Scientific Forecaster Discussion

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Area forecast discussion 
National Weather Service northern Indiana
411 PM EDT sun Apr 20 2014

issued at 415 am EDT sun Apr 20 2014

Strong high pressure will begin to shift east today but will still
support mostly sunny skies and dry conditions. Southerly winds
behind this high pressure will bring temperatures in the low to
middle 70s today with overnight lows in the upper 40s to around 50.
There is a chance of rain late Monday as a cold front sweeps
through the region.


Short term...(this evening through monday)
issued at 410 PM EDT sun Apr 20 2014

Shortwave moving through southern Saskatchewan/NE Montana this afternoon will move east to
Ontario/upper Great Lakes by Monday evening and phase with Southern Plains upper low.
This should result in increasing moisture/lift across our area over
the next 24hrs with scattered showers developing Monday afternoon. Weak instability and
850 mb-500 mb lapse rates around 6c/km expected Monday afternoon... so a few
thunderstorms not out of the question...mainly northwest 1/2 of County Warning Area.

Decent radiational cooling conditions again tonight with fairly
light winds, dry low levels, and mostly clear skies at least through
midnight should allow temperatures to fall into the M-u40s over most
of the area following afternoon highs in the l-m70s. Warmer start to the
day Monday combined with a little stronger gradient mixing expected
to allow for highs in the m70s despite incrsg cloudiness.


Long term...(monday night through sunday)
issued at 410 PM EDT sun Apr 20 2014

A couple of short wave troughs will move across the area this
period...accompanied by showers Monday night and then showers with
possible thunder late in the week. The ongoing forecast/grids reflect
the latest handling by the GFS of these systems. Temperatures
will warm up ahead of late week system...with readings rising above
normal. For this package...favored the GFS with corresponding model
guidance temperatures and probability of precipitation. However...the GFS appears to be generating
too much precipitation Monday night given limited moisture and lift.
The GFS has had good run to run consistency and appears to be
handling the synoptic systems well. Rejected allblend temperatures and rain
chances. The allblend was finally catching up to the GFS after being
apparently too warm earlier with lows Tuesday night. Also...can not
buy allblend rain chances this coming weekend. The European model (ecmwf) of
the few supporting wet runs has a large spread among ensemble kept this weekend dry. The GFS advertises a large surface
anticyclone with a cool and dry north to northeast fetch out of
Canada. Still on board with chilly temperatures with areas of front
Tuesday night. Ideal radiational cooling with dry conditions should
cause temperatures to dip close to freezing or below freezing.


Aviation...(for the 18z tafs through 18z Monday afternoon)
issued at 1253 PM EDT sun Apr 20 2014

VFR conditions expected to continue through the period. Moisture will
gradually increase across northern Indiana over the next 24hrs as shortwaves
over the northern rockies and Southern Plains move east. Expect mainly broken
cirrus overnight with scattered-broken cumulus Monday. Scattered rain showers expected Monday
afternoon as weak instability develops ahead of an approaching cold front.


Iwx watches/warnings/advisories...


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

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