Scientific Forecaster Discussion
fxus63 kind 180348
Area forecast discussion
National Weather Service Indianapolis in
1148 PM EDT Mon Jun 17 2019
the aviation section has been updated below.
issued at 320 PM EDT Mon Jun 17 2019
Upper waves combined with some meandering fronts will keep chances
for showers and thunderstorms across central Indiana into early next
week. The wet pattern will keep temperatures near normal to below
normal through the period.
Near term /tonight/...
issued at 845 PM EDT Mon Jun 17 2019
Most of the organized rainfall has pushed off to the east, in
conjunction with a mid level disturbance. Scattered showers and a
few thunderstorms linger over parts of the area, mainly near a
weak low level convergent zone. Threat for scattered activity
expected to continue tonight, given the low level boundary in the
Short term model data suggest some increase in the warm advection
pattern and 850mb flow is possible over southern Indiana by the
pre dawn hours of Tuesday, so there may be an increase in activity
from the south towards daybreak.
Will add some fog to the forecast later tonight, given the residual
moisture and low level convergent flow.
Will continue the flood headlines as is, considering the ongoing
flood issues, and the threat for additional organized activity
Previous discussion follows.
This afternoon showers and thunderstorms are developing across the
central and southern forecast area near an old front. An upper level
trough was back across Missouri, with some upper energy moving out
ahead of the trough as well.
Expect the convection to continue to develop this afternoon with
some upper energy and the old front. At the moment it appears that
most coverage will be across the southern half to perhaps two-thirds
of the area. Will go with likely pops south with chance or lower
pops north through the remainder of the afternoon.
Can't rule out a strong to severe storm this afternoon into early
evening, especially south, given the instability present there.
Pops will diminish this evening with lower forcing around. However
late tonight they will ramp back up again, especially south, as the
weakening upper trough moves closer to the area.
With precipitable water values remaining above 1.5 inches for many
areas, any thunderstorm will be capable of producing heavy rain and
adding to ongoing flooding woes. Will continue the Flood Watch as is.
The blend looks reasonable for temperatures given expected
Short term...(tuesday through thursday)
issued at 320 PM EDT Mon Jun 17 2019
Models are close enough that the nbm initialization was accepted for
The upper trough will continue to bring more rain to mainly the
southern forecast area Tuesday morning. Will have a few hours of
likely category pops in the south during the morning, with lower
chances to the north. During the afternoon more scattered convection
will fire with the front in the area.
Chances for rain will diminish Tuesday evening and may actually end
overnight Tuesday night with little forcing over the area. However,
more rain will move into the area by Wednesday afternoon and
continue Wednesday night as a stronger upper trough and surface
system moves into the area.
Will have to watch for more flooding issues with this stronger
system, and severe weather may also be an issue if enough parameters
come together. Will continue to monitor.
Chances for rain will gradually diminish Thursday as the system
exits to the east.
Long term /Thursday night through Monday/...
issued at 333 PM EDT Mon Jun 17 2019
The extended period starts with the region under the influence of
surface high pressure, northwest flow aloft, and a weak upper
ridge approaching from the west. This is the only dry period we
will see during this timeframe. As a warm front moves northeast
across the forecast area on Friday and Friday night...chances for
showers and thunderstorms increase slightly. On Saturday, an upper
level wave looks to move through the upper ridge and increase
shower and thunderstorm chances across the region. The European model (ecmwf)
keeps the impacts from this wave further north than the GFS. The
National blend seemed reasonable with 40-50 pop on Saturday. Model
timing then diverges with the European model (ecmwf) bringing the next wave through
the upper ridge Saturday night, while the GFS provides a bit of a
break in the convection Saturday night and brings the upper wave
through on Sunday. Thus, confidence not great on timing of
convection during the weekend timeframe. Nevertheless, any
additional heavy rain, especially along and south of Interstate
70, will exacerbate current flooding across that area. Expect near
normal temperatures during the extended timeframe in the low to
Aviation /discussion for the 180600z tafs/...
issued at 1145 PM EDT Mon Jun 17 2019
Small potential for convection at the terminals overnight, but
overall pattern not very favorable for nocturnal convection, given
light flow at 850mb. Short term model guidance suggests warm
advection and 850mb flow may increase over southern Indiana
towards daybreak Tuesday, which may result in an increased threat
for rain and convection in the kbmg vicinity by that time.
Otherwise, residual moisture and weak low level convergent flow
suggests fog and IFR/LIFR ceilings will become more prevalent
overnight. These conditions may linger through the late morning
hours of Tuesday.
Surface winds generally at or below 6 kts through midday Tuesday.
Flash Flood Watch through Tuesday afternoon for inz037-039-