Area Forecast Discussion
Issued by NWS Jackson, MS

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476
FXUS64 KJAN 281621
AFDJAN

Area Forecast Discussion
National Weather Service Jackson MS
1121 AM CDT Fri Apr 28 2017

.UPDATE...
Updated for morning discussion.

&&

.DISCUSSION...
A warm and humid airmass is in place across the region.
Temperatures have risen this morning into the lower 80s for
locations along and south of I-20, and upper 70s north of I-20.
Dewpoints are also rather moist with readings in the lower 70s.
With the amount of instability in the atmosphere today, it would
make for good potential for storms. However, we do remain capped
and this will likely result in a lack of convection today. Hi-res
guidance doesn`t show much in the way of activity but there could
be a small chance for something to break the cap and have left
slight chance POPs in the forecast. Overall, though, most
locations will remain dry but very muggy and windy. Southerly
winds will gust to around 30mph at times. Current forecast is in
decent shape and only minor adjustments were needed. /28/

Prior discussion below:

Today and tonight: It will be warmer, breezy, and morehumid. With
the exception of our southeast most zones, a cool dry airmass was
still noted over our CWA at 3AM with dew points in the mid to
upper 50s and temperatures in the upper 50s to lower 60s. A rapid
moisture increase is expected this morning that may also lead to a
few light showers. Early morning surface analysis had a 995mb low
over the Texas panhandle and 1014mb high along the southeast
coast. Water vapor imagery showed a potent shortwave over the
western CONUS that wl help develop a closed low over the four
corners region by this evening. A mid level high will strengthen
at the same time just off the southeast coast. Together, these
features will result in warm breezy south winds today that will
also bring a warm front back across our CWA this morning. The 00Z
Fri JAN sounding had a PWAT of a half inch and the JAN dew point
at 3AM was 58F. Before noon today, lower 70 dew points are progged
to be back over central Mississippi with PWATs back above an inch
and a quarter. Hi-res models suggest a few showers may develop
this morning but our airmass will remain capped and heights will
increase 60m through afternoon thanks to the strengthening mid
level high to our east. This should hinder thunder development and
end the low rain chances this afternoon. The strongest winds
today will be over the delta again but remain just below Wind
Advisory criteria. The strong gusts will make for hazardous
driving conditions for high profile vehicles and may down a few
limbs. Wl continue this mention in our HWO. Despite cloud cover
today, afternoon temperatures will top out above normal. By
tonight upper 60 to lower 70 dew points will remain over the area.
Combined with a south wind, temperatures will be held above
normal with most sites bottoming out in the lower 70s. /22/

Saturday through Thursday Night: The overall forecast for this
weekend into next week remains largely unchanged from what has
been advertised. The upper-level closed low digging into the Four
Corners region today will lift into the Central Plains by Sunday,
with its attendant surface low wrapping into the system by late in
the weekend. Thunderstorms firing up along a cold front are
expected to develop into a squall line approaching our northeast
Louisiana parishes and southeast Arkansas counties by late
Saturday night. Very heavy rainfall will be possible with the line
of thunderstorms, as moisture-rich air is advected northward from
the Gulf of Mexico ahead of the front. PWAT values around 2
inches would be near the climatological maximum for this time of
year, indicating storms will be efficient rainfall producers. The
line of storms should move from west to east across most of
Mississippi by Sunday evening, with some uncertainty regarding the
exact speed of the line. Regardless of the line`s speed, it is
not expected to stall out anywhere and thus long residence times
of storms should not be as much of a concern this time around. The
possibility for flash flooding and river flooding will exist due
to heavy rainfall rates over short periods of time. Instability
and deep layer shear values are sufficient enough along and ahead
of the line to support at least a Slight Risk for severe weather
as well, with damaging wind gusts being the primary severe threat
and to a lesser degree - hail and possible embedded tornadoes
along the line.

Apart from the weekend heavy rain concerns, gusty winds are
expected to continue across the area on Saturday. Locations through
the Delta could see the strongest winds develop, and a Wind Advisory
may be necessary through that area. Another round of thunderstorms
will be possible with a midweek system, but confidence in timing and
location is low at this time. Model depictions of the upper-level
pattern begin to diverge by late in the week, so have kept with a
consensus of models for Wednesday and later. /NF/

&&

.AVIATION...
12Z TAF discussion:

Satellite imagery showed a stratus layer spreading north over the
area. This will result in MVFR-IFR Cigs at most TAF sites until
after 16Z when cigs should lift above 3kft. A few -SHRA will be
possible this morning but no PCPN is expected this afternoon.
Southerly winds will become strong and gusty areawide by 17Z with
the strongest winds at GLH. /22/

&&

.PRELIMINARY POINT TEMPS/POPS...
Jackson       87  71  90  72 /  16   6  25  13
Meridian      86  70  89  71 /  16   7  18  11
Vicksburg     87  71  88  72 /  16   8  27  32
Hattiesburg   86  71  88  71 /  17   8  24  15
Natchez       86  72  87  71 /  16   9  30  34
Greenville    85  71  88  73 /  16  15  29  41
Greenwood     86  70  89  72 /  16  10  23  17

&&

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

&&


$$

28



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