Area Forecast Discussion
Issued by NWS Jackson, MS

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FXUS64 KJAN 231619 AAA
AFDJAN

Area Forecast Discussion...UPDATED
National Weather Service Jackson MS
1119 AM CDT SAT JUL 23 2016

.UPDATE...Temperatures have been a little slower to warm today but
are still warming into the upper 80s/lower 90s. With dewpoints
running in the 70s, heat indices are approaching the upper 90s/near
100 degrees. Some showers and storms have been moving very slowly
across portions of Grenada County this morning in association with a
shortwave dropping into the region. Expect that as temperatures
continue to warm, we should see another day of scattered afternoon
showers and storms. Going forecast is in decent shape. The only
changes were to account for current trends and to drop PoPs for
earlier in the day. /28/

&&

.AVIATION...VFR conditions will prevail through much of the TAF
period. However, scattered to numerous SHRA/TSRA will develop
through the day, primarily during the afternoon and early evening
hours. This activity could bring brief ceiling/visibility reductions
and strong storms will be capable of strong wind gusts.
Redevelopment of areas fog and low stratus resulting in IFR/LIFR
flight rules will be possible late tonight into early Sunday
morning, especially in areas that receive rain today. /DL/


&&

.PREV DISCUSSION... /issued 433 AM CDT SAT JUL 23 2016/

SHORT TERM...Today through Sunday night...Overall models have come
in a little cooler and wetter for this weekend. The large mid level
ridge that has brought above normal temperatures this week will
continue to weaken through Sunday. Early morning water vapor
imagery/RAP analysis had a 596dam high centered over the southern
plains ridging east with the 592dam height nearly along the
Mississippi river. A shortwave was noted dropping south over west
Tennessee that will drop over our CWA later this afternoon and
evening. Models agree that this feature will help lead to a greater
coverage of storms over our CWA. Until then, we are expected to heat
up and maintain an anomalously  moist airmass over our CWA. Some
patchy dense fog has developed over southeast Mississippi this
morning along with some stratus north to the Interstate 20 corridor.
This may delay warming early this morning but maximum temperatures
are expected to reach 94-98F at most locations. These temperatures
will combine with high humidity to result in peak heat index values
above 105 over much of the area again today. The greatest heat index
values are expected in our western zones. The inherited Heat
Advisory will remain in effect until 7PM this evening. There will be
a distinct diurnal trend to the convection this evening but the
shortwave is expected to still be over our western zones Sunday
morning and will therefore maintain a chance of rain through the
night. The NAM and Canadian close off the shortwave over our western
zones Sunday morning. Models agree that this feature will west
southwest and be over east Texas by sunrise Monday. It will help
increase PWATS to near two and a quarter inches over most of our CWA
Sunday before slightly drier air moves back in from the east by
Monday morning. The rain chances and associated cloud cover will
limit insolation Sunday with maximum temperatures only reaching the
lower 90s which is normal for this time of the year. It will still
be quite humid resulting in peak heat index values above 100 but
below 105 so wl not extend the Heat Advisory this forecast package.
Our western zones will see the greatest heat index values so wl
include a limited area there in our HWO. /22/

LONG TERM...Monday through next weekend...

Upper ridge that has been entrenched over the region over the past
week will have gradually begun to weaken late this weekend into
Monday. The upper ridge axis will flatten and become more situated
into the central Plains to eastern Rockies. That will help two
decent shortwaves to move through the region. Monday the PW`s will
still be pretty high near two inches in the west with some sub 2
inch PW`s finally nosing in the east in the wake of the southwest-
westerly moving shortwave moving into the southern Plains. This
perturbation will continue to move west along the periphery of the
ridge while upper ridging over the western Atlantic will swing in an
easterly wave/TUTT across the Florida Panhandle on Monday morning
into afternoon near the Gulf Coast. This will help keep moisture the
best along the southern half and kept the best POPS in that area
with less in the north. Heat issues will be less of a concern on
Monday but there will still be lingering high dewpoints in the Delta
and near the I-55 corridor. Highs will be slightly lower in the low-
mid 90s but enough areas topping out in the 103-105 range to include
a limited for heat in the Delta and central Mississippi and north of
I-20 near the I-55 corridor.

A cold front will stall just north of the area early next week and
this in addition to the easterly wave moving over southern Louisiana
and southwest Mississippi will help spark more convection on Tuesday
and into Wednesday, mainly over the southern and western portions of
the region. Heat issues will again be further confined into the
Delta on Tuesday before clouds and convection on Wednesday will help
keep highs into the lower 90s and preclude any heat issues. As the
easterly wave moves northwest out of the area under the ridge
further building west towards the Rockies, a deep trough and cold
front will take shape over the north-central Plains. Our area will
be in weak ridging but gradually this weakness will increase over
our area, helping to bring the cold front down near our area and
increase rain and storm chances from the north Thursday into the
weekend. This will keep some temperatures down in the north but
overall near normal temperatures and increased chances of storms
later in the work week. /DC/

&&

.PRELIMINARY POINT TEMPS/POPS...
Jackson       95  75  93  74 /  40  44  41  28
Meridian      95  73  93  73 /  28  37  29  20
Vicksburg     96  75  93  74 /  45  46  54  31
Hattiesburg   93  74  92  74 /  29  29  43  32
Natchez       93  75  91  74 /  46  34  57  34
Greenville    96  76  93  75 /  48  48  57  25
Greenwood     94  75  92  74 /  51  48  48  21

&&

.JAN Watches/Warnings/Advisories...
MS...Heat Advisory until 7 PM CDT this evening for MSZ018-019-025>057-
     059>065.

LA...Heat Advisory until 7 PM CDT this evening for LAZ007>009-015-016-
     023>026.

AR...Heat Advisory until 7 PM CDT this evening for ARZ074-075.

&&

$$


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