Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Memphis Tennessee
1242 PM CDT Thursday Oct 30 2014
Updated to include 18z aviation discussion.
Previous discussion... /issued 952 am CDT Thursday Oct 30 2014/
Surface high pressure over the Mississippi River valley has caused
for a cool clear morning throughout the midsouth. Temperatures
remain in the lower to middle 50s throughout most of the region as of
1030 am... except near the Tennessee River where readings in the
40s can still be found. Forecast seems to be on track... only
minor tweaks were made. Decreased highs for Thursday 1 degree area
wide and slightly increased probability of precipitation before 00z for our northern-most
counties due to an approaching cold front.
Previous discussion... /issued 416 am CDT Thursday Oct 30 2014/
Discussion...surface analysis this morning places a 1021 mb ridge
of high pressure over the lower Mississippi Valley this morning.
This is resulting in clear skies across the middle south and
temperatures as of 4 am CDT ranging from the upper 30s along the
Tennessee River and 40s elsewhere. Rain chances
tonight...frost/freeze potential Friday night and Saturday
night...and shower/thunderstorm chances in the long term forecast
are the predominant challenges in this morning/S forecast issuance.
Short term...(today through Saturday night)...temperatures across
the middle south this morning have fallen into the upper 30s into the
40s across the middle south and approaching current surface
dewpoints. Thus...patchy fog is possible through sunrise across many
locations. Otherwise...high pressure will remain in place but
gradually shift southeast throughout today. Short term models
indicate another cold front will drop through the forecast area
tonight. Model soundings indicate a potential for isolated rain
showers across portions of west Tennessee and perhaps the Missouri
bootheel as the front moves across the lower Mississippi Valley.
Much cooler air behind this front will filter into the lower
Mississippi Valley throughout the day on Friday with highs on
Friday ranging from the lower 50s north and upper 50s to lower 60s
across north Mississippi and 40s to lower 50s on Saturday. Low
temperatures Friday night and Saturday night are anticipated to
drop into the upper 20s to lower 30s across the area. These low
temperatures combined with light/nearly calm winds may result in
the development of frost and possibly a freeze. Later shifts will
consider frost/freeze headlines if these trends continue in
subsequent model runs.
Long term...(sunday through wednesday)...GFS/ECMWF long term
models indicate another cold front will gradually drop into the
lower Mississippi Valley early next week. Model trends continue to
indicate a slower progression across the region as the front
becomes nearly parallel to upper level flow aloft. Overall
instability is anticipated to be minimal at best and kept thunder
mention to a minimum. Long term models disagree on timing towards
the middle of next week with this front but best chances for rain
at this point will be Tuesday night and Wednesday.
18z taf cycle
VFR conditions will prevail throughout the entire period. Winds
initially from a southerly direction will transition to be from a
more northerly direction overnight as a cold front moves through
the region. Moisture is limited with this front so no mention of
precipitation at this time as confidence is low. Clouds and drier near
surface environment will likely prohibit fog formation overnight.
Winds will increase and become gusty late in the period as the
pressure gradient strengthens behind the front with a strong and
cold high inbound.