Area Forecast Discussion
Issued by NWS Northern Indiana

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FXUS63 KIWX 031744

Area Forecast Discussion
National Weather Service Northern Indiana
144 PM EDT Mon Aug 3 2020

Issued at 341 AM EDT Mon Aug 3 2020

An upper level system will move across the area today in tandem
with a cold front and will bring showers and a few thunderstorms.
Cooler air will then spread over the region behind this system
with dry weather from Tuesday through Friday. Highs will be in the
70s through Thursday with lows mostly in the 50s. The active
weather pattern will cause dangerous swimming conditions on Lake
Michigan through at least Tuesday.


Issued at 1113 AM EDT Mon Aug 3 2020

Some changes made to the forecast in the late morning update. Mid
lake convergence boundary and mesolow type feature continues to
be forcing mechanism for isolated showers over lake Michigan.
Focus for these showers should drift toward the southeast
shoreline this afternoon as upper level trough and cold front
shift eastward. Already seeing reflection of sfc trough from near
Three Rivers MI extending southwest to South Bend IN to just
north of Knox IN. Would suspect that in addition to showers moving
inland with mesovort feature, this inland convergent zone may
serve as initiating point for scattered showers/isolated
thunderstorms this afternoon. Given increasing lake induced
instability and fairly impressive lake induced equilibrium levels,
cannot rule out potential of an isolated waterspout this
afternoon across southern Lake Michigan.

Otherwise across the remainder of the area, broad low level
confluence should focus best instability along and south of Route
24 corridor this afternoon. Low level frontal convergence is
somewhat broad in this area, but will maintain likely PoPs in
these areas coincident with peak heating. Secondary max coverage
area may be across southern Lower Michigan where reinforcing low
level trough provides some uptick in low level convergence this
afternoon, although instability will be more lacking. Have trended
gridded forecast to consensus in idea in latest guidance of
minimum in PoPs (chance) across much of central portion of the
forecast area due to the above factors while confining likely PoPs
to south of Route 24. Still not expecting severe weather to be
much of a concern today with just an outside chance of a stray
strong wind gust across the south with better precip loading.

For marine interests, wave heights have exhibited a sharp increase
in Michigan City IN vicinity this morning likely tied to prolonged
mid level convergence/mesovortex type feature. Southeast
progression of this feature early this afternoon should allow for
these building wave heights to overspread remainder of nearshore
waters this afternoon. Have moved up onset timing of small craft
advisory/Beach Hazard Statement to the current time with waves
already in the 5-6 ft range at Michigan City.


.SHORT TERM...(Today through Tuesday)
Issued at 341 AM EDT Mon Aug 3 2020

An upper level system and a cold front were over eastern
Wisconsin. The system will move east across the area and will
bring a round of showers and scattered storms. Modest instability
up to 1000 J/kg of CAPE with a relatively weak wind field should
support storms with gusty winds and locally heavy rainfall. No
flooding is expected given antecedently dry conditions. Cooler and
drier air will spread across the area with lingering showers
ending overnight. Anomalously cooler weather is ahead Tuesday with
850 mb temperatures falling below 8C. Afternoon temperatures may
not rise much out of the low 70s.


.LONG TERM...(Tuesday night through Sunday)
Issued at 341 AM EDT Mon Aug 3 2020

Unseasonably cool and dry weather is ahead through the middle of
the week as the upper level trof lifts northeast and as an upper
level ridge gradually builds into the region. Temperatures should
then rise above normal by Sunday afternoon with a return of the
summer heat and humidity at the same time. Have chances for
showers and storms returning to the area this weekend.


.AVIATION...(For the 18Z TAFS through 18Z Tuesday Afternoon)
Issued at 144 PM EDT Mon Aug 3 2020

The latest radar trends have shown two area of interest. The
first is a broken line of showers off of southeast Lake Michigan
and moving off to the east due to a lake enhanced convergence
boundary. Further southeast across western Ohio and central
Indiana, more widespread showers and storms have formed in an
area of somewhat broad confluence/surface trough. This has helped
to focus the deeper moisture pool coming into afternoon period of max
heating. Included a vcnty for tstms at kfwa to account for an
development from aftn heating. Otherwise the terminal sites
should be mostly dry for this aftn and evening. Winds have turned
nw at KSBN and are expected to at KFWA later this evening. With
lack of precip this aftn, do not anticipate fog being an issue as
was the case this morning.


IN...Beach Hazards Statement through Wednesday morning for INZ003.

     Lakeshore Flood Advisory until 7 AM CDT Wednesday for INZ003.

MI...Beach Hazards Statement through Wednesday morning for MIZ077.

     Lakeshore Flood Advisory until 8 AM EDT Wednesday for MIZ077.

LM...Small Craft Advisory until 5 AM EDT Wednesday for LMZ043-046.



SHORT TERM...Skipper
LONG TERM...Skipper

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