FXUS64 KJAN 201714 AAA

Area Forecast Discussion...UPDATED
National Weather Service Jackson MS
1114 AM CST Tue Nov 20 2018

Updated for 18Z aviation discussion


18Z TAF discussion:
Any lingering MVFR low stratus is quickly eroding, with the only
areas slowest to clear near GTR & especially PIB & HBG. Expect the
last two TAF sites to erode over the next hour, with all sites
then at VFR flight categories through the evening. Winds will
mainly be out of the north-northwest around 5-10mph, becoming
light in the evening. Expect similar VFR conditions into tomorrow
afternoon with light north-northeast winds. /DC/


No major changes needed for the going forecast. Expect a nice &
cooler afternoon today. Morning synoptic & water vapor analysis
indicates a trough swinging off to the east-northeast with a
developing low pressure off the Mid-Atlantic & Atlantic seaboard,
with our area in the wake of the cold front & post frontal cold
air advection. Due to this, water vapor in GOES-East imagery shows
much drier air aloft advecting in. However, there is some brief
lingering low level moisture, per the low-level stratus filtering
in the cold air advection environment. As surface ridge of 1028mb
high pressure over the central Plains builds east-southeast,
expect a continued isentropic subsidence & decrease & clearing of
moisture & these clouds into the early-mid afternoon. PWs will
quickly fall to a quarter to half an inch through the afternoon,
so expect a dry afternoon. With cooling thermal profiles (i.e. ~5
degrees C. cooler @ 925mb per 12Z regional sounding analysis),
highs will ~8-12 degrees below average, in the low-mid 50s in the
north to upper 50s in the south. /DC/

Prior discussion below:

Today and Tonight:

A cooler, drier airmass will continue to filter into the region
from the NW today behind yesterday's frontal passage. A roughly 20
degree temperature gradient exists across ArkLaMiss this morning
as temperatures have fallen into the upper 30s in the Delta region
where skies have cleared, but still remain in the 40s to upper
50s elsewhere due to post frontal low clouds helping to keep heat
near the surface. Temperatures will continue to fall as the cloud
deck diminishes and pushes east of our region and cold air
continues to advect into the region.

Sunny skies should prevail area wide as we get into the late
morning hours. High temperatures will remain about 10 degrees
below average today ranging from near 50 in the NW to near 60 in
the Pinebelt. By tonight, a broad surface high centered over
Arkansas will encompass the lower MS River Valley region. Light
winds and clear skies will help aid in the radiational cooling
effect for locations closer to the center of the high. Areas north
of the I-20 corridor could fall near to slightly below the
freezing mark. /JM/

Wednesday through Monday night:

NWP models remain consistent in showing an active, progressive
weather pattern with three quick-moving systems expected to affect
the ArkLaMiss region from late this week into early next week. The
first system will move through Wednesday night into early
Thanksgiving Day and be confined to the coast with minimal impact on
the forecast area in the form of light rain chances mainly south of
the Highway 84 corridor. The next system moving through from Friday
into Friday night will be stronger with tremendous shear owing to to
intense jet streams, but the fast system speed will limit return
flow duration and widespread rainfall will further hinder northward
intrusion of the warm sector. Precipitable water values around 1.25
inches combined with the trough passage will bring potential for one
to two inches of rain over mainly eastern portions of MS, so locally
heavy rainfall should be the biggest impact.

The next system pushing through from Sunday into Sunday night still
requires the most attention in the longer range as there should be
greater upper level support and potential instability, depending
on system speed, to go along with tremendous wind shear. For now
it looks like the richer/deeper moisture will team up with greater
dynamics just to our east. If the system slows and digs just a
bit more, then ingredients could come together for a severe
weather event in our region, but confidence is still too low for
outlooking any severe threat at this time range given the
thermodynamic uncertainties in NWP guidance. Beyond this system,
it looks like significantly colder air will move into the region
to finish up the month of November. /EC/


Jackson 55 34 56 37 / 1 0 0 6
Meridian 56 34 57 37 / 3 0 0 2
Vicksburg 56 33 56 37 / 0 0 0 10
Hattiesburg 59 37 59 39 / 11 0 0 10
Natchez 55 35 57 39 / 0 0 0 20
Greenville 52 30 54 36 / 0 0 0 1
Greenwood 54 30 55 36 / 1 0 0 1





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