Area Forecast Discussion
Issued by NWS Jackson, MS

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FXUS64 KJAN 201040

Area Forecast Discussion
National Weather Service Jackson MS
540 AM CDT Fri Apr 20 2018

Updated for 12Z aviation discussion


12Z TAF discussion:
VFR conditions will prevail through the period. Northerly winds
will be around 10-15kts today with some higher gusts. These should
diminish to around 5kts tonight. No aviation weather concerns
expected so today may be a good day to fly! /28/



Today and tonight:

High pressure at the surface and shortwave ridging aloft will
prevail today. This will allow for sunny skies and temperatures to
reach a few degrees warmer than Thursday. North winds may be gusty
at times, especially in the Delta, but should diminish through the
afternoon. Overnight lows will once again be cool with readings in
the 40s and a few lower 50s. /28/

Tomorrow (Saturday) through next Thursday:

Expect another active period of weather as we move through the
weekend as potential for heavy rainfall and some severe weather look
possible. On Saturday, as a strong mid-level ridge continues to
build to the east, expect increasing warmth and slow advection of
moisture into our southwest throughout the day. This will help us
warm closer to normals, even with increasing widespread
cloudiness. With PWs creeping up in the inch and a quarter or so
over northeast Louisiana and far southwest Mississippi, can`t rule
out some showers moving in there by mid-late Saturday afternoon.
Elsewhere, we should remain dry for most of Saturday.

As the closed upper low dives down, increasing synoptic lift and
favorable jet dynamics (front left entrance region) will continue to
increase lift on Saturday night-Sunday. With moisture creeping up
towards an inch and a half or so and low pressure gradually
developing over southern Arkansas and northern Louisiana, expect
efficient moisture transport and widespread convection to develop
right near the warm front and baroclinic zone. With increasing
instability and somewhat lighter Corfidi vectors, we could see some
areas of training and heavy convective rates. In addition, PWs
around an inch and a half around anomalous around 90th percentile.
Due to this and after coordination with WPC, introduced a "Limited"
in the HWO/graphics for heavy rain and flooding. This threat will
gradually progress across the region through Sunday afternoon and
mainly be along and east of the I-55 corridor. In addition, due to
deepening low pressure, low-mid level effective shear will be
efficient (~30-50kts) and some decent lapse rates and some
destabilization around. This environment looks to be a high shear-
lower CAPE (until mid level dry by the afternoon in the wake). Right
now it looks as though there may be some indication of some
potential for some damaging winds, some hail up to quarter size (if
any stronger storms can persist into the afternoon) and a tornado
can`t be ruled out. Introduced this "Marginal" in the HWO/graphics.
Expect this more organized activity to move out by Sunday
evening. One question mark could be any coastal convection but
GFS/Euro continue to indicate enough convective potential. Stay
tuned as we fine tune these details.

As the upper low dives down through the area Monday and east of our
area Tuesday, expect northerly cold air advection, lingering clouds
and light rain chances through early week (Monday-Tuesday). This
could hamper temperatures and bring them down some below normals
while keeping temperatures up overnight. As weak shortwave ridging
moves through Wednesday morning, this will only be a short reprieve
from the rain as another cold front and rain chances increase
around Wednesday-Thursday. Looking at the Euro ensemble, the
operational Euro is slightly slower while the ensembles are
slightly more progressive, like the GFS/Canadian. Due to this,
bumped up the PoPS on Wednesday while slightly lowering them on
Thursday morning. Wanted to maintain some PoPs until then to at
least account for any uncertainties. However, only maintained
around slight chance PoPs both days due to this. This will be
ironed out over the next few days. /DC/


Jackson       69  49  74  60 /   0   0   8  72
Meridian      70  47  75  59 /   0   0   3  53
Vicksburg     68  49  74  60 /   0   0  10  91
Hattiesburg   70  50  75  62 /   0   0   7  51
Natchez       68  49  74  62 /   0   0  15  86
Greenville    67  48  72  59 /   0   0   9  96
Greenwood     68  48  74  58 /   0   0   7  82





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