IWX issues Area Forecast Discussion (AFD) at May 4, 1:20 PM EDT483
FXUS63 KIWX 041720
AFDIWX
Area Forecast Discussion
National Weather Service Northern Indiana
120 PM EDT Sun May 4 2025
.KEY MESSAGES...
- Rain will spread northwest across the entire area today and may be
briefly heavy
- Rain chances continue Monday and Tuesday.
- Mainly dry and seasonably mild Wednesday through Saturday with
highs from the mid 60s to mid 70s
&&
.DISCUSSION...
Issued at 233 AM EDT Sun May 4 2025
The upper low that had become stationary over the region was near
the Ohio River early this morning. Precipitation was developing
rapidly south of the forecast area from Swayzee to Portland. The
area of rain should continue to fill in as the upper low drifts
north and as a deformation zone develops. The upper low was
part of a highly amplified pattern that included a very sharp
upper level trof along the west coast of North America, a large
blocking omega type ridge across the continental interior and
the upper low farther downstream near the Ohio River. The upper
low will keep chilly air over the forecast area through Monday.
Highs today will only be around 50 to 55.
As for rainfall, a number of other models have joined the ECMWF
and GFS with an area of deformation zone type rain of 1.00" to
1.50" over northern Indiana to northwest Ohio. Believe the risk
of flooding is limited given initial dry conditions and very
low streams/rivers at the onset of this event. Left an mention
of isolated thunder for elevated storms. Severe weather is not
expected given virtually no CAPE and more of a stratiform
deformation zone structure. Otherwise, a stagnant pattern will
develop over the area after the upper low eventually moves out
of the region with weak upper level troffing late this week.
Temperatures should be close to normal after Monday with highs
in the upper 60s to mid 70s and lows in the mid 40s.
&&
.AVIATION /18Z TAFS THROUGH 18Z MONDAY/...
Issued at 119 PM EDT Sun May 4 2025
Impacts of the nearly stationary upper low over far N Kentucky
will linger through the period with MVFR conditions likely to
trend to IFR and possibly LIFR tonight before some improvement
occurs Monday.
The rain has ended at KFWA with limited precip chances through
most if not all of the period. Cigs at KFWA have been bouncing
around 1000 ft with upstream trends and model guidance
suggesting solid IFR cigs should establish themselves over the
next couple of hours and then remain in place into Monday
morning with a period of LIFR cigs possible late evening into
the overnight hours. Vsbys thus far have not been impacted much
but should drop into the 3 to 5 sm range and possibly lower.
At KSBN VFR conditions are still in control with the rain having
just arrived over the past hour or so. As saturation occurs MVFR
cigs should settle in near/after 20Z and hold through much of
the period. The band of rain will persist for at least a few
hours, with models varying on location and duration wrt the
airport as well as the potential for IFR conditions in the wake
of the rain. Have went with periods of light rain through 00Z,
but end of the rain or transition to drizzle could occur a few
hours sooner or later. Deeper low level moisture may stay just
southeast of the airport, allowing for low end MVFR cigs and
eventually vsbys to persist. As a result, will limit cigs to
1000 ft and let later forecasts determine if IFR cigs can make
it into the site.
Towards the end of the period, some mixing may occur in the low
levels to allow cigs to improve with some limited breaks in the
clouds. Another weak disturbance will arrive as well to bring
showers and maybe a rumble of thunder to the area vs the steady
rainfall. With the best chances remaining closer to the end of
the period, have left out any precip for the time being.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...None.
OH...None.
MI...None.
MARINE...Small Craft Advisory until 5 AM EDT Monday for LMZ043-046.
&&
$$
DISCUSSION...Skipper
AVIATION...Fisher
Source:
IWX issues Area Forecast Discussion (AFD) at May 4, 1:20 PM EDT---------------
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