Area Forecast Discussion
Issued by NWS Jackson, MS

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FXUS64 KJAN 260221 AAA

Area Forecast Discussion...UPDATED
National Weather Service Jackson MS
921 PM CDT SAT JUN 25 2016

.UPDATE...Though the upper ridge axis is almost directly over the
area, isolated showers are hanging on in a few spots this evening.
This activity has continued to be brief and disorganized given the
lack of any notable forcing or shear, but it will likely persist
over the next few hours given sufficient deep layer moisture and
continued steep low level lapse rates. While a stray shower still
couldn`t be ruled out overnight, this is less likely, so we`ll keep
the official forecast dry. But, for the evening hours, isolated
showers were added to the forecast. Otherwise, hourly temps/
dewpoints were updated to account for current trends and min temps
were tweaked up a degree or two in a few spots. /DL/


.AVIATION...Expect primarily VFR conditions over the next 24 hours
although a patch or two of MVFR vis or ceiling restriction cannot be
entirely ruled out around daybreak through 9 AM tomorrow. Winds will
be quite light and variable, even during the daytime. Expect a few
thunderstorms to pop up tomorrow afternoon but chances of impacting
a TAF site are too low to include any mention in the official
aviation forecast. /BB/


SHORT TERM...tonight through Monday night...Mid afternoon water
vapor imagery/rap analysis showed the circulation around a 594dam
high centered over the western half of our CWA. Mid afternoon
surface analysis had a 1019mb ridge axis near the Gulf coast.
Together these highs were contributing to warmer than normal
temperatures and helping maintain a moist air mass over our region.
Afternoon heat index values were being observed in the lower 100s
with dew point temperatures mixing out into the upper 60s and
temperatures climbing into the mid 90s. Little change is expected
Sunday before the mid level high breaks down Monday. Afternoon
temperatures Sunday will top out a degree or two warmer than today
which will place peal heat index values close to 105 at more
locations. Have opted to continue the mention of this as a limited
threat in our HWO for Sunday but a Heat Advisory for portions of the
CWA may be needed Sunday if it becomes more apparent that dew points
will remain in the lower 70s. Local radars only showed a few
isolated showers over east central Mississippi this afternoon as the
subsidence inversion continues to prevail. Although the mid level
high will change little Sunday, a little higher temperatures and a
little weaker cap as progged by model soundings may allow for a
little greater coverage of convection and a few rumbles of thunder.
Monday will feature a change in the weather pattern as the mid level
high weakens and mid level troughing develops over the eastern CONUS.
This will translate into greater rain chances for our CWA during the
afternoon and early evening hours. Afternoon highs will be back into
the mid 90s over areas that don`t experience an early storm and dew
points may hold higher resulting in peak heat index values near 105
again. /22/

LONG TERM...Tuesday through Saturday...Tuesday the large mid level
high will be centered over the four corners region with a mid level
trough overt the eastern CONUS. This will help support a cold front
dropping into our CWA and a greater coverage of storms. A little
better shear and lapse rates may help lead to a strong storm or two
Tuesday afternoon and evening. The cold front itself will be slow to
move through the CWA and take until Wednesday afternoon to stall near
the Gulf coast. In it`s wake slightly cooler temperatures and a drier
air mass can be expected. /22/

Upper troughing will develop over the eastern CONUS by the middle of
the week. This will result in a frontal boundary coming down into the
region at this time. The frontal boundary will waver back and forth
across the region as upper level disturbances cross the region in
northwest flow. Afternoon temperatures will be cooler mainly in the
lower 90s. Afternoon peak heat indices will fall back to more
typical values with better chances of rain around. With this pattern
there could be some strong storm complexes crossing the CWA in
northwest flow. As we push later into the work week another northern
stream short wave will help to maintain the trough over the eastern
CONUS. /17/22/


.JAN Watches/Warnings/Advisories...


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