IWX issues Area Forecast Discussion (AFD) at Nov 4, 12:40 PM EST675
FXUS63 KIWX 041740
AFDIWX
Area Forecast Discussion
National Weather Service Northern Indiana
1240 PM EST Mon Nov 4 2024
.KEY MESSAGES...
-Periods of light rain are expected today and tomorrow with the best
chances west of Interstate 69.
-Winds from the south will gust up to 40 mph today and 4Tuesday.
-Record warm temperatures are expected today and tomorrow.
Cooler weather returns for the end of the week but it will
still be above normal.
&&
.DISCUSSION...
Issued at 314 AM EST Mon Nov 4 2024
Shortwave embedded within deep SSW flow is currently lifting into
the area and supporting widespread light rain generally west of I-
69. Deep isentropic upglide (from 295-310K) noted along with strong
moisture advection on the nose of a 50+ kt LLJ (850mb dewpoints near
12C). Forecast soundings show very limited instability though with
general moist adiabatic lapse rates through the column along with
pockets of more stable layers that will likely prevent most if not
all thunder and potential for heavier rain. Still, some pockets of
moderate rain are possible in our NW zones through mid-morning as
this shortwave passes. Expect a lull in rainfall amounts/coverage
during the afternoon as shortwave lifts north and only some modest
isentropic ascent remains. Hi-res models suggest at least SCT
showers will remain roughly along the US-24 corridor into the
evening though and have adjusted PoP's to account for that. Current
temps holding in record warm low territory with low/mid 60s.
Abundant clouds/rain will keep a lid on highs today but still expect
around 70F (NW) to perhaps mid 70s (SE) which would be close to a
record for FWA.
Much of the CWA will trend dry late tonight as focus for ascent
turns to approaching trough axis and primary surface frontal
boundary. As has been discussed...this trough will be rapidly
lifting and weakening Tue as jet core rounds the base of the trough
and lifts NE while another strong Pacific jet/PV anomaly digs into
the northern Rockies. Still some residual CVA though along with
modest convergence in a moist environment that will yield a few
tenths of rain for most areas late Tue afternoon into the early
overnight. Continued to hold off on thunder mention given virtually
no instability. Tue will likely be a touch warmer given potential
for less clouds/rain particularly in our SE. Mid 70s seem like a
safer bet here which would break FWA's record high. (Record warm
lows for both SBN and FWA would also be in jeopardy on Tue though
front may push through early enough Tue night for a midnight low at
SBN.)
Other item of note for today and Tue will be wind. Gradient
continues to tighten today with model soundings indicating wind
speeds 30-35 kts at the top of the boundary layer. (Despite strong
WAA even the NAM suggests mixing to around 925mb.) Expect gusts
around 30-35 mph this afternoon. Tomorrow is a bit more concerning
as gradient tightens further and some guidance suggests mixing into
some 40-45 kt winds around 925mb. Always skeptical of raw model wind
gusts in WAA regime but some gusts up to 40 mph may be possible.
Confidence in 45+ mph is far too low at this point for an advisory
but it is something to watch in the next few forecast updates.
Postfrontal airmass is extremely dry and building subsidence/high
pressure will ensure dry conditions Wed through at least Fri. Next
upper low ejects out of the southwest this weekend. Some ensembles
suggest a quicker ejection that may impact Sat (and thus influence
NBM PoP's) but most deterministic guidance holds off on rain
until Sat night and is preferred based on general tendency for
these upper lows to eject on the slower side. While temps cool
off slightly it will remain above normal through this entire
period.
&&
.AVIATION /18Z TAFS THROUGH 18Z TUESDAY/...
Issued at 1233 PM EST Mon Nov 4 2024
Axis of rainfall is now generally southeast of KSBN but
encroaching on KFWA. Confidence is high for the end time of
rainfall at KFWA. Rain may return to KSBN near/after 00z, but
high resolution guidance favors a very narrow axis of precip
that could fall just west of the airport; low confidence.
Wind shear is a concern overnight and perhaps well into Tuesday
with an energetic wind field in place. A cold front sweeps
through brining more rain and a wind shift just outside of this
TAF period.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...None.
OH...None.
MI...None.
MARINE...Small Craft Advisory until 7 AM EST Tuesday for LMZ043-046.
Gale Warning from 7 AM to 4 PM EST Tuesday for LMZ043-046.
&&
$$
DISCUSSION...AGD
AVIATION...Brown
Source:
IWX issues Area Forecast Discussion (AFD) at Nov 4, 12:40 PM EST---------------
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