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Area forecast discussion 
National Weather Service Jackson MS
309 PM CDT Wednesday Aug 20 2014

Short term...
the upper ridge and high pressure system is dominating the weather
over arklamiss today and it will continue to do so through the rest
of the week. Currently...we can count the number of showers within
the County Warning Area this afternoon on one hand. Expect these showers to
dissipate completely with the onset of Twilight this evening. Some
light and patchy fog is possible overnight and in the morning hours
of Thursday. As the upper high centers itself over arklamiss on
Thursday...rain chances for the afternoon will remain confined to the
southwest portions of the County Warning Area.

Through the rest of the work week...conditions will be pretty
consistent from day to day. Afternoon highs will be in the middle to
upper 90s with morning lows in the low to middle 70s each day. Went
with a mixture of the GFS MOS and Euro MOS for temperatures in the short
term. The GFS had highs approaching 100f pretty quickly but with
precipitable waters between 1.5 and 2 inches it can become difficult to achieve
temperatures so high. Therefore to tone the temperatures down a bit went
with a combo of the two models. With such a moist airmass over top
of US...heat indices will be in the 100s each day. This qualifies as
an elevated risk for heat within our severe weather potential statement. /10/

Long term...
Friday through Wednesday...the main story for much of
the long term will be the building heat and humidity. The weather
pattern we have seen a good bit this Summer of a trough over the
east and ridge over the west will be reversed for a few days.
Conditions will feel a bit more like a true deep south Summer as a
593dm ridge will set up right over the arklamiss region. This will
allow for temperatures to heat up for the first real time this
Summer with highs reaching into the middle and upper 90s. That...
coupled with dewpoints in the 70s...will allow heat indices to be a
concern through the weekend. It could be possible that dewpoints
will mix out just enough to keep heat index readings a little more
in check. However...the current forecast looks like with those 70s
dewpoints we could see heat indices nearing 105 degrees areawide and
some locations could see slightly higher than this. Overnight lows
should cool enough to preclude the need for a heat advisory. Mex
guidance continues to come in warmer than the other temperature
guidance and have cut highs during this hot stretch by 1-2
degrees...closer to ensemble guidance and the European model (ecmwf). In addition to
the heat...this ridge will keep convection at Bay during this time.

By the beginning of next work week...the center of the ridge will
move north of the region and heights will be slightly lower. This
may allow for some afternoon showers and storms to develop...
especially in the east on Monday and across the south and west on
Tuesday. By Wednesday the region will be sandwiched between the
departing/weakening ridge to the east and an approaching front to
the northwest. This will increase rain chances for the entire area
on Wednesday and keep temperatures cooler in the lower 90s along
with considerable cloud cover.

Further into the extended forecast...the tropics are being monitored
for possible development over the next several days. NHC has a
medium chance of development on an area of low pressure located
several hundred miles east of the southern Windward Islands. The GFS
continues to be the most aggressive in bringing this system as a
very developed tropical cyclone into the Gulf at 240 hours. The
European model (ecmwf) this morning does show this system entering the Gulf as well
before getting swept up with the approaching front. This scenario is
beyond 200 hours and is way too early to make any conjectures yet as
to what will happen...especially considering the system has not
developed yet. We will definitely continue to monitor latest model
trends and forecasts from NHC. /28/


VFR conditions will continue to prevail at all taf sites through
tonight. Isolated convection will be possible across mainly east
central and south Mississippi...khbg...kmei...& kgtr...this
afternoon. This could result in a brief period of MVFR/IFR ceilings
and/or visibilities if convection is observed within each sites'
respected Aerodrome. Convection will quickly dissipate this evening
as daytime heating is lost. Winds will gradually subside to light to
calm through the evening...and remain so overnight and into Thursday
morning. /19/


Preliminary point temps/pops...
Jackson 73 96 74 97 / 4 7 4 8
Meridian 71 96 71 97 / 4 6 4 8
Vicksburg 72 95 73 96 / 4 8 5 7
Hattiesburg 74 96 74 97 / 4 12 6 13
Natchez 73 93 74 94 / 3 17 5 11
Greenville 73 96 74 98 / 4 5 4 4
Greenwood 72 95 73 97 / 4 6 4 5


Jan watches/warnings/advisories...



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