Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

Area forecast discussion...updated 
National Weather Service Jackson MS
931 am CDT Thursday Jul 31 2014

Update...dropped high temperatures by 3-5f degrees due to ongoing
and expected cloud and rain shower coverage. Hourly temperatures
were adjusted accordingly.

Discussion...a shortwave trough over Arkansas and north MS embedded in the 500 mb northwest
flow is resulting in overcast conditions and light rain showers. It
appears there are several separate shortwave troughs with one pushing
east of region through afternoon but another remaining over the arklatex
through tonight. Expecting continued scattered light to at times
moderate shower activity through afternoon with some lingering overnight.
Near moist adiabatic lapse rates and positive showalters still look
to preclude any thunder possibilities today.

Text updates are out and graphics will be out shortly. An updated
aviation discussion can be found directly below. /Allen/


Aviation...VFR conditions are prevailing this morning. An upper
level disturbance is bringing mostly light rain to the region and
will continue through the day. A brief bout of mainly MVFR
visibilities could be possible with some of the more moderate
rainfall. Winds for today will be from the northeast between 5-8
knots...and gradually subside to light to calm later this evening.


Previous discussion... /issued 345 am CDT Thursday Jul 31 2014/

Short through Friday night...broad longwave troughing
will remain in place over the eastern half United States through the
forecast period...resulting in west northwest flow aloft over the
forecast area. During this time...a series of upper level
disturbances embedded in this trough will propagate east into and
through the region bringing decent chances for rain each time they
move through. Although there will be some gradual moistening at the
surface and lower levels of the overall lack of
forcing and instability continues to keep any chances for storms
during the short term on the low end.

As far as temperatures are concerned...both clouds and showers
should keep highs in check both today and Friday. Highs today will
range from the upper 70s in the Delta to the upper 80s across
southeast Mississippi. Then for Friday...highs will range from the
low to upper 80s. Then for lows...clouds will again aid in keeping
lows a little warmer than previous nights as they range in the middle
and upper 60s both nights. /19/

Long term...Saturday through Thursday...Saturday will feature
slightly cooler than normal temperatures with above normal chances
for rain as a large amplitude upper level trough remains over the
region. Precipitable waters will start out around two inches Saturday areawide but
drier air from the north will knock precipitable waters down to around one inch
along the Highway 82 corridor by Sunday evening as a shortwave
swings through shifting much of the upper trough to the east. Gfsmos
probability of precipitation were good Saturday into Sunday but Saturday maximum temperatures
were among the highest ensemble members and a couple degrees too
warm for Saturday afternoon areawide. Leaned toward the European model (ecmwf) and
NAM which were close. A much weaker upper level trough will be over
our County Warning Area come Monday. A 1020mb high is expected to be centered over
the middle Mississippi River valley through Monday maintaining a dry
north to northeast low level flow that will limit moisture across
the northern half of the County Warning Area while precipitable waters around an inch and a quarter
hold on over our southern zones. The greatest chance for mainly
diurnally driven rain Monday through Wednesday will be south of
Interstate 20. Afternoon maximum temperatures will be near normal in the
lower 90s Monday through Wednesday. Morning lows will start off
below normal Monday and Tuesday mornings in the middle to upper 60s and
be near normal in the lower 70s at most locations Wednesday morning.
The flow aloft will start out nearly zonal Wednesday night into
Thursday morning but another shortwave will drop out of the northern
plains to the Great Lakes region by Friday morning. This will help
drive a cold front into northwest Mississippi by Friday morning.
Greatest probability of precipitation Thursday will be carried in the south during the day
due to sea breeze activity but shift to our northern zones overnight
as the front approaches. /22/


Preliminary point temps/pops...
Jackson 80 65 85 69 / 39 21 39 28
Meridian 81 64 86 67 / 25 19 27 17
Vicksburg 78 66 84 67 / 53 34 53 35
Hattiesburg 83 66 89 70 / 26 10 36 21
Natchez 80 64 85 68 / 42 28 52 35
Greenville 77 66 83 69 / 70 34 37 22
Greenwood 79 65 83 67 / 58 25 26 19


Jan watches/warnings/advisories...



National Weather Service Glossary of Abbreviations