Area Forecast Discussion
Issued by NWS Jackson, MS

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409
FXUS64 KJAN 251507 AAA
AFDJAN

Area Forecast Discussion...UPDATED
National Weather Service Jackson MS
1007 AM CDT SUN SEP 25 2016

.UPDATE...
Only made small adjustments to hourly temperatures and dewpoints
curves to, mainly to account for faster warmup and quicker mixing. No
other major changes needed. /DC/

&&

.DISCUSSION...

The region continues to be situated under an upper high that is
slowly flattening over the mid Mississippi Valley and surface ridging.
Also the distinct upper low is spinning over the western Florida
Panhandle. Due to continued anomalously warm low level boundary layer
temperatures, with 850mb and 925mb temps warming slightly today from
yesterday, and efficient mixing this afternoon with dewpoints in the
low to mid 60s, expect another very hot afternoon with highs in the
mid to upper 90s. Some areas, especially in much drier soil
conditions near Meridian, could approach the century mark again. Due
to this, highs could peak near or break some record highs this
afternoon at most sites across the region. Due to moisture and
enhanced lift from the upper low to our east, diurnal showers and
storms are again possible across most of the area this afternoon,
other than the northeast where there is some slightly drier air to
our east. /DC/

&&

.AVIATION...VFR flight categories will prevail at all sites this
afternoon and tonight.  Some isolated convection will be possible
this afternoon beginning around 18Z.  Flight categories could
briefly be reduced to MVFR/IFR status if convection is observed on
station.  Otherwise, any convection that develops will dissipate
around 00Z this evening.  Winds today will be from the light and
variable across the region. /19/

&&

.PREV DISCUSSION... /issued 334 AM CDT SUN SEP 25 2016/

SHORT TERM...Mid/upper level ridge continues to dominate the
weather over the area providing mostly dry and unseasonably hot
daytime conditions. This will continue for one more day before the
first significant cold front of the season moves through Monday.
Though hot conditions will continue today, the mid/upper ridge will
begin to be squeezed somewhat by approaching wave over the mid MS
valley and a weak westward moving cold core low over south
AL/northwest FL. Despite surface dewpoints in the 60s, precipitable
waters remain at or above 1.5 inches, especially over the
southwestern half of the forecast area. Strong surface heating again
today should take advantage of the available moisture for isolated
afternoon convection, especially over the south where the cold core
low will provide additional ascent.

While majority of upper level support for the approaching cold front
will lift off to the northeast tonight, support will remain
sufficient to push the boundary through the forecast area during the
day Monday. Precipitable waters at or above 1.75 inches pooling along
the boundary should be sufficient with the expected low level
convergence and ambient heating to produce a good scattering of
showers and thunderstorms over the forecast area Monday. Weak lapse
rates and low CAPE should keep the convection sub-severe.

The boundary will clear the area during the evening Monday with
clouds decreasing and temperatures falling off into the 50s and 60s
after midnight./26/

LONG TERM...Tuesday through Saturday...On Tuesday the upper trough
will be centered over the Great Lakes region with the axis stretching
down to the Tennessee Valley region. The models continue to diverge
at the latter part of the work week as the Euro takes the upper
trough and spins it down into the southeast US. The GFS and Canadian
takes the northern stream trough and pushes it into the eastern Sea
Board by Friday. Both models bring upper ridging back to the region
for Thursday through Saturday, while the European model cuts off the
upper low as it spins down to the Tennessee Valley Thursday into
Friday before it lifts the cut off low into the Great Lakes region by
Saturday night. The Euro solution would result in some cooler temps
for the region especially during the day. With the persistent
progressive solutions of the GFS and Canadian along with their
ensembles, will continue to favor that solution. In the wake of the
front pwats will be less than one inch with a deep layer dry air
which will suppress our rain chances for Tuesday through Saturday.
With cool dewpoints, minimum humidities during the afternoons will
be on the low side, but surface winds will be light during this dry
period. Also in the wake of the front models continue to show some
relief at night with nightly lows in the 50s and 60s. Daily high
temps will cool into the lower to middle 80s for the rest of the
period./17/

&&

.PRELIMINARY POINT TEMPS/POPS...
Jackson       96  71  92  63 /  19  21  25  14
Meridian      99  68  93  64 /  17  13  29  21
Vicksburg     96  71  89  63 /  18  22  26  11
Hattiesburg   96  70  92  67 /  24  17  26  19
Natchez       93  71  91  65 /  18  21  27  16
Greenville    97  71  87  59 /  16  18  26   9
Greenwood     97  69  89  59 /  16  14  26  11

&&

.JAN Watches/Warnings/Advisories...
MS...None.
LA...None.
AR...None.
&&

$$

DC/19



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