Area Forecast Discussion
Issued by NWS Paducah, KY

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000
FXUS63 KPAH 311140
AFDPAH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PADUCAH KY
640 AM CDT Thu Jul 31 2014

.UPDATE...
Issued at 640 AM CDT THU JUL 31 2014

Updated the pubic grids an hour ago to add patchy dense fog to
southern Illinois and adjacent portions of southeast Missouri.

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

&&

.SHORT TERM...(Today through Saturday)
Issued at 318 AM CDT THU JUL 31 2014

Troughing aloft will sharpen across the area through Saturday,
At the surface, the pattern will remain very flat, with very light
winds through the period. The bottom line is that there will be
little warm or moist advection through the period.

The dry airmass will slowly moderate due to transpiration/evaporation,
which may lead to a slight warming trend in low temperatures
tonight and Friday night. High temperatures will be modulated by
cloud cover, and should be capped in the middle 80s where there is
plentiful sunshine. Generally stayed on the cool side of guidance
for highs through the period. Consensus guidance for lows may be a
bit cool, depending on how much airmass modification actually
occurs.

00Z NAM soundings indicate a layer of instability beneath a mid-
level inversion that could possibly produce a few showers toward
midday today, mainly over the southwest half of the area. Not sure
if the mid-level inversion will cap convection, it`s conceivable
that a few thunderstorms could develop as well. Given the weak
flow through the troposphere, any storms should be short-lived and
weak.

As the troughing begins to sharpen Friday, there will be a little
better chance of deep convection developing, but mainly over
southeast Missouri and southern Illinois. As the main mid/upper-
level trough pivots eastward through the region, the best chance
for convection will be over the eastern half of the area Saturday.
There is even some model signal for development in the east late
Friday night. Given the weak lift and generally poor moisture to
work with, will keep PoPs at or below 30% through the short term
period. Severe weather seems very unlikely given the weak
instability and generally weak flow through the column.

.LONG TERM...(Saturday Night through Thursday Night)
Issued at 318 AM CDT THU JUL 31 2014

The beginning of the extended forecast period places the WFO PAH
forecast area under increasing influence of the Central/Southern
Plains ridge axis, effectively stopping sufficient lift for
convective activity.

The passage of the middle/upper level trough through the area does
leave a closed circulation over the Southeast U.S., but its
influence is too far displaced to impact the local area, with the
exception of some potential cloudiness over Kentucky.

The medium range models, in various degrees, flatten the upper ridge
early next week, placing the WFO PAH near the base of the westerlies
and the ridge.  A series of minor impulses work toward the area, but
remain sufficiently out of phase to provide focused lift. By next
Wednesday evening, a progressive shortwave moves toward the WFO PAH
forecast are in broad southerly flow.. Could see an adjustment in
the PoPs for next Thursday and Friday time period.

&&

.AVIATION...
Issued at 640 AM CDT THU JUL 31 2014

Weak troughing in the upper-levels of the troposphere, and a very
weak surface pressure pattern make for a low-confidence cloud and
precipitation forecast. If any showers or storms can develop today,
they will not likely be widespread enough to warrant mentioning
at KPAH and KCGI. Some of the latest guidance even develops some
convection near these sites overnight tonight. Will let later
issuances consider that possibility. Patchy dense fog at KPAH and
KCGI should dissipate very quickly this morning. If skies are
mostly clear tonight, fog is a good bet to develop at all sites.

&&

.PAH WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
MO...NONE.
IN...NONE.
KY...NONE.
&&

$$

UPDATE...DRS
SHORT TERM...DRS
LONG TERM...Smith
AVIATION...DRS





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