Area forecast discussion
National Weather Service Indianapolis in
640 PM EDT Friday may 24 2013
Update...
the aviation section has been updated below.
&&
Synopsis...
issued at 250 PM EDT Friday may 24 2013
Cool Canadian high pressure will result in below normal temperatures
for Memorial Day weekend. Meanwhile...a warm front will lift
northeast across central Indiana Monday night and Tuesday which will
bring thunderstorm chances back to central Indiana especially late
Sunday through Monday night. Temperatures will also climb to above
normal by Tuesday as the warm front lifts into Michigan.
&&
Near term /tonight/...
Issued at 250 PM EDT Friday may 24 2013
Main challenge tonight will be temperatures as cool Canadian high
pressure from Hudson Bay to the Ohio Valley and southern states
dominates the weather.
Temperatures last night in the clear air fell to near the cooler GFS
MOS...and see no reason why they will not again tonight with light
to calm winds and clear skies resulting in decoupling and ideal
radiational setup. Look for overnight lows in the lower to the middle
40s per allblend and consall.
&&
Short term /Saturday through Monday/...
Issued at 250 PM EDT Friday may 24 2013
Main challenge to the forecast will be timing and coverage of
showers and thunderstorms this Memorial Day weekend.
Models in good agreement this weekend. Warm front is expected to
lift northeast and move slowly across central Indiana Monday and
Tuesday as cool Canadian high pressure moves off to the east. Upper
pattern has an upper ridge across the plains with a disturbances
dropping southeast across central Indiana. The 12z and 00z GFS and
00z European model (ecmwf) were in close regarding timing of the various disturbances
and were the most consistent of the models...so will lean more on
their solutions.
First disturbance and slug of moisture along with isentropic lift on
the 305k level should impact central Indiana on Saturday. Brought in
slight probability of precipitation northwest on Saturday morning and low probability of precipitation across all
but far northeast central Indiana Saturday afternoon. Continuing
warm air advection should result in additional shower chances
Saturday night. By Sunday...the warm front should be getting
closer...and another disturbance approaches overtop the plains ridge.
Thus...shower chances continue on Sunday with chances increasing
during the afternoon. Increased afternoon probability of precipitation to around 40
percent...except lower far northeast. With the front in the
area...highest probability of precipitation expected Sunday night and Monday. Good chance or
better probability of precipitation look good then.
Most unstable cape forecasts suggest...thunder not expected until Sunday
afternoon south and west of Indianapolis. By Sunday night...threw
thunder in all zones.
With clouds increasing on Saturday...diurnal swing in temperatures
will be limited. Went on the low side of MOS with afternoon highs
mostly in the 60s and slightly warmer than MOS at night with lows
mostly in the 50s.
&&
Long term /Monday night through Friday/...
issued at 211 PM EDT Thursday may 23 2013
Models are close enough that the allblend initialization can be used
for most items.
A warm front will linger in the area for the early part of the
extended...then an upper ridge will build into the area. Thus kept
low chances for rain into Tuesday night...then went dry. /Allblend/S
probability of precipitation for Friday look too high with upper ridge in place./
Temperatures will warm through the period to above average.
&&
Aviation /discussion for 250000z taf issuance/...
Issued at 640 PM EDT Friday may 24 2013
VFR conditions expected throughout the forecast period.
Clear skies across central Indiana this evening with high pressure
and deep subsidence in place. Middle and high level clouds will spill
over top of the upper ridge across the Mississippi Valley and into
the region by daybreak...gradually thickening through the day
Saturday as a warm front approaches from the west. Expect a dense
canopy of middle level clouds by afternoon and possibly a few
sprinkles or very light showers. Chances for precipitation remain very
low through 00z Sunday with presence of dry air through the
boundary layer and will make no mention in terminals at this time.
Light north/NE flow overnight will shift to predominantly southeast
at 5-10kts Saturday.
&&
Ind watches/warnings/advisories...none.
&&
$$
Synopsis...mk
near term...mk
short term...mk
long term....jas
aviation...Ryan
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