Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 05/12/24
Area Forecast Discussion
National Weather Service Denver/Boulder CO
902 PM MDT Sat May 11 2024
.KEY MESSAGES...
- Showers/thunderstorms are possible (>50%) for much of the day
Sunday, with locally moderate rainfall. Thunderstorms could
begin as early as 9 AM, but become more favorable during the
afternoon hours. Several inches of snow are possible above 9,500
ft elevation.
- Drier and milder Monday outside of a few mountain
showers/storms.
- Turning more active again Tuesday and Wednesday with increased
chances for showers and thunderstorms across high country and
lower elevations.
&&
.UPDATE...
Issued at 855 PM MDT Sat May 11 2024
Radar this evening shows a couple of lingering showers across the
Denver metro this evening, with a slightly more organized cluster
in Lincoln county. This activity is expected to wane through the
early overnight hours. However, substantial cloud cover will
remain and gradually drift north towards the Wyoming border
overnight.
As the previous discussion noted, there is a fair amount of
uncertainty regarding tomorrow morning`s rain and low cloud cover.
While afternoon guidance was rather bullish bringing this into the
Denver metro, early 00z guidance has shifted much further south,
keeping the axis of heaviest precipitation towards the Palmer into
Lincoln county. Did make some minor adjustments through 12z
tomorrow morning but will let the overnight shift make the final
call for Sunday`s forecast.
&&
.SHORT TERM /Through Sunday/...
Issued at 131 PM MDT Sat May 11 2024
GOES-17 water vapor imagery shows a slowly moving vorticity max
moving slowly to the east across the AZ/UT border. By sunrise
Sunday the trough should be directly overhead the central part of
Colorado, then over western Kansas by Sunday evening. Several
sources of lift should be in place as the trough moves overhead.
There is a fair amount of QG lift as well as a deformation zone
that wraps around the 500 mb low, especially Sunday morning.
Additionally, the core of the trough is -18 degC at 500 mb, and
not to be outdone, there is strong northeast flow across the
plains starting mid-morning Sunday. Overall it will be hard to pin
down best periods and locations of rain because of a few
competing factors, including the potential for a stratus layer
Sunday morning. Let`s start with overnight first.
Scattered showers and isolated thunderstorms should dissipate
and/or move east of our area before midnight tonight. We`ve
lowered PoPs a bit overnight between midnight and sunrise as most
CAMs do not break out much precip, which makes sense with the loss
of sun/instability and before the arrival of the QG lift and
deformation zone. Those features look to arrive between 8-10 AM
more or less, but models have been backing off QPF associated with
this banded feature. Instability is lacking, so much that if the
band forms, it`ll probably just be light rain without any thunder.
CAMs have likewise been wishy-washy on the location of this
banded rainfall, but latest trends have the band across I-70 or
points south. The uncertainty has led to PoPs going from 20
percent across the northern tier Colorado Counties to 60 percent
across I-70 and the Palmer Divide during the morning hours. Most
CAMs, other than the HRRR, have low clouds in place which would
limit instability as mentioned earlier, and even without the
clouds the HRRR has been backing off on QPF from this first round
of showers. Assuming low clouds either don`t form or evaporate by
midday, there should be enough instability to form showers and
thunderstorms in the afternoon across all but the areas near the
Wyoming border. These will be widely scattered and thus the
highest PoPs are still only about 60%, but if you happen to be
under one of these showers you might experience moderate rain,
gusty winds 25-30 mph, and very small hail are possible. In terms
of temperatures, it`s interesting that after the trough axis
passes and northerly flow kicks in aloft by late morning, there
will actually be warm advection in the 700-500 mb layer, and areas
with more sun like along and north of US-34, high temps will top
out near 70 deg. In the thicker cloud cover, including
Denver/Boulder metro areas and the plains to the east and south,
highs will likely only be in the low to mid 60s. Middle/North
Parks should also be in the 50s to near 60, but thick clouds and
also probably the best chance of precip across Park County and
the foothills from Boulder County to the Palmer Divide should
result in temps barely reaching 50. Snow levels throughout Sunday
should remain above 9500 ft MSL. 36 hour snowfall totals above
10,000 ft could be over 6", but a good chunk of that amount
depends on the banded precipitation Sunday morning through midday,
as well as the convection Sunday afternoon, so totals are likely
to be widely varying or short distances.
&&
.LONG TERM /Sunday night through Saturday/...
Issued at 131 PM MDT Sat May 11 2024
Sunday evening, northeast Colorado will be under the backside of the
exiting upper low/trough system. Weak synoptic ascent builds in with
showers and storms tapering off generally from north to south.
Monday, an upper level ridge moves in with northwesterly flow aloft.
Subsident flow under the ridge will keep it much drier than Sunday.
Model cross sections show residual moisture in the flow coupled with
marginal instability (MLCAPE < 400 J/kg), mainly across the high
country. This will support scattered showers/storms, primarily
confined to the higher elevations. A shower or two may stray onto
the plains although, with dry lower levels it is more likely to be
virga. With the ridge overhead, 700mb temperatures warm, supporting
highs in the low-mid 70s across the lower elevations and 40s/50s for
most of the high country.
There is a general consensus among ensemble guidance that flow aloft
transitions to westerly Tues/Weds in response to an approach
shortwave trough. While there is good agreement on a trough moving
through mid-week, there is still uncertainty in the details.
Moisture returns to Colorado ahead of the trough with synoptic
ascent and cooler air aloft bringing instability. Expect increased
chances for showers/thunderstorm those days. Instability still stays
on the marginal side with MLCAPE < 500 J/kg. Tuesday afternoon the
"higher" instability will likely be positioned across the far east
plains. A few stronger storms can`t be ruled out on the east plains
as a result. Despite small differences in track, timing with the
trough there will be another shot at afternoon showers/storms
Wednesday. Expect mild temperatures Tuesday with mid to upper 70s
across the lower elevations. Cooler temperatures Wednesday with the
trough/front passage. Zonal flow over the region for Thursday with
drier conditions expected and temperatures closer to normal. Warm-up
Friday into the weekend.
&&
.AVIATION /00Z TAFS through 00Z Sunday/...
Issued at 540 PM MDT Sat May 11 2024
Complicated TAF forecast through the majority of the period.
Ongoing SHRA/TSRA has been disorganized and has thus far stayed
reasonably far away from the terminals. A more organized batch of
precip is attempting to drift towards APA this evening, along with
a few showers in the periphery of a weak Denver Cyclone near DEN.
The first area of uncertainty is how this remaining activity
evolves over the next few hours. With decreasing instability, the
main concern this evening would be briefly lowered cigs, but
guidance offers little insight here. Can`t rule out some brief
MVFR/ILS cigs and briefly reduced visibility. In general, expect
a gradual lowering cigs overnight but confidence in this timing is
low.
Next question is if a band of rain makes it into the Denver metro
on Sunday AM. Recent trends have generally bumped this north to
the point where even BJC/DEN could see a few hours of rain near
daybreak Sunday, with greater confidence towards APA. Again main
impacts here would be reduced visibility and MVFR cigs/visby with
a limited chance of any TS.
Finally, there is the potential for additional scattered
showers/isolated thunder in the afternoon hours. This will likely
be dependent on how the AM rain evolves and little change was made
beyond 18z for the DEN TAF.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
UPDATE...Hiris
SHORT TERM...Schlatter
LONG TERM...Mensch
AVIATION...Hiris
Area Forecast Discussion
National Weather Service Quad Cities IA IL
834 PM CDT Sat May 11 2024
.KEY MESSAGES...
- Quiet weather through Sunday morning. Clear skies expected
tonight.
- Sunday will be the warmest day of the next seven with highs in
the lower 80s. Isolated to scattered storms are possible late
Sunday afternoon into Sunday night.
- Zonal flow across the CONUS will result in active weather
continuing through the next week.
&&
.SHORT TERM /THROUGH SUNDAY NIGHT/...
Issued at 206 PM CDT Sat May 11 2024
Confluent flow aloft over Upper Midwest this afternoon as 500 MB
ridging builds into the area at the surface and aloft. Visible
satellite imagery is showing some areas of diurnally driven
cumulus developing across Illinois and parts of Iowa. The KDVN
sounding showed a convective temperature of 69 degrees.
Temperatures at 2 PM ranged from 69 degrees at Freeport and
Dubuque to 76 degrees at Macomb. Northwest winds have been
gusting up to 35 MPH at times this afternoon but in general
winds are gusting up to 25 MPH.
High pressure will move southeastward across the area at the
surface and aloft through Sunday morning. This will bring quiet
weather to the area overnight The HRRR and HREF have been
showing some thinning high clouds moving across the area this
evening but do not expect widespread cloud overnight with dry
air in place. Winds will diminish tonight and become light and
variable. Low temperatures will generally be around 50 north of
a Independence to Clinton to Princeton Illinois line with lower
to mid 50s south.
On Sunday, the ridge axis will push to the southeast during the
morning as one shortwave dives into Michigan. The ECWMF is the
faster and farther south of the different solutions with the
cool front approaching the area by 00 UTC Sunday. CAMs do have
isolated to scattered showers and storms developing across the
area from 20 UTC (3 PM) along the Highway 20 corridor. Model
soundings show that brief gusty winds will be the main threat
but moisture is very limited and soundings are showing
inverted-V or onion sounding characteristics. Temperatures on
Sunday will be in the lower 80s. Forecast soundings show the
potential for gusty winds once again with a few gusts especially
across northwest Illinois and far eastern Iowa near 25 MPH.
Models have slowed precipitation moving into the area on Sunday
in association with a closed upper level low moving from
Colorado into eastern Kansas by 12 UTC Monday. The better
chances of 30 to 40 percent will remain west of the Mississippi
River overnight. Rainfall amounts will be light and range from
one to two tenths.
&&
.LONG TERM /MONDAY THROUGH SATURDAY/...
Issued at 206 PM CDT Sat May 11 2024
The 500 MB flow will remain zonal through the upcoming week
with an active northern (polar) and southern (sub tropical)
branches of the jet streams across the continental US. This will
result in several more chances for showers and storms. High
temperatures will be in the lower to mid 70s through mid week
before a warming trend beings into next weekend.
Monday: An upper low on the northern periphery of the
subtropical jet is forecast to slowly track from the Southern
Rockies to the Lower to Mid Mississippi Valley early in the
week. This will keep the local area on the cooler and more
stable side of the surface low. Rain is likely to spread in
from SW to NE during the morning and afternoon. NBM chances for
measurable rain range from near 50% in the far NW corner of the
outlook area to ~90% south of I-80. The 24 hour probability for
0.50" or more of rain reaches 50-70% south of I-80 and drops
down to 20% near Highway 20. The NBM may still be running too
warm for max temps due to the likelihood for widespread clouds
and rain; these may need to be lowered by several degrees in
later updates.
Tuesday - Friday: There remains uncertainty with how fast the
rain moves out on Tuesday. The ECMWF lingers the rain through
the morning across the south half of the outlook area, while
the GFS/CMC shift it to the SE more quickly. Our current
forecast is leaning towards the latter scenario. Then it looks
like we will get a break from the rain later Tuesday through
Wednesday before the next shortwave trough and associated cold
front arrive by Wednesday night into Thursday. Late week temps
are forecast to be slightly above normal in the low/mid 70s.
&&
.AVIATION /00Z TAFS THROUGH 00Z MONDAY/...
Issued at 637 PM CDT Sat May 11 2024
Quiet weather for next 20 hours as VFR conditions are expected.
Winds are expected to decrease after sunset and increase again
tomorrow in the AM like today. Late in the period isolated
thunderstorms are possible, but timing and limited coverage
precludes adding them to the TAF at this time.
&&
.HYDROLOGY...
Issued at 833 PM CDT Sat May 11 2024
Latest forecast this evening for the Wapsipinicon River near De
Witt has a slower rise by several tenths of a foot. However,
minor flooding is still expected but a little later now on
Tuesday May 14th. Given how the initial crest was lower and
attenuation of routed flow confidence is dropping, confidence is
low in just how high above flood stage the river will get. Will
continue the Flood Warning with this issuance.
In addition, the forecasts on the Cedar and Iowa Rivers have
lowered at Conesville and Marengo. Both sites now just touch
flood stage on Wednesday. Will continue the flood watches for
now, but if trends continue in the coming days the flood watches
may need to be cancelled.
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...None.
IL...None.
MO...None.
&&
$$
SHORT TERM...Cousins
LONG TERM...Cousins/Uttech
AVIATION...Gibbs
HYDROLOGY...Gross
Area Forecast Discussion
National Weather Service Hastings NE
640 PM CDT Sat May 11 2024
.KEY MESSAGES...
- Expect increasing clouds, and at least a chance for isolated
showers and thunderstorms, tonight. More scattered activity is
likely on Sunday, particularly during the afternoon and
evening. The morning hours will not be a complete "washout".
- Overall, seasonably mild temperatures with off and on again
chances for thunderstorms remain in the forecast through the
end up the upcoming week.
- Despite it being mid-May and nearing climatological peak
severe weather season, chances for severe thunderstorms over
the next 7 days is pretty low.
&&
.DISCUSSION...
Issued at 242 PM CDT Sat May 11 2024
EXTREMELY nice and pleasant weather out there currently - it
really doesn`t get much better than this for mid-May.
Temperatures in the 70s to low 80s, low dew points, plentiful
sunshine, and wind speeds 10-15 MPH, or less. It will cloud up a
bit more for the eve hrs, but dry conditions should prevail
through 03Z, at least for all but perhaps Furnas and Rooks Co.
Chances for isolated showers and thunderstorms will gradually
increase through the overnight, but general consensus in latest
hi-res guidance was for lesser coverage/organization tonight
into Sun AM, and slower arrival. So main change this forecast
package was to lower and slower the PoP grid. We still have
"likely" level PoPs for S/SW 2/3rds of the CWA by midday Sunday,
but this may still be overdone and make the AM hrs sound
worse/wetter than what I think they`ll be. In fact, latest 18Z
HRRR doesn`t have anything more than isolated to widely
scattered activity until at least early aftn hrs. Cold mid level
temps associated with the incoming upper trough should steepen
lapse rates enough to get some tall, skinny CAPE and actual
thunderstorms for the mid afternoon through early eve time
frame, and the uptick in forcing/ascent should help to increase
the overall coverage. So if you have outdoor plans for Mother`s
Day, earlier in the day will be better than later. CAPE will
likely remain less than 1000 J/kg, and all but our KS zones will
have weak deep layer shear, so severe weather appears unlikely.
Perhaps the higher shear (30-35kt from 0-6km) could lead to a
few cores with small hail, but this seems like worst case. Highs
are a bit tricky with the cloud cover and pcpn, but a lack of
significant cold push should still support 60s and 70s, warmest
N and E of the Tri-Cities where it takes the longest for thicker
cloud cover to arrive.
It`s a fairly slow moving upper trough with no real rush of dry
air, so chances continue through Sun night (50-80%), and even
into Mon AM (20-80%) - particularly for areas E and S of the
Tri-Cities. This activity will be on the NW side of main
mid/upper low, so severe weather remains unlikely. Temps will be
similar to Sun in that 60s to low 70s will be most favored
where dense overcast/pcpn are most likely to last the longest,
with more low to mid 70s for areas that clear out sooner.
We look to clear out behind this system for Tuesday, which
should allow for a rather nice day with highs in the 70s/80s
amidst seasonably light winds. Shower/storm chances return to
the area already Tue night into Wed associated with a weak cold
front. Deep moisture and instability is lacking, so not
expecting any severe weather or widespread rainfall. Temps will
only be slightly cooler for Wednesday. The rest of the forecast
will feature more of the same with generally split, zonal upper
flow and only minor/weak disturbances. So we`ll see more 70s/80s
and off and on shower/storm chances.
&&
.AVIATION /00Z TAFS THROUGH 00Z MONDAY/...
Issued at 632 PM CDT Sat May 11 2024
Will be keeping this TAF VFR for now, but will have to watch out
for some showers and thunderstorms in and around the area on
Sunday. Can not rule out a brief period of MVFR ceilings or
visibility within a thunderstorm mainly Sunday afternoon, but
most of the period should remain VFR. Our westerly winds early
this evening will become more southwesterly to even southerly by
mid to late evening, but will be on the light side, generally
around or less than 10 kts.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...None.
KS...None.
&&
$$
DISCUSSION...Thies
AVIATION...Wesely
Area Forecast Discussion
National Weather Service Goodland KS
438 PM MDT Sat May 11 2024
.KEY MESSAGES...
- Run of the mill showers/storms this afternoon into tonight,
mainly south of Interstate 70.
- Numerous showers and storms are expected on Sunday, beginning
during the early afternoon and ending from west to east
Sunday night and Monday morning. A few severe storms capable
of producing quarter sized hail and wind gusts up to 60 mph
are possible, mainly in northwest Kansas between 2-8 PM MDT
Sunday.
- Average rainfall amounts today through Monday near 0.50" to
1.25", highest south of a line from Norton to Sharon Springs.
- Unsettled pattern will continue to support a chances for
showers/storms Tuesday through Thursday.
&&
.SHORT TERM /THROUGH SUNDAY NIGHT/...
Issued at 212 PM MDT Sat May 11 2024
This afternoon, a 500 mb low pressure system over the western
Rockies is starting to influence the CWA and showers are moving
in from the southwest. These showers and thunderstorms are
expected to continue into the night with spotty coverage. The
threat for severe weather is very low, but not 0. MUCAPE looks
to be limited to around 300-800 J/KG and effective shear is
about 15-20 kts or less. The SPC has placed the extreme
southwestern portion of the CWA is in a marginal ERO, however
there is less than 5% confidence that flooding will occur today.
Tomorrow will have more widespread precipitation, stronger
storms, although no severe weather parameters look very
impressive. An 850 mb lee low is expected to form in the very
early morning hours Sunday and move across the CWA in the mid-
day as the 500 mb low moves over Colorado to the east. Supplied
with a 20-35 kts LLJ that is expected to start up around 3-6Z
tonight, we will have plenty of moisture to work with throughout
the day Sunday. This which does cause some concern for flooding
potential Sunday when we have another marginal ERO in the far
southeastern CWA. However, due to little rainfall over the
previous week, soundings show upshear speeds around 20-25 kts (a
little fast for flooding), and the types of storm formation
expected, there is only about 5-10% confidence flooding would
occur. PWATS are near 1 inch and there is an fairly elevated
freezing level which adds to the confidence, but does not make
it certain. CAPE looks to be around 1,000-1,500 J/kg with EBWD
shear around 25-30 kts, making low-end severe storms possible
(~5-10% chance). If severe weather were to occur, it would
likely be winds near 60 MPH and a few isolated 1" hailstones.
The HRRR has been doing a pretty good job with today`s showers,
so timing will be based on the 12Z and 18Z HRRR. The surface
low looks to move into the western CWA around 14Z and slowly
move to the east. The will cause wrap-around moisture to be
pulled in and around 18Z a line of showers and storms form along
the northern CWA. This line will move to the south- southeast
and as it does, additional bands of showers and storms look to
form, so the rain may come in waves tomorrow. The entire system
will be moving to the east and the northerly winds push the
storms to the south. Precipitation looks to begin tapering off
around 9Z Monday, but could linger into mid-day Monday.
Sunday will be cooler than today due to mostly cloudy skies and
a cold front moving through in the morning/mid-day, highs will
be in the 60s. Tonight will see the LLJ moving warm, moist air
into the region. The western CWA will remain in the mid 40s but
the eastern CWA looks to stay in the mid 50s. Sunday night will
be slightly cooler behind the cold front, likely down into the
40s to low 50s.
&&
.LONG TERM /MONDAY THROUGH SATURDAY/...
Issued at 228 PM MDT Sat May 11 2024
The extended forecast begins with split flow across the eastern
two thirds of the nation. The northern split has an upper
trough extending west to east from Minnesota to New England and
a ridge over the Dakotas and Big Sky Country (Montana). The
southern split has a trough over the Kansas/Oklahoma border, a
ridge over the Wyoming Big Horns, and northerly flow over the
Tri-State area. A closed 500mb low will be centered over central
Kansas. Starting out in the morning, chances for rain will
persist, with 10-20 percent chances for areas along and west of
Hwy 27. Areas east of the highway will have a 20-50 percent
chance of rain. This will be due to wrap around on the back side
of the low. Winds may be a tad breezy through the afternoon as
the system moves off to the east. The GFS, NAM, and ECMWF all
show the low becoming an open wave as it moves out of the
region. For the afternoon, shower and thunderstorm activity
remains possible. Severe weather is not currently anticipated
with any storms that develop.
The area comes under westerly flow Tuesday as a weak upper
ridge moves over the area. Expect dry conditions for the first
part of the day, with a few showers and thunderstorms moving in
during the afternoon and evening. High temperatures will be
above normal, reaching the 80s in many areas.
Expect a shift in the pattern Wednesday through the end of the
forecast period as a slow moving, upper trough moves across the
region Wednesday through Friday. There will be a cool down
coming with temperatures returning to the 70s on Wednesday and
Thursday. Periodic shower and thunderstorms will be possible
between Wednesday and Friday.
&&
.AVIATION /00Z TAFS THROUGH 00Z MONDAY/...
Issued at 430 PM MDT Sat May 11 2024
Sub-VFR conditions associated with episodic showers/storms
and/or low ceilings are anticipated this evening, overnight and
throughout the day on Sunday. S to SW winds at 10-15 knots this
afternoon will become light/variable overnight.. as a weak low
pressure system in CO progresses eastward over western KS. Light
and variable winds will prevail through mid to late Sunday
afternoon, shifting to the N or NNE at 15-20 knots near the end
of the TAF period (~00Z Monday).. as the aforementioned low
pressure system progresses eastward into central Kansas. Gusty/
erratic winds can be expected in vicinity of any thunderstorms.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...None.
CO...None.
NE...None.
&&
$$
SHORT TERM...CA
LONG TERM...Wekesser
AVIATION...Vincent
Area Forecast Discussion...Updated
National Weather Service Lincoln IL
743 PM CDT Sat May 11 2024
.KEY MESSAGES...
- In the Monday to Tuesday timeframe, there is a 40-60% chance
for more than an inch of rainfall south of I-74. This rain will
contribute to area rivers and streams already running high,
increasing the risk for localized inundation near riverbanks.
This could perhaps also further delay planting and inhibit
germination of agricultural seedlings.
&&
.UPDATE...
Issued at 743 PM CDT Sat May 11 2024
Nothing weather-wise to worry about for any aurora hunters
tonight, as any lingering clouds from earlier are very patchy and
on their way out. The breezy conditions have largely subsided, and
winds gradually trend more toward the southwest overnight.
Temperatures are expected to drop into the lower 50s over most of
the forecast area, though a few upper 40s can`t be ruled out,
especially near the I-74 corridor.
Geelhart
&&
.DISCUSSION...
Issued at 137 PM CDT Sat May 11 2024
A beautiful and seasonably breezy spring afternoon continues across
central and southeast Illinois, offering a reprieve from the
excessive rainfall which has thus far delayed planting and
germination for many. Those traveling on rural stretches of
roadway should be aware, though, that in spots the topmost layer
of soil may be dry enough to get whisked up by these gusty
northwest winds and locally reduce visibility, as a few have
reported. Subsidence associated with the ridge expanding into the
region from the west has suppressed even fair weather cu
development, but the few that formed should diminish with
insolation loss in several hours, and with winds also dropping off
tonight lows will likely fall into the upper 40s in many
locations. The dry airmass, however, will also foster sharp
warming tomorrow, particularly when any low level moisture
attempting to creep up from the south gets mixed out (dewpoints
drop several degrees) during the afternoon as the 12z HRRR would
suggest. If the HRRR is right - and it has already this year done
a good job of handling these type of situations several times -
temps will climb into the low to mid 80s across much of the ILX
CWA tomorrow afternoon, warmest north of the I-70 corridor. One
thing to watch: Virtually all of the CAMs from the 12z HREF depict
at least isolated convection to our north and west, and a couple
of them even paint some simulated reflectivities in our area north
of I-72, tomorrow evening when the same ensemble`s mean MUCAPE
values exceed 750 J/kg northwest of the IL River. Given low levels
will be on the dry side, it would take a fairly hefty shower to
reach the sfc, but LREF does have 25+% chances for measurable
precip northwest of the IL River and 10+% north of I-72.
Dewpoints will increase again tomorrow evening, into the upper 50s
per HREF mean, given (1) southerly flow and (2) compression of low
level moisture with diurnal decoupling. Rain chances rise sharply on
Monday, as the cut off low (and associated moisture and forcing for
ascent) drifting our way from the Plains approaches. The LREF mean
wind field at 850mb suggested the low would track from roughly
Springfield, MO to Louisville, KY yesterday, but today that track
has shifted north to a roughly Columbia, MO to Cincinnati, OH
line, which suggests more rain for us. South of I-74, NBM would
suggest a 40-60% chance for more than an inch of QPF by the time
this system departs and its faucet finally turns off across our
area late Tuesday. This would increase runoff into rivers which
have been running a bit on the high side recently - a couple
points along the IL still in flood - perhaps contributing to some
localized inundation along creeks, streams, and rivers, and
perhaps further delaying planting or inhibiting germination of
crop seedlings.
The deterministic models suggest a shortwave ridge will build in the
wake of this low, but differ on how long we`ll be dry before the
arrival of the next system - the track of which is also nebulous at
this point. Unfortunately, the dry portion of the work week (Tuesday
night through Wednesday is the most likely rain-free time period)
could be quite short with NBM bringing rain chances back up to 40+%
by Wednesday night-Thursday morning. Behind the first system,
lingering cloud cover and cool advection will make Tuesday the
coolest day with forecast highs in the mid to upper 60s north of I-
70, with a gradual warming trend (though increasing model spread,
given uncertainty in storm track) the remainder of the week.
Bumgardner
&&
.AVIATION... (For the 00z TAFs through 00z Sunday Evening)
Issued at 611 PM CDT Sat May 11 2024
VFR conditions expected the next 24 hours, with mainly a few
clouds around 10kft at times. Gusty northwest winds have been
tailing off recently, and should be about 5-7 knots by sunset
(01Z). Expect a trend toward the west/southwest overnight with
winds picking back up to 10-15 knots by mid morning Sunday.
Geelhart
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
Area Forecast Discussion
National Weather Service Lubbock TX
633 PM CDT Sat May 11 2024
...New AVIATION...
.SHORT TERM...
(This evening through Sunday)
Issued at 225 PM CDT Sat May 11 2024
A broad conveyor of isentropic ascent continued this afternoon well
north of a stationary front draped near the Rio Grande. This ascent
has been enhanced at times by a few ripples in southwest upper flow
downstream of an upper low near the Four Corners. One of these
ripples was sampled by morning RAOBs over Far West TX and can now be
seen about to pass MAF`s 88D as shown by SE winds at 700 mb veering
SW. This impulse is driving scattered to numerous elevated showers
and storms from Midland to Lubbock this afternoon with the
expectation for this activity to dwindle from west to east later
this afternoon from west to east as the H7 wave departs.
By this evening, NBM`s PoPs look too biased by multiple runs of the
HRRR that depict robust upslope storms from southeast NM racing east
and becoming elevated over the South Plains. While not unlikely,
believe we`re more likely to see a tamer version of this scenario
pan out hence only 20-40 PoPs. The greater signal for storms tonight
is across northeast NM under an increasingly difluent flow and nose
of ample moisture advection all taking aim ahead of the approaching
upper low. An uptick in WAA ahead of this low and veering low-level
flow will pull the stationary front north overnight as a warm front.
As this warm front becomes more N-S oriented toward daybreak over
the CWA, PoPs will favor areas off the Caprock where elevated ascent
is greatest. Farther northwest, it`s not out of the question that
the tail end of an MCS from nern NM grazes our southwest Panhandle
counties which could also throw a wildcard into the afternoon setup
in the form of an outflow boundary. Even without this outflow, the
surface pattern by midday becomes more interesting as a weak surface
low emerges anywhere from AMA and LBB with a dryline to boot. How
far east this dryline mixes is contingent on any lingering precip and
clouds off the Caprock. Given these scenarios in the past, wouldn`t
be surprised to see cool easterly flow off the Caprock retard the
dryline closer to I27 by the afternoon as shown by various higher
res models. As such, PoPs were nudged westward a bit. Severe
potential may be limited to a smaller E-W corridor if areas off
the Caprock fail to recover from earlier precip and clouds.
Still,areas immediately ahead of the dryline look to see around
1500 J/kg of MLCAPE with deep layer shear of 40-50 knots, so some
supercells (surface based this time) are on the table. Tomorrow`s
W-E gradient in high temps may need considerable sharpening if
stratus off the Caprock looks to more stubborn.
&&
.LONG TERM...
(Sunday night through next Friday)
Issued at 225 PM CDT Sat May 11 2024
Lingering showers Monday morning across the far southeastern TX
Panhandle will quickly come to an end around daybreak as the upper
level system tracks out of the region. Thanks to an overnight
front, northerly winds will help keep temperatures from climbing
too much with highs in upper 70s to low 80s expected. Shortwave
ridging will move into the region as the shortwave trough ejects
into the Central Plains which will influence relatively quiet and
warm conditions across the FA, with above seasonal normal
temperatures in the mid to upper 80s expected. Northerly winds
will begin to veer out of the southeast Tuesday as a surface low
over eastern NM develops. This southerly component to the wind
will work to pump in low level moisture from the Gulf of Mexico
beginning as early as Tuesday afternoon. Ensemble guidance
continues to hint at our next chance of rainfall Wednesday and
Thursday as ridging departs to the east as a shortwave trough
track through the desert southwest from the Baja Peninsula. Ahead
of the trough, disturbances in the flow aloft and subtropical jet
will provide efficient elevated instability across the FA for
shower and thunderstorm development. Strong to severe storms may
be possible with forecast models depicting a favorable environment
with MUCAPE values around 2000-3000 J/kg and increased amounts of
shear. Seeing that this is still a few days out, details on the
evolution and timing will become more clear and be re-evaluated in
the next forecast package.
Much warmer and drier conditions return by the end of the work week
as the upper level shortwave tracks out of the region and upper
level ridging builds back in. Northerly winds early Friday morning
will begin to back out of the southwest as surface troughing
develops and amplifies over southeastern CO. These conditions will
help influence above seasonal normal temperatures Friday in the mid
to upper 80s. Saturday looks to be the hottest day of the week in
the 90s area-wide as breezy southwesterly winds prevail around 15 to
20 mph.
&&
.AVIATION...
(00Z TAFS)
Issued at 633 PM CDT Sat May 11 2024
VCTS will continue at KLBB for the next 1-2 hours before moving
off to the east. Expect CIGs to lower into MVFR heading into
tonight with IFR developing at KCDS, KLBB, and KPVW heading into
early tomorrow morning. Scattered -SHRA/-TSRA will be possible
during the overnight hours at KLBB and KPVW as well, and
confidence is high enough to warrant TEMPO groups. Small hail
surface-to-aloft and variable gusts to 30 kt will accompany
overnight convection. CIGs will begin to improve tomorrow morning
with VCTS possible at KCDS during the mid-to-late morning hours
followed by renewed chances for severe thunderstorms at KCDS on
Sunday afternoon.
Sincavage
&&
.LUB WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SHORT TERM...93
LONG TERM....12
AVIATION...09
Area Forecast Discussion
National Weather Service Marquette MI
731 PM EDT Sat May 11 2024
.KEY MESSAGES...
- A few rumbles of thunder possible late tonight west, then
scattered thunderstorms to develop Sunday afternoon into early
evening, especially south central. There is a marginal risk
(5%) of large hail and/or damaging wind south central.
- Dry weather returns by Monday, continuing through Wednesday
afternoon.
&&
.SHORT TERM /THROUGH SUNDAY/...
Issued at 424 PM EDT Sat May 11 2024
Water vapor imagery and RAP analysis show nw flow from western
Canada to the Great Lakes region. The vigorous shortwave that
brought shra to Upper MI last night is now tracking into southern
Ontario. A much weaker shortwave is currently over central Lake
Superior/central Upper MI. Upstream, the next vigorous shortwave is
dropping se into northern Manitoba. Shortwave currently over the
area combined along with MLCAPE increasing to 100-300j/kg per latest
RAP has supported isold/sct shra development across central Upper MI
this aftn. A few rumbles of thunder have occurred from around
Escanaba into Menominee County where MLCAPE is maximized. To the e,
low stratus is noted along Pictured Rocks extending e and ne over
the lake. Current temps range from the 40s e along Lake Superior to
the lower 60s F well inland over western Upper MI.
Ongoing isold/sct shra over central Upper MI will end over the next
few hrs. Attention then turns to the shortwave currently over
northern Manitoba. It will reach northern Ontario Sun morning. In
response, a 35-45kt low-level jet develops into Upper MI late
tonight/Sun morning, leading to a good push of waa/isentropic ascent
and rather sharp theta-e advection. As a result, sct -shra should
develop into roughly the w half of Upper MI overnight, spreading
eastward Sun morning. Initial surge of theta-e advection may support
some -shra into western Upper MI this evening, but there is a good
layer of dry air from around 800mb to the sfc. Might be a few
sprinkles. Expect min temps tonight ranging from the low/mid 30s e
where skies will be mainly clear longest to the mid/upper 40s far w
where clouds increase before sunset.
After the initial waa/isentropic ascent pcpn moves across the area,
attention on Sun aftn turns to lake breeze aided cold front that
moves across the area. Timing of this feature will be coincident
with peak heating across the central, s central in particular.
Consensus model guidance has MLCAPE increasing to around 400-700
j/kg Sun aftn though NAM/RAP are up to 1000j/kg. Deep layer shear of
30-40kt will support storm organization and an isolated svr risk for
large hail and damaging winds. Wetbulb zero heights at 7-9kft are
supportive of a large hail risk while dry subcloud air/inverted v
profile will enhance potential of strong winds. Expect highs on Sun
in the 60s along Lake Superior w and also across the e into the mid
70s F interior west half.
&&
.LONG TERM /SUNDAY NIGHT THROUGH SATURDAY/...
Issued at 331 PM EDT Sat May 11 2024
A couple cold fronts will press through the Upper Great Lakes Sunday
evening, allowing a cool to seasonable airmass to break into the
region through at least mid-week. Ahead of the initial cold front on
Sunday, afternoon shower and thunderstorm development may occur if
we`re able to destabilize enough following the Sunday morning
isentropically/warm frontally forced showers. By 0z Sunday and the
start of this forecast period, the cold front looks to be draped
across the central UP with the aforementioned shower/thunderstorm
region out ahead stretching from Menominee County northeastward
into the eastern UP. The environment at this point should be less
conducive for any new convective development given the quickly
waning influence of the day`s diurnal heating. However, if a strong
or severe storm does develop earlier, guidance suggests enough deep
layer shear could sustain updrafts into the evening hours. However,
the window will be short lived given the cold front`s fast eastward
progression. By 3z, CAMS all suggest convective activity should be
outside of the forecast area.
Behind the cold front, a dry airmass will press into the region
while a secondary cold front moves through after midnight Sunday
night. This, in addition to surface ridging building over the area,
will sustain a dry couple of days for the forecast area. The daytime
high temperature gradient Monday and Tuesday should stretch from
near 50F by Lake Superior to the low-mid 60s across the south-
central. On Wednesday, more widespread 60s are expected, with most
areas outside of the immediate lakeshores and Keweenaw looking to
climb into the low-mid 60s. Overnight lows should be mostly in the
30s, with chances for sub-freezing temperatures in the interior-
central spots (20-30% chance). Fire weather concerns should be
mitigated by the near to slightly cooler then normal conditions and
light winds these days. But daytime mixing into a dry airmass aloft
may support RH values nearing 30% for some interior central and west
locations.
Mid-level ridging shifts through the region on Wednesday followed by
a shortwave pressing through Minnesota/western Ontario Wednesday
night. Consensus among the 12z deterministic guidance suite has this
pressing into our forecast area Thursday, supporting another round
of showers through the day. This contrasts some with the GEFS, EC,
and GEPS ensemble systems, where some members suggest precip could
start Wednesday night.
&&
.AVIATION /00Z TAFS THROUGH 00Z MONDAY/...
Issued at 729 PM EDT Sat May 11 2024
VFR conditions will prevail thru this fcst period at IWD/CMX/SAW. As
low pres drops into far northern Ontario tonight, a low-level jet
will develop into Upper MI late tonight into Sun morning, resulting
in 2-6hrs of LLWS at all terminals, lasting longest at IWD. The low-
level jet will also generate sct showers, but confidence in a
shower passing over any of the terminals is low. Not expecting
conditions to drop out of VFR if a shower does occur. More
showers/possible t-storm will develop Sun afternoon across
central Upper MI, possibly affecting SAW.
&&
.MARINE...
Issued at 331 PM EDT Sat May 11 2024
Winds are mainly expected to remain below 20 kts through the
entire forecast period, with some exceptions.
A warm front will lift through the lake late tonight and early
Sunday. Ahead of and behind the front, some isolated 20-25 kt wind
gusts will be possible. The stronger pressure gradient will be
Sunday across the east half and behind the warm front; however, the
increasingly stable airmass over the lake should work against mixing
the stronger southerly winds to the surface. Given the environment,
higher reporting platforms would be more likely to observed these
stronger winds then the surface buoys. A cold front will press from
west to east through Lake Superior through the day as well. A shower
or thunderstorm can`t be ruled out by afternoon across the east
half, but with the focus for convection being over Upper Michigan
and not Minnesota, the probability is low (20-30%). Behind the
front, high pressure will settle over the lake, supporting a few
days of mostly 20kts or less over the lake through at least midweek.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
None.
Lake Michigan...
Small Craft Advisory from 2 PM to 11 PM EDT Sunday for LMZ248-
250.
&&
$$
SHORT TERM...Rolfson
LONG TERM...JTP
AVIATION...Voss
MARINE...JTP