IWX issues Area Forecast Discussion (AFD) at Mar 27, 3:54 AM EDT649
FXUS63 KIWX 270754
AFDIWX
Area Forecast Discussion
National Weather Service Northern Indiana
354 AM EDT Thu Mar 27 2025
.KEY MESSAGES...
- Low chances (20-35%) of rain showers today mainly south of US
Route 30 across northern Indiana.
- Greater chances of rain (60-80%) arrive late tonight into early
Friday with a few thunderstorms possible.
- Notably warmer Friday through the weekend with showers and some
thunderstorms. Greatest chance of thunderstorms late Sunday
afternoon into Sunday evening.
- Windy on Friday with southwest wind gusts as high as 40 mph
possible in the afternoon.
- Sharply colder Monday.
&&
.DISCUSSION...
Issued at 350 AM EDT Thu Mar 27 2025
Low level warm advection will strengthen today as a low level ridge
axis builds in from the west. Frontogenetic low/mid level flow in
wake of this low level ridge axis and some elevated moisture
return will allow for the potential of some isolated to
scattered light showers. Primary low level theta-e gradient
should remain anchored well back to the southwest today with a
relatively dry sub-cloud layer persisting. Based on
guidance/observational trends, have continued trend of previous
forecast in cutting back northward/eastward extent of PoPs
today. A weak mid level disturbance tracking across the Great
Lakes region could activate a secondary frontal zone for another
area of weaker fgen forcing across Lower Michigan, and
particularly across west central Lower Michigan. Any precip with
this forcing would likely be of the trace variety however.
In terms of temperatures today, departing cold pool to the
eastern Great Lakes early this morning has allowed for some
thinning of mid level clouds across bulk of the area, although
expecting these clouds to fill back in across the west as the
fgen forcing becomes more pronounced later day. This could set
up best insolation today for areas east of I-69 and into
northwest Ohio where the potential exists for highs into the
upper 50s. Elsewhere, modest warm advection will be partially
offset by better cloud cover which should keep highs in the mid
50s (possibly low 50s in areas of thicker clouds far west-
southwest).
Some isolated showers/sprinkles may linger south of US Route 24 into
this evening, but still expecting greater rain shower coverage
during the overnight hours as more substantial low level moisture
gradient surges east-northeast from the Mid MS Valley. Other than
stronger advective forcing with developing warm frontal boundary
late tonight into Friday, large scale mid/upper level support is
rather meager. The higher theta-e low level air will also be
accompanied by some steeper mid level lapse rates tonight,
particularly into early Friday morning when a few storms are
possible.
Showers and a few embedded storms will continue through late Friday
morning/early PM before ending as the area gets into warm sector.
Forecast soundings suggest top of boundary layer winds around 40-45
knots which would be supportive of sfc wind gusts as high as 40
mph Friday afternoon across northern Indiana. Probabilistic
guidance from higher res short-term guidance suggests 50-70%
probs of wind gusts to 40 mph but sharply decreasing to 10-20%
for wind gusts in excess of 45 mph. It will be warm on Friday
with highs ranging from upper 60s far north to mid 70s south.
Lull in precip chances still looks plausible Friday night into early
Saturday AM. By later Saturday morning, southward sagging sfc front
across southern Great Lakes and renewed area of moisture transport
working into the south from the Ohio Valley could be two separate
focal points for renewed shower chances. Otherwise, it will remain
mild on Saturday with highs upper 60s/lower 70s.
A stronger short wave trough is still expected to emerge from
central CONUS Saturday night into Sunday. Stalled low level
baroclinic zone and good flow downstream of this feature should
support additional showers and thunderstorms Sunday, with perhaps a
window of some strong/severe potential given potential of some
better mid level lapse rates advecting in during the afternoon.
Shear profiles look supportive of some severe potential, but
northward extent of better sfc/near sfc based instability appears to
be a limiting factor at this forecast distance. Confidence in
details in mass fields is still somewhat low given a wide spread in
deterministic/ensemble solutions with speed/depth of mid level
trough, but given consensus low level height minimum track and
climatologically favored placement of stalled baroclinic zone
across far northern Indiana, still feel that approximately
southern half of the area would have best chance for strong
storm potential in a window from later Sunday afternoon into
Sunday evening.
Strong large scale frontal response will keep rain showers into
Sunday night/early Monday morning as conditions turns sharply
colder. This colder air will be short-lived as a series of
additional eastern Pacific waves to likely bring more
showers/possible storms middle/late next work week as temperatures
moderate back above normal.
&&
.AVIATION /00Z TAFS THROUGH 00Z FRIDAY/...
Issued at 1106 PM EDT Wed Mar 26 2025
The surface ridge has moved far enough to the east to allow
return flow to begin over northern Indiana. The lower layers
were initially dry, but as the frontogenetic area approaches
from the southwest, some lower clouds are likely to fill in
over the area. For now, kept TAFs VFR but did mention ceilings
lowering to 035 at FWA. MVFR ceilings are likely just after the
end of the TAF period.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...None.
OH...None.
MI...None.
MARINE...None.
&&
$$
DISCUSSION...Marsili
AVIATION...Skipper
Source:
IWX issues Area Forecast Discussion (AFD) at Mar 27, 3:54 AM EDT---------------
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