Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

Area forecast discussion 
National Weather Service Indianapolis in
945 am EDT Monday Aug 31 2015

the near term section has been updated below


issued at 246 am EDT Monday Aug 31 2015

Surface high pressure will generally be in control across the forecast
area this week.


Near term /rest of today/...
issued at 945 am EDT Monday Aug 31 2015

Scattered clouds across the region this morning as most fog has
burned off. Muggy with temperatures at 1330z in the upper 60s and lower

Little change needed for the morning update. Area of slow moving
convection developed earlier this morning over eastern and south
central Illinois within a pocket of slightly greater instability
and on the edge of the Theta-E ridge. Storms have gotten to within
about a County of the Indiana state line...and have prompted an
earlier introduction of isolated probability of precipitation in the Terre Haute area as
of 14z.

Still anticipate greater convective coverage comes during the
afternoon as the airmass destabilizes and interacts with an
elongated middle level vorticity axis over the region. Not everyone will
see storms but those that do are likely to see quick soakers with
storm motions generally less than 20mph. Could see gusty winds
with any stronger cell but lack of bl shear and flow aloft should
keep storms subsevere with pulsing intensity. Highs will rise
generally into the middle to possibly upper 80s.

Zone and grid updates out.


Short term /tonight through Wednesday night/...
issued at 246 am EDT Monday Aug 31 2015

Model data indicate a rather stagnant upper pattern during this period.
An upper level shear axis and associated cold pocket will linger
over the Ohio Valley through Tuesday...embedded within a large
upper ridge. The presence of the shear axis and cold pocket aloft
may spark some mainly afternoon and early evening convection on
Tuesday. Will keep some chance probability of precipitation going on Tuesday afternoon and
early evening to cover this. By Wednesday...the models suggest
this shear axis will get shunted off to the east as upper heights
and temperatures rise a bit. This may help to cap off convective
potential by that time. Based on this...will go dry on Wednesday.

Based on prognosticated low level thicknesses...the GFS MOS temperature guidance
in the later periods look will not stray too far from them.


Long term /Thursday through Sunday/...
issued at 335 am EDT Monday Aug 31 2015

A broad upper ridge of high pressure will strengthen over the central
and eastern U.S. Toward the end of this week and weaken some early
next week as an upper trough moves east into the Pacific northwest
and then across the northern rockies. Temperatures will be warmer
than normal through the long term with highs in the upper 80s to lower
90s and lows in the upper 60s to around 70.

Models indicate isolated convection possible across our northeast
Thursday and far south Sunday. An isolated thunderstorm can not
be ruled out any day...but with high pressure across our area expect
most areas to stay dry.

Went close to model initialization on temperatures...but tweaked probability of precipitation
down slightly some areas Thursday and Sunday as MOS seems a bit too high.


Aviation /discussion for the 311200z taf issuance/...
issued at 700 am EDT Monday Aug 31 2015

MVFR or IFR fog possible at outlying sites another hour or two and again
late tonight. Otherwise...VFR.

Fog should burn off by 14z...otherwise scattered cumulus with scattered to
broken high clouds. Some models indicate an isolated thunderstorm
possible this afternoon. But chances too low for any timing in tafs.
Even thunderstorms in the vicinity may be overdoing it a bit and will leave out mention for now.

Becoming mostly clear after sunset with areas of fog again late tonight.
South winds 5 to 8 knots today becoming light tonight.


Ind watches/warnings/advisories...none.



near term...Ryan
short term...jas
long term....jh

National Weather Service Glossary of Abbreviations