Area Forecast Discussion
Issued by NWS Jackson, MS

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FXUS64 KJAN 281143 AAA

Area Forecast Discussion...UPDATED
National Weather Service Jackson MS
643 AM CDT Fri Apr 28 2017

Updated for 12Z aviation discussion.


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/


.DISCUSSION...Today and tonight: It will be warmer, breezy, and more
humid. 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/


Jackson       87  71  90  72 /  17   6  25  13
Meridian      85  70  89  71 /  18   7  18  11
Vicksburg     87  71  88  72 /  16   8  27  32
Hattiesburg   86  71  88  71 /  19   8  24  15
Natchez       86  72  87  71 /  18   9  30  34
Greenville    85  71  88  73 /  17  15  29  41
Greenwood     85  70  89  72 /  17  10  23  17





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