AP-IN--SDF-IN S Area Forecast Discussion, IN


FXUS63 KLMK 151052




652 AM EDT Wed Jul 15 2015

...Updated Aviation Discussion...

.SHORT TERM (Now through Thursday)...

Issued at 305 AM EDT Wed Jul 15 2015

Sfc high pressure and upper level ridging will move into the region

today and tomorrow providing relief from the rainfall and heat.

Early this morning, some isolated patches of light fog have

developed. Think we'll continue to see some light patchy fog

develop through sunrise but don't think visibilities will drop too

low given the upper level clouds over much of the area currently and

some low clouds progged to work into the region from the NE during

the pre-dawn hours. Will continue to monitor though.

Portions of southern Indiana and north central KY may have a blanket

of low clouds for a good portion of the morning hours before these

clouds break up and lift. This may limit high temperatures to the

upper 70s and lower 80s in the cloudy areas. Elsewhere over south

central, west central KY, and southwest IN, expect high temps to

range from the low to mid 80s.

Tonight skies will go mostly clear with only a few upper level

clouds expected over the region. Winds will go calm or light and

variable with soundings looking a little more favorable for fog.

Will insert light patchy fog for much of the area late tonight and

let coming shifts decide if more coverage or lower vsbys are

warranted in the forecast. Low temps should range from the lower

60s to around 70.

For Thursday, expect another dry and mostly sunny day with high

temperatures ranging through the 80s.

.LONG TERM (Thursday night through Tuesday)...

Issued at 310 AM EDT Wed Jul 15 2015

Forecast pattern in extended continues to emphasize persistent

mid-level high pressure and ridge over the southern Plains and

southeast U.S. with faster flow and various shortwaves across the

northern Plains and Great Lakes. The Ohio Valley will continue to be

positioned between these major features with west to northwest flow

aloft as the ridging aloft tries to poke into our area late this

week into early next week. As a result, parts of the Ohio Valley and

southern Great Lakes should remain in the axis of active periodic

convective systems (MCSs).

It is difficult at this time range to determine where such mesoscale

systems will set up exactly, but the synoptic setup again suggests

such systems could occur. At this time, it appears the main action

should remain just north of our forecast area over the weekend into

Monday where better forcing and instability will reside. Neverthe-

less, isolated to scattered thunderstorms will still be possible in

parts of our area, i.e.. mainly southern IN into north-central and

east-central KY, with dry weather over southern/western areas where

mid-level capping and less instability will reside. It will not be

out of the question that an MCS could turn enough southeast to

affect mainly our northeastern counties sometime in the Saturday to

Monday time frame. The Canadian GEM would suggest this most, while

the GFS and ECMWF are a little more ridgey keeping more widespread

convection to our north. Will continue to indicate our northern

counties as the best chance of convection, but not the widespread

MCSs we have seen lately.

Deeper into the extended there is some model discrepancy with the

approach from the west of an elongated moisture and instability axis

associated with a cool front. The GFS and ECMWF are most consistent

with this, albeit different in timing (ECMWF faster), while the GEM

appears as an outlier. Thus, an axis of convection may occur in the

late Monday or Tuesday time frame depending on system speed and

mid-level flow characteristics. As always, convection would be

associated with more heavy rain potential.

Friday through Sunday will also feature hot mid-summer temperatures

across much of our area. Highs will be in the lower and mid 90s with

surface dewpoints rising into the upper 60s to perhaps mid 70s at

times (mainly north). This would push afternoon heat indices over

100, especially in western/northern areas. Temperatures should then

recede somewhat late in the period associated with the cool front.


.AVIATION (12Z TAF Update)...

Updated 650 AM EDT Wed Jul 15 2015

Low MVFR/IFR clouds are expected to build south from Indiana and

Ohio into the SDF/LEX TAFs around or just before 12Z. This low

cloud deck should persist for at least 2-4 hours before beginning to

break up and lift by mid to late morning resulting in a return to

VFR conditions. Northerly winds will become light or calm tonight

with light br possible tomorrow morning.







Short Term........AMS

Long Term.........TWF


Delivered by Weather Underground Inc. Wed Jul 15 2015 6:52AM EDT