Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

Area forecast discussion 
National Weather Service northern Indiana
407 PM EDT Friday Jul 31 2015

issued at 400 PM EDT Friday Jul 31 2015

Showers and thunderstorms across the southern portions of
the forecast area will diminish this evening. Otherwise...
expect dry conditions to prevail overnight. Lows will be
in the upper 50s and 60s. On Saturday expect mostly sunny
skies through early afternoon...then increasing clouds and a
slight chance of showers and thunderstorms. Highs will range
from the upper 70s near Lake Michigan to the middle 80s inland.


Short term...(this evening through saturday)
issued at 400 PM EDT Friday Jul 31 2015

Quiet forecast in store for the immediate short term with dry
weather expected tonight and Saturday morning in the wake of the
frontal passage this afternoon. High pressure centered over Missouri
will shift eastward into western Tennessee by 21z Saturday...which
keeps our County Warning Area on the periphery under continued westerly winds. Flow
aloft remains fairly zonal out of the west-northwest as fairly
stationary 500mb low spins over Hudson Bay. Models once again
conflicting on probability of precipitation Saturday afternoon. A weak shortwave rotating
around the low will approach the area...providing some support for
precipitation. Moisture will once again be advected into the
region...with precipitable waters expected to be similar to today/around 1.3
inches. Instability is forecast to rise into the 1500 j/kg ml cape thinking isolated showers/T-storms are not out of the
question. However...forcing is not as strong as it was
kept low chance probability of precipitation for now.

Otherwise...gusty onshore winds Saturday will lead to wave heights
of 2 to 3 feet and strong currents along the Berrien County shoreline.
Kept a moderate swim risk for this time period.


Long term...(saturday night through friday)
issued at 400 PM EDT Friday Jul 31 2015

Pesky upper low will continue to meander over the Hudson Bay
region through middle of next week. Central Continental U.S. Ridge to also
build west and north keeping northwest flow over the Great Lakes.
This will result in normal to below normal temperatures for much
of the period along with periodic chances for showers and
thunderstorms with weak embedded short waves and attendant surface

Best chances for showers and storms still looks to be Sunday and
Sunday night. Sharp short wave trough will rotate through the lakes
region along with associated surface cold front. Moisture advection
ahead of this wave and decent middle level forcing should allow area of
precipitation to move through the region. Raised probability of precipitation further to
high chance category but stopped short of likely given convective
nature and model issues. Front now looks to be exiting the area on
Monday but secondary short wave could produce some afternoon
convection so allowed low chance probability of precipitation to continue for now Monday
afternoon. Remainder of forecast remains uncertain with models flip
flopping on a stronger wave middle week moving through the Ohio Valley.
Stayed with some low chance probability of precipitation with highest in the south near surface
boundary. Expect additional changes in guidance as they try to
resolve the weak waves within long wave trough and any convectively
induced short waves upstream.


Aviation...(for the 18z tafs through 18z Saturday afternoon)
issued at 400 PM EDT Friday Jul 31 2015

Forecast still looking on track for VFR conditions
through the taf period. Isolated showers and thunderstorms
moved south of the taf sites after 20z.


Iwx watches/warnings/advisories...


Synopsis...mesoscale discussion
short term...mesoscale discussion
long term...slash
aviation...mesoscale discussion

Visit US at www.Weather.Gov/iwx (all lower case)

Follow US on facebook...twitter...and youtube at:

National Weather Service Glossary of Abbreviations