Category: Weather

Two rounds of storms are likely on Saturday. The first round is likely to come through the northern suburbs between 7 AM and 11 AM. Widespread severe weather is not expected with this round, but the stronger of these storms may produce some small hail. The second round of storms is expected to come through the area during the afternoon/early evening and may contain some severe storms with damaging winds, large hail, and possibly a tornado or two.

Dry conditions will remain through the evening. Hazy skies are possible tonight as a result of smoke from ongoing fires in southern Canada.

Storms are likely along and ahead of a cold front on Saturday.
Strong to severe storms will be possible.

Conditions will turn dry and cooler behind the cold front for Sunday.

Monday and Tuesday look to be dry and mild, with increasing rain chances late Tuesday.

A Tornado Watch has been issued until midnight for Winnebago, Lee, Ogle, LaSalle, Grundy and Livingston counties. Have multiple ways to receive warnings if any are issued for your area and a plan to access safe shelter if needed

URGENT – IMMEDIATE BROADCAST REQUESTED
Tornado Watch Number 236
NWS Storm Prediction Center Norman OK
625 PM CDT Fri May 24 2019

The NWS Storm Prediction Center has issued a

* Tornado Watch for portions of
Eastern Iowa
Northern and central Illinois
Far northeast Missouri

* Effective this Friday night from 625 PM until Midnight CDT.

* Primary threats include…
A few tornadoes possible
Scattered large hail and isolated very large hail events to 2
inches in diameter possible
Scattered damaging wind gusts to 65 mph possible

SUMMARY…A few supercells should develop along a residual boundary
from eastern Iowa into west-central Illinois. This activity should
spread east-northeast in northern Illinois through late evening.

The tornado watch area is approximately along and 85 statute miles
north and south of a line from 45 miles north northwest of
Burlington IA to 40 miles north northeast of Bloomington IL. For a
complete depiction of the watch see the associated watch outline
update (WOUS64 KWNS WOU6).

PRECAUTIONARY/PREPAREDNESS ACTIONS…

REMEMBER…A Tornado Watch means conditions are favorable for
tornadoes and severe thunderstorms in and close to the watch
area. Persons in these areas should be on the lookout for
threatening weather conditions and listen for later statements
and possible warnings.

MESOSCALE DISCUSSION…
553 PM CDT

The weather forecast over the next 12+ hours remains fairly
complicated, and uncertainties abound mainly due to the weak
nature of large-scale forcing for ascent. While a threat for
strong to severe thunderstorms certainly exists this evening and
into the nighttime hours, how this threat materializes remains
tied to mainly subtle mesoscale processes and subtle waves of
synoptic ascent which are both difficult to diagnose and pinpoint
with much certainty.

Surface analysis late this afternoon depicts a northwest to
southeast arcing warm front–reinforced by this morning’s
convection which laid out an outflow boundary–likely just
entering portions of La Salle, Livingston, and Ford Counties.
Dewpoints immediately to the south of this boundary jump into the
70s with breezy south to south-southwesterly winds, and this
seems to be demarcated pretty well by an area of bubbling Cumulus
and HCRs which are steadily building northward. Recent RAP
soundings and SPC mesoanalysis reveal that this is a relatively
high-quality warm sector, with mean mixing ratios pushing 16 g/kg
and decent moisture through a fairly deep layer (up to 700 mb). An
earlier tornadic supercell, which was riding along the northern
extent of this warm frontal boundary, quickly dissipated a few
hours ago as it approached Bloomington, likely as it encountered a
pocket of warmer air aloft with 700 mb temperatures analyzed at
+9 to +10C. This is indicative of lingering capping, which has
thus far suppressed any additional convective initiation attempts
in the warm sector. Recent GOES-16 visible satellite loops reveal
some towering Cu development taking place across West Central
Illinois, however, where capping is lower due to cooler
temperatures aloft.

Farther to our west, an additional area of bubbling cumulus has
been noted across central and eastern Iowa, although recent radar
trends suggest incipient updrafts are struggling to develop.
Large scale forcing for ascent is not strong here, but modest
mid-level height falls (20-40 m/12 hours) are noted in recent
analyses nosing into far northwestern Iowa at the leading edge of
a very subtle shortwave. It’s possible some lingering mesoscale
subsidence is still in place across eastern Iowa in the wake of
this morning’s MCS, tempering additional robust convective
development at this juncture, but conditions do appear favorable
for robust updraft development over the next few hours.

With this all laid out, it does appear there may be two favored
corridors for potential convective development over the next few
hours: /1/ near and south of the incoming warm front and /2/
across eastern Iowa. All modes of severe weather would be possible
across our area, including the threat for a few tornadoes. Deep
layer shear in excess of 50 kts will support rotating storms and
supercell structures and sizable CAPE in the hail growth zone
will foster large hail development, potentially to the size of
golf balls or even larger with some analogs supporting 2″+ hail
not out of the question.

Recent runs of the HRRR have been a bit concerning, developing
robust storms near the incoming warm front and into the I-80
corridor. Locally backed surface flow would support a tornadic
potential with these storms as they interact with the front and
gain access to considerable streamwise vorticity. Think it looks
too aggressive based on latest satellite trends, but we will need
to keep our eyes peeled for development near and south of I-80
during the 8 to 11 PM time frame. The other area of convection–to
our west in eastern Iowa–may attempt to develop into our western
counties later this evening, likely after 10 PM or so. A tornado
threat will continue here, although CAM guidance indicates some
propensity for storms to congeal into clusters which may
eventually deliver more of a damaging wind and hail threat as this
second area of activity pushes eastward into the overnight hours.

Finally, a flash flood potential does exist this evening and
overnight, although the spatial breadth and magnitude of this
threat still is uncertain due to the mesoscale processes involved.
Current thinking is that the Flash Flood Watch captures the
favored corridor well, and no immediate changes are planned.

http://RickieTraeger.com

As of 1 PM: We are monitoring for severe storms this afternoon across the area this afternoon. Best timing for the severe storms could start as early as mid afternoon and continue into the evening hours. Keep a close watch on the forecast for later watches and warnings.

http://RickieTraeger.com

Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
711 PM CDT Wed May 22 2019

.MESOSCALE DISCUSSION…
711 PM CDT

A few showers and storms developed a bit earlier across portions
of northeastern Missouri, but have struggled to maintain intensity
as they progressed into northern Illinois, likely as they outran a
narrow plume of increased low-mid level moisture. With limited
instability present across our region, think the severe threat in
the immediate term (over the next hour or two) appears fairly
low although a stronger storms will be possible across our
northwest.

However, strong flow in the 850-700 mb layer will continue to
transport a higher theta-e airmass into the region over the next
several hours along with an associated uptick in elevated
instability. Based on the most recent guidance, it appears as if
the most favorable axis of moisture and instability will develop
essentially across the southeastern half of the CWA (perhaps from
a La Salle to Midway line). Farther to the north and west of this
line, increased westerly flow aloft should drive a drier airmass
eastward, reducing the amount of instability available to support
more robust thunderstorm development.

The kinematic environment will be favorable for severe storms,
with deep layer shear values pushing 50-55 kts at times. Recent
point soundings reveal a lingering layer of warm air in the mid-
levels centered around 500 mb, which will limit the overall amount
of instability this evening, but steep lapse rates do exist in
narrow layers under 500 mb which, when combined with the
aforementioned robust deep layer shear, will support rotating
thunderstorms with a potential for large hail (quarter to golf
ball sized based on SHIP parameters). In addition, recent CAM
guidance suggests a propensity for storms to quickly grow upscale
into a surging MCS later tonight, which could deliver an
increasing threat for strong to locally damaging wind gusts
potentially for locales along and east of I-55 later tonight.
Current thinking is the main window for severe weather across our
region will be during the 9 PM to 3 AM timeframe or so.

While plenty of clockwise curvature is noted in regional
hodographs this evening, we believe the tornado threat will remain
tempered somewhat by a lack of truly surface-based instability as
the low-levels begin to decouple with the loss of daytime
heating. That said, if a surging line of storms can get going, any
segments that orient in a more NW to SE manner would have access
to ample low-level shear for a spin-up QLCS tornado, once again
mainly for locales east and south of I-55.

Finally, while a threat for heavy rainfall exists, the push of
westerly momentum aloft should keep things moving along tonight–
especially if a MCS materializes as many of the CAMs indicate. As
a result, while locally heavy rainfall will be possible but this
threat should remain fairly localized and there are no plans to
hoist a Flash Flood Watch at this point.

Warmer air has finally moved into the area, and it will stick around into the holiday weekend. There will be periodic chances of thunderstorms from tonight into the weekend. The storms tonight and on Friday could be strong to severe, with damaging winds and hail a possibility. Another concern is the locally heavy rain tonight, as the ground is already saturated.

4:18 PM Wednesday May 22nd:
A Tornado Watch has been issued off to the west and southwest of our county warning area counties. We do expect a severe threat to evolve this evening for portions of the area. Continue to stay tuned for updates

Latest trends an increasing threat of severe thunderstorms tonight across northern and central Illinois and possibly into northwest Indiana.

A cold front will encounter the warm and increasingly humid air mass and result in rapid thunderstorm development this evening and continuing into portions of the overnight hours.

The primary risk will be hail, possibly up to golf ball sized, locally damaging winds up to 70 mph, and a small threat for tornadoes, especially southwest of a Dixon to Pontiac line

http://RickieTraeger.com

A round of non-severe showers and a couple storms will move north through the region this morning with rain-free conditions expected late this morning and into the early-afternoon for much of the region. Temperatures today will range from the 50s near the Wisconsin/Illinois state line to near 80 south of a Pontiac to Rensselaer line as a warm front lifts northward.

By late this afternoon and into the evening, the threat for a few strong to severe storms will increase with the main threat west of a Pontiac to Rockford line. Strong wind gusts will be the main threat, although a tornado or two can’t be ruled out this afternoon. The severe threat will gradually diminish this evening, but gusty winds will be possible into the Chicago area tonight.

Locally heavy rainfall may also lead to renewed river rises and isolated instances of flooding

I was holding off on posting about this, because I was hoping it was just a bad dream and I would wake up and it would all go away, LOL.

National Weather Service has issued a Winter Storm WATCH for our area.

Yup, they are predicting that dreaded 4 letter word, SNOW  🙁

WINTER STORM WARNING IN EFFECT FROM 11 AM TO 11 PM CDT
SATURDAY…

* WHAT…Heavy wet snow expected. Total snow accumulations of 5
to 8 inches expected. Winds gusting as high as 35 mph.

* WHERE…Winnebago and Boone Counties.

* WHEN…From 11 AM to 11 PM CDT Saturday.

* ADDITIONAL DETAILS…Travel will likely be very difficult in
heavy snowfall with greatly reduced visibilities. In the
heaviest snowfall, rates could approach 1 to 2 inches per hour.

PRECAUTIONARY/PREPAREDNESS ACTIONS…

A Winter Storm Warning for snow means severe winter weather
conditions will make travel very hazardous or impossible. If you
must travel, keep an extra flashlight, food and water in your
vehicle in case of an emergency.

WINTER STORM WATCH IN EFFECT FROM SATURDAY MORNING THROUGH
SATURDAY EVENING…

* WHAT…Rain, transitioning to a heavy, wet snow late Saturday
morning and into the afternoon hours. Total snow accumulations
of 4 to 8 inches will be possible by Saturday evening. Winds
could gust as high as 35 mph resulting in reduced visibilities
and hazardous travel.

* WHERE…Winnebago, Boone, Ogle and DeKalb Counties.

* WHEN…From Saturday morning through Saturday evening.

* ADDITIONAL DETAILS…Travel could be very difficult in heavy
snowfall with greatly reduced visibilities. In the heaviest
snowfall, rates could approach 1 to 2 inches per hour.

PRECAUTIONARY/PREPAREDNESS ACTIONS…

A Winter Storm Watch means there is potential for significant
snow, sleet or ice accumulations that may impact travel. Continue
to monitor the latest forecasts.