IWX issues Area Forecast Discussion (AFD) at Oct 26, 11:24 AM EDT935
FXUS63 KIWX 261524
AFDIWX
Area Forecast Discussion
National Weather Service Northern Indiana
1124 AM EDT Sat Oct 26 2024
.KEY MESSAGES...
- Cool temperatures in the low 30s tonight and low to mid 30s
tomorrow night are expected.
- A warming trend can be expected from Sunday into Tuesday as
highs rise from either side of 60 on Sunday to the upper 70s
and around 80 on Tuesday.
- Gusty winds are expected to Tuesday with an initial forecast
estimate of between 30 and 35 mph.
- Our next chance for rain is Wednesday night into Thursday.
&&
.DISCUSSION...
Issued at 332 AM EDT Sat Oct 26 2024
As the trough that brought the cold front through the area today
pushes eastward, surface high pressure follows and influences the
area with dry weather through Monday. Nearly dry adiabatic lapse
rates, today, allows mixing to create sub 30 degree dew points
across northwest OH. Behind yesterday's cold front, temperatures are
only in the 50s today, so this only creates 25 to 40 percent MinRH
values as opposed to if we were warmer. Our main limiting factor is
the weak low level jet for any fire weather conditions along with
the likely still moist fuels from yesterday's rain. Sunday sees
slightly warmer temperatures and similar, if not slightly drier dew
points allowing for similar atmospheric dryness, but drier
fuels, and light winds with the high pressure center now
shifting eastward away from the area. Monday, a warm air
advection pattern ensues allowing 60 degree temperatures to
return and for the 20 degree dew points to moisten back into the
30s. A slightly more gusty day with 15 to 20 mph winds will
combine with 25 to 40 MinRH values to be a little bit higher
fire weather day. For Monday night into Tuesday, a moisture axis
combines with a northward surging warm front to allow for cloud
cover. Given better forcing in the form of large scale ascent
passes by just to our north, am still skeptical of all the
precipitation the GFS indicates so will just stick with slight
chance PoPs north of the Toll Road mainly between 6 and 12z.
Tuesday is expected to be dry again, but a developing low
passing to our north increases wind gusts to 25 to 35 mph, but
the warm advection has increased our dew points back into the
50s at this point. One thing to watch here is that we could mix
dew points drier and, with that, could see higher gusts creating
a better fire weather day and we could edge near a wind
advisory day. We'll be much warmer still with upper 70s to
around 80 degrees for highs.
Positive NAO blocking across the Atlantic really begins to show its
affect on the CONUS pattern as surface high pressure stalls out in
the Western Atlantic. During this time, the vorticity within the
trough in the western CONUS undergoes a cyclonic wave break as it
becomes cut off from the upper flow. This often creates a lower
confidence forecast especially as it pertains to timing of critical
components, but model confluence does still exist on bringing a cold
front into the area late Wednesday night into Thursday morning. It
is interesting to see how far northward the moisture stream is able
to get into southeastern Canada. The PWATs are modeled as being 2 to
3 SDs above normal with 60+F degree surface dew points and 10+C 850
mb dew points indicating how moist the column is. Given the timing
of this (morning), the convective component appears weak with MUCAPE
failing to even reach 250 J/kg. Storm motion also appears quick to
the northeast, which would also limit precipitation output despite
the moisture content. Another component of this is that the vort max
goes into the Northern Great Lakes and away from the area limiting
the forcing along the front as it moves southeastward. As a result,
the NBM only has a 30 percent chance for greater than 1 inch of
precipitation in 24 hours up to 00z Thu along our lake MI adjacent
counties and another area into IND's area like the area is split by
the better precipitation output. Gusty winds may also factor into
this because, as the area of vorticity moves northward, there are
signs that a wave may be able to form along the cold front inducing
a pressure gradient with a 40 to 50 kt jet just to our northwest.
The next chance for precipitation looks to be not too long after
this, around Saturday night (holding to the ECMWF and CMC camp).
There is some signal that a negative tilt in the trough could occur
further enhance the wet signal for this period.
&&
.AVIATION /18Z TAFS THROUGH 18Z SUNDAY/...
Issued at 1120 AM EDT Sat Oct 26 2024
VFR conditions anticipated through the period with winds picking
up during peak mixing this afternoon/early evening. High
pressure will drift overhead and bring light and variable winds
for the remainder of the period.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...None.
OH...None.
MI...None.
MARINE...Small Craft Advisory until 8 PM EDT this evening for LMZ043.
Small Craft Advisory until 5 PM EDT this afternoon for LMZ046.
&&
$$
DISCUSSION...Roller
AVIATION...Fisher
Source:
IWX issues Area Forecast Discussion (AFD) at Oct 26, 11:24 AM EDT---------------
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