Area Forecast Discussion
Issued by NWS Northern Indiana

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FXUS63 KIWX 301749

Area Forecast Discussion
National Weather Service Northern Indiana
149 PM EDT MON MAY 30 2016

Issued at 142 PM EDT Mon May 30 2016

High pressure moving across the Great Lakes and Ohio Valley will
provide fair weather across our area today and tonight. A cold
front will move east across the Midwest mid-week bringing a
chance of showers and thunderstorms. Temperatures will remain
above normal ahead of the front with highs in the lower and middle
80s... and lows ranging from the upper 50s to the mid 60s.


.SHORT TERM...(Today and Tonight)
Issued at 410 AM EDT Mon May 30 2016

Despite high pressure over the region today there are a couple minor
concerns with forecast. First...water vapor shows short wave over WI
moving quickly east this morning. This has helped spark a few
showers and thunderstorms upstream across NW IL. HIRES models
showing this activity weakening as it moves east into drier air and
subsidence early this morning. IR showing some residual cloudiness
which may drift across the area this morning but expecting it to be
high and thin around daybreak.

Next concern is whether any isolated shra or tsra will develop early
to mid afternoon over the local area. Models have been hinting at
very isolated development for several days and now most HIRES
guidance is developing very weak and isolated reflectivity and a few
hundredths of QPF over central and eastern areas this afternoon. The
output is small and represents less than 15 percent coverage. This
development appears to be in response to instability gradient that
develops and is enhanced between meso high over relatively stable
southern Lake Michigan expanding inland and lingering low level
moisture and diurnal heating south and east. NAM12 goes bonkers with
CAPE this afternoon in excess of 2k J/kg and is discounted as usual.
GFS and HRRR/RAP guidance more plausible around 1000-1500 J/kg at
worst with afternoon heating. This gradient maximizes from near
Coldwater to Warsaw to Monticello and points eastward with
relatively stable air off the lake over NW areas. Model point
soundings show just a slight increase in 850-700mb layer moisture
with low level lapse rates increasing to over 9.5 c/km. However...
mid level lapse rates remain a paltry 5-6 c/km. Models do show a
very weak short wave crossing the region but overall soundings look
rather dry and not convinced enough forcing to produce more than
some virga or sprinkles. With moisture and forcing today even
weaker/less than over last few days just cannot justify adding more
than a 10 percent PoP to forecast and will leave mention out of
public products and grids.

High temps next issue. Last several days have seen temps jump into
upper 80s where clouds cleared. Despite weak cold frontal
passage...airmass not much cooler with only slightly lower 925-850mb
temps. Overall lower levels remain dry and expect temps closer to
higher end guidance again today.


.LONG TERM...(Tuesday through Sunday)
Issued at 410 AM EDT Mon May 30 2016

Rather straight forward long term period with superblend init
generally accepted. High pressure at surface will drift east on
Tuesday with return flow developing ahead of upper low drifting
across the CONUS and Canadian border. This system now looking rather
progressive with main area of lowering heights and associated
surface cold front crossing the region later Wednesday and Wednesday
night. This is when best chances for precipitation will arrive.
Stayed short of likely pops given convective nature and projection
time range. Models in good agreement with front clearing the area
early Thursday with high pressure and drying moving in quickly.
Trimmed pops back Thursday with latest timing among models. Next
chances for pcpn arrive over the weekend with just low chances for
now as large scale trough sets up over the Western Great Lakes and
several short waves likely to rotate through with limited moisture.
Temps will trend warmer Tue and Wed followed by cooler temps late
in the week.


.AVIATION...(For the 18Z TAFS through 18Z Tuesday Afternoon)
Issued at 142 PM EDT Mon May 30 2016

High pressure over the wrn grtlks and the lwr oh valley will
provide vfr conditions through this period. Mainly sct cu expected
across the area this aftn... less at sbn with greater marine layer
influence. NW winds generally 10kt or less this aftn become east
tonight as high pressure ridge moves to ern ontario and oh.


.IWX Watches/Warnings/Advisories...


SHORT TERM...Lashley
LONG TERM...Lashley

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