Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Indianapolis in
159 PM EDT Monday Oct 20 2014
the long term section has been updated below.
issued at 327 am EDT Monday Oct 20 2014
A cold front and sharp upper trough will bring shower chances to
central Indiana today. Otherwise...high pressure will provide for
dry weather through next weekend. After seasonable temperatures with
highs in the 60s today...temperatures will be below normal with
afternoon highs in the 50s through late week before temperatures
rebound this weekend with a return to the 60s.
Near term /today/...
issued at 1235 PM EDT Monday Oct 20 2014
Added isolated thunder to the grids as showers north of ind have
displayed a few strikes in the last hour or so. Small hail may be
possible with sub 10k freezing levels but impacts expected to be
minimal beyond lightning threat. Previous discussion follows.
Issued at 937 am EDT Monday Oct 20 2014
Going forecast in relatively good shape. Showers have developed
along the frontal zone moving into the northwestern forecast
area...so have backed up slight chance probability of precipitation into that area and
delayed dry forecast moving into the area this afternoon. Previous
Issued at 608 am EDT Monday Oct 20 2014
Pulled pre-first period probability of precipitation across our northwest counties...roughly
north of a terre haut to Noblesville line per radar trends.
Previous discussion follows...
Focus today will be on shower coverage and timing. Models in good
agreement that a cold front will drop southeast across central
Indiana this afternoon and early evening as a sharp upper trough
digs southeast across the Great Lakes.
300k isentropic analysis...850-500 millibar q-vector
divergence...very dry air moving in aloft and finally radar trends
suggest best probability of precipitation today will be early in the day and across our
southeastern counties. Even there...with limited moisture...will
only go with slight chance probability of precipitation. Far northwestern counties should be
dry after the current shower activity there exits prior to 12z. With
1000-850 millibar layer remaining moist...cold air moving in aloft
and cyclonic upper flow in the wake of the upper trough...should see
plenty of afternoon cumulus and a few showers lingering through late day
With warmer MOS numbers from the 00z run...prefer temperatures a
couple of degrees higher than consall with highs in the lower 60s
northeast to the upper 60s southwest looking reasonable.
Short term /tonight through Wednesday night/...
issued at 327 am EDT Monday Oct 20 2014
Short term focus will be on any lingering showers...cloud cover and
temperatures as models in good agreement that sharp upper trough
digging across the Great Lakes today will form a closed low over the
Appalachians by Tuesday afternoon with cyclonic flow on the back
side of it along with fetch off Lake Michigan. As a result...would
not rule out a few showers or sprinkles Monday night and Tuesday
mainly north and east. However...prefer to just keep more cloud
cover there for now as boundary layer flow off the lake is not
overly impressive and dry forecast matches up better with our
By midweek...cool Canadian high pressure will gradually build in
from the Great Lakes to the Ohio Valley which will provide cool
and dry weather. Clouds will be decreasing from west to east.
Afternoon highs per blend only expected to reach the 50s Tuesday and
Wednesday except perhaps lower 60s southwest on Tuesday.
Meanwhile...frost looks like a possibility Tuesday night and even
more so Wednesday night with clear skies and light winds.
Long term /Thursday night through Monday/...
Issued at 157 PM EDT Monday Oct 20 2014
An upper ridge will build over the eastern half of the country
through the long term producing dry weather over central Indiana.
Temperatures will warm to slightly above normal temperatures by
Friday. No changes made to the superblend initialization. Next
possible system will approach the area next Monday night or Tuesday.
Aviation /discussion for 201800z taf issuance/...
Issued at 1259 PM EDT Monday Oct 20 2014
Mainly VFR conditions expected during the first half of the
period...then mfvr early Tuesday morning.
After a stronger thin line of showers and a few embedded
thunderstorms moved through central Indiana...some light scattered
rain showers are occurring across or near some of the
sites...however does not appear that these will impact flight
category and thus will just include vcsh with them. Tonight time
heights and forecast soundings indicate some potential for MVFR
ceilings/visibilities starting after around 6z and potentially
continuing for a good portion of the day Tuesday which was
indicated in many of the terminals.
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