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Area forecast discussion 
National Weather Service northern Indiana
128 am EDT Friday Apr 18 2014

issued at 816 PM EDT Thursday Apr 17 2014

An upper level disturbance will approach the region tonight. A
slow moving frontal boundary associated with this system will
bring a chance of some light rain showers tonight into early
Friday. A ridge of high pressure will then build into the region
Friday afternoon providing dry conditions through the weekend. Low
temperatures tonight will range from the upper 30s to middle 40s.
High temperatures on Friday will range from the middle 50s to middle
60s...but north winds off Lake Michigan will provide cooler
conditions for far Northwest Indiana and southwest lower Michigan.


issued at 816 PM EDT Thursday Apr 17 2014

An upper level vorticity maximum tracking across western Iowa this evening
should allow for expanding coverage of light rain showers along
an upper level front this evening...mainly across northwest third
of the area. Regional amdar soundings still exhibiting a dry sub
cloud layer with sizable low level dew point depressions however.
This should limit intensity of any precipitation tonight and given these
low level moisture considerations...have opted to keep chance probability of precipitation
going. Updated evening forecast sent mainly to refresh late
afternoon wording and to slightly delay probability of precipitation across the northwest
until late evening.


Short term...(this evening through friday)
issued at 338 PM EDT Thursday Apr 17 2014

Shortwave over the plains this afternoon expected to move east-NE across the
Great Lakes/Ohio Valley tngt/Fri. Although moisture is lacking with Gulf
cut off... 12z models in fairly good agreement that there will be
sufficient forcing and Theta-E advection for showers to form along
the surface cold front as it moves across our area tonight and Friday. Some
indication that the front may be becoming a little more active this
afternoon with radar echoes and surface observation suggesting some light showers
forming Kansas-northern MO-northwest Illinois. Best forcing in our area should occur
overnight across northwest 1/2. However... given less support for precipitation
development in our County Warning Area by rap/hrrr and generally dry airmass... kept
probability of precipitation in this area in the chance range. Better forcing should move NE of
our County Warning Area on Friday... so trended probability of precipitation lower in this period.

Diurnal cooling overnight should be enhanced by light winds...dry
low levels and perhaps some evaporational cooling with showers northwest...
though cloud cover will be a limiting factor everywhere. Expect lows
to be in the l-m40s...except in the M-u30s with developing onshore flow
near Lake Michigan. With a better chance of staying dry and associated
potential deeper mixing... bumped up highs a few degrees into the
l-m60s southeast Friday while northwest should be in the M-u50s...except only
M-u40s near Lake Michigan with onshore flow continuing.


Long term...(friday night through thursday)
issued at 338 PM EDT Thursday Apr 17 2014

Fairly tranquil weather is expected this period as a couple of
short wave troughs bring a chance for showers next week. Otherwise...
conditions should be dry with temperatures near to above normal.
Favored the GFS this package which has good run to run consistency
with recent runs. Given this consistency...raised rain chances a
little Monday into Monday night. Kept thunder out for now given
limited moisture and limited cape. Also...GFS/BUFKIT profiles
indicate Narrow Cape with limited bulk/shear. Temperatures should be
mild this period...even considered warm given the lingering seemingly
endless cold pattern with highs in the 60s to lower 70s. However...the
GFS looks too warm during the middle of next week given 850 mb temperatures
falling to around 0c and recent warm bias in this pattern.


Aviation...(for the 06z tafs through 06z Friday night)
issued at 128 am EDT Friday Apr 18 2014

Weak elevated cold front is currently crossing the area with a few
light rain showers being produced across Northwest Indiana. Very
dry low levels as seen on 00z kilx sounding...and a lack of any
substantial synoptic forcing aloft...are expected to keep conditions
VFR though. Brief period of MVFR may be possible at ksbn but this
still appears unlikely. High pressure will gradually build into
the region later today with just some low end VFR cumulus to contend


Iwx watches/warnings/advisories...


short term...jt
long term...skipper

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