Area Forecast Discussion
Issued by NWS Jackson, KY-- Highlight Changed Discussion --
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FXUS63 KJKL 220619 AAA
Area Forecast Discussion...UPDATED
National Weather Service Jackson KY
219 AM EDT FRI JUL 22 2016
Issued at 219 AM EDT FRI JUL 22 2016
Updated the latest hourly temperatures and dew points through the
rest of the night. The forecast remains on track, as valleys drop
off into the mid 60s, with a few lower 60s likely in a few
sheltered spots. The thunderstorm complex up to our north is
showing warming cloud tops on the IR Satellite, with the more
sustained cells becoming limited to the southwestern flank. As
such, only some high cirrus clouds will be overspreading from the
north through the rest of the overnight period.
UPDATE Issued at 1125 PM EDT THU JUL 21 2016
Hourly grids have been updated based on recent short term model
runs and observations. We are not confident that any activity
overnight will occur in the north as has been in a few recent
HRRR runs, but this scenario will be monitored.
UPDATE Issued at 835 PM EDT THU JUL 21 2016
Debris clouds continue to move into Eastern and South Central KY
from weakening convection over OH and IN. A southward moving
outflow is in the vicinity of the I 71 corridor from near CVG to
near ILN but it also extends further west near or just north of
the OH River and then north near the I 65 corridor to near IND.
Even the more substantial convection that was over parts of
southern IN has waned over the past hour. This convection should
continue to wane as it moves into an area of drier air and with
the loss of daytime heating and a resurgence is not anticipated.
However, the outflow boundary should reach the northern CWA likely
settling somewhere near the I 64 corridor. Some debris clouds
perhaps a bit of mid clouds in this across the far north should
continue to move across the area over the next few hours, but
surface high pressure to the east of the area should bring mostly
clear skies overall with light winds. Sky cover was adjusted
accordingly. The previously forecast lows are on target so no
substantial changes were needed at this time. The outflow boundary
could serve as a focus for convection on Friday afternoon.
.SHORT TERM...(This evening through Friday night)
Issued at 308 PM EDT THU JUL 21 2016
Dewpoints over all but the far southwest part of the area have
fallen into the upper 50s to lower 60s as drier air has mixed down
from the mid levels. Low level moisture will begin to increase
again tonight, with dewpoints getting back to 70 or above on
Friday. Overnight lows should not be quite as low as last night
with the rising dewpoints, but should still see numerous spots get
into the mid 60s. The combination of highs in the lower 90s and
dewpoints around 70 on Friday will push heat index values to
around 100 in some areas, but still below advisory criteria.
After a couple days of dry weather prevailing across the entire
forecast area, we will see a return of thunderstorm chances Friday
afternoon as instability increases and a weak wave moves southeast
around the upper ridge. The chance for thunderstorms will continue
into Friday night.
.LONG TERM...(Saturday through Thursday)
Issued at 308 PM EDT THU JUL 21 2016
Dominant upper level ridge will flatten out through time with the
core shifting to the west as disturbances drop southeast into the
Ohio Valley. This will result in almost daily chances for
thunderstorms throughout the period in an entrenched very warm and
muggy airmass. In fact, the weekend forecast is trending more
unsettled as a weak front is progged to drop into the area on
Saturday then waffle around overhead or nearby into next week.
This stormier forecast means that ambient temperatures may not get
as warm as previously advertised, but dewpoints still climb well
into the 70s and the heat index remains progged to reach near 100
each day Saturday through at least Monday.
.AVIATION...(For the 06Z TAFS through 06Z Friday night)
ISSUED AT 219 AM EDT FRI JUL 22 2016
VFR conditions will prevail through the majority of the time as an
upper level ridge of high pressure will remain the dominant
weather feature through the period. Some IFR or worse river
valley fog will develop; however, still expecting this to steer
clear of the TAF sites, with the exception of some temporary
restrictions closer to dawn. During the day on Friday, enough
heating and moisture return will allow for a few showers and
thunderstorms to develop during the afternoon. The better
coverage will be along and west of I-75, as well as along and
north of I-64. Have allowed for VCSH at SME and LOZ, and VCTS at
SYM. Isolated convection will drop off this evening as we lose
heating. Winds will remain at or below 5 kts through the period.