Area Forecast Discussion
Issued by NWS Wilmington, OH

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FXUS61 KILN 251506
AFDILN

Area Forecast Discussion
National Weather Service Wilmington OH
1106 AM EDT MON JUL 25 2016

.SYNOPSIS...
Showers and thunderstorms will be observed in the hot and humid
air mass which is in place, ahead of cold front which will move
through the region this afternoon. This front will stall out
across Kentucky, bringing a continued threat for storms across
southern portions of the region Tuesday and Wednesday. The front
is expected to lift north as warm front, as a wave of low pressure
tracks through the Great Lakes late in the week. This will bring
the threat for widespread thunderstorms Thursday night and Friday.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Elongated upper level ridge stretches from central plains to
southeastern coast. Northern fringe of ridge will be flattened by
progressive shortwave pivoting east through the Great Lakes
region. At the surface, a weak cold front currently stretches MI
southwestward through northern IL and central MO. This front will
slowly drift southeast through the day, providing the possibility
of storm development during peak diurnal heating.

Although forcing should still be fairly weak, the airmass will be
unstable, with MLCAPE exceeding 3000j/kg, especially for southern
half of FA. Hi-res models, particularly the HRRR and RAP, continue
to struggle with potential timing and coverage of convection this
afternoon, mostly likely due to unrealistically high BL mixing in
their solutions. Nevertheless, still expect scattered storm
development this afternoon with greatest coverage south and east
of the I-71 corridor. Given high instby, environment may be
supportive of a few strong to possibly severe storms, particularly
for southern half of FA. Damaging winds will be the primary threat
with strongest storms.

After reviewing temperature and dewpoint trends this morning,
have expanded heat advisory for a tier or two of counties to the
north. Very high dewpoints in the mid to even upper 70s will
combine with temperatures around or in excess of 90 degrees to
create heat indices in the lower 100s at times this afternoon and
early evening. For northwestern parts of FA, lower dewpoints will
keep heat indices below 100.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY/...
Surface cold front to push south of the Ohio river and stall out
south of the Ohio river tonight. Storms will end from the north
across all but the far south overnight. Temperatures will be a
little cooler with lows from the mid 60s north to the lower 70s
south.

Surface cold front to stall out east-west just south of the Ohio
river at the south end of the mid level westerlies. This front
will be the focus for diurnal storm development Tuesday. Will
mention this potential along and south of the Ohio river. Further
north, drier air should inhibit thunderstorm development. Highs on
Tuesday will be slightly cooler and generally in the mid and upper
80s.

Weak surface high pressure to build acrs the Great Lakes with a
continued threat of showers and thunderstorms along and south of
the Ohio river Wednesday. Have limited mention to slight chance.
Generally expect highs in the upper 80s Wednesday.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
Boundary will lift north as a warm front late Wednesday night
into Thursday. This will allow precipitable water values to
increase northward, placing the CWA back in a very moist
environment for Thursday.

Models show a shortwave approaching late Thursday or Thursday night.
Timing is still somewhat in question, but there is decent consensus
on the track which will bring it across the Ohio Valley. Therefore,
begin to increase pops for Thursday afternoon and will continue
chance pops into Thursday night for possible influence from
shortwave.

Additional shortwaves may affect the Ohio Valley Friday through
Saturday. Details associated with the shortwaves (such as
track/timing/strength) are in question and will need to be resolved
with time. But the potential for shortwaves combined with a warm
moist air mass means that chance pops for convection will continue
through at least Saturday. Eventually, a cold front may move through
and this could occur late Saturday into Sunday but confidence is low
on the timing of the frontal passage.

Temperatures are forecast to favor near average to slightly above
average values through the long term.

&&

.AVIATION /15Z MONDAY THROUGH FRIDAY/...
Cold front lies across Illinois, moving toward Ohio.
Thunderstorms that developed in the very humid airmass along and
ahead of the front have now dissipated west of TAF sites. VFR
conditions are forecast to persist through the early part of the
TAF period.

Thunderstorms are expected to develop in the vicinity of TAF
sites this afternoon as forcing increases near the approaching
front, while instability rises toward daytime maxima. The chance
for thunderstorms will then linger into evening as the front
makes its way toward the Ohio River. Will issue amendments to
better indicate timing and effects of thunderstorms closer to
their time of occurrence. Look for improving conditions late in
the forecast as instability drops off with loss of daytime
heating. Winds will generally out of the west with speeds close to
10 knots during the afternoon. BR may reduce visibility at ILN and
LUK late in the forecast. CVG should see VFR and light northwest
winds after 12Z Tuesday.

OUTLOOK...Thunderstorms possible Thursday.

&&

.ILN WATCHES/WARNINGS/ADVISORIES...
OH...Heat Advisory until 8 PM EDT this evening for OHZ055-056-
     063>065-070>074-078>082-088.
     Excessive Heat Warning until 8 PM EDT this evening for OHZ077.
KY...Heat Advisory until 8 PM EDT this evening for KYZ089>100.
IN...Heat Advisory until 8 PM EDT this evening for INZ066-073>075-
     080.

&&

$$
SYNOPSIS...AR
NEAR TERM...KC
SHORT TERM...AR
LONG TERM...BPP
AVIATION...Coniglio



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