Area forecast discussion
National Weather Service Jackson MS
1114 am CDT Wednesday may 22 2013
Update...
The current weather analysis for the arklamiss is complex but
typical for may. A convective system has move southeast of the
forecast area and the atmosphere will need to undergo substantial
recovery and destabilization to produce additional thunderstorm
activity late this afternoon. The most recent guidance including hrrr/NAM
are not very robust with convective development...but there are signs
of a developing instability/moisture convergence axis upstream
along/ahead of the approaching weak cold front and this should be
sufficient for scattered storm development. In the forecast have
reduced thunderstorm chances based on the trends and will consider removing
the strong thunderstorm references depending on radar/observation trends in the
next couple of hours. The updated aviation discussion is below. /Ec/
&&
Previous discussion... /issued 440 am CDT Wednesday may 22 2013/
Short term...drier and cooler air will filter into our area tonight
as the shortwaves shifts east. The Ops GFS was among the coolest
ensemble member and quite cooler than the NAM MOS. Have gone closer
to GFS MOS ensemble means for lows tonight. Will maintain northwest
flow aloft Thursday as upper level ridging amplifies over the central
Continental U.S.. models differ on precipitation develop over our area with the sref and
NAM bringing precipitation while GFS and European model (ecmwf) are mostly dry. Have included
slight chance probability of precipitation across southern half of the area by afternoon as
enough available moisture and a subtle shortwave combine with daytime
heating to produce a few showers and storms. Surface high pressure
over the Great Lakes region will spread south into our area and bring
cooler than normal morning lows for Friday morning. /22/
Long term...Friday through Wednesday...the air mass will continue
to dry Friday as high pressure becomes more established. Upper
ridging will remain in place Saturday with weak troughing forecast
to flatten ridging for the area Sunday. Low level southerly flow will be
in place again by Sunday but the air mass should remain relatively
dry. The Euro brings slightly stronger upper troughing to the region
Sunday with increasing moisture from the northwest. Its also more
indicative of at least isolated showers for Monday...primarily in
the north...developing surface troughing into northern Arkansas and Tennessee while
the GFS keeps these features farther north. The drier GFS solution will
be followed for now in the longer range but rain chances will be
added if it begins to trend toward the slightly more active looking
Euro.
Cold air advection will be ongoing early Friday in the wake of the
secondary boundary. Will follow unseasonably cool mex MOS highs for
Friday afternoon...cutting MOS highs slightly in the far south to
the middle 80s considering the cooler low level temperatures advertised by the
models/forecast soundings. Significantly cooler lows are forecast by
mex MOS for Saturday morning...including readings in the middle 40s
over much of the area north of I-20 and east of I-55. Have adjusted these
slightly warmer more in line with the GFS ensemble and Euro but kept
temperatures in the upper 40s/near 50 for many of those areas for now. A
gradual warming trend begins Saturday afternoon with a return to
warmer temperatures and more humid conditions for Sunday into early next
week in low level southerly flow. /03/
&&
Aviation...still expect temporary IFR conditions through midday
across portions of the Aerodrome...at glh/gwo due to low ceilings
and at hbg/pib due to reduced visible and low ceilings associated with
showers and embedded thunderstorms. Otherwise expect VFR conditions to
generally predominate today with periodic cloud ceilings from 4 to
10 kft. There will be the chance for some thunderstorm redevelopment
during the afternoon...roughly along and southeast of the Natchez
trace corridor. Any storms here are not expected to be severe but
could provide very localized instances of turbulence and IFR
conditions. A front will be pushing south into the region later
today through tonight causing generally light and variable winds to
become more solidly from the west and northwest. Tonight there is a
decent probability of low clouds and fog giving IFR restrictions at
hks/Jan/nmm/mei/pib/hbg. /Bb/
&&
Preliminary point temps/pops...
Jackson 84 64 89 63 / 41 4 15 8
Meridian 85 64 90 60 / 47 13 15 5
Vicksburg 84 66 89 61 / 37 4 15 11
Hattiesburg 84 66 91 64 / 48 17 19 10
Natchez 85 66 90 65 / 40 4 19 15
Greenville 84 65 88 62 / 22 4 10 10
Greenwood 83 62 88 60 / 34 4 10 7
&&
Jan watches/warnings/advisories...
MS...none.
La...none.
Arkansas...none.
&&
$$
Ec/03/22/bb
