Area Forecast Discussion
Issued by NWS Northern Indiana

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FXUS63 KIWX 200906
AFDIWX

Area Forecast Discussion
National Weather Service Northern Indiana
506 AM EDT Sat May 20 2017

.SYNOPSIS...
Issued at 500 AM EDT Sat May 20 2017

Low pressure over the southern Plains will move slowly northeast
into the upper Great Lakes this weekend causing showers and
thunderstorms at times across our area through Sunday morning,
with best chances late today through tonight. High pressure will
build then into the area later in the day Sunday providing dry
weather which should then continue through Monday night.
Temperatures over the next few days will be falling below normal
early next week.

&&

.SHORT TERM...(Today through Sunday)
Issued at 456 AM EDT Sat May 20 2017

An upper low will move from the High Plains into the Upper
Midwest by Sunday morning. Ahead of this system, a warm front from
southeast Missouri extending along the Ohio River will move
north. Showers and storms will increase across the area later
today into tonight. An initial meso convective vortex over
northeast Illinois early this morning will move northeast and
spread a few showers and possibly a storm into northwest Indiana
around daybreak. A second system will move northeast and help
shower and storm chances increase as the front moves north later
today as very moist air spreads north. Precipitable water values
of 1.7 inch per GFS will top the average climate maxes for this
time of year. There is the potential for severe weather later
today and tonight as surface based instability increases and may
possibly top 3000 J/Kg if the surface warm front moves into the
southern part of the forecast area. The instability combined with
low level shear will favor the chance for severe storms. Rainfall
amounts are expected to range from around an inch to an inch and a
half by late Sunday night.

&&

.LONG TERM...(Sunday through Friday)
Issued at 456 AM EDT Sat May 20 2017

Sunday night through Friday... An amplifying upstream ridge will
cause a broad upper level trof to develop and deepen through the
middle of the upcoming week. Another round of rain is expected as an
upper level disturbance moves south out of Canada and deepens the
main trof. Chilly air behind the next system will cause high
temperatures to struggle to reach 60 Wednesday.

&&

.AVIATION...(For the 06Z TAFS through 06Z Saturday Night)
Issued at 158 AM EDT Sat May 20 2017

Terminals will remain north of the sfc boundary through this
period. Easterly flow will continue north of this boundary with
strongest winds today expected at KSBN due to a pocket of fairly
strong sfc pressure falls working across the western Great Lakes
later today. Continued strong low level inversion and easterly
flow should be conducive for maintenance of low clouds through
most of this period. Generally expecting cigs fairly close to
current levels to persist although some cigs closer to 1000 feet
cannot be ruled out. Stronger mid/upper level forcing will remain
west of the terminals today, although increasing isentropic ascent
today and approach of a few weaker embedded southwest flow short
waves should allow scattered showers/isolated thunderstorms to
affect northern Indiana late morning/afternoon. Confidence in
thunder is too low for inclusion at this time. Better chance of
scattered thunderstorms tonight as low level warm front begins to
approach northern Indiana with more robust instability and
eventual eastward migration of stronger upper forcing. At this
forecast distance, will keep thunder mention to VCTS.


&&

.IWX WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
MI...NONE.
OH...NONE.
LM...Small Craft Advisory until 4 PM EDT this afternoon for LMZ043-
     046.

&&

$$

SYNOPSIS...Skipper
SHORT TERM...Skipper
LONG TERM...Skipper
AVIATION...Marsili


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