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Area forecast discussion 
National Weather Service Indianapolis in
416 am EDT Friday Jul 25 2014

Update...
the aviation section has been updated below.

&&

Synopsis...
issued at 248 am EDT Friday Jul 25 2014

Dry and comfortable weather will give way to warm...humid and
stormy weather this weekend as a cold front gradually drops
southeast across the area. Severe storms are a possibility by late
Saturday. Meanwhile...an upper wave will drop southeast across the
lower Great Lakes Sunday night pushing the front to the southern
states and allowing for more below normal temperatures next week.

&&

Near term /today/...
issued at 248 am EDT Friday Jul 25 2014

Temperatures and late day probability of precipitation will be the main focus for the near
term today as a warm front approaches from the west.

Models in good agreement that isentropic lift ahead of the
approaching warm front will bring increasing middle level moisture to
central Indiana late today. Low level jet and upper wave will also
be approaching far northwestern counties this afternoon.
However...model soundings were showing a decent cap near 850
millibars with even elevated instability lacking. So...although
would not rule out a light shower or sprinkles across our northwest
counties...not enough confidence to include probability of precipitation.

Despite increase in high and middle clouds...850 millibar temperatures
will be near 10 degrees celsius warmer late in the day across our
western counties than they were yesterday with the potential for
mixing below the cap...so will go at or above 00z MOS for afternoon
highs.

&&

Short term /tonight through Sunday night/...
issued at 248 am EDT Friday Jul 25 2014

A convectively active short term will provide many challenges to the
forecast..not the least of which is the potential for severe weather
and heavy rain Saturday PM...illustrated by the day2 Storm Prediction Center outlook.

Models are in good agreement that a sharp upper trough will drop
southeast across the eastern Great Lakes and Ohio on Sunday night
which will force a strong cold front southeast across the forecast
area. The front will interact with increasing moisture and
instability and result in thunderstorm chances starting Friday night
and continuing through Sunday night. The best chances will be
Saturday night and Sunday morning as a low level jet settles across
south central Indiana resulting in precipitable water values around
2 inches there. In addition...upper jet will stretch out across the
lower Great Lakes with embedded jet maxima aiding in rainfall
efficiency and severe potential. So...with abundant
forcing...instability and moisture...potential severe mesoscale convective system activity
looks like a good bet Saturday night with damaging winds and heavy
rain the main concerns. If the atmosphere can recover enough from
the Friday night and Saturday night storms...could also see a few
severe storms during the afternoon and evening hours Saturday and
Sunday before the cold front moves through Sunday night.

Sided closer to the cooler 00z NAM MOS for afternoon highs as the
00z GFS and Jul 24 00z ecm look too warm by Saturday considering
cloud cover and effect of Friday night and Saturday morning
convection.

&&

Long term /Monday through Thursday night/...

Issued at 340 am EDT Friday Jul 25 2014

Scattered rain showers will be possible across central Indiana on
Monday as an upper level trough and associated surface cold front
depart the area. After that...high pressure will result in dry
conditions through mid-week. At that point...models become
inconsistent for the end of long term period. Latest regional
initialization is picking up on an upper trough for Thursday...but
is struggling with timing. Due to the model inconsistency...will
not deviate from initialization at this time which has periods of
slight chance probability of precipitation for Thursday/Thursday night. Temperatures through the
period will be well below normal with highs only in the 70s and
lows in the 50s. Temperatures will increase slightly by the end of the
period...but will still be below normal.

&&

Aviation /discussion for the 25/09z taf update/...

Issued at 415 am EDT Friday Jul 25 2014

Update...
no changes at kind.

Previous discussion...
largely VFR through the period. Some potential for MVFR visibilities
in light fog near daybreak at the outlying sites. Will handle with
tempo groups as fog may be transient in nature.

Expect only some high cloud much of the night. This combined with
light winds may promote some fog...but not expecting worse than MVFR
at this time.

Any fog will quickly burn off Friday morning. Some scattered cumulus
and increasing middle cloud expected ahead of next system during the
day Friday.

Winds will be less than 10kt throughout the period.



&&

Ind watches/warnings/advisories...none.

&&

$$

Synopsis...mk
near term...mk
short term...mk
long term....tdud
aviation...nield/tdud

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