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Area forecast discussion 
National Weather Service northern Indiana
647 am EDT Wednesday may 27 2015

issued at 420 am EDT Wednesday may 27 2015

A weak cold front is expected to move across the area this
afternoon causing scattered showers and thunderstorms. High
pressure will build into the area tonight providing fair weather.
Highs today will be in the upper 70s and lower 80s... with lows
tonight in the middle and upper 50s.


Short term...(today and tonight)
issued at 420 am EDT Wednesday may 27 2015

Shortwave and associated cold front over the upper MS valley this morning
expected to move east-NE across our County Warning Area this afternoon. Diurnal heating
should result in around 1000j/kg cape while still respectable
30-40kt unidirectional deep layer shear remains over the area ahead
of the upper level trough suggesting some potential for severe storms with
damaging winds across the southeast portion of County Warning Area where later frontal passage should
allow for better instability. High res convective allowing models in
decent agreement suggesting thunderstorms will impact southeast 1/2 of area this
afternoon so bumped up probability of precipitation in this area to likely range. Rather strong
gradient/mixing ahead of the front should result in breezy/warm
conditions once again with high temperatures ranging from the u70s northwest to
the l80s southeast.

Surface high expected to move east across the area tonight as the front
sinks S-southeast to southern in/OH. Light winds and clearing skies should
provide good radiational cooling allowing temperatures to fall into the
M-u50s. Some potential for fog development but held off adding to
forecast to see how significant the drying is behind the front this afternoon.


Long term...(thursday through tuesday)
issued at 420 am EDT Wednesday may 27 2015

The main challenges this period concern the evolution and phasing of
a northern stream system dropping south out of Canada and a southern
stream wave ejecting east across the Continental U.S. Friday and Saturday. For
this package...favored the European model (ecmwf). The European model (ecmwf) continues to have a
better overall handle with this system which is reflected in better
run to run consistency than the GFS. Also...the upstream airmass has
been very efficient in producing showers and storms. Thermal and
wind profiles support only a marginal severe storm threat...but
given the history of this airmass and the likely hydrologic
recycling upstream...have raised rain chances Friday night and
Saturday. Precipitable water values should rise close to 1.75. Cape
values should remain around or under 1000 j/ locally heavy
rainfall is likely. After Saturday night...removed all rain chances
except for a low chance for a lingering shower over southeast areas
Sunday. Temperatures should be very warm Thursday and Friday with
highs from 82f to 86f.


Aviation...(for the 12z tafs through 12z Thursday morning)
issued at 644 am EDT Wednesday may 27 2015

Weak cold front over northwest Illinois this morning expected to move east across northern
Indiana today with frontal passage at sbn around 16z and around 20z at FWA.
Diurnal heating should lead to scattered thunderstorms and rain forming in vicinity of the
front with greater coverage NE Indiana where more instability should
be in place by frontal passage. With the exception of a tempo MVFR group in
thunderstorms and rain at FWA this afternoon... VFR conditions forecast through this evening.
Some br may form overnight as a surface high moves across the area
providing light winds and good radiational cooling.


Iwx watches/warnings/advisories...


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

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