lower through Tuesday across
Carbon and Albany counties before a strong Pacific storm system
moves into the central Rockys. Models are starting to come into
better agreement with the track of this system and potential
impacts, not only from a river flooding perspective...but also
areal and general flooding due to heavy rainfall and rain on
snowpack in the mountains. Will have to closely monitor the
high mountain snowpack and the potential for heavy rainfall
Wednesday. Another slow increase in river levels are expected
starting late on Tuesday...mainly the Little Snake, Laramie, and
Medicine Bow rivers and associated smaller tributaries.
&&
.CYS WATCHES/WARNINGS/ADVISORIES...
WY...None.
NE...None.
&&
$$
SHORT TERM...TJT
LONG TERM...MN
AVIATION...BW
FIRE WEATHER...TJT
HYDROLOGY...TJT
Area Forecast Discussion
National Weather Service Dodge City KS
1100 PM CDT Mon May 8 2023
...updated aviation...
.SHORT TERM...(This evening through Tuesday night)
Issued at 1245 PM CDT Mon May 8 2023
17Z observations show an upper level pattern with winds out of the
west southwest in response to an upper low over the Pacific coast.
At the surface a cold front from last night`s MCS is into
northern Oklahoma with a surface high located in northern Kansas
which has led to sunshine across much of western Kansas.
Overall for the evening hours it should be quiet across Dodge
City`s CWA. Short term models (HRRR/RAP/NAM) show a developing
MCS over northeast Colorado and southwest Nebraska in response to
an upper level shortwave riding over a baroclinic zone in the
early morning hours. Some of the CAMs have a variance in whether
or not the MCS makes it into the I-70 corridor however it should
be close enough I kept POPs up around sunrise for our north
central counties. Skew t soundings show good shear and plenty of
instability that if the MCS is just one lone supercell it could be
impactful in the ability to produce large hail in the morning.
Tuesday`s setup will depend on what develops through the morning
as it looks like the MCS will continue to dive south and east into
the more moisture rich air and have upscale expansion along a
frontal boundary in central Kansas. The HRRR is thinking a pretty
stout outflow boundary will develop and push at least into the
eastern third of our CWA. A dryline will also develop during the
day in our southwest and we should see an area of good convergence
during the afternoon between the moist and dry air roughly
somewhere around highway 283. The CAMs once again vary in where
the initiation starts but the highest confidence looks to be in
our southeast zones where CAPE values will be ~ 3000 J/kg and 0-6
km bulk shear values increase to > 40 kts by the late afternoon.
The main question will be if the CAP from the outflow holds or not
and based on the latest Skew-t soundings around PTT and P28 it
should erode. This environment would certain support some large
hail potential and perhaps a brief window for an isolated tornado
between 6-9 pm with SRH values increasing to around 150-200 m2/s2.
Tuesday evening the convection that does develop should move out
of the area as the vort max & forcing moves into central Kansas.
.LONG TERM...(Wednesday through Monday)
Issued at 239 PM CDT Mon May 8 2023
Key messaging will be the chances of severe weather for Wednesday
and Thursday.
The setup for severe weather will be dependent on the track of an
upper low coming in from the Pacific coast and then being directed
north and east along the southwest flow aloft. Wednesday the
center of the upper low should be around the 4 corners region and
the upper level winds will start to become difluent in the
central plains. We should see a shortwave eject out of the Rockies
into western Kansas. A dryline should set up in the late
afternoon around highway 283 by late afternoon. With skew t
soundings showing around 40 m/s 0-6 km shear and CAPE values
around 2000 this would support an environment of some large hail
potential for any storms to form. The downside for storm potential
at this point is the forcing still looks somewhat weak as we will
still be under the influence of an upper ridge with the better
forcing not arriving until during the night.
Thursday...while the setup looks better for severe weather, the
confidence on where the severe weather will occur is still
somewhat low. Most of the long term models and ensembles prefer a
track which takes the upper low into northeast Colorado and
negative tilt trough through central Kansas and Nebraska. These
setups also bring in the forcing earlier in the day with parts of
western Kansas being in the area of forcing by sunrise. This
would support more eastward momentum for the dryline and may only
have our eastern third counties in a chance of storms. The outlier
is still the deterministic Euro which is also slower in the
timeframe and further south. This would give much of the area the
best chance of more widespread strong to severe storms. We may
start to see a shift in where the severe risk sets up for the
updated day 3 to areas more into central Kansas. For the areas
that stay in the moist air the CAPE and shear values are looking
good for another round of storms with large hail and gusty winds
potential.
The rest of the long term looks more benign as the storm system
exits on Friday and surface and upper level winds turn more
northeasterly through the weekend which would bring in more cool
stable air. Rain chances are possible mainly along the Oklahoma
border for Saturday night into Sunday as a slow moving upper low
moves through Texas.
&&
.AVIATION...(For the 06Z TAFS through 06Z Tuesday night)
Issued at 1111 PM CDT Mon May 8 2023
VFR is expected through TAF pd. If showers/storms located across NE
CO NW KS hold on, then KHYS may see VCTS/CB activity Tuesday morning.
Will keep VCTS/CB groups in for that TAF. Tranquil weather is expected
for the rest of the terminals through the overnight hours. Patchy AM
fog may stay SE of the terminals. E to SE winds 15-30 kt will continue
through much of the period. Right now confidence is too low to add
TS in the TAFs for Tuesday evening. Early consensus shows that KDDC/KHYS
could end up likely to be the most impacted.
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 58 91 61 86 / 10 20 20 40
GCK 56 91 59 86 / 10 10 10 30
EHA 53 94 59 86 / 10 10 10 40
LBL 56 94 59 87 / 10 10 10 30
HYS 58 86 60 85 / 30 40 50 50
P28 62 90 63 84 / 20 40 40 50
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...Tatro
LONG TERM...Tatro
AVIATION...Sugden
Area Forecast Discussion
National Weather Service Des Moines IA
1042 PM CDT Mon May 8 2023
...Updated for the 06z Aviation Discussion...
.DISCUSSION.../Tonight through Monday/
Issued at 236 PM CDT Mon May 8 2023
Key Messages:
-Isolated to scattered convection this evening north.
-Relatively quiet into Tuesday.
-Chances for convection from time to time Tuesday night into the
weekend. Severe potential appears low at this time.
Stratus lingered across a good portion of the forecast area this
morning but has become more cellular as daytime heating has
progressed. A few showers have developed in northeast Iowa along a
narrow convergence axis and these are likely to pose some limited
rain threat to the far northeast CWA over the next few hours.
Additional showers and convection is expected in the northwest where
weak convergence should lead to development by early evening.
Soundings are relatively dry near surface in this area which may
lead to gusty winds near this activity. Modest CAPE may also lead
to some hail production with the strongest cells but in most cases
this is expected to remain sub-severe. The activity is mostly
diurnally driven and is expected to fade by late evening with quiet
conditions the rest of the night.
A return to weak warm advection is expected on Tuesday although the
main push of moisture remains west of the state. Relatively quiet
weather is anticipated for much of the day with some shower activity
grazing the far north associated with a weak shortwave passing
through the Dakotas and into Minnesota. Guidance begins to vary a
bit more into Tuesday night with GFS and some CAMS, namely the HRRR
bringing an MCS across Nebraska on nose of low level jet across the
Plains. This impinges on western Iowa by Wednesday morning with
decent rainfall. The Euro and NAM remain farther west and much more
muted with the MCS development during the night with little impact
into Iowa on Wednesday morning. Ensembles appear to lie somewhere in
the middle and given the fickleness of convection, PoPs have gone
this middle road.
Thereafter, the upper flow consists of ridge across the central
US as an upper low moves from the southwest and into the Plains by
Saturday. Iowa remains in an area of persistent warm advection
along periods of modest moisture transport providing chances of
precipitation from time to time. With the proximity of the ridge,
the shear profile weakens in the soundings by midweek which should
limit the overall severe weather threat during this time.
Temperatures during the week are expected to remain at or above
normal as the upper ridging remains in place.
&&
.AVIATION.../For the 06Z TAFS through 06Z Tuesday night/
Issued at 1037 PM CDT Mon May 8 2023
Last remnants of the storms are weakening as they move into
northeast Iowa. Next aviation concern is potential for fog
development overnight. With clearing skies, light winds, and
ample low level moisture in the wake the last 2 days` rainfall,
there is potential for areas of fog, especially in the eastern and
northeastern parts of the forecast area closer to the surface
ridge axis.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
DISCUSSION...Cogil
AVIATION...DMD
AREA FORECAST DISCUSSION
National Weather Service Kansas City/Pleasant Hill MO
704 PM CDT Mon May 8 2023
.Discussion...
Issued at 254 PM CDT MON MAY 8 2023
Key Messages:
- Isolated Thunderstorms South of Interstate 70 Possible This
Afternoon
- Above Normal Temperatures This Week
- Multiple Rounds of Showers/Storms This Week
Discussion:
The trough axis over the western CONUS that provided persistent
southwesterly flow over the weekend has lifted into the Canadian
Prairie provinces. This has resulted in zonal flow at the mid-levels
this morning. Surface analysis is a bit sloppy this morning, there
are few outflow boundaries that have been floating around southern
Missouri that emanated from the MCS late last night and early this
morning. The surface cyclone also stalled to our northeast a bit,
and the approaching cold front became a stationary boundary
overnight. This afternoon though, that has been moving slightly
southward, providing some cumulus clouds out there. The increasing
H5 heights have provided enough subsidence to prevent dense cloud
cover across the area. Insolation has been present on both sides of
the boundary, and overall has actually weakened the temperature
gradient somewhat throughout the afternoon. Only a subtle shift in
wind direction has been noted with its passage. This has allowed for
temperatures to bounce back up despite the strong evaporative
cooling with the previous rain showers and approach of the cold
front. For the rest of this afternoon, the boundary moving south in
conjunction with a weak remnant outflow may produce some isolated to
scattered shower/storm activity in our far southern counties. Areas
south of Interstate 44 though are more likely for wider coverage of
storms. There is a decent degree of instability building along and
south of I-44 with some wind shear along the boundary that may
support an isolated severe storm. The HRRR and other CAMs have not
been overly robust with production for our southern counties though,
thus will call the overall threat low.
There is another H5 trough moving toward the west coast associated
with the stronger PV anomaly that remains over the western CONUS.
The general response ahead of this for the Central CONUS will be
amplified ridging, with lower-level flow turning south to
southwesterly. This will continue to keep afternoon high
temperatures this week well above normal. For the rest of the work
week, the inner-quartile max temperatures are in the 80s, with
overnight lows in the 50s. Even though the pattern will generally be
described as a ridge, would anticipate multiple vort maximums
ejecting from the PV anomaly out west that will present localized
short periods of height falls. With the WAA and moisture transport
back into the area, would expect there to be some degree of
kinematic forcing that will bring multiple rain shower and
thunderstorm opportunities to our forecast area. Late Tuesday, first
wave comes through and concentrates convergence mainly along the
Interstate 49/29 corridor and westward. This continues into
Wednesday morning. The instability axis is strongest just west of
the forecast area, and overall shear is weak. Therefore looking at
just general shower/thunderstorm concerns late Tuesday through
Wednesday. Better chances for strong to severe storms will be
westward over the Plains.
Thursday, H5 trough is progged to lift out of the four corners
region. A strong surface cyclone develops downstream with strong
dCVA, and a surface response extends into the region strengthening
southerly flow and moisture transport. This will allow for more
widespread precipitation potential across most of forecast area.
Expecting stronger instability to develop across the area that will
support thunderstorm activity. While there will be a secondary short-
wave and localized vort max across our area, the stronger flow will
stay with the main trough axis. This keeps better deep layer shear
over the High Plains and toward the Front Range, and thus the
potential for organized severe potential is well west of the area.
However, the rainfall will certainly be welcomed for areas still
experiencing drought conditions. Heading into the rest of the
weekend, the H5 trough likely closes off somewhere between the
central and northern High Plains and will maintain low-level
meridional flow across the region. Most ensemble members keeps
multiple rounds of rain showers and thunderstorms through the
weekend. There is not any clear signal for severe weather at this
time, will just need watch the position of that trough. If the
stronger flow moves further east, the potential could increase for
organized activity. With respect to rainfall across the area,
several ensemble members bring between 1 and 2 inches of QPF across
most of the forecast area between Tuesday afternoon and Saturday
afternoon. Localized amounts could certainly be greater in some
locations depending mostly on convection occurrence and then
stratiform rainfall. The POP forecast may look like a complete wash
out over the next 7 Days but with the ridge in place there will be
dry periods with warm temperatures.
&&
.Aviation...(For the 00Z TAFS through 00Z Tuesday Evening)
Issued at 703 PM CDT MON MAY 8 2023
VFR conditions continue through much of the overnight. There is
the potential for some BR/FG development as winds calm toward
sunrise. Confidence is higher in BR/FG formation near the river
valleys (STJ & MKC). A dip to IFR conditions is possible. Winds
pick up after sunrise quickly dissipating any FG/BR impacts and
returning VFR conditions.
&&
.EAX WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
MO...NONE.
&&
$$
Discussion...Krull
Aviation...Pesel
forecast discussion, the NBM probabilities continue to indicate
greater than 50% chance of at least 3 inches of rain from Friday
through the weekend. While this is a good sign that a lot of the
area will receive beneficial rainfall, there is the concern for
Flash Flooding, if too much rain comes down in a too short of a
period of time. Otherwise, expect for cooler daytime temperatures
with all the cloud cover and moisture while the overnights will
remain warm and humid. Stay tuned to the forecast during the days
ahead as confidence increases leading up to this potential heavy
rainfall event.
&&
.AVIATION...
(00Z TAFS)
Issued at 623 PM CDT Mon May 8 2023
A cluster of SHRA/TSRA will impact KAUS in the next few hours and
have gone with TEMPOs through 03Z. As SHRA/TSRA get further organized
over west central Texas and near the Rio Grande this evening they may
impact KSAT/KSSF overnight and have replaced TEMPOs with VCTS. Then,
SHRA/TSRA will redevelop on Tuesday and have maintained PROB30s for
the afternoon hours. Otherwise, VFR skies turn MVFR overnight, then
gradually lift on Tuesday. Light to moderate S to SE winds prevail.
&&
.PRELIMINARY POINT TEMPS/POPS...
Austin Camp Mabry 70 85 68 81 / 10 50 30 50
Austin Bergstrom Intl Airport 68 84 66 80 / 10 50 30 50
New Braunfels Muni Airport 70 85 68 81 / 20 50 30 50
Burnet Muni Airport 67 84 66 81 / 30 40 20 40
Del Rio Intl Airport 71 93 72 90 / 30 30 40 20
Georgetown Muni Airport 68 84 66 79 / 10 50 30 50
Hondo Muni Airport 69 87 69 84 / 30 40 30 40
San Marcos Muni Airport 69 84 67 80 / 20 50 30 50
La Grange - Fayette Regional 72 82 69 81 / 20 60 40 50
San Antonio Intl Airport 70 85 69 81 / 20 50 30 40
Stinson Muni Airport 71 86 70 83 / 20 50 30 40
&&
.EWX WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
Short-Term...04
Long-Term...05
Aviation...04
Area Forecast Discussion
National Weather Service Grand Forks ND
1032 PM CDT Mon May 8 2023
.UPDATE...
Issued at 947 PM CDT Mon May 8 2023
Showers have cleared out but clouds are sticking around. Looks
like the southern valley will be most at risk for more dense fog
this evening as they are clearer, but wouldn`t rule out fog under
the cloud deck as it will be pretty moist and winds will be light
overnight. Forecast remains on track.
UPDATE Issued at 640 PM CDT Mon May 8 2023
Some showers could still linger in the area, but most of them have
lost their juice with the cloud cover and the sun setting. Fog
still looks to be a possibility into early Tuesday morning, but
impacts and where the fog will be is uncertain.
&&
.SHORT TERM...(This evening through Tuesday night)
Issued at 245 PM CDT Mon May 8 2023
Key Message
- The degree of clearing/decrease of clouds tonight will play into
many other components of the short term (fog later tonight, high
temps Tue, etc.)
The regional radars continue to show a nearly stationary line of
light showers between Rugby, Harvey and Cooperstown. Looking at
water vapor imagery, this looks to be the pivot point between one
nice circulation up near Brandon Manitoba and another lobe of
short wave energy moving along the North and South Dakota border
south of Bismarck. The 12z model runs initialized these features
pretty well overall, with the wave south of Bismarck expected to
continue to push nearly straight east, into the Red River Valley
and adjacent area of west central Minnesota tonight. The SPC meso
page shows some weak instability along the Dakotas border now and
some higher mid level lapse rates. However, there has just not
been much sun or warming today in this FA. That hasn`t been
stopping the HRRR from generating spotty showers along the I94
corridor in southeast North Dakota late this afternoon into the
early evening. Outside of this area, there have been a few spots
still reporting drizzle. All precipitation activity should wane
after sunset.
The question then turns to how much clearing may occur tonight.
There is more cellular cumulus along the Dakotas border, which may
favor some clearing south of I94 tonight. However, surface winds
should continue to remain on the lower end, so if there is
clearing, more fog could develop. Fog and cloud cover could last
well into Tuesday morning, with some portions of the FA keeping
mostly cloudy conditions through the rest of the day as well.
There could be some sunny or partly sunny areas as well, it is
just quite difficult narrow that down. The next batch of
precipitation begins to move northward into the FA late Tuesday
afternoon or night, so more clouds and wet conditions.
.LONG TERM...(Wednesday through Monday)
Issued at 245 PM CDT Mon May 8 2023
Key Messages:
-Continued SW flow keeps the pattern aloft active through the end of
the work week. Temperatures warm and stay above average. NW flow
takes hold this weekend and early next week.
-Chance for some thunderstorms Wednesday evening/overnight and
periodically near the end of the work week. Otherwise, rain showers
continue through the long term periodically.
Discussion:
Upper level flow continues to be out of the SW in the 500-250mb
level. The trough out west digs in deeper toward the SW United
States and the ridge out east amplifies. This helps to bring
temperatures into the upper 60s for Wednesday and the low to mid 70s
by the end of the work week into the weekend. This adds moisture to
the area and is noted in the 700mb level where moisture advection is
fairly present. PWAT values range between an inch and 1.5 inches.
Comparing this to climatological averages we are sitting at the 95-
97.5th percentiles for Thursday and Friday. This means higher than
normal PWATs are a possibility end of the work week. For Wednesday,
its on the lower end, with around 0.75-1.0 inch PWATS. 24 QPF could
reach over 0.5 inches. The probability of this occuring starting
Wednesday is 30-40% chance for the forecast area. 48 hour QPF
Thursday through Friday has the potential to reach over an inch in
some areas.
Turning toward the chance for thunderstorms Wednesday, the main
synoptic pattern favors the moisture and instability across the
area. CAPE values reach 1000 J/kg and moisture advection is modest
in the mid levels. The one lacking factor is the timing of the
system and the shear component to fuel the thunderstorm development.
Winds have more directional component then speed within the lower
levels of the atmosphere. The strongest shear is also during the
daytime when the system is still working its way into the region.
The timing of the shear on top of the instability/moisture is not
quite lining up. This plays the biggest role in development. The
chance for thunderstorms are there, but if the atmosphere can`t line
up the ingredients the severity starts to become more uncertain than
it already is. The chance for thunderstorms are there, but strong to
severe storm chances are low in predictability at this time.
Continuing chances for thunderstorms are possible end of the work
week and into the weekend, but instability looks limited as flow
starts to shift toward the NW. A ridge begins to build into the
western United States setting up a NW flow aloft and allowing
clippers to move across the region.
&&
.AVIATION...(For the 06Z TAFS through 06Z Tuesday night)
Issued at 1032 PM CDT Mon May 8 2023
Fog will be the main issue in this TAF period. Winds will be light
through the entire period, and it looks increasingly likely there
could be fog Tuesday morning. Not just limited to clearer TAF
sites, but all could see at least patchy fog. Some rain showers
could develop Tuesday afternoon, and could be thunderstorms as
well. MVFR will be predominant conditions through Monday night and
Tuesday.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...None.
MN...None.
&&
$$
UPDATE...AK
SHORT TERM...Godon
LONG TERM...Spender
AVIATION...AK
Area Forecast Discussion
National Weather Service Grand Rapids MI
1024 PM EDT Mon May 8 2023
LATEST UPDATE...
Update
.UPDATE...
Issued at 1019 PM EDT Mon May 8 2023
The main change to the forecast was to add patchy fog to the
marine forecast. Webcams from around South Haven are showing fog
developing. The latest HRRR does indicate fog in and around the
nearshore waters tonight. Earlier 18z runs suggest the fog may be
an issue over the next couple of periods over the nearshore waters
so we will need to monitor trends beyond tonight.
&&
.DISCUSSION...(This evening through next Monday)
Issued at 323 PM EDT Mon May 8 2023
--Evening Rain, Decreasing Clouds Late--
Solid area of rain associated with mid level shortwave continues
to advance slowly east from Lk MI/WI. Dry air below 8000 ft
should cause this to decrease in intensity and coverage to some
extent, with the rain becoming more scattered after 00Z per CAM
guidance. The rain ends after 06Z with the passage of the
shortwave, then a gradual clearing from north to south takes
place as drier air/subsidence filters in.
--Pleasant Tuesday through Thursday with Warming Trend--
Surface ridging and very dry air mass dominates our weather
Tuesday through Thursday leading to clear to partly cloudy skies.
Building upper ridge allow temps to moderate from around 70 on
Tuesday to near 80 by Thursday and humidity levels will be in the
quite comfortable/pleasant category due to dew points only in the
30s and 40s. The dry air will also promote chilly overnight
temperatures.
--Rain Risk Returns by the Weekend--
As we approach the weekend an upper low begins to drift our way
from the Plains then is eventually absorbed by another trough
dropping in from the northwest over the weekend. Confidence is
currently low regarding the coverage/probability of rain/storms
Friday into Saturday as a warm front and higher PWATS/dewpoints
lift in our direction. Latest deterministic solutions are most
aggressive with rain on Sunday when a robust northwest flow
shortwave is passing through the area.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 733 PM EDT Mon May 8 2023
Radar trends show the area of rain diminishing over the TAF sites
as a result of the weakening low pressure system pulling away from
the region. A weak area of high pressure is forecast to build in
for Tuesday. Dry air advection is expected and should result in
VFR conditions through the period. Also...the pressure gradient is
shown to be weak...which will support wind values mostly under 10
knots.
&&
.MARINE...
Issued at 323 PM EDT Mon May 8 2023
High pressure will build into the Great Lakes Region Tuesday and
remain in place through Thursday. Winds and waves will stay below
advisory criteria, although onshore lake breezes related to
differential heating at the land/lake interface could result in
briefly stronger winds from mid afternoon through early evening.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...None.
LM...None.
&&
$$
UPDATE...MJS
DISCUSSION...Meade
AVIATION...MJS
MARINE...Meade
Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
1015 PM EDT Mon May 8 2023
.SYNOPSIS...
An active weather pattern with above normal temperatures will remain
across the area through Tuesday, along with chances of showers and.
thunderstorms. A cold front crosses our region from the north by
late Tuesday. By Wednesday, drier high pressure will build in from
the north and remain into the weekend. Moisture will increase again
over the weekend as a cold front approaches from the northwest.
&&
.NEAR TERM /THROUGH TUESDAY/...
As of 1010 pm EDT: All remains quiet over the western Carolinas and
northeast Georgia late this evening, with stabilization underway
across the region. Upstream, radars across western Kentucky are
showing convection developing and beginning to organize. This will
likely compose the MCS that recent HRRR runs have propagating toward
the southern Appalachians overnight into daybreak. Will gradually
bring PoPs back to the western mountains for the overnight hours,
with a peak of likely PoPs around sunrise near the TN border. With
limited instability east of the mountains, it remains questionable
how much activity can survive east of the Blue Ridge Mountains after
sunrise. Minimum temperatures should be similar to those observed
this morning in most areas.
A cold front approaching from the north tomorrow morning will settle
southward into the region through the afternoon hours. Once again,
lapse rates will not be great on Tuesday afternoon, but temperatures
will rise to about 8-10 degrees above climo given warming
thicknesses ahead of the boundary. Model profiles should build
slightly better surface-based instability of 1500-2000 J/kg by late
day mainly in the southern half, if any debris clouds clear quickly
enough, along with about 20 to 30 kt of deep layer WNW flow shear. A
damaging wind threat could develop Tuesday afternoon if this
materializes, but uncertainty is rather high with regard to the
environment. Max temps in a few southern tier locations could touch
90 degrees.
&&
.SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY/...
As of 200 pm Monday: Isolated convection may linger into Tue
evening, mainly across southern areas before a lower theta-E air
mass completely overtakes the CWA. This more stable air mass will
otherwise predominate through the short term, bringing an end to the
relatively active convective weather. Still cannot completely rule
out a stray diurnal shower along the ridge tops Wed and Thu
afternoons, but that potential doesn`t even warrant a 20 PoP.
Temperatures are forecast to be very close to normal through the
period.
&&
.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
As of 210 pm Monday: Rather weak NW flow will persist atop the
region through much of the extended, as an upper ridge axis lingers
in the vicinity of the Miss Valley, before beginning to flatten next
weekend as a series of upper lows and short wave troughs impact the
northern Conus. Low level moisture will slowly increase across the
forecast area, as surface high pressure/sprawling ridge over the
western Atlantic gradually weakens and oozes east. The potential for
isolated/scattered diurnal convection (mainly mountain-centric) is
expected to return as early as Friday, gradually ramping up easy day
through the end of the period, with PoPs reaching their peak
(generally solid chance) next Monday, when the global models
indicate height falls and an associated frontal boundary impacting
the Southeast and Mid-Atlantic. Otherwise, after one more day of
near-normal temperatures on Friday, the main story will become the
heat, as temps are expected to be as much as 10 degrees above climo
next weekend into Monday.
&&
.AVIATION /02Z TUESDAY THROUGH SATURDAY/...
At KCLT and elsewhere: Terminals will remain dry through late
evening and early overnight as profiles continue to stabilize. MCS
remnants may return to the mountains from the northwest overnight
and that will be the next best chance for any showers and
thunderstorms near KAVL. A VCSH is carried there after 09Z.
Scattered, possibly strong, convection could then develop Tuesday
afternoon as a cold front settles south into the terminal forecast
area. Conditions will be generally VFR at all sites except under any
heavy rain showers or storms, with perhaps some MVFR valley fog
around KAVL at daybreak. Expect mainly SW to WSW winds tonight,
except NW flow at KAVL. Winds will toggle more WNW to NW through
Tuesday with the approaching front, then northerly with fropa late
in the period. Will continue to feature PROB30 for TSRA during peak
heating Tuesday, and gusty winds may need to be added as we get
closer in time.
Outlook: High pressure and drier conditions are anticipated to
move in by mid-week and persist through Friday.
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...None.
NC...None.
SC...None.
&&
$$
SYNOPSIS...DEO
NEAR TERM...HG
SHORT TERM...JDL
LONG TERM...JDL
AVIATION...HG
Area Forecast Discussion...Updated
National Weather Service Lincoln IL
911 PM CDT Mon May 8 2023
.SYNOPSIS...
Issued at 910 PM CDT Mon May 8 2023
High pressure will drift into the Great Lakes region, keeping our
weather dry through Wednesday. While high temperatures will still
be well into the 70s, northeast winds will result in much less
humid conditions.
&&
.UPDATE...
Issued at 910 PM CDT Mon May 8 2023
High pressure behind the cold front that just finished pushing
south of the forecast area will bring an end to any precipitation
chances, while a cooler air mass moves in bringing lows well down into
the 50s tonight. An area of low cloud cover in northern IL pushing
southwestward in the northeast winds could result in patchy fog
overnight, mainly Peoria northwestward, but the cloud cover and
light breeze should prevent this from becoming dense. Have added
patchy fog for tonight for this, and have trimmed out all PoPs the
remainder of the night.
37
&&
.SHORT TERM... (Through Late Tuesday Night)
Issued at 252 PM CDT Mon May 8 2023
Main forecast issue for this period is with the potential for any
strong/severe storms through about sunset.
Latest surface map shows a few boundaries across the area, with the
one of interest for convection extending from near Bloomington and
Springfield southwest toward the St. Louis metro. With a fair amount
of sunshine this afternoon south of I-72, SPC mesoanalysis shows
minimal cap and surface based CAPE`s over 2000 J/kg. Morning HREF
shows the CAPE`s north of I-70 will begin to be suppressed a bit
later this afternoon as the boundary sinks southward, and morning
CAM`s all suggest the main threat of strong/severe storms will be
south of I-70. Just how far south that occurs is still up for
debate. The latest HRRR has been suggesting our bottom 3 counties
(Clay, Richland, Lawrence) as being the initiation point, while a
few other CAM`s place it a bit closer to the boundary, which will
be near I-70 by 4 pm. High mid-level lapse rates would suggest
hail being a concern again, along with damaging winds. In any
event, the threat should be over by sunset as the boundary moves
closer to the Ohio River.
Behind the front, a northeast flow sets up as high pressure settles
into the Great Lakes and drifts through the Midwest into mid week.
While temperatures still reach the mid 70s to around 80 degrees both
Tuesday and Wednesday, humidity levels will be much more tolerable
with dew points only in the 40s to around 50.
Geelhart
&&
.LONG TERM... (Wednesday through Next Monday)
Issued at 252 PM CDT Mon May 8 2023
The extended period begins Thursday with a warm front arriving from
the south ahead of a sfc low lifting northeastward across the
Plains. Both the GFS and ECMWF have a nose of 16+ degC 850mb temps
spreading into Illinois from the southwest with the northeastward
advection of the EML by late Thursday and especially Friday. As a
result, increasing mid level lapse rates may foster sufficient
instability for thunder and perhaps even some small hail with storms
both Thursday and Friday. However, the deterministic models are each
showing little QPF across central Illinois on Friday, implying that
with the warm front to our north, we may be capped and without a
sufficient trigger for convective initiation. Nonetheless, any
outflow boundaries from Thursday`s showers/storms could ignite
updrafts in an increasingly unstable air mass. NBM suggests that
probabilities will increase from 20-40% to 40-70% (highest south)
for SBCAPE values over 1000 J/kg between Friday and Saturday,
indicating the best potential for thunderstorms (possibly severe)
will be Saturday. Fortunately, each deterministic model suggests the
upper level trough will be weakening as it draws near to us, which
would hopefully limit shear enough (GFS forecast sounding suggests
only 20-30 kt of 0-6km bulk) to significantly inhibit the potential
for organized thunderstorms. At this time, CSU`s machine learning
algorithm has only a 5% contour for severe potential over central
Illinois on Saturday, and CIPS has nothing. Given the low
predictability of severe weather at that time range in the absence
of high confidence in a significant forcing mechanism, and that
probabilities are looking lower than 15%, SPC doesn`t have us
outlooked.
Temperatures will be pleasant through at least the first three days
in the extended forecast period. Roughly 60% of the Low Resolution
Ensemble Forecast (LREF) system have highs greater than 80 degF in
Lincoln on Friday, while 75% have highs 80+ on Saturday. Cooling
behind some sort of washed out cold front appears likely by Sunday
and especially Monday, when around 40% of the LREF have high temps
less than 70 degF. Fortunately, no ensemble members thus far have
sub freezing overnight low temps early next week and NBM suggests
chances for a freeze are less than 2%, so at this time the potential
for a hard freeze (and even a frost) appears quite low.
Bumgardner
&&
.AVIATION... (For the 18z TAFs through 18z Tuesday Afternoon)
Issued at 1220 PM CDT Mon May 8 2023
Ceilings below 3,000 feet are fairly widespread around KPIA/KBMI
at midday, though scattered further south. A southward push is
expected later this afternoon and especially this evening, in the
wake of a cold front. As winds turn more toward the northeast,
there will likely be a period of IFR conditions (HREF suggesting
60-90% chances of this between 06-12Z, before the low ceilings
push southwest of the TAF sites. Conditions should improve by mid
morning Tuesday.
Precip-wise, while some isolated thunder can`t be ruled out near
KBMI/KCMI mid/late afternoon, the main threat will be further
south. Will not include a VCTS mention at this point.
Geelhart
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
Flash Flood Watch until 8 AM CDT Tuesday for Sangamon.
&&
$$
WFO ILX
Area Forecast Discussion
National Weather Service New Orleans LA
838 PM CDT Mon May 8 2023
...New UPDATE...
.UPDATE...
Issued at 828 PM CDT Mon May 8 2023
Update already issued to raise precipitation chances for at least
the next 6 hours. Since sunset we`ve seen convection develop
between Baton Rouge and McComb in an area of enhanced instability
where CAPE values are approaching 3000 J/kg and LI`s of -6 to -7.
00z LIX and JAN soundings would indicate conditions would be less
favorable as storms move northeast or east with lower layers
fairly dry, so would expect storms to eventually weaken. 00z HRRR
does hint at potential for precipitation toward sunrise further
east toward the Mississippi coast, and will continue to monitor
that trend.
Didn`t address anything beyond 12z Tuesday, as convective trends
over the next 6 hours or so may dictate timing of any storm
development during the day.
Will not rule out an additional update later this evening as
conditions dictate. RW
&&
.SHORT TERM...
(This evening through Tuesday night)
Issued at 156 PM CDT Mon May 8 2023
Showers across the western tier have become a bit more scattered
as they move east of I55 this afternoon. In this region there has
been a bit more surface heating/insolation, which is helping
ignite isolated convection along the southshore of the Lake. This
activity remains rather weak, but there have been several
lightning strikes with these cells. Overall, shear is fairly weak,
but instability isn`t lacking. H5 temps are also rather cool and
may cool another 1C or two as the upper level impulse moves
overhead. Latest CAMs still vary somewhat with this
afternoon/evening convection. As the early shower/cloud debris
moves east, this may limit convection slightly. However, globals
(which have been slightly more reliable over the last several
days) continue to indicate rain potential into the early evening
before chances drop with the loss of surface heating overnight.
Regardless, cannot rule out a stronger updraft or two this
afternoon or early evening. Overnight, with the flow weakening and
recent rainfall, some patchy fog may be possible, especially over
interior south MS and the Florida Parishes (aka more fog favored
locations).
Another subtle impulse moves into the region on Tuesday, which may
again increase rain chances from late morning through the
afternoon hours. Again, mesoscale models aren`t in much of
agreement and even the QPF from globals have some timing
issues...so went with a bit wider window for potential, but think
the highest potential across the landbased zones given the
pattern would be during the late morning into early evening
respectively due to diurnal influences. (Frye)
&&
.LONG TERM...
(Wednesday through Sunday night)
Issued at 156 PM CDT Mon May 8 2023
By Wednesday an upper low closes off across the upper Texas Gulf
Coast and then progresses northward around the western periphery
of a rather strong ridge over the Midsouth and MO Ozarks. This
trough may bring a slightly higher chance of showers and storms
across the western tier parishes/counties, but largely most of the
upper level forcing will be just west of our CWFA. This feature
eventually gets absorbed into the broader longwave across the
Rockies going into Thursday. At the surface, pressure gradient
tightens between a high pressure off the US east coast and a
leeside low over the high plains. Southerly winds should gradually
increase in response to the tightening gradient. From this point
forward, globals tend to disagree in terms of QPF/POPs. This
pattern seems to favor a more summer-like pattern so therefore it
would be tough to NOT mention diurnally driven POPs with the
boundary layer being rather moist. The ECMWF is the wetter
solution, but the GFS still has some QPF signal during this time
so no big changes outside of blending POPs with a little more
weight on the GFS, especially with some upper ridging in both
solutions as a weak Rex Block tries to develop over the SE US.
(Frye)
&&
.AVIATION...
(00Z TAFS)
Issued at 625 PM CDT Mon May 8 2023
All terminals currently VFR with all convection well east or west
of all terminals. Main forecast questions are fog and convective
threats/timing.
Expect low cloud development overnight, as has occurred the last
several nights with low end MVFR or high end IFR ceilings. Cirrus
overcast and light onshore wind flow have generally prevented
extremely low visibilities, and will only knock those down to
3-5SM. Should see improvement to any flight restrictions by 15z
Tuesday.
As has been the case for the last 4-5 nights, model guidance has
been extremely mixed on convective development. With the exception
of Saturday night, models have done a poor job of diagnosing
overnight convective development to our west, not only regarding
timing, but location as well. There are at least a few signs of
possible overnight convection across terminals south of Lake
Pontchartrain...KMSY/KNEW/KHUM, but not high enough confidence to
buy off on it yet. Better signal is during the day on Tuesday, and
will carry VCTS at most terminals by late morning or early
afternoon Tuesday.
&&
.MARINE...
Issued at 156 PM CDT Mon May 8 2023
Generally, favorable marine conditions are expected through much
of the week. However, in and around convection expected locally
higher winds and seas. Southerly winds will begin to increase
closer to the upcoming weekend. At least cautionary headlines will
be needed as the low level flow strengths on the western periphery
of a strong high pressure across the western portions of the
Atlantic. (Frye)
&&
.PRELIMINARY POINT TEMPS/POPS...
MCB 66 85 66 85 / 30 50 20 50
BTR 71 88 69 88 / 30 50 10 30
ASD 70 87 69 88 / 20 40 10 20
MSY 72 86 71 87 / 40 40 10 10
GPT 70 84 69 84 / 20 40 10 20
PQL 68 86 67 87 / 30 30 10 20
&&
.LIX WATCHES/WARNINGS/ADVISORIES...
LA...None.
GM...None.
MS...None.
GM...None.
&&
$$
SHORT TERM...RDF
LONG TERM....RDF
AVIATION/UPDATE...RW
MARINE...RDF
Area Forecast Discussion
National Weather Service Marquette MI
728 PM EDT Mon May 8 2023
.SHORT TERM...(The rest of this afternoon through Tonight)
Issued at 230 PM EDT MON MAY 8 2023
Sfc high pressure is building in from the north and fighting two
shortwave lows this afternoon through tonight, one to our west
digging through the Upper Midwest and another passing through the
Lower Midwest. This is bringing mid- to high-level cloud cover
across the CWA today into this evening, with some low-level clouds
possibly moving over the far west late tonight. Still, temps today
have already gotten into the mid to upper 60s in many of the
interior areas, and spots have already broken 70F; with cloud cover
breaking up over most of the area tonight, expect lows to drop into
the mid 40s over the far west to mid 30s in the interior
east/central.
As for rain chances, CAMs show that there is a chance that some
showers and possibly a thunderstorm or two moves over the far west
late this afternoon and continues into this evening. That being, the
recent RAP and HRRR guidance has really backed off on precip chances
over the far west, with the HRRR almost completely getting rid of
the rainfall altogether. Therefore, I`m keeping the far west under a
low chance (20-30%) for rain showers, with thunderstorm chances
being around 20% or less. Moving into late tonight, thinking that
fog is going to develop over the western CWA as less dry air is
expected at the sfc; the fog could be dense in spots. However, the
further east you go in the U.P., the lower the chance of fog
tonight; don`t expect any east of Marquette and Menominee counties.
.LONG TERM...(Tuesday through Monday)
Issued at 402 PM EDT MON MAY 8 2023
The big picture of the extended forecast is below normal precip and
and above normal temps through much of the forecast. The ECMWF EFI
is showing anomalous temps values through Saturday night which is
supported by positive 500 mb height anomalies through Saturday
between 100 to 150 meters. Some chances for rain arrive late week
and continue into the weekend will be followed up by slight chances
on Monday before dry conditions return again. With the ridging
building in through mid-week, more sunshine is expected to mix in
through which will be a nice change from the gloomy clouds and fog
that have filled the last few periods.
Starting Tuesday, mid-level ridging begins to build in over the UP
with a surface high pressure settling south through Ontario Tuesday
morning and the into Upper Great Lakes the rest of the day. This
will yield light winds/possibly variable winds, plenty of sunshine,
and dry conditions. I continued the forecast for lake breeze
development on Tuesday with the warmer temps expected to be warmer
than Lake Superior surface temps. A few of the CAMS do highlight
some stray showers mainly over the far west with the RAP and HRRR
bringing them along the WI/MI state line through the evening hours.
This could be supported by the mid-level shortwave that is most
visible in the NAM. However, with surface high pressure building in
and not much there for forcing I am not very convinced. Also a deep
layer of dry air up to the 850mb level builds in across the UP as
noted in the BUFKIT soundings will work against any potential to
develop showers as well as mix down some drier dew point temps,
especially in the east.
Wednesday through Thursday morning will see the mid-level ridging
continue over the Upper Midwest and the surface high pressure track
southeast toward the Atlantic, continuing the mostly dry weather. A
few diurnal showers alongside a few potential rumbles of thunder are
possible Wednesday afternoon. Otherwise dry weather and partly cloudy
skies are expected on Wednesday. Thursday reintroduces chances for
precip across much of the UP as a mid-level short wave tracks into
northern Wisconsin. Confidence in much accumulation or even any
showers at all with this initial wave is still low as the past 4 GFS
and ECMWF ensemble QPF probabilities of greater than 0.1 inches are
all low (20% to 40% chance). A closed off mid-level low will track
northeast off the Rockies on Thursday and then take a north to north-
northeast track through the Dakotas and Minnesota Friday/Saturday.
This system brings the better shot for precip across the UP. If the
drier trend continues this week, POPs may need to be brought down
for the late week systems.
Temps look to drop down near normal late in the weekend and into
next week. With dry air moving in early next week, more sunshine and
dry weather should be expected. Also with less precip in the
forecast, flooding risks should taper down through the week with
some exceptions into the weekend. RHs on Tuesday will drop around
30% along light winds over the central/eastern UP yielding
borderline elevated fire weather conditions.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 709 PM EDT MON MAY 8 2023
at IWD, A low pressure trough over the western UP has been the
focus for isolated to scattered showers over western Gogebic and
Ontonagon counties early this evening. Will keep VCSH in the forecast
this evening for IWD and then with added moisture from the showers
expect a gradual lowering of ceilings to MVFR this evening and
then lowering to IFR in patchy fog overnight. Patchy fog should
dissipate by late Tue morning with improvement to MVFR conditions.
Drier air under high pressure ahead of the western UP trough will
result in dry conditions should yield VFR conditions through the
period at CMX and SAW. &&
.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 402 PM EDT MON MAY 8 2023
Northeast winds gusting around 20 knots will continue through this
afternoon across the western third of Lake Superior. With surface
ridging continuing to build in through Tuesday, winds look to become
light tonight below 15 knots. Light winds below 15 knots are
expected across the lake through Wednesday night. Thursday will see
generally southerly winds around 10 to 15 knots which will stay
light overnight into Friday. Winds will back northeast on Friday and
increase to 10 to 20 knots as a low pressure system tracks northeast
into the Dakotas and Minnesota. Depending on the low`s track on
Saturday, northeast gusts up to 25 knots are possible in the west
third of the lake Saturday afternoon/evening.
There is the potential for a few weak thunderstorms across the far
western lake this afternoon, diminishing this evening evening with
some showers continuing through the overnight hours. The primary
hazards are a few lightning strikes and some brief periods of small
hail.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
None.
Lake Michigan...
None.
&&
$$
SHORT TERM...TAP
LONG TERM...Jablonski
AVIATION...Voss
MARINE...Jablonski
Area Forecast Discussion
National Weather Service Morristown TN
1042 PM EDT Mon May 8 2023
...New UPDATE...
.UPDATE...
Issued at 1029 PM EDT Mon May 8 2023
The MCV and associated convection across SE MO tonight will move
southeast towards the Tennessee Valley tonight. Additional
scattered showers and thunderstorms are forecast to initiate
ahead of this MCV and along residual outflow boundaries late
tonight as this feature moves across our forecast area between
08z and 12z. RAP guidance continues to indicate a marginally
favorable environment for isolated strong to severe thunderstorms
with MLCAPE around 1000 J/Kg along with relatively steep mid-level
lapse rates near 7-7.5 deg C/km favorable for some hail risk. The
thermodynamic profile is also resulting in DCAPE values of 900 to
1000 J/Kg which is sufficient for some damaging wind gusts with
the strongest surface based convection.
Deep layer winds will be on the rise overnight ahead
of a stronger shortwave across the Great Lakes. This will increase
effective deep layer shear to around 30 to 40 kt across the
region which will help with storm organization. The severe risk
remains low since thunderstorms are expected to generally weaken
late tonight and early Tuesday morning, but there is at least a
low risk for thunderstorms capable of some strong winds and hail
between 08z and 12z Tuesday.
Overall, the forecast remains on track with some minor updates to
temperatures and PoPs based on current observations and expected
trends.
JB
&&
.SHORT TERM...
(This evening through Tuesday)
Issued at 328 PM EDT Mon May 8 2023
Key Messages:
1. Another round of convection expected tonight. Severe chances
seem low given overnight arrival.
Discussion:
Regional radar and satellite imagery show remnant MCS and likely
an MCV moving east through eastern Kentucky this afternoon. Models
have not resolved this well, but think there will likely be a few
scattered showers and thunderstorms pop up over our Virginia
counties and possibly far northeastern TN this afternoon and
evening as this passes by. Otherwise, do not expect much in the
way of any convection through late this evening as the region
remains worked over from the storms that moved through yesterday
and overnight.
However, further west from the Ozarks ENE into the Ohio valley,
another MCS is expected to form later this evening. This will
eventually work its way southeast through eastern Tennessee. Given
the overnight arrival time, severe chances seem to be low. This is
supported by forecast soundings from across the CWA. An outside
chance for some damaging winds could exist but otherwise expect
this to just be another chance for some moderate rainfall. There`s
some uncertainty with regards to what portions of the CWA will see
this MCS move through. Current thinking is that the northern half
of the forecast area will see the best coverage and PoPs reflect
this.
For tomorrow, expect any rainfall to gradually shift south through
the morning hours, leaving most of the area dry by the afternoon
hours. Temperatures will be a bit tricky, as they were today,
given the potential for lingering convective debris cloud cover.
Undercut NBM guidance a tad to hedge towards cooler than expected
highs.
&&
.LONG TERM...
(Tuesday night through next Monday)
Issued at 328 PM EDT Mon May 8 2023
Key Messages:
1. Mostly dry through the mid-week with increasing chances for rain
and storms late week and into the weekend.
2. Above normal temperatures expected through the long term.
Discussion:
Shortwave ridging will build over the region Tuesday night into
Wednesday along with surface high pressure transitioning southeast
from the Great Lakes. The increased subsidence will result in sunny
to mostly sunny skies with conditions remaining primarily dry. Some
guidance hints at a few spots of weak returns Thursday afternoon,
thus, PoPs has been limited to slight chance in the southern valley,
along the Cumberland Plateau, and the GSMNP.
More favorable moisture transport will return as we approach the
late week, with PWATs increasing to around 1.3 inches per latest
ensemble guidance. In combination with the aforementioned surface
high pressure meandering further east and the above normal
temperatures, conditions will become increasingly favorable for
showers and thunderstorms in a typical diurnal manner. There is
potential to have minor isentropic lift associated with weak
southwesterly H85 flow, but given the low amplitude of the flow and
no other significant forcing mechanisms on the synoptic scale have
currently restricted wording to chance.
Various impulses translating through the mean flow aloft late
weekend and into the new week will further weaken the ridge. While
there are discrepancies among any finer details, guidance generally
has a low pressure system traversing the Ohio Valley with a west-
east oriented front to our north. This results in increased chances
in showers and thunderstorms. Temperatures through the long term
will continue to be above normal, with even a slight warming trend
into the weekend.
&&
.AVIATION...
(00Z TAFS)
Issued at 653 PM EDT Mon May 8 2023
Scattered showers and thunderstorms are expected to develop along
a weak cold front tonight and move southeast across the Tennessee
Valley and Southern Appalachians with flight impacts expected at
all TAF sites. Predominant VFR conditions are forecast, but
periods of MVFR, and potential tempo IFR/LIFR, will be possible
late tonight and early Tuesday within areas of heavier convection.
Drier air arrives and winds shift to the NW/NNW on Tuesday
afternoon with clearing sky conditions and decreasing chances of
thunderstorms.
&&
.PRELIMINARY POINT TEMPS/POPS...
Chattanooga Airport, TN 65 85 59 83 / 50 30 0 10
Knoxville McGhee Tyson Airport, TN 63 80 56 80 / 60 40 0 10
Oak Ridge, TN 63 82 56 81 / 60 30 0 0
Tri Cities Airport, TN 60 77 50 78 / 60 50 0 0
&&
.MRX WATCHES/WARNINGS/ADVISORIES...
NC...NONE.
TN...NONE.
VA...NONE.
&&
$$
SHORT TERM...CD
LONG TERM....KRS
AVIATION...JB
Area Forecast Discussion
National Weather Service Norman OK
1022 PM CDT Mon May 8 2023
...New AVIATION...
.SHORT TERM...
(This evening through Tuesday)
Issued at 246 PM CDT Mon May 8 2023
We have entered "mesoscale season", where forecast predictability
becomes very low and each forecast is dependent on how the
previous day`s storms evolve. Below is a snapshot of how the
forecast looks right now, but things could change rather
dramatically in subsequent forecasts.
Thunderstorms are possible within two regimes this evening, although
neither regime contains a super large chance of convection. The
first area to watch will be in western north Texas, where a weak
inverted surface trough across the Llano Estacado will lead to
easterly surface winds and westward-surging moisture across the
Caprock this evening. The 12Z HRRR and 12Z NAM 3KM show a comical
difference in moisture quality - the NAM shows upper 60s dewpoints
and 4,500 CAPE around sunset, while the HRRR shows upper 50s and
2,000, respectively. Both may be sufficient for rather short-lived,
slow-moving multicell clusters capable of downburst winds and
downpours. However, given very weak forcing, this is a low-
likelihood scenario.
The second, likelier scenario for thunderstorm development will
occur this evening and overnight across north central Oklahoma. A
subtle impulse will round the top of the shortwave ridge anchored
over us, and most CAMs suggest that this impulse will be the impetus
for CI along a frontal boundary lifting into southern Kansas after
sunset. These storms will slowly sag southward into northeast
Oklahoma. The best chance for thunderstorms tonight in our area will
be north of a Stillwater to Cherokee line.
Otherwise, expect lows tonight to drop into a soupy low-to-mid-60s
as the dryline once again sloshes westward after sunset. Cloud cover
will largely be regulated by any anvil debris from storms over or
east of our area, but the night looks to be clearer to the west.
Some patchy fog is possible in western and northwestern Oklahoma
late as moisture surges in from the east.
Storms may linger into the morning in north central and northeast
Oklahoma, though they should decay not long after daybreak as the
shortwave ridge strengthens over the Red River. Another impulse is
expected to develop atop the ridge and intersect the frontal
boundary tomorrow evening. This time, flow will be somewhat stronger
in the frontal region and a supercell storm mode appears possible.
There is some uncertainty regarding the northward advance of the
front, with the NAM maintaining it near the OK/KS border and most
other models lifting the front near I-70. The chance for organized
severe storms will thus be dependent on that frontal location, and
will be monitored in subsequent forecasts. There is an outside
chance of a storm or two along the dryline in western OK and western
north TX, but both forcing and deep-layer shear are incredibly poor
in this region.
A soupy airmass will remain in place across most of our area
tomorrow with highs in the low 90s to the west and the mid-80s to
the east.
Meister
&&
.LONG TERM...
(Tuesday night through next Sunday)
Issued at 246 PM CDT Mon May 8 2023
Tomorrow night, the core of the ridge will shift slightly north,
bringing easterly flow aloft to the Red River region and raising
heights further to the north. This will effectively kill any storms
that are ongoing. The ridge axis will finally begin to shift
eastward slightly on Wednesday as a powerful shortwave trough begins
to overspread the High Plains. Some guidance shows a weak trough/MCV-
like feature sliding northward through eastern Oklahoma and western
Arkansas Wednesday evening. All told, this will probably mean two
things: first, a break from the constant low storm chances that many
areas have seen over the past week. Second, a break from the early
summer impression that everyone has seen over the last week. Highs
will drop into the low-80s area-wide with quite a bit more cloud
cover than previous days.
On Thursday, the High Plains trough will eject into the central
Plains. There is some uncertainty about the exact placement of the
40-50 knot flow aloft by Thursday evening, but a best guess would
say western Kansas. Even if western Oklahoma only sees glancing
influence as the NAM suggests, subtle height falls and 35 knots of
500 mb flow across deep-layer moisture are often all severe weather
events in this area require in mid-May. Trends will continue to be
watched, but Thursday looks to be the likeliest day for impactful
severe weather in our area.
This coming weekend gives off strong "washout" vibes, particularly
across southwest Oklahoma and western north Texas. This is due to a
resurgent STJ, which will eject northeastward from Mexico in time to
cut off the High Plains low and trap the cutoff across the
southwest. Northwest flow across the northern Plains will encourage
a synoptic-scale front to surge southward. The result will likely be
a stalled frontal boundary somewhere in our area with plenty of
Pacific moisture atop it, a classic recipe for high rainfall amounts.
Meister
&&
.AVIATION...
(06Z TAFS)
Issued at 1016 PM CDT Mon May 8 2023
Still expecting some low stratus and BR to develop late tonight
into early Tuesday over central OK. Some IFR cigs will briefly be
possible. Winds will remain southerly and less than 10 kt. Cirrus
clouds will stream in from TX overnight too. There`s a low chance
of showers and thunderstorms developing around 06-09Z across
northern OK but confidence is far too low to include any mention
of TSRA at PNC.
&&
.PRELIMINARY POINT TEMPS/POPS...
Oklahoma City OK 87 65 85 65 / 0 10 20 20
Hobart OK 92 63 91 62 / 0 10 20 20
Wichita Falls TX 91 64 89 64 / 10 10 10 20
Gage OK 88 60 93 61 / 0 10 20 20
Ponca City OK 89 64 86 64 / 10 40 50 40
Durant OK 87 66 86 65 / 20 0 20 20
&&
.OUN WATCHES/WARNINGS/ADVISORIES...
OK...None.
TX...None.
&&
$$
SHORT TERM...04
LONG TERM....04
AVIATION...03
Area Forecast Discussion
National Weather Service Salt Lake City UT
227 PM MDT Mon May 8 2023
.SYNOPSIS...An unsettled pattern will continue through the
weekend with several disturbances expected to bring convection to
at least northern Utah today and Tuesday, with more widespread
convection possible Wednesday.
&&
.SHORT TERM (Through 12Z Wednesday)...A relatively chaotic
spring-time pattern continues across the Interior West. Afternoon
upper air and satellite analysis indicates a relatively strong
shortwave trough crossing northern California. The attendant jet
max is noted on satellite, with a broad area of upper level
diffluence shifting into northern Utah. Additional shortwave
troughs are noted upstream across the eastern Pacific.
Current mesoanalysis suggests sufficient destabilization...with
SBCAPE values near 500 J/kg. Latest RAP suggests this
destabilization will continue with a broad area of SBCAPE values
near 500-1000 J/kg by 00Z. Deep layer shear is averaging between
40-55kts across northern Utah. Given synoptic support combined
with more than sufficient instability and deep layer shear, expect
convection will continue to develop across northern Utah and Uinta
County, WY into the evening.
Looking at the CAMS and current RADAR trends, the evolution of
this convection seems on track with a developmental quasi-linear
feature noted near the Utah/Nevada border. Looking at the pre-
convective environment, dewpoint depressions across western Utah
are around 30 degrees or so. As one would expect, model soundings
suggest inverted-v type profiles.
Expect convection to continue to shift east with time into the
Wasatch Front through Uinta County WY. The highest threat period
for the Wasatch Front looks to be 4 PM - 7 PM. Given the degree of
instability combined with deep layer shear and antecedent
conditions, expect the threat of microburst winds and small hail
with any deeper convection.
With the shortwave trough shifting east, convection should
gradually end from west to east through the evening.
The next shortwave trough will drop south along the California
coast Tuesday afternoon. Upper level diffluence will again set up
across portions of western Utah. HREF ensemble mean SBCAPE values
will again range around 250-500 J/kg across northern Utah, with
deep layer shear around 30kts or so. CAMS are decidedly less
impressed, with most convective activity confined to the western
and northern border areas. This may be underdone and bears
watching with the next forecast update.
.LONG TERM (After 12Z Wednesday)...Two main periods of possible
sensible weather impacts across the region in the extended
forecast. The first comes Wednesday as scattered showers and
thunderstorms move through the area in association with a trough
passage, with relatively high snow levels to around 8.5-9k feet.
The second potential impact is canyon or downslope winds along the
Wasatch Front Saturday into Sunday as an unusual high over low
(Rex Block) scenario develops across the West and supports a
period of easterly flow over northern Utah.
A trough axis passage on Wednesday as the main low center moves
through the Four Corners will support the development of scattered
showers and thunderstorms with with relatively steep low and mid
level lapse rates. Flow will be very light under the trough axis,
resulting in very little shear or even steering flow for that
matter. Popup scattered shower and thunderstorms with around 500
J/kg of CAPE will largely struggle to organize given this
environment, and briefly heavy rain showers are possible,
especially over and tied to the higher terrain as anything that
develops on the terrain will struggle to move off of the terrain
in this environment. Thus some localized rain on snow could
increase runoff potential over mid/high elevations where snow
remain on the ground. Fortunately temperatures will continue to be
seasonable in this pattern.
By Thursday, the upper low will only move into the Colorado /
Wyoming Front range, with eastern Utah still under the western
periphery of its cyclonic flow aloft. Thus while we will be drying
out on the back side of the low, there still will be enough
moisture/support diurnal pop up showers and thunderstorms over the
mountains, although becoming more isolated to widely scattered in
nature.
The more unusual pattern starts to develop Friday through the
weekend, as ridge builds to our north over the Pacific Northwest
into British Columbia and Alberta, while lower pressure remains in
place over the Great Basin into the Southwest US. This Rex Block
type setup starts a more unusual easterly flow across northern
Utah that gets kicked off on Saturday as vort max on the back side
of our aforementioned low gets pinched off and ejects westward
across northern Utah all the way toward Northern California by
late Saturday evening. This easterly flow sets up the potential
for at least a period of gusty canyon winds along the Wasatch
Front Saturday into Sunday. Digging into this setup a bit more -
we can be very confident on the overall pattern as all clusters of
the available 100 ensembles solutions between the GEFS/EPS/CMCE
all show this Rex Block development with easterly flow across
Utah. The main differences between the clusters comes down to the
strength of the 700 mb easterly flow, and strength of the easterly
surface pressure gradient that develops across northern Utah.
Thus there is potential for a stronger downslope storm, however
only about 20% of EPS members show wind gusts of 40 mph or greater
at Hill AFB (proxy location for prime downslope location along
northern Wasatch Front). Balancing the fact that all models are
showing this easterly flow with the fact that there are several
smaller scale details to iron out being a day 5/6 forecast, have
started with introducing some sub- advisory level canyon winds in
the forecast for the main canyons between Brigham City and Salt
Lake City, and we`ll continue monitoring this setup for any
stronger potential.
&&
.HYDROLOGY...Rivers continue to run fast, cold and high area-wide.
A reminder to keep pets on leashes and children away from these
waterways for the foreseeable future. River flood warnings
continue for the Bear River at Corinne, the South Fork of the
Ogden near Huntsville and the Sevier near Hatch. A river flood
watch remains in effect for the lower Weber River near Plain City.
An areal flood warning is now in effect for the Bear River from
the Woodruff Narrows northward to the Utah/Wyoming state line west
of Sage Junction, WY. An areal flood watch remains in effect
along the Little Bear south of Hyrum Reservoir.
Over the next week, flows are forecast to increase on many
additional creeks, streams and rivers. The Little Bear near
Paradise is the first river that may approach flood stage later
this week...and will be monitored for a potential watch over the
next 24 hours.
&&
.AVIATION...KSLC...VFR conditions with brief MVFR/IFR conditions
this afternoon as convective showers and thunderstorms move
through. These will contain gusty and erratic winds along with
lightning. These will move out of the area after 03Z with clearing
skies and light winds prevailing.
.REST OF UTAH AND SOUTHWEST WYOMING...VFR conditions across all
of the area aside from northern sites that could see brief
MVFR/IFR conditions as convective showers and thunderstorms move
through between 20-03Z. These storms will contain gusty and
erratic winds along with lightning. Skies will begin to clear
after 03Z with winds becoming light and variable. Southern Utah
will remain dry with VFR conditions.
&&
.SLC WATCHES/WARNINGS/ADVISORIES...
UT...Flood Watch through Friday afternoon for UTZ107.
WY...None.
&&
$$
Kruse/Church/Mahan
For more information from NOAA`s National Weather Service visit...
http://weather.gov/saltlakecity