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Area forecast discussion 
National Weather Service Paducah Kentucky
548 PM CDT Monday Aug 3 2015

Update...
issued at 548 PM CDT Monday Aug 3 2015

Updated aviation discussion for 00z tafs.

&&

Short term...(this evening through Wednesday night)
issued at 307 PM CDT Monday Aug 3 2015

Ended up issuing a Special Weather Statement for triple digit heat
indices over south and east portions of the region this afternoon.
Have been waiting on dewpoints to mix out a bit down there...but
they have been stubborn. Depending on convection and associated
cloud cover the southwest third of the area may see 100 to 105
heat indices again Tuesday afternoon. Given the uncertainties that
exist...will not issue a statement for it at this time.

Finally seeing some cumulus development through the middle-section of the
forecast area...so will continue to monitor for thunderstorm
development. The hrrr runs continue to be very dry...so we may not
see any development at all.

Confidence in a wet period is rather high as a middle /upper-level
storm system moves into/through the region Wednesday into
Wednesday night. There is still quite a bit of variability in the
timing and track through the region...so cannot get too carried
away with heavy rainfall potential at this time.
However...precipitable water values will be over 2 inches...and
the storm system will not be moving very quickly...so a somewhat
prolonged period of heavy rainfall is a real possibility. A Flash
Flood Watch may eventually be necessary.

From tonight through Tuesday night...the forecast is rather
murky...but in general feel that drier is better. There will be a
very weak boundary in the region...but the convergence along it is
quite weak...so it may not be much of a focus for convective
initiation. Will have some small chance probability of precipitation through Tuesday
evening...and then will ramp up a bit from the west heading into
Wednesday morning.

Long term...(thursday through monday)
issued at 307 PM CDT Monday Aug 3 2015

There is still quite a bit of model inconsistency in the long term
period...more than average for this time of year. The general theme
is that slightly cooler and drier air will arrive by the
weekend...followed by a return flow of moisture early next week.

As far as the daily details...

There is poor agreement on the specifics Thursday into Friday. A
pair of 500 mb shortwaves will traverse our region in the northwest
flow pattern. The 12z GFS /supported by the gefs mean/ now reserves
the strongest shortwave and associated surface front for Friday. The
12z European model (ecmwf) is more consistent with previous guidance in bringing the
stronger shortwave across the region Thursday. The forecast will
lean toward the more consistent European model (ecmwf)...which means the highest probability of precipitation
will continue to be Thursday. Since both models indicate a shortwave
passage on Friday...will tweak probability of precipitation upward. However...they will only
range from slight chance in the northeast to chance in southeast Missouri.
Extensive clouds and precipitation should temper the influence of low level
warm advection...with highs generally in the lower to middle 80s both
days.

Surface high pressure will move east across the Great Lakes region
over the weekend. This high will bring a northeast wind flow of
slightly cooler and drier air. Despite the presence of the
high...the 12z European model (ecmwf) has quantitative precipitation forecast and very warm 850 mb temperatures in the lower
20s over our region this weekend. This looks a little unrealistic
and is not consistent with most previous runs. Will keep the
forecast mainly dry...in line with the GFS Camp.

By early next week...guidance is in fair agreement that the upper
ridge will build a little east and northeast from the plains. At the
same time...the low level flow will turn more southerly on the back
side of the high. Will bring back small probability of precipitation...starting in southwest
Illinois on Sunday afternoon and across the region Monday. A small
increase in temperatures and dew points is also forecast.

&&

Aviation...
issued at 548 PM CDT Monday Aug 3 2015

Diurnal cumulus will disperse soon with loss of fuel. Some middle or high
scattered blow over cloud may impact mainly kcgi...otherwise moclear
night with maybe temporary MVFR patches of fog at fog prone kcgi.
Diurnal cumulus again tmrw with similar blow over high clouds possible.
Probability of precipitation too low at this point to mention.

&&

Pah watches/warnings/advisories...
Illinois...none.
MO...none.
In...none.
Kentucky...none.
&&

$$

Short term...drs
long term...my
aviation...dh

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