Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Indianapolis in
1023 PM EDT Tuesday Jul 7 2015
the aviation section has been updated below.
issued at 230 PM EDT Tuesday Jul 7 2015
Frontal boundary settling south across Indiana today has been a
heavy rain producer. Several more short waves will gradually lift
this boundary back to the Great Lakes this weekend but establish a
northwest flow scenario for thunderstorm complexes early next week.
Widespread 2 to 5 inches rainfall coming 7 days with locally
higher amounts likely to cause short term street flooding problems
at times and renew longer term river flooding issues again.
Cloudy and wet start to period keeps temperatures below normal the next
few days but gradual warming to normal by weeks end and above
normal early next week as upper ridge axis builds over plains.
Near term /rest of tonight/...
issued at 1000 EDT Tuesday Jul 7 2015
Most of the showers have moved south of our forecast area this
evening...but areas of drizzle have been reported as far north as
Muncie. High resolution models indicate only scattered light
showers across southern sections overnight with some increase
towards morning across southwest and west central sections. Will go
with chance probability of precipitation over the southern half to two thirds of our area
and will drop all mention of thunders except for the southern row of
counties late tonight and even there no more than isolated thunder.
Models indicate cooler and drier air will spread south into north
and central sections overnight. Have adjusted temperatures slightly
lower overnight...but not as much as lav guidance as it seems a bit
too cool with clouds remaining over most of our area. Went with
lows from the middle 50s northwest to the middle 60s southeast.
Short term /Wednesday through Friday/...
Issued at 230 PM EDT Tuesday Jul 7 2015
As mentioned...models differ on speed of low pressure and upper
wave lifting northeast from Texas along with associated rain
amounts. Have used a blend and made slight adjustments to current
forecast. Looks like this next wave will lift across central Missouri
Wednesday and northern Indiana Wednesday night. This will help lift
frontal boundary a bit further north in our southern counties but
main forcing will remain northwest of our forecast area. This should result
in periods of showers lifting northeast Wednesday and Wednesday
night and exiting Thursday morning. Heaviest rain amounts expected
closest to surface low track and in our northwest counties which
fortunately did not see much rain today.
Yet one more wave finally lifts the surface boundary back to
northern Indiana Friday as upper ridge builds in plains states
ahead of unusually deep trough over western states. Boundary lift
across the area results in yet another round of showers and storms
Friday but best odds and rain amounts occur just northwest of our area.
Temperatures in this period have been blended again with mins near or
slightly below normal and maximums below normal until Friday when warm
front pushes through and returns highs to the 80s.
Long term /Friday night through Tuesday/...
Issued at 200 PM EDT Tuesday Jul 7 2015
Deterministic models continue to have issues in various small scale
features...at times complicated by convective feedback.
Thus...continue to favor blend of ensemble means and have a warm
front lift northeast across central Indiana on Friday and Friday
night before stalling. Then...a retrograding upper dome of high
pressure over the south will result in northwest flow aloft over the
upper Midwest and Ohio Valley by late in the weekend. This setup
will drive a backdoor cold front southeast over the area early next
Regional blend probability of precipitation look OK. With the front lifting northeast of the
area by Saturday morning...the blend has chance or slight chance
probability of precipitation close to the front or roughly the northeast half Friday night
through Sunday. Then...chances increase early next week with the
backdoor front. All this seems reasonable and also consistent with
regards to the previous forecast.
Slightly above normal temperatures at the beginning of the long term
will cool a bit with the increasing convection associated with the
front next week. Overall regional initialization highs in the middle
80s to around 90 look good for the weekend with highs early next
week in the lower to upper 80s.
Aviation /discussion for the 080300z kind taf update/...
issued at 1023 PM EDT Tuesday Jul 7 2015
No significant changes made to the forecast at this time. Previous
Radar loop indicates the bulk of the organized rain will have moved
off to the southeast of the terminals by issuance time.
Appears most of the IFR ceilings/visibilities have been associated
with the precipitation area...so expecting ceilings generally
015-040 tonight...with the lowest ceilings in the kbmg area.
Rain may begin to increase in coverage again towards/after 081200z
as the next wave...currently over Oklahoma/Arkansas...lifts up into
the local area.
Surface winds generally 340-360 degrees at 9-13 kts early
tonight...gradually veering around to 030-050 degrees at 5-8 kts by
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