Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Memphis Tennessee
1133 PM CST Tuesday Dec 1 2015
updated for 06z aviation discussion.
Previous discussion... /issued 1026 PM CST Tuesday Dec 1 2015/
Minor update to add fog and remove probability of precipitation.
Clouds will be slow to clear from the northwest overnight but
should progress southeast to a line just east of Jackson Tennessee
to Memphis Tennessee to Helena Arkansas by sunrise. Areas of fog
should develop where skies clear...with patchy fog and low
ceilings expected elsewhere. All rain has ended across northeast
Mississippi this evening and conditions should remain dry through
the remainder of the night. Therefore...have removed remaining
probability of precipitation from the forecast.
Updated grids and forecast have been sent.
Previous discussion... /issued 243 PM CST Tuesday Dec 1 2015/
midafternoon GOES water vapor imagery showed a large upper level
low centered just north of Omaha. An extensive subtropical moisture
plume extended from the eastern Pacific...across northern Mexico...
and southeastern third of the contiguous United States.
Although the upper low had shown little movement since early this
morning... GFS/European model (ecmwf) both depict it lifting into the western Great
Lakes by Wednesday morning...in response to a progressive upstream
wave over the Pacific northwest. Concurrently...a shortwave will
drop south through the plains...around the western periphery of
the upper low. This shortwave will drive height falls over the middle
and lower MS River Valley on Wednesday...displacing the midlevel
dryslot from MO into the midsouth...and the subtropical moisture
feed to the Gulf Coast. Sunshine should prevail Wednesday afternoon
over a good portion of the midsouth. 18z NAM low level moisture
forecasts suggest Tupelo will see sunny skies as early as midmorning
Dry conditions and seasonal temperatures will prevail during the
latter of the week...under weak zonal flow aloft. Will need to
watch for patchy night time radiational fog development Thursday
and Friday mornings.
Next rain chance...albeit slight...appears to arrive Sunday night
into Monday. 12z GFS and European model (ecmwf) showed good timing and location
agreement with respect to a small closed upper low lifting from
the Southern Plains in the lower MS River Valley. An initially dry
midcontinental airmass over the midsouth should preclude higher
rain chances. At this early time...it appears the primary impact
will be extensive midlevel cloudiness...with light rain amounts.
By Tuesday of next week...sunny conditions should return.
06z taf cycle
IFR/LIFR weather at tup will improve to MVFR and VFR by middle
morning. Remaining sites will be VFR...though light fog may cause
MVFR visibility at jbr near sunrise. A weak cold front will push through
shifting light southwest winds more westerly and increasing speeds
to 7-10 kts. Winds will diminish and skies will clear by sunset.