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000
FXUS64 KJAN 271203 AAA
AFDJAN

Area Forecast Discussion...UPDATED
National Weather Service Jackson MS
703 AM CDT Sun May 27 2018

...WATCHING ALBERTO WITH POTENTIAL TO PRODUCE FLOODING IN EASTERN
MISSISSIPPI...

.UPDATE...
Updated for 12Z aviation discussion.

&&

.AVIATION...

12Z TAF discussion:
A mix of IFR to MVFR conditions to start the period at most TAF
sites, due to areas of low stratus and BR across the region. A few
patches of dense fog are scattered around as well, but most
visibilities at TAF sites expected to remain greater than 1SM this
morning. By 15Z, stratus and BR should mix out and lift, leaving
prevailing VFR conditions through the remainder of the period.
Shower and thunderstorm coverage is expected to be less this
afternoon than in recent days, so do not have prevailing SHRA or
TSRA at any sites. Any showers or storms could briefly lower
visibility and ceilings. There is some chance for MVFR or lower
conditions to develop again by 12Z Monday. /NF/

&&

.DISCUSSION...

Today and Tonight:

First off, a relatively early end to convection yesterday evening
has allowed for patchy clearing over the region with moist ground
and light winds leading to spots of thickening "radiation" fog.
Dense fog should not be at all widespread, but pockets of dense
fog is enough to warrant mention in the HWO and graphics this
morning. Anticipate fog and low clouds to lift before 9 am this
morning, although it could be a little more dogged into the
morning hours across portions of the Arklamiss Delta.

Subsequently, easterly flow on the far northwest periphery of the
circulation associated with Subtropical Storm Alberto in the
southeast Gulf of Mexico will become apparent across our region as
the day progresses. Winds at the surface will still not be gusty
or strong by any means, but the increasing flow aloft will cause
isolated to scattered "heat of the day" convection to progress
east /southeast-ward. Instantaneous coverage of activity may only
be isolated at most times, but the fact cells will be moving
necessitated raising PoPs over model blends (because it only takes
0.01" in the bucket to count). Fortunately, instability will be
held down a bit in comparison to the past few days with
temperatures likely holding below 90 degrees in all areas. This
fact should translate to less overall storm vigor (and thankfully
less lightning), although a few strong storms still cannot be
ruled out.

Tonight, most of the showers and storms will reduce in coverage
this evening. However, strengthening easterly flow and moisture
advection on northward-advancing Alberto should instigate some
showers and perhaps a stray storm coming into eastern MS late in
the night. The low level easterly flow across the region should
keep most of the fog at bay. /BB/

Monday through Saturday:

For the first half of the work week, regional focus will be on
the arrival of Subtropical Storm Alberto to the central Gulf
Coast. From the latest National Hurricane Center forecast, Alberto
is expected to make landfall Monday afternoon somewhere along
Florida Panhandle coastline between Pensacola and Panama City.
Given the irregular organization and a farther eastward nudge to
the forecast track, expected impacts to the ArkLaMiss region have
been lowered with this latest forecast. Heavy rainfall is still
possible with Alberto (both with banded convection in advance of
Alberto and nearer to its core), so a Limited threat for flash
flooding will be maintained for areas in Mississippi east of
Interstate 55. Total amounts of 1 to 3 inches will be possible for
those areas. The threat for possible flash flooding will be
mainly between Monday afternoon and Tuesday afternoon. Please see
our latest Hazardous Weather Outlook graphics and the latest
National Hurricane Center forecasts for spatial extent of flooding
rain potential. Due to the asymmetrical nature of the storm and
eastward adjustment to the forecast track, there is very little
potential for tropical storm force winds across our area.

In the wake of Alberto, the second half of this week and into the
weekend look to be HOT! The ridge of high pressure anchored over
northern Mexico and Texas looks to strengthen and extend northeast
over our region as a shortwave ridge moves across the northern
half of the country. Under the building mid-level ridge, mid-level
temperatures are expected to increase to around the 99th
percentile especially across northeast Louisiana, southeast
Arkansas, and at least western Mississippi by Friday and Saturday.
The strong cap should limit the full mixing potential of the
boundary layer, so humidity should persist into the afternoon
hours and combine with temperatures climbing into the mid-upper
90s. By Thursday, max heat index values are likely to be in the
100-105 range for much of our area, and by Saturday heat index
values exceed 105 degrees at many locations. With the focus on
Alberto in the short-term, we will hold off on introducing
dangerous heat in our Hazardous Weather Outlook, but local
residents should prepare for Heat Advisory levels of heat by the
end of this week. So make sure those air conditioners are working.
As the shortwave passes our region, there will be an increasing
potential for an MCS to bring thunderstorm chances back to the
region possibly by Saturday. We`ll continue to monitor that
potential as well. /NF/

&&

.PRELIMINARY POINT TEMPS/POPS...
Jackson       87  69  86  69 /  29  19  48  30
Meridian      88  68  85  69 /  39  36  71  72
Vicksburg     88  70  88  70 /  28  18  43  22
Hattiesburg   88  68  85  69 /  32  31  73  51
Natchez       88  70  87  70 /  32  23  47  20
Greenville    88  71  88  70 /  25  21  32  19
Greenwood     88  70  87  70 /  28  19  43  25

&&

.JAN WATCHES/WARNINGS/ADVISORIES...
MS...None.
LA...None.
AR...None.

&&


$$

NF/BB