Area forecast discussion
National Weather Service Indianapolis in
720 am EDT Sat may 18 2013
Update...
The aviation section has been updated below.
&&
Synopsis...
issued at 143 am EDT Sat may 18 2013
A weak area of low pressure will drift into the Ohio Valley and
across southern Indiana. This will bring chances for showers and
thunderstorms today. A weak ridge of high pressure will build across
the area on Sunday. Early next week a large trough carves out over
the western half of the country into the weekend which will bring
warmer air for much of next week along with another couple days of
stormy weather Monday into middle week.
&&
Near term /today/...
issued at 143 am EDT Sat may 18 2013
Models depict a weak upper low pushing through the Ohio Valley and
southern Indiana...then exiting the area by late this afternoon.
Appears weak forcing associated with the shortwave and daytime heating
will be the main forcing mechanisms for convective development.
Guidance is showing chances for this activity all across the
forecast area...with best chances south of I-70...but not limited to
this area. Bumped up probability of precipitation and trended temperatures at or slightly above MOS
despite cloud cover and precipitation chances we should easily be able to
achieve temperatures ranging from upper 70s to around 80.
&&
Short term /tonight through Monday night/...
issued at 143 am EDT Sat may 18 2013
Drier air will quickly be infiltrating back into the area by this
evening...not before a few showers exit the region to the east. Weak
ridging builds back over the area tonight and skies will attempt to
clear out...but some middle to high level clouds will remain. Possibly
some patchy fog early Sunday morning. Will continue with a dry
forecast starting late tonight through early Monday. 850 mb temperatures
still look quite warm by early next week. Look for high temperatures in the
middle 80s both Sunday and Monday. Models are in a bit of a
disagreement with regard to the timing of the next system. For now
have introduced slight chance to low chance probability of precipitation starting Monday
afternoon and Monday night.
&&
Long term /Tuesday through Saturday/...
issued at 229 am EDT Sat may 18 2013
Long term continues to be dominated by one main surface and upper
level low moving extremely slowly from the northern plains/upper
Midwest into the Ohio Valley and the midatlantic states through
the coming week. Broad southwest flow moving warm moist air into
the area will merit at least chance probability of precipitation most all periods through
the late portion of the week...with some likelies late Tuesday
into Wednesday as The Heart of the system approaches the area.
Initialization handled this well and only a few minor tweaks were
required.
Temperatures initialized well and should be gradually cooling back down
to near or just slightly below normal values by late in the week
as cooler air moves into the area on the back side of the low.
&&
Aviation /discussion for the 18/12z tafs/...
issued at 720 am EDT Sat may 18 2013
Fog this morning will give way to VFR conditions and potential
showers/thunderstorms. Scattered light showers are already
developing across the southeastern half of the area moving
northwest. Instability will increase later today and will insert
thunderstorms in the vicinity after convective temperatures are reached.
This evening...showers and storms will dissipate and clouds should
begin to thin out. Fog may develop across the area...especially
where the best clearing occurs. IFR cannot be ruled out but will
confine to MVFR for now.
Winds will generally be out of the east/southeast throughout the
period less than 10kt.
&&
Ind watches/warnings/advisories...none.
&&
$$
Synopsis...smf
near term...smf
short term...smf
long term....nield
aviation...nield
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