Area Forecast Discussion
Issued by NWS Jackson, MS

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FXUS64 KJAN 281127
AFDJAN

Area Forecast Discussion
National Weather Service Jackson MS
627 AM CDT Fri Jul 28 2017

.UPDATE...
Updated for 12Z aviation discussion

&&

.AVIATION...
12Z TAF discussion:
Outside of convective precipitation, VFR conditions are expected
to prevail today through tonight. The main emphasis for aviation
weather hazards will be the increasing threat for TSRA/SHRA
developing from north to south late this afternoon and tonight
ahead of the approaching cold front. /EC/

&&

.DISCUSSION...

Today through tonight...

Not much has changed concerning the forecast thinking for today
through tonight with marginal/limited threats for severe weather
and flooding still anticipated. Considerable low level moisture
convergence exists across much of northern Arkansas into western
Tennessee where H850 dewpoints are exceeding 16 deg C in ~ 25 kt
of flow, and this is supporting current convective development
in that area. In the forecast area, showers have struggled to move
south of the Highway 82 corridor as mid level ridging continues
to have the strongest influence.

Expect better moisture/flow to shift south later this afternoon
and tonight into the ArkLaMiss region ahead of a cold front, and
this will support the potential for multicell storms with a few
strong/severe storms as hot/humid air provides plenty of
instability in spite of ordinary mid level lapse rates. The bulk
of near term model solutions support continued shower activity
this morning into North Central MS with the better chances for
intense convection holding off until late this afternoon/evening.

If storms can organize enough, a convective system pushing south
through most of the area will be possible overnight. There should
be just enough support for a few severe storms with a few
locations perhaps experiencing damaging wind gusts as been
advertised the past couple of days...and can`t see a reason to
change the message at this point. Will also keep the mention of
heavy rainfall/localized flooding potential with deep convection
expected in the very moist airmass, and some indications that
localized training may be a problem. Otherwise, we will keep the
mention of heat going in the HWO/graphics, particularly along/west
of the MS River where insolation should be greatest. /EC/

Saturday through next Thursday...

A cold front will continue its southward trek through the
forecast area during the course of the day on Saturday. With some
scattered showers and isolated thunderstorms ongoing in the
vicinity of the front as day breaks Saturday, convection is
expected to further increase in coverage across mainly central and
southern portions of the forecast area through the morning and
afternoon hours as daytime heating commences. A severe storm can`t
be ruled out, primarily across portions of South Central and
Southeast Mississippi, due to the timing of the front over that
area during peak heating with an unstable airmass in place.
Damaging wind gusts of 60 mph with be the primary concern with
such storms. Also, given precipitable H2O values hovering around
the 2 inch mark Saturday, mainly along and south of the Interstate
20 corridor, in addition to the already saturated soils over
these areas from recent heavy rains, a "limited" threat for flash
flooding will exist as a result of convection potentially
producing some heavy downpours. This threat will be further
promoted if convection trains across the same locales.

Drier air will filter into the forecast area behind the passage of
the front Saturday night into Sunday, as high pressure to the north
builds into the region.  Skies will continue to clear overnight
Saturday, with sunny skies expected areawide on Sunday.  Highs will
still remain warm on Sunday as they top out in the mid 80s to around
90, but the noticeably drier airmass will make conditions more
tolerable as dew points fall into the middle 60s.

Overall, quiet conditions will persist across the CWA Monday through
Wednesday as northwest flow aloft persists, and by mid-summer
standards, a somewhat dry airmass remains over the CWA.  Conditions
will gradually begin to moisten Thursday, with chances for
convection returning to the forecast.  A disturbance embedded in the
troughing pattern over the region could further enhance rain chances
over the CWA Thursday, but this is quite a ways out in the forecast
to have much confidence in forecasting anything above guidance. /19/

&&

.PRELIMINARY POINT TEMPS/POPS...
Jackson       93  75  90  67 /  10  57  52   5
Meridian      92  74  89  67 /  15  57  52   6
Vicksburg     93  74  90  66 /   9  53  47   6
Hattiesburg   94  74  89  68 /   6  55  62  18
Natchez       92  74  86  66 /   7  55  54  14
Greenville    92  73  88  64 /  35  51  19   4
Greenwood     90  72  89  63 /  40  56  16   4

&&

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

&&


$$



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