NWS Lincoln, IL wrote its last area forecast discussion before the first event at May 1, 9:39 AM CST, 6 minutes earlier.
Area forecast discussion, May 1, 9:39 AM CST, 6 minutes before
Area Forecast Discussion...Updated
National Weather Service Lincoln IL
1039 AM CDT Mon May 1 2023
.SYNOPSIS...
Issued at 1036 AM CDT Mon May 1 2023
May begins with another day of below normal temperatures and breezy
west-northwest winds. Gusts up to 45 mph are possible this
afternoon. Scattered showers are also possible north of I-74 this
afternoon. A gradual warming trend is expected this week, with highs
returning to the low 70s by Thursday.
&&
.UPDATE...
Issued at 1039 AM CDT Mon May 1 2023
Made some adjustments to the cloud cover in the forecast as
western areas are in the clear and areas to the east are still
cloudy or mostly cloud. Full clearing will not occur til this
evening as the upper level system moves east. Rest of the day
areas to the east could become scattered as the edge moves east.
No need for an adjustment at this point, but may need to adjust
again early this afternoon.
Auten
&&
.SHORT TERM... (Through Late Tonight)
Issued at 258 AM CDT Mon May 1 2023
---------- Key Messages ------------
1. Another windy day, with west-northwest winds gusting 40-45 mph
during the day.
2. Showers are possible (30%), mainly along/northeast of a
Bloomington-Champaign line, but it would not be a surprise to have
occasional light sprinkles throughout the entire CWA today.
-------------------------------------
We had our fair share of April showers to end the month, but it'll
be a few days before there's decent weather for heading outside to
view the May flowers. An upper level Omega block continues to
dominate the weather across the CONUS. The upper low is easily
distinguishable in water vapor imagery early Monday morning,
situated over Michigan. Today will be quite similar to Sunday, but
the upper low shifts slightly to the northeast. That will
translate to slightly warmer temps and fewer showers, but also
slightly windier.
Primary forecast concerns for today is the breezy wind gusts.
Forecast soundings once again show a deep, well-mixed PBL that
will easily transport stronger gusts to the sfc. 40+ mph gusts are
looking likely, but 45+ mph gusts are more questionable. HREF-
based guidance is not enthusiastic about gusts exceeding 45 mph.
Global ensembles are split, with the more bullish ECMWF ens
showing a mean peak gust right at 45 mph. Ultimately, could have
gone either way on a wind advisory, as we'll be close to criteria
(gusts over 45 mph).
Regarding precip chances today, soundings keep some shallow
instability present above cloud base, but it will be shallower
than Sunday and the column as a whole will be trending drier. It
would not be a surprise to have sprinkles during the morning, but
the best chance for showers should be in the afternoon
along/northeast of a Bloomington/Champaign line. That increase in
shower activity will be aided by a vort lobe pivoting around the
upper low.
Temperatures remain below normal today, but about 5 degrees warmer
than Sunday, with highs in the mid 50s. Skies will be more cloudy
than not today, although there will be a gradient, with more
breaks in the cloud cover the further southwest you get from the
I-74 corridor. Into tonight, winds remain brisk, and skies partly
to mostly cloudy prevent temperatures from cooling too much, with
lows near 40F.
Erwin
.LONG TERM... (Tuesday through Sunday)
Issued at 258 AM CDT Mon May 1 2023
---------- Key Messages ------------
1. A gradual warming trend is expected through Thursday, by which
point high temperatures will be back in the low 70s.
2. Frost remains a possibility across the northern half of the CWA
on Tuesday night, with the best chance being northwest of the IL
River.
3. Aside from isolated rain Tuesday afternoon, the next chance for
rain won't arrive until Thursday night into Friday.
-------------------------------------
Overall, no real change to the thinking regarding the highlights
of the long term forecast. The upper level pattern continues to
revolve around the evolution (and eventual erosion) of the Omega
block.
Tues will be quite similar to Mon, but with wind gusts decreasing
into the 30-35 mph range, and the upper low shifting even further
northeast, allowing temps to continue their gradual warming trend.
One challenge for Tuesday: a compact shortwave is forecast to
sweep through the area during the afternoon, and this will
introduce yet another chance of sprinkles or light showers.
Forecast soundings are split on the concept, with NAM soundings
showing a good signal for showers, while the GFS soundings are too
dry. Ultimately, think the presence of that shortwave warrants at
least a mention of sprinkles Tues afternoon until there is better
agreement on the low-level moisture profile.
The coldest night of the week is expected to be Tues night, as sfc
high pressure starts to nudge into the area from the west.
Diminishing cloud cover and weakening winds will result in
favorable radiational cooling, with lows falling into the
mid/upper 30s. Right now it still looks like winds stay around 10
mph overnight, especially in the eastern CWA, which should limit
frost potential. Think the best chance would be northwest of the
IL River, which will be closer to the sfc high and have the
lightest sfc winds.
Wed continues to look quiet nice as the sfc high pressure takes
control. Extrapolating 850mb temps looks like a useful first guess
for high temps on Wed, as both NAM and GFS soundings show the top
of the well-mixed PBL right at 850mb. 850mb temps around 2 degC
translate to the low 60s, and after factoring in a superadiabatic
layer at the sfc beneath abundant sunshine, mid 60s can be
expected.
The warming trend continues Thurs, with highs returning to the
70s, which is seasonable for early May, but will only be the
second time in almost two weeks that we've seen highs above 70F.
Have been monitored precip chances for Thurs, and looks like the
blended guidance is finally showing the anticipated slowing trend.
Precip during the day Thurs should stay southwest of the ILX CWA,
and forecast soundings support the notion that we stay dry, with
a considerable dry layer in the lowest 7000 feet. It does look
like we'll have a better chance of rain on Friday, especially
across the southern half of the CWA (40% chance) as the ejecting
shortwave tracks closer to the area. Increasing cloud cover, and
some rain, should keep temps a bit cooler Fri, in the upper 60s.
Sporadic rain chances will linger into the weekend, with the next
best chance of rain after Fri currently forecast to be Sun night
into Mon as a system passes to the northwest.
Erwin
&&
.AVIATION... (For the 12z TAFs through 12z Tuesday Morning)
Issued at 552 AM CDT Mon May 1 2023
The southern edge of the MVFR cloud deck sits very near the
northern terminals at the start of the period. KBMI/KCMI have the
best chance of seeing MVFR ceilings this morning, then all sites
should be VFR after about 16-17z. A few showers are possible in
the afternoon at KBMI/KCMI. Breezy northwest winds are expected
through the period, with gusts around 35 knots during the
afternoon.
Erwin
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
None.
&&
WFO ILX