IWX issues Area Forecast Discussion (AFD) at May 15, 7:39 PM EDT789
FXUS63 KIWX 152339
AFDIWX
Area Forecast Discussion
National Weather Service Northern Indiana
739 PM EDT Wed May 15 2024
.KEY MESSAGES...
- A period of dry weather this evening into Thursday morning.
- More showers with scattered storms at times Thursday through
the middle of next week, aside from Sunday. Locally heavy
downpours possible.
- The strongest storms are most possible on Monday and Tuesday.
- Highs in the 70s to low 80s into the middle of next week.
&&
.DISCUSSION...
Issued at 243 PM EDT Wed May 15 2024
The broad trough across the eastern half of the CONUS slides east
this afternoon and tonight ushering in a drier airmass for tonight.
This is expected to scatter out overcast cloudiness, but partly
cloudy skies are still possible tonight into Thursday morning.
Perhaps a few areas could see BR, fog down to 2 to 4 miles or so,
with dew points not dropping too far below 50 degrees and light
winds taking over. There's not great confidence on where this
occurs, but perhaps east winds and lingering low level moisture can
create an environment conducive to it south of US-30. It's a quick
reprieve from the rainfall, though, as moisture advects back in as a
warm front encroaches on our western flank Thursday morning. It
appears the better moisture stays west of I-69 for much of the day
allowing the best chance for showers to be there perhaps along any
convergent boundary that can come in there. Model confluence on
showers in this same area occurs Thursday afternoon as instability
between 500 and 1000 J/kg of MUCAPE forms overhead. The NAM appears
to bring 30 kts of effective shear into areas south of US-30 so
perhaps a strong thunderstorm could be possible, but think they
would be isolated. These showers and storms look to spread eastward
overnight perhaps along an outflow boundary with the 6 C/km mid
level lapse rates and ~200 J/kg of MUCAPE. Continued chances for
scattered off an on showers occur on Friday, but despite better
chance for seeing 1000 J/kg of MUCAPE, we'll lack in the shear
department so severe weather will be harder to come by.
Mid level height rises and resultant ridging moves in by Saturday
morning restricting the chance for more organized showers and
storms, but pop-up showers and storms will be possible with 500 to
1500 J/kg of MUCAPE around. Shear, once again, appears lacking
likely restricting overall severity of these storms. The mid
level ridging and lack of forcing underneath an area of surface
high pressure is expected to keep Sunday the driest of the next
few days.
Meanwhile, subtropical ridging takes root across the Gulf States
next week as a trough digs across the West Coast. This sets up yet
another active pattern as areas of vorticity are pushed into the
area within a wet and moist environment with 60+F dew points. This
allows for chances for showers and thunderstorms as afternoon
instability allows for initiating cells. One ingredient for stronger
storms makes an attempt to come into the region later Sunday and
Monday time frame as 6 to 7 C/km lapse rates edge into the area. Am
a little skeptical about how much overturning and mixing can occur
within that airmass before it finally gets here, but that could make
sustaining larger hail stones possible with some shear around.
Between Monday and Tuesday, that does look possible with some shear
to work with along with instability.
Perhaps more urban areas could see standing water/flooding issues
from these repeated rainfall events along with a little lower level
of tolerance for increased rainfall in these areas. Highs
generally range from the upper 60s to low 80s with the warmest
days being Monday and Tuesday. Next Wednesday may provide
another brief break as surface high pressure comes into the
area.
&&
.AVIATION /00Z TAFS THROUGH 00Z FRIDAY/...
Issued at 725 PM EDT Wed May 15 2024
Skies will continue to clear over the next couple of hours with
winds becoming light and variable. Some concerns linger for some
patchy fog, especially at KFWA. Have left a tempo MVFR vsby in
for KFWA and kept with no restrictions at KSBN. Mid clouds will
begin to move in later in the period at KSBN in advance of the
next system.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...None.
OH...None.
MI...None.
MARINE...None.
&&
$$
DISCUSSION...Roller
AVIATION...Fisher
Source:
IWX issues Area Forecast Discussion (AFD) at May 15, 7:39 PM EDT---------------
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