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Area forecast discussion 
National Weather Service northern Indiana
813 PM EDT Monday Jun 29 2015

issued at 813 PM EDT Monday Jun 29 2015

Little more than an isolated light shower or two is expected
overnight...otherwise most areas will be dry for a change. Patchy
fog may form toward daybreak...especially in the most wet areas.
There is another chance for showers and thunderstorms on Tuesday
as an upper level system rotates across the region. Lows overnight
will drop into the upper 50s and lower 60s. Highs on Tuesday will
be in the 70s.


Short term...(this evening through tuesday)
issued at 320 PM EDT Monday Jun 29 2015

Short waves embedded within large scale trough have been
responsible for todays rainfall. Deformation area in base of
trough over Northwest Indiana has been slow to move east and weaken but
finally showing signs last hour or so. With continued weak diurnal
heating and upper trough expect scattered showers and an isolated
thunderstorms and rain through early evening before loss of heating leads to
diminishing showers. Then expect variable clouds overnight but
moist low levels and light winds will allow for some patchy fog
development especially where skies clear. This could lead to more
stratus development as well toward daybreak as well.

Another short wave will drop into the area Tuesday. Hires
convective models indicate some development but differences in
timing and degree of development continue. Precipitable waters will be around
1.5 inches and will not take much to get convection going. Best
chances will be central and east from middle morning into afternoon.
Models showing MUCAPES of 1500-2000 j/kg but shear remains weak
with 15-20 knots coincident with these maximum cape values. Morning
cloud cover will also play a role as usual so opted to keep probability of precipitation
in high chance category with scattered coverage most likely.
Locally heavy rainfall again possible but more localized nature


Long term...(tuesday night through monday)
issued at 320 PM EDT Monday Jun 29 2015

Amplified upper air pattern with mean trough axis in place across
the eastern US through middle-late week will weaken east by this
weekend/early next week. The result will be a continuation of
unseasonably cool temperatures warming closer to normal toward the
end of the period. Precipitation chances will depend on individual
timing/track of smaller scale shortwaves embedded in west-northwest flow
aloft. First feature of interest likely clips the local area on
Wednesday. Associated weak forcing along attendant surface trough and
steepening lapse rates within the surface-750 mb layer suggest
isolated convection possible across east-southeast zones Wednesday
aftn/eve...with deeper moisture shunted well east limiting

The last several model cycles have continued the trend of forcing
strengthening frontal boundary and better rainfall chances south
of the area Wednesday night through Thursday night as area of
anti- cyclonic flow drops southeast into the Great Lakes region. As a
result lowered probability of precipitation within stable low level easterly flow during
these periods. Retained low-middle chance probability of precipitation for showers/thunder
Friday into the weekend as frontal boundary tries to return north
and several convectively aided impulses drop through on northeast
fringe of a building plains ridge.


Aviation...(for the 00z tafs through 00z Tuesday evening)
issued at 810 PM EDT Monday Jun 29 2015

Light flow and rich low level moisture continue to favor lower ceilings
and at least minor br formation espcly late overnight/daybreak.
Guidance/model soundings indicate best potnl for IFR conds at kfwa and
trended slightly more optimistic at ksbn. Upper level shortwave
energy along with attendant surface troffing may yield scattered/chance rain showers
middle am/midday across northern Indiana...cover with period of vcsh as
coverage/duration should be minor.


Iwx watches/warnings/advisories...


short term...Lashley
long term...steinwedel

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