Area Forecast Discussion
Issued by NWS Paducah, KY

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833
FXUS63 KPAH 251727
AFDPAH

Area Forecast Discussion
National Weather Service Paducah KY
1127 AM CST Sat Feb 25 2017

.UPDATE...
Issued at 1127 AM CST Sat Feb 25 2017

Aviation update.

&&

.SHORT TERM...(Today through Monday night)
Issued at 145 AM CST Sat Feb 25 2017

After record breaking temperatures yesterday, today will see the
much cooler air working into the Quad State, with highs topping
out some 30 degrees colder. And that`s with a mix of cyclonic
cloud and sun, as a better clear out and the heart of the colder
air won`t work in til tonight, as surface High pressure works
across the Tennessee valley. Lows will likewise be some 30 to even
35 degrees colder than the previous night, with bottom out numbers
in the hard freeze mid 20s. Everyone should be falling to or below
freezing by late this evening, so a good 6 or 7 hours of sub
freezing temperatures can be expected tonight.

Surface dew points in the teens will help relative humidity
values plummet through the 30s percentile, despite the cooler
temperatures this afternoon. For the SEMO Ozarks, mid to upper
20s relative humidity minimums might be realized. And with the
surface ridge still to the West for much of the day, gradient
winds/gusts in/thru the teens mph will combine with these low rh
values to heighten the fire danger this afternoon.

As the High shifts east Sunday, return flow southerlies regenerate
a warm air advection pattern that results in returning rain
chances by the afternoon. The warm and moist air advection
continues/deepens thru Sunday night into Monday morning, with pcpn
chances peaking in the likely and even low categorical (south)
range. After a brief pause Monday afternoon, another short
wave/energy rotates in and spikes pcpn chances again into the
likely category. This second bout starts to destabilize the
atmosphere a little by late Monday night, as a warm front
generates and returns north. But at this writing, it looks like
convective instability fields supportive of thunder look like
remain just to our south through the duration of the short term
forecast period/ie Monday Night.

.LONG TERM...(Tuesday through Friday)
Issued at 221 AM CST Sat Feb 25 2017

A broad southwest flow aloft will already have been in place for
nearly 48 hours with low amplitude disturbances embedded in the flow
across the WFO PAH forecast area by the start of the extended
forecast period. This active flow will continue through midnight
Wednesday night. Beyond that time, ridging will dominate the area at
the surface and aloft, leading to drier and near seasonable
temperatures for the beginning of March.

Given the periodic intrusions of low level moisture advection and
dynamically induced sharper lapse rates, opted toward a greater
mention of thunderstorms from Tuesday through Wednesday morning.
There may be some near severe potential on Tuesday/Tuesday night.
This will be reflected in the Hazardous Weather Outlook. Adjusted
PoPs and thunderstorm coverage to reflect the influence of the
CMCnh (Canadian-Northern Hemisphere) in the medium range), given
the better initialization of the guidance in the short term.

&&

.AVIATION...
Issued at 1127 AM CST Sat Feb 25 2017

VFR cigs east of a KFWC-KHOP line will scatter as clouds move off
to the east. Mostly clear elsewhere through 00z with gusty WNW
winds continuing, generally 10-20 kts with gusts to 25 kts or so.
Tonight high pressure moving across the area will result in light
winds and clear skies. Late tonight, through midday Sunday, high
level clouds will spread from west to east across the area with
SSE winds 5-10 kts developing.

&&

.FIRE WEATHER...
Issued at 221 AM CST Sat Feb 25 2017

There has been a persistent signal since last weekend`s Fire
Weather Planning Forecasts for low relative humidity across
Southeast Missouri today (Saturday).

Conditions are going to be extremely close to Red Flag conditions
from 1pm to 5 pm CST today over parts of Oregon, Shannon, and
western sections of Carter and Ripley Counties in Southeast
Missouri. With little in the way of any rainfall, combined with
fuel moistures close to eight percent, sustained wind and relative
humidity conditions will already be within tolerance. Day crew may
need to coordinate with the Mark Twain N.F. to determine the need
for any warning at this time.

Minimum Daytime relative humidity values across the the remainder
of the WFO PAH Fire Weather Forecast area will reach into the 25
to 35 percent range today. The driest air (15 to 25%) will move
into West Kentucky and Southwest Indiana on Sunday, but wind and
fuel loads will remain below threshold for any Red Flag potential.

With the return to a more active weather pattern, relative
humidities will be elevated Monday through Wednesday. Minimum
relative humidities in the 20 to 35 percent range will likely
return next Thursday and Friday. At this time, surface winds
should remain below any critical thresholds for elevated fire
danger for Thursday and Friday, especially if sufficient wetting
of short period fuel load occurs during the early part of next
week.

&&

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

$$



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