Scientific Forecaster Discussion
fxus64 kmeg 181105
Area forecast discussion
National Weather Service Memphis Tennessee
505 am CST Thu Jan 18 2018
Previous discussion... /issued 308 am CST Thu Jan 18 2018/
Another cold night across the midsouth with skies clear under
high pressure. Temperatures reflected where the deeper snowpack
was still on going...with single digits roughly east of I-55 and
teens to the west. Winds were starting to pickup from the
southwest...bringing warmer air into northeast Arkansas this hour.
Walnut Ridge is showing 8kts and a balmy 17f...a wind chill of 6f.
For today and tomorrow...surface high pressure of near a 1030mb
will anchor itself from the lower Mississippi Valley to the
Appalachians this time frame. The midsouth being just to the north
will see southwest winds of generally 5 to 15 mph and the start
of warmer boundary layer air surging out of Texas. Temperatures
will reach close to freezing today...while the far south should
reach around 40f. Clear...but not as cold tonight with most
locations dropping into the upper teens to low 20s. Wind chills
will fall to around 10f. Tomorrow a weak impulse aloft will drift
along the I-20 corridor with mid level moisture potentially
reaching portions of north Mississippi. Otherwise...skies will be
mostly sunny and with less snow cover highs in the 40s.
Saturday through Monday...warmer still this period as both upper
level heights and a southerly low level fetch increase. Models
haven't really budged from previous run solutions with regards to
the timing of an approaching Pacific trough. The GFS still
indicating faster...about 6 hours. But there is disparity with
the track of the closed 500mb low...with the GFS farther north now
into the upper Great Lakes...while the Euro takes it near Chicago.
Clouds will be on the increase Saturday...but temperatures will
be offset by stronger warm air advection...so highs will reach into the 50s for
most. Light sprinkles can't be ruled out either in the west during
the afternoon and evening hours. Deeper moisture will arrive late
Saturday night through midday Monday as a surface low of 1003mb
ejects northeast out of the Central Plains along a 80-90kt 500mb
jet streak. By the time the low reaches the Midwest on Monday...it
will have deepened to 993mb and gone occlusion. South winds will
increase to near advisory criteria Sunday afternoon and evening
along and west of the Mississippi River as an 850mb low level jet of near
70kts swings over the Delta by late evening. Have taken a blend
of the models with the associated cold front timing...tracking it
through our area from 2 am Monday morning to about 12 PM Monday.
Dewpoints could reach the mid 50s west of I-55 yielding cape
valleys of 50 to 200 j/kg and Li's near zero. Due to the
incredibly strong forecasted shear have introduced a few strong
storms in the severe weather potential statement for the western County Warning Area...where a fast moving
narrow band of low topped convection may fire out ahead of the
front. Skies will clear from west to east late Monday with
westerly winds ushering in mild Pacific air.
Middle of next week...zonal flow aloft will keep the area dry and
very seasonal. A very welcome relief.
Aviation...12z taf set
VFR conditions expected to persist through the period. Light
winds increasing to south-southwest winds between 5-7 kts then becoming light
Arkansas...Wind Chill Advisory until 9 am CST this morning for Mississippi.
MO...Wind Chill Advisory until 9 am CST this morning for Dunklin-
MS...Wind Chill Advisory until 9 am CST this morning for Alcorn-
Tennessee...Wind Chill Advisory until 9 am CST this morning for Benton Tennessee-