Area Forecast Discussion
Issued by NWS Paducah, KY

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FXUS63 KPAH 172012
AFDPAH

Area Forecast Discussion
National Weather Service Paducah KY
312 PM CDT Wed May 17 2017

.SHORT TERM...(Tonight through Friday night)
Issued at 311 PM CDT Wed May 17 2017

Main near term concerns are the winds this afternoon followed by
convection chances late this afternoon through overnight. On and
off thunderstorm chances will continue through the rest of the
short term period.

Sufficient high clouds seem to have held temperatures down a few
degrees this afternoon and kept winds a tad lower. However, gusts
have still ranged from around 25 mph in west Kentucky to upwards
of 35 mph in southeast Missouri and portions of southern Illinois.
Isolated showers and even a few lightning strikes have been noted
over southeast Missouri and far southwest Illinois so far this
afternoon. Convective coverage is anticipated to ramp up through
early evening and continue through the overnight hours, with some
gradual reduction in coverage anticipated. A strong storm or two
can`t be ruled out with sufficient instability, moisture, and
shear present. However, the main concern for severe weather will
be tied closer to the surface low and shortwave moving from Iowa
into the western Great Lakes tonight.

A weak cold front will be focused to our north on Thursday. Upper
level ridging tries to build back into our area, and combined
with weak forcing, not expecting coverage of convection to be that
great. Will mainly be instability driven. PoPs will increase
Thursday night into Friday as a surface low develops off to our
west and the front to our north sags further south toward our
northern counties. Not too overly concerned with the severe
storm chances for Friday, but the potential does exist for a few.
Guidance is hinting at a lull toward Friday evening as the front
lifts further north and NVA develops across the area. As the
surface low moves northeast into the Midwest and the main trough
to our west approaches, PoP chances should gradually increase
later Friday night into the weekend.

Temperatures will remain warm through the period with highs mostly
in the 80s and lows in the mid 60s to lower 70s. Humidity levels
will also remain summer-like with dewpoints well into the 60s and
even low 70s from time to time.

.LONG TERM...(Saturday through Wednesday)
Issued at 311 PM CDT Wed May 17 2017

Forecast confidence is high and increasing through the weekend, but
drops off by next Tuesday and Wednesday.

There is much better clustering of the 12Z GFS, GEM, and ECMWF
solutions over the weekend. The upper-level storm system will lift
northeast from the northern Plains into western Ontario by 12Z
Sunday. This will push a cold front through our region early Sunday,
and the precipitation will come to an end Sunday afternoon and
evening.

The models have no problem generating enough instability to support
a full mention of thunderstorms along and ahead of the front through
the period. However, wind fields will not be strong at all, so
organized severe storms will be hard to achieve. Precipitable Water
values over 1.6" will be pushing the 99th percentile for May, so
locally heavy rainfall will be more of a concern.

The 12Z models agree that the Sunday night and Monday will be dry
throughout the area, as cooler, drier surface high pressure builds
over the region and the flow aloft relaxes and becomes nearly zonal.
More energy will be moving south on the backside of the departing
storm system the first half of the next week, but the models
disagree on how quickly it will impact our region with showers/rain.
The ECMWF is the most aggressive and would bring showers across at
least southeast Missouri overnight Monday night, while the GFS and
GEM hold it off until Tuesday night into Wednesday.

The result for the forecast will be to slowly ramp up PoPs from late
Monday night through next Wednesday. The models do not develop much
instability surface-based or otherwise, so left TS out for now. Once
a better consensus develops on the precipitation timing, we can
reconsider if/when/where to mention TS.

As for temperatures, we will see well above normal temperatures
Saturday and Saturday night and then cool to at or slightly below
normal levels Sunday through Wednesday.

&&

.AVIATION...
Issued at 311 PM CDT Wed May 17 2017

Main concerns are winds, scattered convection, and possible LLWS.
Southerly winds will remain gusty up around 25 to 35 kts this
afternoon before decreasing toward 00z. Winds remain up around
10-12 kts through the night, however gustiness should subside for
the most part. Some concern for LLWS to develop sometime this
evening and last much of the night as guidance showing southwest
winds around 40-45 kts at 2kft. Didn`t include for this issuance
but will have to monitor. Isolated to scattered convection
expected to develop by early evening and impact the area this
evening/overnight. Confidence too low in timing at any one
terminal to include more than VCTS mention at this time. Will need
to monitor radar trends and future guidance trends. Brief
vsby/cig reductions can be expected in the heavier storms.

&&

.PAH WATCHES/WARNINGS/ADVISORIES...
IL...Wind Advisory until 6 PM CDT this evening for ILZ075>078-080>094.

MO...Wind Advisory until 6 PM CDT this evening for MOZ076-086-087-100-
     107>112-114.

IN...Wind Advisory until 6 PM CDT this evening for INZ081-082-085>088.

KY...Wind Advisory until 6 PM CDT this evening for KYZ001>022.

&&

$$

SHORT TERM...SP
LONG TERM...DRS
AVIATION...SP



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