IWX issues Area Forecast Discussion (AFD) at Jan 8, 12:37 AM EST062
FXUS63 KIWX 080537
AFDIWX
Area Forecast Discussion
National Weather Service Northern Indiana
1237 AM EST Wed Jan 8 2025
.KEY MESSAGES...
- Typical cold January temperatures continue for at least the
next 10 days.
- Lake effect snow showers develop late tonight near Lake
Michigan and then spread well inland Wednesday afternoon and
evening, mainly north of US 30. Light accumulations and minor
travel impacts expected.
- Additional light snow chances arrive Friday into Friday night,
and then again late Sunday into Monday.
&&
.UPDATE...
Issued at 930 PM EST Tue Jan 7 2025
As of 02Z this evening, regional radar mosaic beginning to show
some development of a more dominant band beginning to form
offshore from KMKG to KBIV. Sfc observations have been showing
weak land breeze development which should continue into
overnight as weak convergent boundary pushes back to the
west/southwest. Low level cold air advection will increase
overnight allowing for increasing inversion heights, which
coupled with sharpening of low level convergence, should allow
band of lake effect snow showers to drop south across
northern/western Berrien County overnight. Some impacts appear
likely but moisture quality looks to be a limiting factor for
this event, particularly by later Wednesday morning when
synoptic flow should tend to back a little more to the west-
northwest allowing for greater chance of dry air entrainment.
Previously forecasted orientation of snowfall amounts still
appears reasonable with greater totals across northern Berrien
County (~1-3"), and lesser amounts for southern lake effect
areas which may be more susceptible to this dry air
entrainment. No significant changes made to the forecast at
this time with primary concern on some possible impacts to the
Wed AM commute.
&&
.DISCUSSION...
Issued at 216 PM EST Tue Jan 7 2025
Perturbed northwest flow will bring LES into the fold later tonight
through Wednesday night. A low amplitude mid level shortwave drops
southeast through the OH Valley tonight with just enough CAA to push
850mb-lake temp differentials into the mid-upper teens. Forecast
soundings suggest some decent snow growth potential given moderate
saturation/lift into at least lower portions of the DGZ. However,
moisture depth appears limited with inversion heights only around 5
kft with overall lake induced parameters not all that impressive.
For later tonight and Wednesday morning, light nnw trajectories
favor the immediate lakeshore (mainly Berrien Ct) for better LES
chances and light accums/impacts. Boundary layer flow then increases
and backs more wnw with time on Wednesday in advance of a potent
vort max and associated lake enhanced low level trough dropping
south into the area Wednesday afternoon-evening. Greater inland
penetration to the LE snow shower activity expected as a result
into areas mainly north of US 30 with steepening lower tropospheric
lapse rates, deep layer QG ascent, and potential seeding supporting
decent bursts of snow well into sc MI, ne IN and nw OH. This
looks like a dusting to 1" event for most north of US 30 with
some minor travel disruptions expected in more robust snow
showers. 1-3" type totals by Wed PM expected, though locally
higher totals possible in northern Berrien Ct. Lake thermal
trough abruptly collapses by early Thursday as ridging quickly
builds in behind the departing vort lobe.
Additional opportunities for light snow will come Friday into Friday
night, and late Sunday into Monday. A deep, positively tilted, upper
trough and associated frontal passage will provide the snow chances
Friday-Friday night. Any accums look to be light (1-2") locally as
most of the energy and more pronounced moisture transport will be in
the base of the trough through the Southern Plains and TN Valley.
The following wave and weak sfc reflection then look to take an
easterly track into the Great Lakes late Sun-Mon for additional snow
shower chances. Remaining seasonably cold otherwise through the
period.
&&
.AVIATION /06Z TAFS THROUGH 06Z THURSDAY/...
Issued at 1221 AM EST Wed Jan 8 2025
Southern Lake Michigan continues to be very mild for this time
of year - according to NOAA CoastWatch, the 2nd warmest in 30
years (only flanked by last year). Water temps >6C over much of
the interior will continue to provide favorable conditions for
lake effect snow showers; however, inversion heights and EQLs
just not very supportive for heavier snow showers. Given notable
shear per radar returns, have gone a little more optimistic at
SBN with visibilities and ceilings. It looks like the bulk of
the TAF period will retain MVFR conditions.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...None.
OH...None.
MI...None.
MARINE...None.
&&
$$
UPDATE...Marsili
DISCUSSION...Steinwedel
AVIATION...Skipper
Source:
IWX issues Area Forecast Discussion (AFD) at Jan 8, 12:37 AM EST---------------
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