Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Jackson MS
400 am CDT Friday Aug 22 2014
Short term...today through Saturday night...continued hot with
afternoon heat index values remaining the main concern. Early
morning surface analysis had a 1020mb high centered just south of
the Mississippi/Louisiana coast. A large 595dam high was noted
centered over our region. Together ridging surface and aloft over
our region will maintain warmer than normal temperatures through
Saturday night. This heat will combine with our moist airmass to
result in heat index values above 100 each afternoon but most sites
will remain shy of 105f and overnight lows will remain below local
heat advisory criteria through the short term period. Gfsmos
guidance was a little too warm with afternoon highs but a little too
cool on overnight lows. The European model (ecmwf) MOS has verified best over the
last several days and was leaned on for highs and lows through the
short term. There was a good bit more convection yesterday than the
00z models suggested but the 12z Thursday hi-res arw handled the afternoon
convection well. Model consensus is rather sparse with convection
this afternoon but the hi-res arw pegs the southeast with some
isolated to scattered coverage due in part to late afternoon sea
breeze convection trying to drift up into our southern zones. Have
carried isolated wording in the southeast this afternoon. Rain
chances overall will remain very low elsewhere through the period.
Long term...Sunday through Thursday...through Sunday heat and
humidity will be the primary issue areawide...but it will be mainly
restricted to the western areas on Monday as mean ridging continues
through Monday...which will continue classic August Summer muggy
conditions. 850mb temperatures will be in the upper 20s to around 30c. This
will bring temperatures in the middle to upper 90s through Sunday. On Monday
temperatures will cool slightly from the east due to increase in cloud
cover...which will confine the warmer temperatures across the western
areas. With lows in the 70s heat indices will be a concern. Heat
indices will be around 100 to 107 on Sunday and 100 to 106 on Monday
mainly in the west. With strong subsidence rain chances will be
rather scarce through Sunday.
As we go into next week moisture will build across the region from
the east. This will give the region a break in warm afternoon high
temperatures. Thus 850mb temperatures will cool some into the middle 20sc.
Rain chances will pick up as deep tropical moisture builds across
the region. Precipitable waters will increase to around 2.2 inches before
fluctuating around 1.5 to 1.9 inches for Wednesday into Thursday.
There will be decent instability for some convective chances from
Monday through Thursday with some locally heavy rainfall potential.
The mean ridging will fluctuate some during the upcoming work week.
As far as the tropics are concern most models are keeping tropical
systems away from the Gulf of Mexico and pushing possible tropical
systems off the East Coast.
As far as model differences are concern most of the ensembles...
Euro...Navy and UK models keep the mean ridge dominant over our
region. The GFS once again tried to bring an upper trough over the
region by the middle of next week. Thus it will try to push a front
into the region toward the weekend...which seems to be an outlier.
Models were in general agreement with the weekend heat and increase
in tropical moisture from the east for next week. The 6 to 10 day
outlook calls for above normal temperatures and rainfall going toward
As far as afternoon high temperatures are concern went with a blend of mex
and Euro guidance for the warm days of Sunday and Monday. Mex and
gmos looked a little high with some locations around the 100. For
the rest of the period went close to mex and gmos guidance. For daily
lows went close to gmos guidance. As far as probability of precipitation are concern went
close to a blend of gmos and mex guidance. Euro probability of precipitation looked a little
high for next week for some periods and too dry for other
Aviation...hbg has reported visibility restrictions most of the night due
to haze and now fog development. Expect MVFR/IFR conds to continue at
hbg though 13z before improving. Confidence is low on restrictions
elsewhere but rainfall across central MS Thursday may lead to a brief
period between 10z-13z of MVFR conds this morning over central and east
MS. VFR conds will prevail areawide after 13z today. Isolated afternoon
thunderstorms will be possible in vcty of mei and hbg this afternoon. /22/
Preliminary point temps/pops...
Jackson 96 72 98 71 / 7 6 5 7
Meridian 96 70 98 70 / 17 6 5 8
Vicksburg 96 71 98 70 / 5 6 5 6
Hattiesburg 97 74 98 74 / 24 6 10 8
Natchez 95 72 96 73 / 12 4 10 8
Greenville 96 72 98 73 / 4 6 3 4
Greenwood 96 71 98 71 / 4 6 3 4