Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

fxus63 kpah 111754 
afdpah

Area forecast discussion
National Weather Service Paducah Kentucky
1154 am CST Mon Nov 11 2019

Update...
issued at 1154 am CST Mon Nov 11 2019

Have already expanded the Winter Weather Advisory to include
Carter and Ripley counties in Missouri to match up with
adjustments from weather forecast office sgf and lzk. It is looking like the path of
least regret will be to expand the advisory over the entire area,
as conditions should deteriorate quickly throughout the area,
after dark. This change will likely be made with the main
forecast package this afternoon.

The aviation section has been updated for the 18z taf issuance.

&&

Short term...
issued at 325 am CST Mon Nov 11 2019

We will be issuing a Winter Weather Advisory with this forecast
package. The headlines and wintry precipitation forecast totals have
been coordinated with wpc and our surrounding offices. Our latest
observations are as follows. The models continue a slight uptick in
overall quantitative precipitation forecast. The models are slightly faster with the advancement of
the cold air from the surface to 925 mb this afternoon. There is
still a fair amount of uncertainty with respect to how antecedent
ground and pavement temperatures will affect overall accumulations.

For the morning hours, rain will develop from west to east across the
area. The strong cold front will push southeast of the area this
morning. The precipitation change over will be in the afternoon
over parts of semo, southern IL, and southwest in, and from late
afternoon into the evening over western Kentucky. There will likely be a
short period of mixed precipitation before going all snow. The
main cause for concern is the models continue to show precip
increasing in coverage over the area in the afternoon when the
good low trop cold air advection develops, along with increasing moisture 700mb
and above and within the dendritic growth zone (including the -12
to -18c layer). The activity will end from northwest to southeast during the
evening hours over west Kentucky. Should be over by midnight all areas.

Looking at the latest model output, there is strong model consensus
that up to 1 inch of snow accumulation is likely this afternoon and
evening after the precipitation changes over. Many of the deterministic
and hi-res models actually show 2- 3 inch amounts, save for maybe
semo and the Kentucky/Tennessee border. However, the ensemble suite point
forecasts that incorporate the ec and GFS show mean values around
1", with a significant spread ranging from not much more than a
trace, to the aforementioned 2-3" amounts. For this event, it's
all about travel vs. What we see on any snow boards in terms of
headlines. The activity will be coming through during the late
afternoon and evening commute (maybe slightly later toward the Tennessee
border). Our snowfall forecast closely mirrors wpc, which is a
forecast just higher than the ensemble mean amounts. The logic
behind the advisory issuance is, it will be our first event of the
season. So with any chance of travel impacts during the late day
commute, we would rather provide the heads up potential. Overall
confidence though, is still not as high as we'd like it to be.
Expect additional adjustments to the forecast.

Late tonight through Tuesday still looks exceptionally cold for
mid November. Northwest winds 10 to 20 mph with some gusts to 30
mph will drop wind chill temperatures down to near zero to 5 above
by early Tuesday morning. Highs Tuesday will only reach the mid
20s to near 30 after morning lows from 14 to 19.

Long term...
issued at 325 am CST Mon Nov 11 2019

For Tuesday night on through the weekend...

Main sensible weather impact for the early part of the extended
forecast period will be the modification of the Arctic airmass as
the surface ridge gradually moves east of the weather forecast office pah forecast area.

To reflect some influence of antecedent snow cover from the Monday
event (lowered maximum temperatures on Tuesday, lesser insolation,
higher snow albedo/shortwave radiation), adjusted Tuesday night
minimum temperatures down one to 3 degrees below National blend of
model (nbm) initialization parameters.

The remainder of the forecast period depicts the slow translation of
the sharp, but persistent meridional ridge axis from the eastern
Pacific to the West Coast, gradually flattening over the weather forecast office pah
forecast area by next weekend. The main synoptic impact will be to
send another shortwave trough through the weather forecast office pah forecast area on
Thursday, serving to keep temperatures 5-15 degrees below normal in
the wake of the passage of the Arctic high pressure center east of
the area by Wednesday. With the absence of any meaningful moisture,
the next cold frontal passage through the area on Thursday should be
dry (no precipitation). Should see a recoup of temperatures Sunday
into Monday of next week as zonal to southwest flow returns.

Again the next significant weather maker for the weather forecast office pah forecast
area still appears to be outside this forecast period, centered on
the November 19th/20th time frame, focused by a large trough axis
diving down the center of the nation. Something Worth watching for
significant weather potential.

&&

Aviation...
issued at 1154 am CST Mon Nov 11 2019

The cold front will be passing through kowb at 18z, and IFR or
low MVFR conditions in light rain and drizzle can be expected at
all sites to begin the forecast. As temperatures continue to fall
and the upper trough approaches, a brief mix of rain, sleet and
snow will be possible before it becomes all snow. Held
visibilities to 1sm or greater in snow, but certainly cannot rule
out some LIFR conditions in the heaviest snow. Looks like the snow
should be done around 00z at kcgi and kmvn and around 03z at the
other sites. Conditions should become VFR at all sites by 08z. In
addition to the snow, very strong north winds will impact the
entire region throughout the period. The strongest gusts will
30-35kts over the southwest half of the area through the evening
hours.

&&

Pah watches/warnings/advisories...
Illinois...Winter Weather Advisory until 9 PM CST this evening for
ilz075>078-080>089.

Winter Weather Advisory from 3 PM this afternoon to midnight CST
tonight for ilz090>094.

MO...Winter Weather Advisory until 9 PM CST this evening for moz076-
086-087-100-107-108.

Winter Weather Advisory from 3 PM this afternoon to midnight CST
tonight for moz111.

In...Winter Weather Advisory from 3 PM this afternoon to midnight CST
tonight for inz081-082-085>088.

Kentucky...Winter Weather Advisory from 3 PM this afternoon to midnight CST
tonight for kyz004-005-007-010-011-013>016-018>020.

&&

$$

National Weather Service Glossary of Abbreviations