Area Forecast Discussion
Issued by NWS Paducah, KY

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FXUS63 KPAH 191157

656 AM CDT Fri Sep 19 2014

Issued at 656 AM CDT FRI SEP 19 2014

The AVIATION section has been updated for the 12Z TAF issuance.


.SHORT TERM...(Today through Sunday)
Issued at 340 AM CDT FRI SEP 19 2014

A light northeast wind and some at least scattered 5-6kft clouds
are helping to keep fog development at bay through 08Z. KCGI and
KMDH have seen visibilities drop to IFR levels periodically since
midnight, but figure if dense fog develops it will be very
localized and likely short-lived. Have no plans for a Special
Weather Statement or mention in the HWO at this time, but will
continue to monitor.

The 00Z models are in agreement that high pressure will dominate
at the surface and aloft today and tonight. There will be a minor
trough at the surface that will lift north and west late today and
tonight on the periphery of the larger-scale high. This will lead
to an increase in low-level moisture, at least in the southern
half of the area.

The models have trended a bit more humid for Saturday, with
dewpoints climbing into the middle and upper 60s ahead of the cold
front. They also continue to keep the cold front well north of the
area through the day, and there should not be much more than some
cu through the day. The lone exception, if the NAM and NMM WRF are
correct, is some isolated convection in a zone from KPAH to near
KEVV and KOWB in the afternoon. NAM soundings show significant
CAPE, over 3000J/Kg, with steep low-level lapse rates and a lot of
dry air in the mid and upper levels. Wind fields are weak, but
some pulsy storms may be able to produce some wind gusts 40kts or
more in this environment, if a storm can develop. Inserted a
slight chance PoP for this possibility. Some of this activity
may linger into the evening, but convection associated with the
cold front is not likely to reach the area until after midnight,
if at all.

The trend for this system is definitely progressive and drier,
with convection generally traversing the area from 06Z-18Z Sunday.
The NAM holds up the front just a bit, and generates a nice area
of convection in the afternoon from the Bootheel through much of
west Kentucky. Given the sharp, amplified mid/upper systems
accompanying the front in the 12Z GFS and ECMWF, really cannot see
the front hanging up. That said, will not cut the PoPs too fine on
Sunday, and just keep one 12-hour PoP for the whole day. PoPs are
generally 30-40% with the best PoPs over the Evansville Tri State
in the overnight hours and early Sunday. There just is not enough
low-level moisture for this system to work with. None of the
models is currently bringing any of the tropical remnants into the
region, so locally heavy rainfall is not that much of a concern

.LONG TERM...(Sunday Night through Thursday)
Issued at 340 AM CDT FRI SEP 19 2014

Surface high pressure will build across the region Sunday night
and Monday in the wake of the weekend storm system. There is some
minor discrepancy between the GFS and ECMWF in how much cold
advection will occur with the northerly winds through Monday. The
GFS is warmer, and that seems reasonable, given the rather short
period of significant advections into the region.

Both models begin to build a ridge of high pressure aloft over the
region as early as Monday afternoon. This will result in high
pressure at the surface and aloft that will persist through the
work week. Look for temperatures to drop just a bit below normal
Monday and possibly Tuesday, but highs should be back into the 80s
for Wednesday through the remainder of the week. Would expect the
forecast to trend warmer with time for the early part of the week,
and possibly through the entire week. There will be a very dry
airmass in place, so guidance may be under-estimating the diurnal
range through the week.


Issued at 656 AM CDT FRI SEP 19 2014

Surface high pressure will continue to dominate the region through
tonight. Winds will be light through the period. East northeast
winds today will gradually veer to southeast tonight. Some
scattered 4-6kft clouds will linger in the vicinity of KCGI and
KPAH through the period. IFR fog at the beginning of the period at
KCGI will dissipate by 14Z. Figure there will be enough wind to
keep fog out of the forecast late tonight. Some guidance is
advertising lower VFR ceilings pushing northwest toward the
terminals late tonight. This would be most likely at KOWB and KPAH.




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