Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 05/25/21
Area Forecast Discussion
National Weather Service Dodge City KS
745 PM CDT Mon May 24 2021
...Mesoscale Discussion...
.MESOSCALE DISCUSSION...
Issued at 737 PM CDT Mon May 24 2021
Severe thunderstorms possible through midnight. The main hazards
will be winds gusting to 60 mph, hail up to 2" and very heavy
rainfall.
Low level jet developing with 0-6km shear 40knots or greater west
of highway 283. Severe thunderstorms are expected to continue and
possibly increase in coverage through early tonight as they move
east southeast across southwest Kansas. As these storms move east
shear and cape will decrease but still enough appears to be
present to continue the threat for severe thunderstorms capable of
producing large hail and strong winds.
&&
.SHORT TERM...(This evening through Tuesday)
Issued at 108 PM CDT Mon May 24 2021
As of 17z it appears that models were having some difficulty in
picking up on a west to east surface boundary that was moving
north across Scott and Lane counties. Satellite loop also
indicates cu developing along this boundary at this time. Along
this boundary SPC Mesoscale Analysis has 0-6km shear of 30 to 40
knots and nice low level shear (15knots 0-1km shear and 20-30knot
0-3km shear) so conditions are looking more and more favorable
that as storms develop in this area over the next few hours that a
the environment will be favorable for not only large hail,
baseballs, but also the potential exists that few tornadoes to be
possible across portions of west central Kansas.
Models earlier this afternoon also showing that these storms will
eventually begin merge into a cluster this evening as they move
across west central Kansas along the northern edge of a mid level
baroclinic zone as the 850mb winds increase. Again the RAP has
this mid level baroclinic zone much further north that what it may
end up being given the potential for convection late today as far
south as Scott and Lane counties. At this time given this
possible bias have shifted the best chance for convection further
south early tonight as these storms cross western Kansas.
As these storms track east overnight an outflow/surface boundary
will cross into southwest Kansas and the models are in decent
agreement with this surface boundary continuing to track southeast
during the day on Tuesday. By late day this surface boundary is
forecast to be located south and east of Dodge City. At this time
models appear to hold off convection until late day and by this
time the most favorable area will be south and east of Dodge City.
If the NAM is correct stronger 0-6km shear will be present late
day along this boundary along with mid level instability. If
convection does develop along this boundary late day severe
thunderstorms will be likely with hail up to baseballs being
possible.
.LONG TERM...(Tuesday night through Monday)
Issued at 108 PM CDT Mon May 24 2021
Early Tuesday night models were in fairly good agreement with a
surface boundary being located just south and east of Dodge City.
Late day heating, mid level instability combined with improving
0-1km moisture convergence along this boundary will favor
scattered thunderstorms early Tuesday night as an embedded upper
wave crosses the Panhandle of Texas and south central Kansas. Some
of these storms early Tuesday night may be severe with larger
hail and strong gusty winds being the main hazards south and east
of Dodge City.
Mid to late week a series of upper level troughs will cross the
Central Plains as a west to southwest flow establishes itself
across the western and central United States. With a surface
boundary oscillating north and south across western Kansas during
this time frame there will be ongoing chances for afternoon and
overnight thunderstorms as each of these upper level troughs
passes. Exactly where, at this time, is unclear given the
uncertainty on timing of each of these upper waves crossing the
Central Plains and where this surface boundary will be located. As
a result of this uncertainty will stay close to the latest
guidance on precipitation chances.
Highs mid to late week will range from the low to mid 80s north
of wherever this surface boundary will be located on that day to
around 90 degrees south of this boundary.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 426 PM CDT Mon May 24 2021
Severe convection in progress from near Scott City to near
Syracuse as of 2120z is expected organize into a mesoscale
convective complex over the next few hours. Used HRRR trends as a
template for convective impacts at the terminals. Confidence for
impacts is highest at HYS, where a convective TEMPO group was
included (03-07z Tue). Storms will most likely graze the DDC/GCK
airports with strong outflow possible; amendments are likely.
Models concur LBL will remain dry and convection free. Stratus is
expected to spread into HYS/GCK/DDC behind the thunderstorm
complex tonight. IFR is most likely at DDC/HYS, and again least
impacts at LBL. Winds will be highly variable this evening around
convection, and in the thunderstorm complex outflow through
tonight.
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 61 83 58 87 / 20 20 20 20
GCK 59 81 57 86 / 20 10 10 20
EHA 57 83 57 89 / 10 10 10 10
LBL 58 85 57 89 / 10 10 10 10
HYS 60 82 56 84 / 60 40 10 30
P28 64 84 62 87 / 20 30 40 10
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
MESOSCALE...Burgert
SHORT TERM...Burgert
LONG TERM...Burgert
AVIATION...Turner
Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
1148 PM EDT Mon May 24 2021
.AVIATION...
Observations support the atmosphere has quickly become stable below
5.0 ft agl with nocturnal longwave cooling. No additional shower
activity is expected through the remainder of tonight. Strong
anticyclonic flow trajectories supports ridging and the warm sector
over Southeast Michigan for tonight and Tuesday. Higher uncertainty
continues with regards to the potential of some shallow ground based
fog, particularly at PTK where rainfall occurred with the
thunderstorm. VFR conditions tonight with cirrus likely pushing
across the terminals. Forecast soundings support high mixing heights
on Tuesday with cloud bases up at 6.0 to 7.0 kft agl.
.DTW THRESHOLD PROBABILITIES...
* Low in ceiling at or below 5000 feet tonight and Tuesday.
* Low for thunder Tuesday evening.
&&
.PREV DISCUSSION...
Issued at 357 PM EDT Mon May 24 2021
DISCUSSION...
Warm and humid air continues making northward progress with the
front through Lower MI this afternoon. There remains a notable
contrast in surface temperature and dewpoint across the frontal zone,
especially with a decrease in clouds that occurred early toward the
southern border, however the wind/pressure field remains weak and
diffuse. Combine this with the ridge dominated flow aloft and
uncapped thermal profile for scattered convection speckled throughout
the warm sector as daytime heating peaks and then lingers into this
evening. Hourly mesoanalysis estimates of surface based CAPE around
1500 J/kg is shown to have a tall and skinny character in the latest
RAP model soundings but with a deep moisture profile supporting PW
around 1.7 inches. All of these elements result in scattered coverage
of a pulsey convective mode fueled by the high moisture content and
peak heating. Heavy downpours remain the primary hazard until the
bulk of coverage dissipates as boundary layer instability fades by
midnight.
Warm and humid conditions remain firmly in place for Tuesday along
with a repeat of scattered showers/storms fueled by afternoon
instability. Near record high temperatures are also in reach but
subject to cloud limitations during peak heating. That being said,
the records for the 25th are a low hanging 89 at Saginaw and Flint,
and 90 and Detroit.
The current Canadian Rockies low pressure system moves into the
northern Great Lakes by Tuesday night into Wednesday. This system
pulls a cold front into Lower MI which is already the focus for
another round of showers and thunderstorms in the Midwest during the
day Tuesday. The activity is expected to hold on into Lower MI while
transitioning from surface based into more of an elevated low level
jet forced pattern Tuesday night and Wednesday morning. This
transition favors greater coverage of showers while the late night
timing becomes a limiting factor for intensity, especially
considering the corridor of steeper mid level lapse rates slides to
the north. The western portion of the marginal day 3 SWO keeps the
door open for storm intensification prior to the cold front exiting
SE MI Wednesday afternoon into evening. This will be a close call in
terms of frontal timing and recovery of instability off the morning
activity.
Cooler air and dry conditions settle in post front which brings
temperatures back down toward normal Wednesday night and Thursday.
Readings briefly drop below normal by Friday as low temperature
projections are advertised in the 40s followed by highs only in the
upper 50s to lower 60s. The cooler air will likely be reinforced by
a pattern of showers moving in with the next upper level system
which has surface low pressure tracking through the Ohio valley.
High pressure of Canadian origin follows this system which allows
late May sun to aid in a temperature rebound for the weekend.
MARINE...
Light east/northeasterly winds below 15 kts will persist through the
evening as the pressure gradient relaxes over the central Great
Lakes. The frontal boundary retreats back over SE MI with winds
gradually veering to the southwest by Tuesday as a result. An uptick
in wind gusts to around 20 kts Tuesday afternoon/evening will be
possible in the wake of increasing southwesterly flow as a low
pressure system approaches from the west. Stronger gust potential to
around 25 kts exists Wednesday as the surface low and its attendant
cold front track across the upper Great Lakes, causing a gradual
wind shift from southwest to northeast. Several rounds of showers
and thunderstorms are possible throughout the week, with best
chances looking to be late Tuesday night into Wednesday and again
during the late week period.
HYDROLOGY...
Warm and humid air moves back into the region today and tonight
which makes scattered showers and isolated thunderstorms with heavy
downpours possible each day through Tuesday. Showers and storms then
become likely Tuesday night and Wednesday as a cold front moves
through Lower Michigan. Average rainfall totals in the 0.25 to 0.5
inch range are expected with locally higher amounts possible in
heavy downpours. Given recent dry conditions over the region,
flooding concerns are limited to just some ponding of water on roads
and in other similarly prone areas.
&&
.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
Lake Huron...NONE.
Lake St Clair...NONE.
Michigan waters of Lake Erie...NONE.
&&
$$
AVIATION.....CB
DISCUSSION...BT
MARINE.......SS
HYDROLOGY....BT
You can obtain your latest National Weather Service forecasts online
at www.weather.gov/detroit.
Area Forecast Discussion
National Weather Service Quad Cities IA IL
250 PM CDT Mon May 24 2021
.SYNOPSIS...
Issued at 250 PM CDT Mon May 24 2021
Another warm and muggy afternoon was unfolding across eastern Iowa,
northwest Illinois and northeast Missouri. Surface analysis depicted
a warm front stretching from central Minnesota southeast towards
central Iowa, with a cold front analyzed from central Minnesota into
far northwest Kansas. This put us right in the midst of the warm
sector, with ridging extending across the area from high pressure
centered over Tennessee. Temperatures as of 2 PM ranged from 78 in
Dubuque to 86 in Moline.
The aforementioned cold front is expected to slowly progress east
over the next 24 hours, and will be our primary weather concern
over the short term period.
&&
.SHORT TERM...(This Evening through Tuesday)
ISSUED AT 250 PM CDT Mon May 24 2021
[Key Messages]
*Isolated showers and storms late this afternoon and evening.
*Marginal risk of severe storms for Tuesday late afternoon and
evening; main concern is damaging wind gusts.
[Discussion]
As has been the case over the past few days, isolated showers and
storms will be a concern once again late this afternoon and evening.
Our 12z balloon showed a convective temperature of 83 F, which given
cloud trends over the past few hours should have zero trouble being
reached. In addition, a weak wave analyzed on SPC mesoanalysis was
centered in northwest Missouri and southeast Iowa, and could provide
some extra forcing needed for development. Indeed, all CAMs are in
agreement of storm initiation, and focus primarily west of a line
from Quincy IL to Dubuque IA for activity. No severe weather is
expected given marginal mid-level lapse rates and shear (0-6 km deep
shear is less than 20 kts), but steeper low-level lapse rates and
the presence of mid-level dry air may promote some gusty winds. What
is most certain, is that any storm will contain heavy rainfall given
PWATs of around 1.20-1.50" are in place.
Diurnally driven activity will diminish just after sunset, but a
renewed round of showers and isolated storms will be possible in
central and east central Iowa on the nose of a developing LLJ
tonight. However, most should remain dry with temperatures only
falling to near 70 or the upper 60s.
Next threat of precipitation potentially arrives mid Tuesday morning
according to the RAP and GFS, which show numerous to widespread rain
showers as a result of several pockets of CVA ahead of a 500 hPa
trough increasing lift across the area. These models are the most
aggressive on precip while the NAMnest, HRRR and NSSL WRF keeping
activity isolated or scattered in nature. This will be key for the
late afternoon and evening, which will need to be monitored for
additional showers and storms ahead of an approaching cold front.
If morning and afternoon precip coverage is less than most current
models advertise, then there will be a higher likelihood of showers
and storms forming in a prefrontal trough, which is forecast to be
centered from the Des Moines metro to near LaCrosse WI late
afternoon Tuesday. This activity would form in the 5-7 PM time
frame, and would arrive across our area during the evening. Some of
these storms may become strong or severe, and is very much dependent
on the amount of instability present. IF storms are able to fire,
then the primary concern would be heavy rainfall (high PWATS) and
damaging wind gusts (steep low-level lapse rates, high DCAPE and dry
air aloft). The risk for large hail and tornadoes is lower given
lack of deep layer shear needed for storm organization. The Storm
Prediction Center maintains a marginal risk across the area mainly
west of the Mississippi River.
Temperatures will be a challenge tomorrow given the uncertainty in
cloud cover and precip, which is leading to large variations in
guidance. Breaks in the clouds and precip will yield highs in the
upper 70s to low 80s, while those that see the opposite only reach
the mid 70s.
.LONG TERM...(Tuesday Night through Monday)
ISSUED AT 250 PM CDT Mon May 24 2021
A zonal flow aloft will result in a more changeable weather pattern
this week going into the holiday weekend. The first of several
systems will bring thunderstorms, possibly strong, ahead of a cold
front Tuesday night. A stronger system is still on track to bring
potentially heavy rainfall Thursday into Thursday night, followed by
sharply cooler temperatures Friday into Saturday.
Scattered thunderstorms will likely be underway Tuesday evening as
upper level forcing increases ahead increasing lift ahead of the
main upper level shortwave advancing across the northern plains.
These could certainly produce heavy rainfall rates due to continued
high dewpoints in the 60s to lower 70s and precipitable water over
1.5 inches. However, wind profiles would favor progressive storm
movement for only localized heavy rainfall like the past several
days. MLCAPE values exceeding 2000 J/KG, especially early evening
could lead to strong or isolated severe storms with primarily a
damaging wind threat, but this will be somewhat limited by the lack
of shear, which looks to be focused further north across MN into WI
under the axis of stronger mid level westerlies. Scattered showers
and thunderstorms will end with passage of the cold front, which
models generally have migrating southeast across the area between
midnight and 8 am.
Wednesday, the front progresses south into the Ohio River Valley
with our weather influenced by a drier airmass from high pressure
over southern Canada and shortwave ridging aloft. Sunshine and deep
mixing into the low level northwesterly flow should lead to highs
back into upper 70s to lower 80s. Dewpoints in the 50s will
lead to much more comfortable humidity levels.
A weak upper level shortwave may bring a few showers late Wednesday
night into Thursday as low level begins to return. Stronger deep
layer lift overspreads the area through the day Thursday ahead of
what is now trending to be a closed upper level low moving across
the northern plains into the upper MS River Valley Thursday into
Thursday night. Moisture return is shown returning precipitable
water values back into a 1.5 inches or higher range Thursday. This
will likely lead to widespread rain, possibly heavy, and a few
thunderstorms along and north of a wave of low pressure that is
shown rippling east roughly along the IA/MO border. A wide swath of
rainfall totals well over one inch looks possible from this system.
Friday into Saturday look dry and much cooler as high pressure
builds into the western Great Lakes. Temperatures will be largely
dependent on how long cloud cover lingers on Friday, which could
limit highs to only the 50s over the north, while 60s are mentioned
elsewhere. The dry air and clearing skies will lead to a very cool
Friday night with expected lows in the 40s. Saturday should recover
back into the 60s with sunshine and easterly winds.
Sunday into Monday will continue the slow day to day warming trend.
Low confidence chance POPs for showers are maintained in the
forecast due to possible impulses in the westerly flow aloft, but
high pressure at the surface may win out keeping these periods
dry.
&&
.AVIATION...(For the 18Z TAFS through 18Z Tuesday Afternoon)
ISSUED AT 1200 PM CDT Mon May 24 2021
VFR conditions are primarily expected at all terminals over the next
24 hours. As has been the case over the past few days, isolated
showers and storms are expected due to daytime heating this
afternoon and evening. Due to little agreement in guidance, did not
include mention in the TAFs due to low confidence of direct impact.
By Tuesday morning, an MVFR cloud deck may impact KCID/KDBQ as the
low-level jet meanders into the area with a train of moisture.
Handled with a SCT015 mention at this time.
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
SYNOPSIS...Speck
SHORT TERM...Speck
LONG TERM...Sheets
AVIATION...Speck
AREA FORECAST DISCUSSION
National Weather Service Sioux Falls SD
1038 PM CDT Mon May 24 2021
.SHORT TERM...(This Evening through Tuesday)
Issued at 256 PM CDT Mon May 24 2021
Surface boundary is currently draped from central NE northeastward
toward southwest MN. Ahead of it, a cumulus field has developed
but any better agitation to this field has been confined to
central NE. Surface heating has been tempered across much of
Nebraska throughout the day owing to lingering mid/upper level
cloud cover. Mid afternoon RAP mesoanalysis suggests a pool of
roughly 500 J/kg of MLCAPE from the MO River and points south with
as much as 30-40 kts of effective deep layer shear. Guidance
shows the potential to build up to 1000 J/kg of MLCAPE with the
better deep layer shear weighted to locations near the boundary.
Latest high-res CAMs have reflected this change in progged
instability and have both delayed the timing of CI as well as
decreased the intensity of convection. If established deep
convection can form near the boundary in the area of better deep
layer shear, could still see the potential for large hail up half
dollar size in borderline supercell structures. As storms move
eastward, they will likely take on more of a multicell
characteristic with any organized bowing structures carrying a
damaging wind threat to 60 mph. The Marginal risk in place from SPC
still seems appropriate given the low end potential for a couple
strong/severe storms although the risk appears lower than was
anticipated.
Surface boundary sinks southeast through the day Tuesday with still
a bit of uncertainty whether it fully clears our forecast area prior
to late afternoon or not. At least some indication that it may be a
bit slow to exit Ida and Buena Vista leaving a small chance at a
rogue thunderstorm however better chances look to be south of our
area. Otherwise, mostly sunny skies are expected with westerly winds
a tad breezy and temperatures a few degrees either side of 80
degrees.
.LONG TERM...(Tuesday Night through Monday)
Issued at 256 PM CDT Mon May 24 2021
Brief period of shortwave ridging will keep quiet conditions in
place for Wednesday although cooler east/northeasterly winds will
keep temperatures in the upper 60s to 70s.
Wednesday night into Thursday will bring a more active period as a
pronounced shortwave exits the Rockies toward the Northern Plains.
Guidance has been somewhat variable on how far north to build the
better instability plume with some tendency over the last 24 hours
for a northern shift. While this would keep the better surface based
instability in Nebraska, at least modest elevated instability would
build north into our coverage area. This would signal the likelihood
of the development of one or more eastward propagating MCS clusters.
Any severe threat is conditional on the northward advection of
adequate instability but at the minimum, it look like many areas
will receive some welcome rainfall with ensemble probability
favorable for most locations to see around or in excess of half an
inch. SPC currently has our MO River counties covered in a Slight
Risk with a Marginal Risk elsewhere which will likely evolve as
better model consensus emerges.
Any remaining convection should exit through the morning hours
although with the mid/upper level low overhead, could see some
additional shows pinwheel through the area during the afternoon.
Temperatures Thursday and Friday will be on the cool side of
normal (mainly 60s) with dry conditions expected Friday.
Next wave and tandem front eject for the weekend and could bring
another chance of showers/storms to the region. Both ensemble and
determinist members still display a large variability in the more
favored timing however. Temperatures should exhibit a gradual
warming trend as well with likely some influence from any daytime
showers/cloud debris.
&&
.AVIATION...(For the 06Z TAFS through 06Z Tuesday night)
Issued at 1035 PM CDT Mon May 24 2021
Scattered convection will diminish after 06Z, with MVFR/IFR
ceilings lifting northward out of NE/IA and into northwestern IA
toward 12Z. These clouds will dissipate after 15Z. Light
southeasterly winds overnight will transition to
west/northwesterly on Tuesday, gusting 20 to 25 kts through the
afternoon. Winds will then drop off by Tuesday evening.
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
&&
$$
SHORT TERM...Kalin
LONG TERM...Kalin
AVIATION...JM
AREA FORECAST DISCUSSION
National Weather Service Hastings NE
728 PM CDT Mon May 24 2021
...Aviation Update...
.DISCUSSION...(This evening through Monday)
Issued at 501 PM CDT Mon May 24 2021
General overview of the entire 7-day forecast:
Precipitation trends:
Overall, we remain in a fairly active late-May weather pattern.
However, the vast majority of rain/thunderstorm chances (Pops) are
concentrated tonight into Tuesday morning, Wednesday evening-
overnight and then again this weekend into early next week
(Memorial Day). In between these myriad Pops, we are actually a
maintaining at least a 24-hour dry period centered on Thursday
night-Friday daytime, which if nothing else will allow those areas
that could see a bit too much rain between now and then a chance
to dry a bit.
Severe thunderstorm/flooding concerns:
Per SPC, our entire coverage area (CWA) remains in a
Marginal/Slight Risk for late this afternoon into tonight (seems
mostly justified...especially within western/southern counties).
The Day 2 then features a Marginal Risk for roughly our
southeastern 1/3, although this forecaster feels this is probably
most justified for possible lingering strong to marginally-severe
storm right away in the morning, and less-so for the "main"
afternoon-evening time frame, which unless a few of the latest
short term models (NAM/HRRR) are really out to lunch, the later-
day threat should focus at least slightly south-southeast of our
CWA altogether. Turning to Day 3, Wednesday evening-overnight is
then our next fairly legitimate threat of severe storms and
possible hydro issues, with SPC already assigning Slight Risk to
the entire CWA (and WPC assigning a Slight Risk of excessive
rainfall to most of the CWA as well). With all the shorter-term
concerns just in the next 12-18 hours, this discussion will not
really further address this Day 3 severe/hydro threat, but want
to make it very clear that this looks like a somewhat later,
mainly post-sunset "show" for most of the CWA, and COULD feature
potential for one of our first somewhat-organized damaging wind
threats of the season. Plenty of details to pin down between now
and then.
Temperature-overview:
Certainly no major changes from previous forecast, but if anything
highs were trended down at least a few degrees in the longer term,
including days such as Saturday (down roughly 5 degrees most
areas). More specifically, the majority of the next week looks to
feature highs in the 70s and lows in the 50s-low 60s. However, a
couple of warmer/cooler exceptions look to be Tuesday-Wednesday
daytime (better chance of warmer highs in the low 80s UNLESS
clouds are more abundant than expected)...and Thursday night (one
of the cooler-looking nights we have seen in a while with lows
perhaps as chilly as the mid-upper 40s most areas).
With the big-picture messages covered above, will now move on to a
look at current conditions and a more detailed look SOLELY at the
next 36 hours/3 forecast periods:
Current/recent weather scene as of 4 PM
(including tying it in with very short term expectations):
Although it`s FAR too early to start downplaying our late
afternoon-evening severe weather threat too aggressively, will
state up front that the widespread low clouds and only
limited/fleeting patches of sunnier skies so far today have not
only caused high temperatures to fall a good 2-5+ degrees short of
early-morning expectations (most areas should top out 73-78), but
it`s also not done any favors for bolstering our severe storm
threat, at least in the near-term (obviously a good thing). In
short, it`s becoming increasingly-clear that the "main show" of
severe storms in the Central Plains this evening should focus
within the GLD/DDC coverage areas in western KS, with our CWA more
along the "fringes of the action" but with a few severe storms
still quite possible. In the mid-upper levels, water vapor
satellite imagery and short term model data reveal broad west-
southwesterly flow overhead, with our region being brushed by the
southern end of a shortwave trough mainly lifting northeastward
from the NE/WY/SD border region. Earlier today, a pesky area of
lighter showers (Nebraska CWA) and non-severe thunderstorms
(mainly KS zones) marched from west-to-east across our area before
moving out/fading away. Most places didn`t receive much rain from
this, but localized parts of mainly KS received in excess of
1-inch. Tying this in with ongoing/upcoming weather, the primary
outflow boundary from the activity overnight-earlier today settled
into northwest/west-central KS, where ongoing severe storms are
most robust. Meanwhile, the extensive clouds and resultant lower
instability/less-focused surface convergence in our CWA has kept
us quiet thus far. At the surface, southerly breezes generally
sustained 10-15 MPH/gusting up to around 25 MPH especially in
eastern zones dominates the current scene.
Late this afternoon-overnight:
We are closely watching mainly our far western/southwestern zones
for the primary possible severe storm threat through sunset.
Latest analysis indicates halfway decent (but not extraordinary)
0-1 kilometer mixed-layer CAPE of 1000-1500 J/kg over our CWA, in
the presence of decent bulk shear as high as 40+ knots west (lower
east). These parameters are certainly supportive of at least
transient supercell structures, but the longer it takes for
convection to develop north-northeastward into our CWA, the more
"iffy" a sustained supercell threat might become as we gradually
lose low-level instability this evening. Certainly if/when severe
storms move in, large hail/damaging winds mainly into the ping
pong ball/60 MPH range are the primary threats, although at least
a brief/transient tornado threat could also exist through mainly
sunset or so. Putting some faith in the last few HRRR runs, it`s
starting to look like our far western zones might be pretty much
the only pre-sunset threat area, while the earlier-initiating
intense storms over western KS instead dive more east-southeast
into central/south central KS and miss our area altogether. Even
if we miss out on the main surface-based threat, at least slightly
elevated strong to marginally-severe storms could blossom later
this evening into northern/even northeast parts of the CWA with
mainly a hail threat. Turning to the later-night hours, our
biggest concern is whether or not a generally west-to-east
oriented storm cluster develops over and/or drifts eastward into
our KS zones along the nose of a roughly 40KT low level jet
(evident at 850 millibars). Both the HRRR/NAMNest show this
"secondary show" in our south to some degree, and if this occurs
the primary concern would in theory turn to hydro. Although most
of our southern CWA has been fairly dry over the past week (since
the localized/significant flooding on the 16th far south),
anything more than 1-2" of rain in a short time could start
causing minor flooding pretty readily, so this will need watched.
Given the fairly dry past week, along with lack of a pronounced
signal for 2+" of rain in the 12Z HREF QPF probability matched-
mean, opted against a formal Flash Flood Watch, but will continue
to carry overnight hydro concerns in our local HWO. Meanwhile,
most of especially our north half should have a dry late night,
and Pops are much lower to non-existent here. Could foresee some
fog development depending on cloud trends, but not enough
confidence to introduce to forecast. Low temps overnight aimed mid
50s far west-central north...to upper 50s-low 60s most places.
Tuesday daytime:
As already touched on, do not have a lot of confidence in the
going Marginal Risk of severe in our southeast 1/3, as normally-
reliable HRRR/NAMNest strongly suggest that the "main show" in the
afternoon-evening should focus at least slightly south-through-
southeast of our CWA, within the main subtle surface convergence
zone along a weak trough axis progged to cross our area during the
daytime hours. However, at least right away in the morning (mainly
sunrise-10 AM, we could still see a cluster of strong to perhaps
marginally-severe storms ongoing over mainly our KS zones
(although the main threat should be lingering heavy rain). Overall
though, the big story for this period is that most of the CWA
looks dry for most of the day, with even a decent chance of
increasing sunshine from west-to-east, especially in the
afternoon. Should this occur, confidence is higher than today in
reaching forecast highs, which were changed little from previous
and mainly aimed 80-82. Afternoon breezes generally around 10 MPH
from a westerly direction most areas behind the aforementioned
weak trough axis.
Tuesday evening-night:
Confidence is growing that this already-mostly-void of PoPs period
will be even more outright-dry, and other than a slight chance of
early-evening storms in our extreme southeast (Mitchell Co area),
have the rest of the night dry with fairly high confidence. With
rather light/variable breezes anticipated, later shifts will have
to take a closer/better look for fog potential, but no big signal
at this time. Low temps generally looking about 5 degrees cooler
than tonight, mainly mid 50s most areas, but ranging low 50s far
northwest to upper 50s far southeast.
&&
.AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Wednesday)
Issued at 728 PM CDT Mon May 24 2021
Ceiling/visibility:
Although a brief period of VFR ceiling could occur mainly within
the first few hours this evening, and a more sustained period of
VFR is likely during much of the latter half of the period
(Tuesday mid-morning through afternoon), the majority of these
first 12-15 hours overnight/early Tuesday morning should feature
sub-VFR with even brief IFR not out out of the question. As for
visibility, have maintained no worse than low-end VFR throughout,
but any heavier storms this evening could obviously result in sub-
VFR briefly, along with perhaps some light fog late tonight-early
Tuesday.
Precipitation/thunderstorms:
Will continue with a 6-hour window of opportunity for
thunderstorms right out of the gate (00-06Z), but with confidence
in coverage still a bit on the lower side even at this very close
range, have refrained from any prevailing mention and simply gone
with "vicinity" (VCTS).
Surface winds:
With the obvious exception of any possible convective outflow this
evening-overnight (which could briefly greatly increase speeds and
result in erratic direction for up to a few hours), no major wind
issues expected. This evening, southerly winds up to only around
10-15KT will be common. Late tonight into the day Tuesday,
direction will gradually become more westerly behind a passing
weak front, but speeds should largely only around 10KT.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
DISCUSSION...Pfannkuch
AVIATION...Pfannkuch
Area Forecast Discussion
National Weather Service Goodland KS
749 PM MDT Mon May 24 2021
.UPDATE...
Issued at 735 PM MDT Mon May 24 2021
First round of storm activity for the day is over. Focus now turns
to the next round that should form in the next couple hours. This
second round will form over southern part of the forecast area as
the LLJ nose moves up. Latest model data shows little to no CINH
over the southern part of the forecast area between the CO border
and Hwy 83 for elevated parcels between 700-800mb. Effective shear
looks to be 30 kts or so, increasing north toward I-70 to 40 kts
or so.
Am thinking a slight shift to the south with the storm
chances is warranted based on the current position of the storms
south of the forecast area. Am thinking these storms are feeding
off the LLJ nose, which lines up with the data shifting the storms
slightly further south. These storms should be elevated, leading
to a main risk of large hail.
&&
.SHORT TERM...(This afternoon through Tuesday)
Issued at 1135 AM MDT Mon May 24 2021
17Z WV imagery and RAP analysis indicate CWA on southern periphery
of trough and associated jet streak, which was centered over the
northern plains. At the surface, fairly widespread stratus remains
over the center portions of the area with fog and even measurable
drizzle occurring along Interstate 70.
Main forecast concerns will be thunderstorm chances and severity
this afternoon and evening.
While stratus deck has complicated forecast , this should continue
to mix out through the afternoon and with dewpoints in the lower
60s, will not take much insolation for atmosphere to destabilize.
With MLCAPES in the 1000-2000 j/kg range and effective shear in
the 35-50 kt range expect environment to be favorable for
development of severe storms. For initation, looking at two areas
of initial thunderstorm development. The first will be along
east- west oriented outflow boundary across southern CWA. Skies
have cleared in this area and with apparent triple point forming
along it, think forcing will be strongest in this area.
A secondary area will extend to the north of Tribune towards
McCook, although recent observations seem to suggest this
convergent area has diminished some what, which lowers confidence
for this area being a primary development area. If storms do not
develop in this area, may have to wait until the evening period
before any storms forming over Colorado can make it into the area.
For threats, large hail appears the most likely threat with
stronger storms, but given supercell potential and aided by
differential heating and backed winds along outflow boundary think
possibility for a tornado remains. Right now, it appears favored
area will be in the Greeley-Wichita county area along
aforementioned outflow boundary. Should areas farther north
destabilize and convergence along trough intensify along a
Goodland to McCook line, may see a threat for a brief tornado or
land spout given the strong low level instability along this
boundary.
Low level jet intensifies in the evening and will support the
development of more widespread precipitation along and north of
H85 frontal zone which may be accompanied by a few larger hail
storms, but with storms not being rooted in boundary layer shear
profiles will not be as strong as the afternoon. Finally,
precipitable water values over an inch and recent trends with
precipitation support the threat for heavy rain. A few areas
received heavy rain last night may be more at risk for flooding,
but confidence not high enough in heavy rain lining up with these
areas to warrant a watch.
Cold front will sweep through the area overnight, clearing out any
fog and storms through the morning hours and ushering in a bit of
quiet weather.
.LONG TERM...(Wednesday through Monday)
Issued at 117 PM MDT Mon May 24 2021
The long term period looks to be unsettled though there should be a
few days with quieter weather. High temperatures should be near to
slightly above average through the week. Potential for slightly
below average temperatures next week.
Wednesday starts with a chance for severe weather during the
afternoon and evening hours with the main threat currently favoring
locales east of Hwy 83. With the area under southwest flow aloft,
there is a chance for a shortwave to move through the area during
the afternoon hours. Guidance is also suggesting that a surface low
will move off the Front Range and into Western KS. Finally, guidance
is suggesting that MLCAPE could reach above 2000 J/KG along with
lapse rates greater than 8C and effective shear reaching 40 knots.
It is still a bit early to assume that those parameters will hold
and be exact, but they do suggest that instability will be present
should storms form. High temperatures are expected to reach the 80`s
though how high they go will depend on when/where cloud cover forms.
Thursday and Friday are forecasted to be a bit quieter as a cold
front moves in from the northwest late Wed/early Thur and brings
slightly cooler temperatures and drier air. The upper air pattern
aloft is expected to be more laminar during these days and higher
surface pressure is expected to move into the Plains. With all of
this in mind, Thursday and Friday will have lower POPs and sunnier
skies are more likely though an isolated thunderstorm can not be
ruled out due to daytime heating and dewpoints potentially reaching
the mid 50`s. High temperatures are expected to be in the mid 70`s
to lower 80`s.
For the weekend, more uncertainty in the forecast as guidance
diverges in the expected solution for the surface pattern. Guidance
agrees on the upper level pattern transitioning to a broad ridge
over the East-Central CONUS with a trough moving into the Western
CONUS. At the surface, guidance does keep lower pressure to the
southwest of the Tri-State area with higher pressure north and east.
However, the GFS bring the center of the low pressure closer to the
area Sunday while the ECMWF keeps the higher pressure over the area.
The closer the low pressure, the greater the synoptic lift will be
present for storms. Meanwhile the pattern supports Gulf of Mexico
moisture moving north into the area similar to the past week. So
depending on how things set up, there will be a chance for
afternoon/evening storms through the weekend with the potential for
severe weather as well. This will become clearer as we get closer to
the weekend.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 505 PM MDT Mon May 24 2021
Low VFR to sub-VFR ceilings are expected to persist through the
TAF period due to ongoing thunderstorms in the area and the large
cloud field extending across portions of NW Kansas. The storms and
clouds are expected to move east. Storms are expected to move into
the vicinity of MCK terminal from TAF issuance until 06Z with
lightning possible, then later after 11Z as a cold front sweeps
across the High Plains. Storms have moved east of GLD and is
expected to remain clear of storms until 06Z. From 06Z-12Z storms
could move into the vicinity of the terminal as the front passes
through. When the storms move over the terminals, MVFR conditions
could be possible with reduced visibilities from heavy rainfall.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
UPDATE...JTL
SHORT TERM...JRM
LONG TERM...KAK
AVIATION...KMK
Area Forecast Discussion
National Weather Service Grand Rapids MI
1036 PM EDT Mon May 24 2021
LATEST UPDATE...
Aviation
.SYNOPSIS...
Issued at 239 PM EDT Mon May 24 2021
- Gusty winds Tuesday
- Stronger thunderstorms later Tuesday into Wednesday AM
- Much cooler and wet for the CWA for later Thursday into Fri night
&&
.UPDATE...
Issued at 1019 PM EDT Mon May 24 2021
Do not see much of a threat of showers overnight, so removed what
small pops we had left in the forecast. The 850mb low level jet
does ramp up and move in from the west and northwest tonight, but
it does not appear that it will be generating any precipitation.
The HRRR and 3km NAM are both for the most part dry tonight. The
models being dry is likely attributable to little to no
instability and ridging aloft.
&&
.DISCUSSION...(This evening through next Monday)
Issued at 239 PM EDT Mon May 24 2021
- Gusty winds Tuesday
On Tuesday...deep southwesterly flow develops. As we heat up during
the day...bufkit overviews from the GFS and NAM 3KM suggest that
inland areas will mix into the 30 to 40kt wind range. These values
are slightly below wind advisory criteria...thus no headlines are
planned. Along the lakeshore...the mixing height will be much
lower...thus less wind will occur there. As a result...Tuesday is
looking like a windy and warm day for much of the region.
- Stronger thunderstorms later Tuesday into Wednesday AM
Instability is shown to build during Tuesday afternoon and models
are showing a few thunderstorms developing. Gusty winds could
accompany any heavier downpour. The 12z HRRR surface wind gust plot
actually shows pockets of higher wind gusts with the precipitation
roughly 21z Tuesday to 01z Wednesday. Then for Tuesday night into
Wednesday morning...the frontal zones drops in from the northwest.
Model guidance shows the instability decreasing along this zone as
it moves into the CWA during the night. ML CAPE values are shown to
mainly be below 500 j/kg. In addition the axis of higher bulk 0 to
6 km shear is shown to be lagging behind the front. So it appears
there will be a line of showers and storms moving in from the
northwest through the night...diminishing as they do. Some
instability tries to reform Wednesday morning over southeast zones
prior to the front clearing the CWA...so thunderstorms could
restrengthen then.
- Much cooler and wet for the CWA for later Thursday into Fri night
While model guidance is not on the same page with the timing and
strength of this next wave of low pressure...they do show it
tracking eastward...just south of the CWA. This puts the CWA on the
colder side of the storm...and it will indeed draw down a chilly
airmass from Ontario. Some of the model guidance is showing temps
of at least 15 degrees below normal for the end of the week. The
GFS and GDPS surface temps for example show the values stuck in
the 40s for Friday north of Grand Rapids. Models have trended
lower with the QPF for this event with most showing a half inch or
less. However the DGZ is shown to moisten up and there is some
lift shown in that zone so confidence is relatively high that we
will see some widespread rain. We will maintain the high POPs for
the passage of this system.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 1031 PM EDT Mon May 24 2021
VFR will dominate the weather overnight as a brief ridge will be
over the region. Clouds will continue to increase overnight.
Winds will shift to the southwest and increase Tuesday morning and
afternoon. Gusts upwards of 30 mph are possible Tuesday
afternoon. Another round of showers and thunderstorms will be
possible late Tuesday afternoon through Tuesday evening. Showers
are expected to get heavier overnight Tuesday into Wednesday
especially at GRR and MKG.
&&
.MARINE...
Issued at 239 PM EDT Mon May 24 2021
Winds and waves will increase considerably Tuesday even with the
limited mixing height as the surface pressure gradient tightens
up ahead of the front. The south to southwesterly flow will favor
the northern zones for the highest waves. We will issue a small
craft advisory for this event.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...None.
LM...Small Craft Advisory from 8 AM Tuesday to 8 AM EDT Wednesday for
LMZ844>849.
&&
$$
UPDATE...Duke
SYNOPSIS...MJS
DISCUSSION...MJS
AVIATION...Ceru
MARINE...MJS
Area Forecast Discussion
National Weather Service Wichita KS
739 PM CDT Mon May 24 2021
...Evening mesoscale update...
.MESOSCALE DISCUSSION...
Issued at 734 PM CDT Mon May 24 2021
BOTTOM LINE UP FRONT: We continue to monitor a conditional severe
weather threat across parts of north-central KS through tonight,
with strong, gusty winds and perhaps some hail being the main
threats.
DISCUSSION
As of 00z/7pm, a SFC low was centered along the CO/KS border (south
of Goodland), with a SFC boundary draped northeast into north-
central KS. Recent RAP analysis suggests the nocturnal LLJ is
developing, but is on the weaker side, and VWP data from KICT points
to this as well. Despite the weaker nature of the LLJ, it should
increase moisture convergence/lift, some, along the SW-NE
oriented SFC boundary this evening. Based on recent radar
imagery, we may already be seeing this process underway. Mid/upper
flow is forecast to weaken with time overnight, keeping effective
shear, and possibly the steering flow, on the weaker side. Still,
some eastward propagation of ongoing, or new, storms is possible
into portions of north-central KS through the night where mid-
level temps are a bit cooler and inhibition is the weakest. The
LLJ veers and weakens fairly quickly overnight, which may tend to
be a limiting factor for maintenance of convection overnight,
possibly limiting how far south and east the thunderstorm threat
will extend. Storms that manage to reach north- central KS will
probably be running into a weak shear/weakening instability
environment, and this should keep the threat of severe weather on
the lower side through tonight. However, effective shear of
25-35kt and MUCAPE of 500-1000 j/kg could support some hail with
any sustained and/or rotating updraft. Gusty winds will be
possible as well, especially if any clustering or upscale growth
occurs. If a severe storm were able to develop/reach our area,
the best chance would be across Russell, Barton, Lincoln, with a
much lower threat further south and east due to stronger
inhibition and weaker shear.
Martin
&&
.SHORT TERM...(This evening through Wednesday night)
Issued at 312 PM CDT Mon May 24 2021
Water vapor imagery shows the subtropical moisture plume remains
in place from central/east TX into the Upper Mississippi Valley.
Meanwhile, closed upper low is situated over southern Saskatchewan
with shortwave energy extending from this feature down into the
Central Rockies. At the surface, rich moisture remains across the
southern and central Plains with a weak surface trough extending
from northeast Nebraska into far western KS.
Storms have developed along the weak surface trough over far
western KS in an area of extreme instability and around 40kts of
effective shear. Just like the last few days, a weak impulse is
embedded in the mid/upper level moisture plume and is keeping
some light showers and drizzle around for areas generally along
and southeast of the KS Turnpike. Should see an overall decrease
in the light showers/drizzle over eastern KS as sunset approaches
with attention turning to the convection over western KS.
With lack of strong mid/upper flow, the western KS activity will
take it`s time working east this evening. Would also not be
surprised to see some backbuilding on the southwest side of this
complex as 850mb jet veers, creating decent moisture transport
into the storms. So feel that our northwest counties will have the
highest chance to seeing storms this evening, generally after
around 02z. With weakening mid/upper flow the further east the
storms track, confidence is low on how intense they will remain.
At this point would be shocked if they held together and moved
into south central KS tonight, so will leave the highest pops up
along I-70.
Messy convective forecast setting up for Tue. Both the GFS and NAM
have been consistent in tracking some energy out of central/west
TX and across central/northern OK on Tue. Feel that some of this
maybe convectively induced, but still feel it`s a good
possibility. This would keep at least some light showers going
over southeast KS for the morning hours. With plenty of moisture
and instability remaining in place for Tue, the big question will
be the location and convergence along any boundaries. Dryline
dosn`t look as defined as it is today across western KS and the
GFS is more agressive with convergence along the surface trough
over northern/central KS compared to other models. Would also
think overnight convection would lay out a boundary that may need
to be watched. Right now focusing on two areas of possible storm
development Tue afternoon. One over the OK Panhandle where
extreme instability will be located and some backing of the sfc
winds in the late afternoon should enhance convergence. The second
area will be over north/central KS where a weak surface
trough/wind shift maybe located, along with possible outflow
boundary.
By Wed afternoon, another shortwave will be tracking over the
Northern/Central Rockies with some additional energy lifting out
of the Desert Southwest. This should set the stage for another
round of severe storms over the High Plains of western KS and
western Nebraska as some better large scale lift and stronger
mid/upper winds move into the High Plains. Feel most of the area
should remain dry during the day Wed. Confidence is high in an MCS
will track across central/southern Nebraska and possibly northern
KS Wed night.
.LONG TERM...(Thursday through Monday)
Issued at 312 PM CDT Mon May 24 2021
Still good model agreement on an upper shortwave tracking across
the Northern Plains Thu which will allow a weak cold front to move
through the forecast area. This will provide the focus for storms
Thu afternoon and evening. With an abundance of instability and
25-35kts of deep layer shear, confidence is high that any storms
that develop along the boundary will be severe. The main question
is the position of the front by the afternoon hours. NAM and ECMWF
are both faster compared to the GFS, so this will be something to
keep an eye on.
We look to get in a more zonal upper flow pattern for Fri with the
highest storm chances west of the forecast area. Some upper energy
will start to move onshore over the western CONUS for Sat and
especially Sun and will bring back storm chances, especially for
the High Plains. At this point, Sun evening through Mon look like
our best period to get convection, as the upper energy starts to
directly impact the area.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 646 PM CDT Mon May 24 2021
* TSRA possible through tonight (mainly north-central KS)
* Low CIGs and DZ through TUE AM (mainly southern KS)
A moist, southerly flow will continue to favor low CIGs and DZ over
the next 12-18 hours, especially across southern KS. From western
into northern KS, the threat of DZ is less certain. Of more
importance there is the threat of TSRA. Over the past couple of
hours, TSRA across western KS haven`t moved much, but we may begin
to see some eastward propagation into north-central KS through
tonight. For continuity`s sake, I left a VCTS mention in at
KRSL/KGBD, but confidence is low regarding how far east this
threat will extend tonight. The low confidence TSRA forecast
extends into Tuesday as well. At this time, it appears that a
surface boundary draped across parts of central KS may provide a
focus for TSRA development Tuesday afternoon. A surface low
moving out of southwest KS may provide a focus as well. Given the
lower confidence, I opted to keep TSRA out of the TAFs for TUE
for now, but stay tuned for updates.
EXTENDED PLANNING OUTLOOK: TSRA and low CIGs will continue to be a
potential concern over the next few days, but it should be noted
that this is a lower confidence pattern for TSRA.
Martin
&&
.PRELIMINARY POINT TEMPS/POPS...
Wichita-KICT 65 81 64 84 / 20 30 40 10
Hutchinson 65 82 61 85 / 30 30 50 10
Newton 65 79 62 83 / 20 30 50 10
ElDorado 65 79 63 83 / 20 50 40 20
Winfield-KWLD 66 81 64 84 / 20 40 40 20
Russell 62 80 58 84 / 50 30 20 30
Great Bend 62 81 59 84 / 30 30 20 20
Salina 66 80 60 86 / 30 30 40 20
McPherson 65 80 60 84 / 20 30 50 10
Coffeyville 65 77 65 82 / 30 60 50 40
Chanute 65 78 65 82 / 30 60 50 40
Iola 65 77 65 82 / 20 60 50 40
Parsons-KPPF 65 77 65 82 / 30 60 50 40
&&
.ICT WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
MESOSCALE...RM
SHORT TERM...RBL
LONG TERM...RBL
AVIATION...RM
Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
640 PM CDT Mon May 24 2021
.UPDATE...
Issued at 631 PM CDT Mon May 24 2021
Updated to include 00z aviation discussion below.
&&
.SHORT TERM...(This evening through Tuesday night)
Issued at 229 PM CDT Mon May 24 2021
The key messages in the short term are continued chances for
thunderstorms later today. A few storms could produce damaging winds
and large hail. Then on Tuesday red flag conditions are possible as
drier air moves in behind the front and winds gust near 25 to 30 mph.
Today and tonight - Early afternoon surface analysis showed a
diffuse cold front approaching I-35, but this was barely discernible
except for the dewpoint field, and the gradient was quite relaxed
across the CWA. Rap 500mb heights and Water Vapor imagery showed a
shortwave trough across eastern South Dakota. Over the next 12 hours
that shortwave trough will lift towards northern Minnesota. The 250
mb jet will increase as well, and this should provide enough forcing
for more widespread showers and thunderstorms to develop. MLCAPE
values of around 750 to 1000 J/kg are marginal for severe weather,
and so is the linear wind shear profile. Still expect a few stronger
pulse-type cells to develop, so the Marginal Risk for severe storms
seems very accurate for later this evening and early tonight.
As for timing, did decrease the rain chances during the afternoon
and evening. It looks like the better chances will be after sunset
when the upper level forcing arrives. The HiRes models seem to
indicate this trend as well.
Tuesday and Tuesday night - The weak frontal boundary will continue
eastward. Forecast soundings show dry and breezy inverted-V
soundings. The HREF min RH drops to around 25 percent in the wake of
the frontal boundary. This will set the stage for dangerously low
fire weather conditions Tuesday afternoon across western and central
Minnesota, which could extend into eastern Minnesota.
Meanwhile farther east there will be more moisture. That should the
RH values around 30 to 40 percent in western Wisconsin. The trade off
is that these higher humidity values could lead to a few scattered
showers or thunderstorms Tuesday afternoon. The better chances will
be in central Wisconsin, but still have a small window of 20 to 30
percent chances for areas east of I-35.
.LONG TERM...(Wednesday through Monday)
Issued at 229 PM CDT Mon May 24 2021
The long term period will mark a change from the warm and humid
conditions we have seen over the last few weeks to colder than normal
conditions through the weekend before warming up again for the
Memorial Day holiday. Broad high pressure centered north of the
Dakotas will bring weak northerly winds on Wednesday before sweeping
trough and surface low makes its way eastwards from the central
Rockies by Thursday afternoon. Chances for precipitation arrive
Thursday by midday and continue through Friday morning before the
system pushes through, with the bulk of the precipitation and storm
potential remaining south of MN and WI. Besides the rain, cloudy
conditions persisting will bring us high temperatures in the mid to
upper 50s on both Thursday and Friday with accompanying lows in the
40s, making for well below normal conditions heading into the
weekend.
Another broad and relatively weak area of high pressure will settle
over the Great Lakes as zonal flow returns, with another surface
trough bringing a chance for showers late Sunday into Monday. This is
much lower confidence than earlier in the period, as the surface low
is significantly weaker and models are having a hard time resolving
the upper versus lower level timings, thus most are giving a broad
area of low precipitation amounts. The GFS keeps us relatively dry
while the ECMWF bring showers and some thunderstorms to far southern
MN, and it is likely we will have to wait until Thursday and Friday`s
system is through before models start resolving this a bit better.
On a brighter note, temperatures swing back towards seasonal norms in
the mid 70s for highs on Sunday and Monday due to the zonal flow
regime.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 631 PM CDT Mon May 24 2021
VFR to start at all terminals but convection is already ongoing in
southeast MN into west-central WI. Specifically, have already seen
TSRA move through the KEAU area but convection is currently to the
east of all terminals. Difficult to get a read on potential for the
remaining TAF sites but running with a HRRR-type look will put
scattered/intermittent SHRA/TSRA generally along and east of a KMKT-
KMSP line roughly between 03z-08z this evening into the early morning
hours. Generally MVFR-level thunderstorms can be expected but IFR
cannot be ruled out should heavy downpours traverse over a terminal.
Some MVFR stratus is possible in western WI overnight thru daybreak
as low level moisture is prevalent before the cold front sweeps
through the region (the remaining terminals will be behind the cold
front overnight). While VFR conditions are expected during the day
Tuesday, breezy winds are again expected from the SW.
KMSP...Best timing for TS this evening looks to be roughly 03z-07z,
possibly give or take an hour either way. Nothing sustained expected
as the storm motions are steadily from the SW, but the storms thus
far do show frequent lightning and brief heavy rains, so this could
be the story should any TS come near/over MSP. Otherwise, the main
concern will be winds as directions will generally remain 200-230,
essentially crosswinds over the parallels, with frequent gusts likely
after sunrise again Tuesday.
/OUTLOOK FOR KMSP/
Wed...VFR. Wind NW 10 kts.
Thu...MVFR/SHRA likely. Chc IFR/TSRA. Wind E 10-15 kts, gusts to 25
kts.
Fri...Mainly VFR. Chc MVFR/SHRA early. Wind E 5-10 kts.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
MN...None.
WI...None.
&&
$$
UPDATE...JPC
SHORT TERM...JRB
LONG TERM...TDH
AVIATION...JPC
Area Forecast Discussion
National Weather Service Marquette MI
755 PM EDT Mon May 24 2021
.SHORT TERM...(This evening through Tuesday)
Issued at 450 PM EDT MON MAY 24 2021
RAP analysis and water vapor imagery showed a strong upper level low
pressure over southern Alberta and Saskatchewan with an upper level
ridge extending from the Gulf Coast to the Great Lakes. The ridge
axis was beginning to shift east with multiple shortwaves in the
flow ahead of the upper level trough. The warm up has been slow
today with widespread cloudiness though the morning giving way to
breaks in the cloud cover out west and at least some thinning of the
clouds in the east. Temperatures had reached the 70s where there was
sun in the west but remained in the 60s in the east with the
combination of clouds and onshore flow from Lake Michigan. A brief
mesoanalysis shows increasing instability approaching the MI/WI
border with MUCAPE of 500-1000 J/kg. 0-6km bulk was 30+ knots over
MN closer to the upper level jet but much weaker over WI and the U.P
further from the jet. Dewpoints were in the mid 60s over NW WI and
had increased to the lower 60s over the western U.P. Expecting
instability to continue spreading east though the evening and upper
level support increasing to bring convection though parts of the
area.
It will be a humid night across the U.P with warm air advection and
moisture from the Gulf of Mexico continuing to spread into the area.
PWATs are progged to reach 1.5+ inches which is above the 90th
percentile in the SPC sounding climo from GRB. Shortwaves will
support multiple rounds of precipitation tonight in the form of
showers and thunderstorms. Storms tonight do not look severe with
minimal CAPE, 500-1000 J/kg and marginal shear. Though severe
hail or winds are not expected some of the storms could produce
heavy rainfall. Storm motions are relatively fast, 30 kts, though
there is a brief period where some of the CAMs have training
convection with the first shortwave late this evening. Wouldn`t be
surprised to see a few isolated locations get over a half inch of
rain but the flash flood threat remains low.
On Tuesday morning the low pressure will be over southern Manitoba
with a cold front extending south into the Dakotas. The low and
associated front will head east though the day. Ahead of the front
shear and instability will increase with MLCAPE of 1000 to 1500 J/KG
and deep layer shear up to 40 knots. 12Z models keep the better
upper level support south of the area with convection weakening as
it enters the western U.P in the afternoon. Also seeing dewpoints
fall in the afternoon with deeper mixing in some of the model
soundings which could really limit the prospects for thunderstorms.
CAMs have generally been indicating convection firing along the
front across ne MN and weaken as it moves into the western U.P.
Overall things look marginal for severe thunderstorms with the
best chance closer to the MI/WI border.
Not anticipating fire weather concerns with precipitation tonight
and minimum RH remaining above 35 percent Tuesday.
.LONG TERM...(Tuesday night through Monday)
Issued at 447 PM EDT MON MAY 24 2021
A deep surface low (~990mb) tracks east across Ontario at the
beginning of the extended period (00Z Wednesday) with the warm
sector covering most of our CWA. The warm and muggy air mass won`t
last long as a pair of cold fronts push through our area on
Wednesday. Thunderstorms will be possible along the first cold front
with a stronger push of cold air behind the secondary cold front.
Despite sunny skies, cold air advection should result in falling
temperatures during the day on Wednesday with blustery NW winds
off Lake Superior. The next system of interest approaches Thursday
morning and passes to our south Thursday night. Below average
temperatures appear to stay entrenched across our CWA through this
weekend with a gradual trend toward near normal temperatures by
early next week.
Overall, it seems like thunderstorm chances are trending lower with
the initial cold front Tuesday evening/overnight. The best chance of
thunderstorms appears to be near the Wisconsin border, especially
farther south near Menominee. There should be adequate bulk shear
for organized thunderstorm updrafts, but the magnitude of
destabilization and strength of the capping inversion are
questionable. This suggests coverage will be low during the
afternoon with an uptick in coverage possible as the LLJ kicks in
Tuesday evening. The secondary cold front appears to pass through
early Wednesday morning and will put a definite end to precipitation
chances. Blustery NW winds combined with falling temperatures will
make for a chilly, raw day on Wednesday ... but an increasingly dry
air mass should allow the sun to make an appearance during the
afternoon.
Cloud cover should increase overnight on Wednesday as the next storm
system enters the plains states. A surface low should be located
between Omaha, NE and Kansas City, MO by noon on Thursday with a
generally easterly trajectory to near Cincinnati, OH by Friday
morning. A low track this far south suggests precipitation should be
confined to our south, especially considering how dry the lowest
layers of the atmosphere will be. Some light rain or rain/snow mix
can`t be ruled out near the Wisconsin border and the 12Z NAM earned
an honorable mention for advertising accumulating snow during the
day on Thursday.
The atmosphere dries out on Friday as the system pulls away from our
CWA, which should allow for clouds to clear out. This should result
in warm sunny days and chilly clear nights on Friday, Saturday, and
perhaps Sunday too. Warm air advection appears to pick up late
Saturday and Sunday as a trough on the Canadian Prairies
approaches. The forecast quickly becomes murky beyond this
weekend, but there seems to be some signal for below average
temperatures to persist into early next week as intense ridging
moves into the Pacific NW.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 746 PM EDT MON MAY 24 2021
A cluster of SHRA/TSRA will move through the area from west to
east this evening although the heavier showers and associated IFR
conditions will likely only impact KSAW. Another round of showers
and possibly a thunderstorm will move into mainly the western U.P
later tonight into early Tue morning though there are varying
solutions of timing and placement. For now didn`t put thunder in
the TAFs for the later half of the TAF period given lower
confidence, but might need to add with subsequent TAF issuances.
Fog looks likely later tonight at KCMX and KSAW, in the wake of
the first wave of rainfall. It`s a little more uncertain that fog
will form at KIWD with downslope winds.
&&
.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 450 PM EDT MON MAY 24 2021
Southerly winds will gust 25-30kt over eastern Lake Superior tonight
with lighter winds over the west. Fog will develop, especially in
the west tonight as a warm/moist airmass spreads across the lake.
Winds will be lighter for Tuesday morning and early afternoon but
increase over the west later in the afternoon as a surface trough
moves across the area, with sw winds gusting to 30kt. Winds will
turn west and gust to 30kt Tuesday night, then shift nw behind a
cold front Wed morning. A few gale force gusts will be possible
behind the front over the east on Wednesday. Winds will diminish
for Thu, but there could be somewhat stronger ne winds locally
gusting to 25kt down western Lake Superior as high pres builds
over northern Ontario.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
Dense Fog Advisory from 11 PM EDT /10 PM CDT/ this evening to 11
AM EDT /10 AM CDT/ Tuesday for LSZ162.
Lake Michigan...
None.
&&
$$
SHORT TERM...NL
LONG TERM...EK
AVIATION...Voss
MARINE...NL
Area Forecast Discussion
National Weather Service Springfield MO
623 PM CDT Mon May 24 2021
...Updated for 00Z Aviation Discussion...
.SHORT TERM...(This evening through Tuesday)
Issued at 243 PM CDT Mon May 24 2021
Will continue to see some isolated to scattered showers and
perhaps a thunderstorm or two into this evening, mainly over the
western CWA.
Much of tonight looks dry for the most part, with potential for
some showers to develop late in the night into Tuesday morning.
Better convective coverage is expected Tuesday afternoon and
evening as a shortwave passes through. Right now widespread severe
weather is not expected, but could see some strong (sub-severe)
storms if enough instability can develop. SREF guidance suggests
between 500 and 1,500 J/kg of SBCAPE, with the HRRR in good
agreement showing near or just under 1,000 J/kg. Shear should be
limited at around 20 kts. At this point will not be widely
advertising any strong storms given uncertainties and marginal
conditions at best.
.LONG TERM...(Tuesday Night through Monday)
Issued at 243 PM CDT Mon May 24 2021
Exactly how convection evolves into Tuesday night is uncertain due
to an increased spread in model guidance. Tend to lean toward HRRR
guidance that shows convection exiting east early in the night
then quiet for the rest of the night. Not seeing any significant
sources of forcing to back up some of the guidance showing
additional convective clusters moving through. That being said,
will not go completely dry in the forecast given the obvious
uncertainties.
A very subtle shortwave is modeled to move nearby Wednesday
afternoon. Models differ on potential convection that may result.
Given how weak the wave is, confidence in convective details for
Wednesday is low. If convection does fire in the afternoon, there
could be some pulse strong to maybe severe storms. Shear is quite
weak on Wednesday, but SBCAPE may be able to get into the
1,500-2,500 J/kg range.
Thursday afternoon into early Thursday night continues to look
like the best shot for widespread convection and severe storms.
Models show a convective cluster moving across northern Missouri
in the morning and afternoon while a front drops into the area in
the afternoon and evening. Models generally keep our area capped
off until the front and a shortwave arrive in the afternoon, then
they develop widespread convection NW of the CWA moving to the SE.
Best chances are over the NW half of the CWA at this time. All
modes of severe weather are possible, but large hail, damaging
winds, and excessive rainfall appear to be the primary threats
given low level shear profiles that are less favorable for
tornadoes. Current thinking is that storm mode will be linear or
in clusters along the front. Even right turning storm motions
would not be favorable to see many discrete cells moving
substantially ahead of the front. With this being on day 4,
uncertainty is naturally a big factor. The convection to the
north in the morning could move farther south, or drop a cold pool
into the area earlier in the day, possibly sparking earlier
convection and/or weakening instability.
Friday looks relatively quiet behind the front, but additional convective
activity is possible Friday night into early next week. Lots of
uncertainty with details at this time, so stay tuned.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 623 PM CDT Mon May 24 2021
VFR flight conditions will prevail through at least 12Z Tuesday.
there could be some isolated showers in areas of west of highway 65
this evening, but thunder chances look quite low. Flight conditions
then will begin to deteriorate after 12Z as showers and possibly a
few storms begin to work there way from west to east across southern
Missouri. VFR ceilings will lower into the MVFR, with isolated IFR
possible within showers/storms.
&&
.SGF WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
KS...NONE.
&&
$$
SHORT TERM...Titus
LONG TERM...Titus
AVIATION...Raberding
...Update to aviation forecast discussion...
.DISCUSSION...
Issued at 344 PM CDT Mon May 24 2021
Some signals of a pattern change beginning to be seen. Isolated to
scattered shower activity in the deep moisture still sampled by the
12Z TOP sounding has been less the most recent days as the higher PW
values nudge east, though recent hours have seen an uptick in
coverage especially into central portions of Oklahoma. Will need to
keep small PoPs going in eastern areas for another night with any
amounts again quite light. An area of weakening elevated convection
was exiting north-central Kansas early this afternoon after being
sustained by modest mid-level isentropic upglide. Much more robust
activity was underway in west-central Kansas and portions of western
Nebraska along the surface front/dryline.
Most focus tonight will be to the west and the evolution of the
eventual MCS. Instability continues to drop off rather quickly over
central Kansas per 12Z model guidance and 850 mb winds are modest
and somewhat veered overnight. Will maintain some chance PoPs here
but the 17/18Z HRRR runs may be on target with only scattered weak
convection reaching the CWA.
The weak front remains on track to push southeast into the area
Tuesday. As previously mentioned, low-level forcing remains modest
with limited convergence and also likely quite a bit of stratus
still in place. Have backed off categorical chances with these
factors in mind. Mid-level flow is also modest and keeps bulk shear
under 30 knots and severe weather chances seasonally small given the
front`s placement. This front pushes on south Tuesday night and much
of Wednesday remains dry, though attention will again turn to the
west and northwest for evening convective trends. Although there are
some differences, there is decent consensus for an MCS to track east
across at least the northern counties late Wednesday night into
Thursday morning supported by a low-level jet nearing 50 knots.
MUCAPE values differ considerably between GFS/ECMWF and NAM
solutions but a least a few severe storms seem possible. Persistence
and outflow of this activity will play a significant role for
Thursday afternoon and evening events with the next front`s passage.
Front could be in southern areas during this time and outside much
influence from the MCS for a decent setup though again warm-sector
shear is limited to less than 30 knots but instability would likely
be enough for severe weather. Rainfall amounts could be locally
heavy especially Wednesday night into Thursday night, with the
greater concern likely to be in the latter portions of this period
when the heavier rains would likely fall on locations that have seen
the heavier rains of late.
A drier period is likely Friday into early Saturday with weak
ridging overhead though some breakdown in the pattern looks to occur
again later in the weekend.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 640 PM CDT Mon May 24 2021
Stratus with MVFR ceilings will develop over the terminals this
evening and probably continue through 00Z WED. There may be some
breaks. Models are showing differing solution on when there may be
showers and thundersotrms may develop across the termianls, some
have everything developing in the mid morning hours and ending by
afternoon. Other, model solutions show a dry morning and showers
and thunderstorms in the afternoon. For now I left thunderstorm
mention out but hopefully timing will be better with 00z model
runs.
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
DISCUSSION...65
AVIATION...Gargan