Area Forecast Discussion
Issued by NWS Jackson, MS

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FXUS64 KJAN 281600 AAA

Area Forecast Discussion...UPDATED
National Weather Service Jackson MS
1100 AM CDT SUN AUG 28 2016

.UPDATE...Apart from minor tweaks to short term grids based on latest
guidance, the forecast for today is largely unchanged. Did pull POPs
back slightly through the central part of the CWA for this afternoon.
Best atmospheric moisture and lift look to stay close to the Gulf
Coast today near an upper-level low pressure system spinning off the
TX/LA border. A few showers or thunderstorms could still develop
around our southern zones especially, with the possibility for some
strong gusty winds if storms do develop today. Max heat index values
are expected to be in the mid to upper 90s, though a few locations
could peak at around 100 degrees for a heat index./NF/


.AVIATION...VFR conditions will prevail for the majority of the
period. Patchy MVFR conditions in fog will develop after 29/06Z and
linger until 29/14Z./26/


.PREV DISCUSSION... /issued 440 AM CDT SUN AUG 28 2016/

SHORT TERM...Today through Monday Night...The expanding west-to-
east oriented subtropical ridge to our north will be the dominant
driver of our local weather through the short term period. As said
yesterday, fortunately our relative position a little south of the
subtropical ridge axis will keep heat from getting out of control
although high temperatures will be at least a few degrees above
normal in all locations. The easterly low level flow regime (which
is also a local symptom of being just south of the tropical ridge
axis) will not be most conducive for efficient transport of gulf
moisture up into the region. Still anticipate heat index values to
near or just eclipse the century mark in most locations this
afternoon although overall heat levels look to remain short of
needing highlighting in the HWO through the short term and certainly
should be shy of advisory thresholds.

High moisture content (precipitable weather values of 2+ inches)
will mostly remain trapped near and south of the coast thanks to the
easterly low level flow regime. Partly owing to the increased
moisture down there chances of rain will be higher to our south.
However, there still should be some cascading seabreeze-type
convection spilling north into southern zones this afternoon,
possibly getting up to the I-20 corridor along and west of the
Jackson Metro by late afternoon into the early evening. A strong and
gusty storm cannot be ruled out in these areas, but the anticipated
environment should not support enough risk to include in the
HWO/graphics. By tomorrow the potential of seabreeze-type activity
getting north into southern zones does not look as great as low
level flow may back enough to lose any southerly component
whatsoever. Despite this development it will be hard to completely
rule out an isolated afternoon storm on Monday owing to some more
subtle moisture convection coming in from the east. /BB/

LONG TERM...Tuesday through Saturday...Warm and relatively drier
conditions will continue into much of the extended portion of the
forecast. We also continue to monitor the tropical wave soon to
enter the Gulf of Mexico for possible development.

On Tuesday a broad and relatively flat ridge will exist over the
southern two thirds of the CONUS. The slightly drier airmass that
has begun filtering into parts of the area this weekend is expected
to still be around. As a result, daytime convection will remain very
isolated, with somewhat better rain chances farther south and west
where greater column moisture will exist.

The warm and drier theme will continue for our area into Wednesday,
but the upper pattern will begin to change as a trough begins to
build along the East Coast. This will push a cold front southward
through the Midwest on Wednesday and Thursday. As upper level
forcing associated with the trough remains north and east of us, the
surface front will begin to stall and weaken as it approaches our
area Friday. Nevertheless, rain chances will tick back up a bit
through the end of the week as deep layer moisture increases again
ahead of this front. Forecast confidence during this time frame of
the forecast decreases due to questions surrounding what will
transpire with the tropical system in the Gulf.

This morning, Invest 99L was tracking WNW off the northern coast of
Cuba toward the Florida Straits. Sporadic convection continued
around the weak low center overnight. Little change in organization
is expected today, but additional development is possible Monday as
the system moves into the Gulf of Mexico. As we have been
reiterating for several days now, until the system develops, model
projections will continue to vary erratically from run to run. Thus,
there is still considerable uncertainty as to how or if this system
will have any impact on local weather conditions. /DL/

AVIATION...Mainly VFR flight cats are expected through the next 24
hours although an less than two hours of MVFR light fog cannot be
ruled this morning at all sites along and before 13 UTC. Otherwise,
anticipate rain chances to mainly be confined south of I-20 this
afternoon and therefore locally highest between 18 UTC and 00 UTC at
PIB/HBG. Outside of any thunderstorms winds will be from the east
and less than 15 mph with ceilings likely remaining in the VFR
range, even in storms. /BB/


Jackson       93  74  95  75 /  14   9  19   8
Meridian      96  74  97  74 /   9   8  12   6
Vicksburg     94  74  95  75 /  17   9  20  10
Hattiesburg   93  74  93  74 /  31  15  17  11
Natchez       90  74  92  74 /  32  16  23  13
Greenville    94  75  95  74 /   7   9  18  11
Greenwood     95  74  95  74 /   6   8  19   9


.JAN Watches/Warnings/Advisories...


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