Peotone Weather

National Weather Service Forecast for: Peotone, IL Issued by: National Weather Service Chicago/Romeoville, IL

Updated: Tue, 07-Apr-2020 4:16am CDT

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Peotone, IL

Tuesday Chance Showers And T-Storms then Mostly Sunny Wednesday Mostly Sunny then Chance Rain Showers Thursday Mostly Sunny then Chance Rain Showers Friday Mostly Sunny Saturday Chance Rain Showers Sunday Chance Rain Showers Monday Partly Sunny then Slight Chance Rain Showers   Hi 78 °F ↓ Hi 70 °F Hi 46 °F Hi 48 °F Hi 56 °F Hi 52 °F Hi 47 °F   Overnight Showers And T-Storms Likely Tuesday Night Chance Showers And T-Storms Wednesday Night Showers And T-Storms Likely Thursday Night Chance Rain Showers then Mostly Clear Friday Night Partly Cloudy Saturday Night Chance Rain Showers Sunday Night Chance Rain Showers   Lo 55 °F Lo 49 °F ↑ Lo 36 °F Lo 30 °F Lo 35 °F Lo 40 °F Lo 33 °F

Forecast from NOAA-NWS for Peotone, IL.

000
FXUS63 KLOT 070859
AFDLOT

Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
359 AM CDT Tue Apr 7 2020

.SHORT TERM...
337 AM CDT

Through Tonight...

Storms that affected the area late this evening into the early
overnight hours are pushing east into IN and MI as very impressive
elevated mixed layer (EML) advects east into the region. Back edge
of the convection continues to move east as well with EML
resulting in increasingly strong CINH, likely precluding any
additional convection from developing this morning as back edge
moves east of the area.

Really haven`t seen much in the way of low clouds and fog develop
north of the warm front as of yet. Warm front appears to stretch
roughly from near DBQ to around VPZ at 08z and given lack of
convection/cold pool to slow its northward advance, would
anticipate the front to continue to lift north this morning with
entire CWA in the warm sector not long after sunrise.

Area of VFR stratus and altostratus across eastern IA into
northern IL is dissipating and this trend will likely continue
this morning. Cirrus plume to our south is expected to push
farther south later this morning setting the stage for ample
sunshine from late morning into the afternoon. The sunshine and
strong warm air advection should set the stage for an unseasonably
warm day. Have nudged high temps up into mostly the upper 70s, but
think there is a fairly good chance that 80F readings could
become fairly common this afternoon.

Question will then turn to convective potential along a weak cold
front progged to approach the area later this afternoon. Forecast
soundings this afternoon show a very strong capping inversion,
which conceptually matches what would be expected with such a
strong EML. That leads to a high degree of uncertainty with
respect to potential convective initiation. Model guidance does
show some modest height falls into northern IL by late this
afternoon, though the stronger height falls associated with the
wave passing well to our north occur this evening possibly lagging
somewhat behind the cold front. The anticipated warmer than
forecast temps will also likely result in dewpoints mixing out,
probably negating the warmer temps in temps of weakening the cap.
Veered surface flow ahead of the front should also result in only
modest convergence along the front. All of these factors would
point toward a fairly low chance of the cap breaking and getting
storms in our CWA this afternoon/early evening, with the best
chances in NW IN this evening as stronger upper forcing starts to
catch up with the surface front.

There is a wide array of solutions in regards to convective
initiation (CI) among the various hydrostatic and convective
allowing models (CAMs) today. Clearest signal that seems to exist,
is that chances of CI seem to increase with northeastward extent,
likely due to closer proximity to the parent shortwave and
stronger forcing. The normally very reliable ECMWF has remained
remarkably consistent in developing a solid line of convection
along the front, with the latest run showing a solid line from
just south of Milwaukee wests-southwest to the quad cities by 23z.
Most other models are slower with CI and some keep any CI east of
our CWA. Given the high degree of uncertainty, opted to just
mainly hang onto chance pops northern IL late this afternoon and
area wide this evening, favoring the eastern portions of the CWA.

Other than the potential problem with a cap, the environment looks
to become very favorable for severe thunderstorms this afternoon
with 0-6km bulk shear of 40-50kt and moderate instability (MLCAPE
1000+ j/kg). So, if storms do develop, conditions would be very
favorable for severe weather with both a very large hail threat
as well as a damaging wind threat, particularly with any line
segments that can form. Tornado threat appears low given the
expected fairly high LCLs and fairly weak low level shear.

- Izzi

&&

.LONG TERM...
359 AM CDT

Wednesday through Monday...

A lot to talk about in the long term, will shoot for brevity by
triaging things as much as possible.

Wednesday:
Will spend most of the day between weather makers, likely
starting the day sunny, rapidly becoming cloudy as strong cold
front begins to encroach on the region late in the afternoon.
Given the expected sunshine and only very limit cooling behind
tonight`s front, expect temps to once again be very mild for this
time of year. Have nudged high temps up into the 70s most area,
though somewhat lighter winds may allow for some slight cooling
near the lake before winds pick up some later in the day.

Somewhat limited moisture ahead of the strong cold front will
likely limit pre-frontal convection and precipitation. However,
cold front looks to be somewhat anafrontal in nature, with
strongly sloping f-gen circulation likely to support an swath of
post-frontal rain. There could be just enough instability for a
narrow line of strongly forcing convection right along the
boundary. There will likely be a surge of strong winds with the
strong pressure rises right behind the front, which could be aided
with some downward momentum transfer should a narrow convective
band form. Wednesday night looks to be quite windy and MUCH colder
with the rain likely to wrap up during the evening hours.

Thursday:
Models are in excellent agreement in developing an anomalously
strong upper low over the Great Lakes with an extraordinarily
impressive cold pool aloft. By Thursday afternoon, a lobe of 700mb
temps around -20C are progged to rotate south into northern
Illinois. This will aid in producing at least dry adiabatic lapse
rates up to around 700mb, which should set the stage for very
efficient mixing of the stronger winds aloft to the surface.
Bufkit soundings from both the GFS and NAM Thursday afternoon have
mean mixed layer winds in the mid 30 knot range, which would
support frequent gusts to 40 mph. Top of the mixed layer in both
the GFS and NAM exceed 45kt, which is probably the higher end of
the surface gust potential. Any shallow convection that does
develop will only increase the chance of seeing gusts to
potentially 50 mph Thursday afternoon.

While models are not producing much in the way of QPF at this
time, resulting in no pops from the NBM, have introduced at least
a chance of sprinkles for now, but possible there could be
isolated showers Thursday afternoon. Given the convective nature
of any precip that does develop and very steep lapse rates and
cold air aloft, it is probably equally if not more likely to see
graupel showers than rain showers.

Friday through the weekend:
Cold upper low will slowly move east of the Great Lakes allowing
for some moderation in temperatures. Medium range models develop a
significant cyclone late in the weekend bring more potential
precipitation, possibly significant, to the area. Timing, track,
strength of any weekend system is extremely low confidence this
far out as medium range models are notorious for being overly
eager to phase jets and over-amplify cyclones. Given the
uncertainty, made no changes to NBM grids, as there will probably
be run-to- tun variability in the handling of this system,
possibly significant variability, so no sense to picking a basket
to put our eggs in this far out.

- Izzi

&&

.AVIATION...
For the 06Z TAFs...

Sctd SHRA and TSRA expected for the few several hours of this TAF
cycle before activity begins to move east into MI/IN prior to
sunrise. Still anticipating lowering CIGS and some potential for
fog development at all of the terminals overnight. Low confidence
in just how low conditions will get tonight, with possibilities
running the gamut from VLIFR to just MVFR. Quick improvement to
VFR expected by mid-morning as warm front lifts north of the
terminals and winds lock in from the SW and begin to increase.
During the afternoon, expecting fairly gusty southwesterly winds
with gusts in the 25-30kt range possible by mid-late afternoon.
There is a threat of isold TSRA development ahead of a cold front
in the 22-00z range at RFD and 23-01z at DPA/ORD/MDW. Chances of
TSRA appear too low to include in the TAFs at this time, but if
storms develop they will likely be strong to severe. Cannot rule
out a solid line forming along the cold front late in the
afternoon, which would be quite impactful, but at this point this
possibility appears to be on the lower end of the spectrum.

- Izzi

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...None.
IN...None.
LM...Dense Fog Advisory...IL nearshore waters until 10 AM Tuesday.

&&

$$

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