IWX issues Area Forecast Discussion (AFD) at Aug 1, 1:59 PM EDT402
FXUS63 KIWX 011759
AFDIWX
Area Forecast Discussion
National Weather Service Northern Indiana
159 PM EDT Thu Aug 1 2024
.KEY MESSAGES...
- Decreasing risk of severe thunderstorms for the remainder of
today.
- Scattered to numerous showers and thunderstorms on Friday.
- Primarily dry this weekend before shower and storms return
starting Monday.
&&
.DISCUSSION...
Issued at 154 PM EDT Thu Aug 1 2024
Mostly cloudy to overcast skies from early-morning convection over
eastern Illinois has so far squashed the day's severe weather risk.
I am beginning to think that will continue to be the case. Multiple
factors are complicating the near-term forecast including an overall
lack of shear, poor lapse rates, and overall cloudiness (details
below). Should storms overcome these obstacles, the primary window
opportunity continues to be 4pm to 10pm EDT with damaging wind gusts
as the primary hazard.
An area of clearing from Evansville northeast through Muncie yields
destablization in those areas. Thunderstorms over far southern
Illinois are currently growing upstream, somewhat consistent with
CAMs, yet it seems unlikely this cluster would continue to develop
cells so far north as to pose a risk to our local forecast area (as
advertised in some CAMs). This is because clouds and instability are
more problematic north of the ongoing convection. Furthermore, storm
motion more east than north leads me to believe ongoing convection
there will not grow upstream into our area.
Next, there is an MCV swirling over southern Lake Michigan per
satellite imagery. Abundant clouds and continued capping here will
also seemingly preclude any severe storms.
Lastly, the synoptic triple point is noted over far southwest
Wisconsin. There, instability is favorable for storms to develop and
perhaps drift east into Michiana toward or after sunset. Yet, a lack
of shear presents doubts with respect to maintenance. Such timing
for storms is less favorable for severe as well.
Turning to tomorrow, the upper-level low currently wrapped up over
eastern MN, is forecast to continue its southeast track bringing
scattered to numerous showers and perhaps a few thunderstorms to the
area. Severe weather is not expected due to 0-6km shear of 15 knots
or less. High temperatures will be near 80, notably cooler for those
in northwest Ohio who saw highs well into the 80s today before
clouds arrived. Drying out Saturday as the trough axis aloft pulls
away.
Sunday through midweek, a ridge is stationed over the Four Corners,
bleeding eastward into the Central and Southern Plains. As a result,
northwest flow prevails aloft which presents numerous opportunities
for POPs Monday through Thursday.
&&
.AVIATION /18Z TAFS THROUGH 18Z FRIDAY/...
Issued at 123 PM EDT Thu Aug 1 2024
The biggest forecast problem this afternoon and evening is when
and where showers or thunderstorms will redevelop. The latest
16Z HRRR run is suggesting that activity over eastern Wisconsin
in association with the surface low and triple point will become
more organized and then travel southeast across Lake Michigan.
This would then impact SBN after 00Z. Confidence is low though,
given a lack of inconsistency among the models throughout the
past several days. Therefore, kept VCSH, but until the storms
become more defined, do not want to mention thunder. FWA will
probably also see some shower activity this evening, but again,
am not confident enough to include thunder at this time.
Significant cloud cover today has limited heating, and therefore
instability.
Concerning cloud cover, expect ceilings to continue to fluctuate
between VFR and MVFR through this evening, then drop to MVFR and
possible IFR overnight. Patchy fog can also again be expected
given the significant low-level moisture, but have not gone
lower than 3SM at this time.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...None.
OH...None.
MI...None.
MARINE...None.
&&
$$
DISCUSSION...Brown
AVIATION...Cobb
Source:
IWX issues Area Forecast Discussion (AFD) at Aug 1, 1:59 PM EDT---------------
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