Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Wilmington Ohio
437 PM EDT Friday Jul 25 2014
as high pressure moves to the southeast tonight...allowing a
return to southerly flow which will bring a warming trend into
Saturday. A series of disturbances and an associated low pressure
system will move through the Great Lakes region Saturday into
Sunday...leading to occasional showers and thunderstorms through
Near term /until 6 am Saturday morning/...
western forecast area under the strong return flow combined with the
high clouds from the convection in the Mississippi Valley will
yield warmer overnight lows in the west. Lows will be a little
closer to normal in the west but still about 5 degrees below
normal in the east. Have gone slightly below MOS for lows tonight.
Short term /6 am Saturday morning through Saturday night/...
as the warm front begins to lift north through the region during
the day...a return to more seasonal temperatures and increasing
low level moisture will bring destabilization through the day.
Path of shortwave and some weak isentopic lift will generally keep the
most favorable area for shower and scatter thunderstorms across
the northern forecast area and points north during the day. Increasing
MLCAPE values >2000 j/kg in the northwest forecast area will
As the day progresses...surface dewpoints will approach 70 to low
70s...with even greater ll moisture surge possible. An increase in
clouds through the day and scattered showers and
thunderstorms...but the primary concern is the steepening lapse
rates ahead of the next shortwave and 0-6km bulk shear reaching 40-50+
kts near/after 00z Sunday. Threat for strong storms in this
timeframe...and then combined with precipitable water values over 2 inches and
strong low level jet developing and diving southeast through southern in...SW Ohio and
northern Kentucky will bring a threat for heavy rain as well overnight Saturday
night. Precipitable water values approach 2sd above normal in strong moisture
convergence at the nose of . Introduced heavy rain wording into
the forecast but premature for Flash Flood Watch issuance at this time
with some timing and placement differences in model runs.
NAM most aggressive with low level jet and moisture convergence...with GFS
less so though still setting a scenario for prolonged thunderstorm
Long term /Sunday through Friday/...
an active weather pattern will be in place for the beginning of
the long term. Early Sunday morning an mesoscale convective system is expected to be
moving through the forecast area. As this feature moves through the forecast area
damaging winds and heavy rain will be possible. Although severe
weather will be possible across the entire area the highest chance
for these threats Sunday morning are across SW portions of the forecast area.
The timing and exact location of this feature will have impacts on
addition thunderstorms and the severe potential for the afternoon
and early evening hours on Sunday. Additional thunderstorm activity
is expected to develop across the forecast area on Sunday in advance and along
a cold front. Damaging winds and heavy rain will again be
possible. In addition an isolated tornado threat and a hail threat
also exists. Thunderstorms will taper off Sunday evening.
Cooler air will move into the area for Monday. An upper level
disturbance will move through during the day. Expect a cloudy and
unseasonably cool day with scattered showers across the area.
Shower activity will taper off Monday evening. Cool northerly flow
will continue for Tuesday. Expect high temperatures on Monday and
Tuesday to be in the low to middle 70s. Temperatures will be
slightly warmer for Wednesday through Friday however still below
normal for this time of year. Weak disturbances will bring off and
on chances for showers and thunderstorms to portions of the area for
Wednesday through Friday.
Aviation /20z Friday through Wednesday/...
diurnal cumulus popped generally southeast of I-71 where residual moisture
remained from overnight clouds. These cumulus should begin to
dissipate later this afternoon. Meanwhile cirrus blowoff form
convection out west continues to spread eastward into the tafs.
Decaying convection will continue to work towards the tafs tonight.
While it should dissipate...am concerned enough to carry a vcsh at
cvg/luk tafs between 06z-12z in case it holds together.
Ceilings should lower overnight as moisture from Midwest convection
works in...however they should remain VFR.
After 12z...getting a variety of solutions on when convection will
start. So put a thunderstorms in the vicinity at the western tafs around 13z...but left
cmh/lck dry through 18z.
Outlook...thunderstorms possible Saturday afternoon through Sunday.