Area forecast discussion
National Weather Service Jackson MS
406 am CDT Thursday Jun 20 2013
Short term...today through Friday night...a weak surface boundary
will continue to meander about just south of the Interstate 20
corridor today while we remain under the influence of a
weakening...yet slowly east northeast departing...upper trough.
This boundary will continue to be the focusing mechanism for mainly
diurnally driven convection this afternoon...primarily across my
southern zones. Again...showers and storms that develop during the
afternoon should begin to dissipate shortly after sunset...with
quiet conditions expected during the overnight hours.
The upper trough continues to depart Friday as upper ridging tries
build in from the west. Once again this scenario keeps northwest
flow...although weak...persistent across the forecast area. The
best chances for showers and storms...at least that of any
confidence...currently look to be across the Highway 84 corridor
during the afternoon hours Friday as the surface boundary remains
present near the area...but is essentially in the process of washing
out.
However...given this continued northwesterly flow aloft over the
region during this time...it's not out of the question that an upper
level disturbance embedded in this northwest flow couldn't spark
some showers and storms over at least the northwest portion of the
forecast area. Models are a bit at odds in this happening...but
given the pattern and having seen some complexes diving southeast
over the plains states and middle-Mississippi River valley the past
couple of night...i'm not ruling this scenario happening here. As a
result...this potential will indeed need to be monitored throughout
the period. For the time being though...i'll stick with the mex
guidance in keeping probability of precipitation mainly south of the Interstate 20 corridor
both today and Friday.
In terms of temperatures...with a slightly drier airmass advecting
in from the east...lows should be a degree or two cooler compared to
recent nights as they range from the middle 60s to around 70 both
tonight and Friday night. Highs also look reasonable both today and
Friday with temperatures expected to top out in the low to middle
90s. Obviously any convection and associated cloud cover during the
afternoon could keep highs down a bit where it occurs. /19/
Long term...Saturday through Wednesday...upper flow will be very
weak across the region in the extended period...the area sitting
between weak anticyclonic flow to the west and the remnants of weak
troughing to the east through most of the extended period. Weak low
level troughing/convergence will maintain the best chance of
afternoon convection over southern zones for Saturday...lifting inland to
maintain afternoon and evening convection for Sunday. Weak
pertubations in the middle/upper flow are indicated through the period
but they will be difficult to pinpoint. Effects of sea breeze
interactions will help keep the highest chances of afternoon and
evening convection across the south. However the air mass will
remain moist at low levels and afternoon heating will result in
healthy instability to continue the possibility of isolated diurnal
convection across all of the area. Weak flow/shear and lapse rates
look insuficient to support much in the way of stronger convection.
&&
Aviation...both patchy fog and low stratus are plaguing some sites
this morning and reducing visibilities and/or ceilings to IFR
status. This will be short-lived as both diminish after sunrise.
VFR conditions will prevail from late morning and continue through
the afternoon and evening hours. Winds today east northeasterly
between 5-8 knots and gradually subside to light to calm this
evening. Isolated convection will be possible south of Interstate 20
this afternoon...khbg...which could obviously degrade flight
statuses when observed within the Aerodrome. /19/
&&
Preliminary point temps/pops...
Jackson 92 68 92 68 / 5 5 6 8
Meridian 92 66 92 67 / 4 5 6 9
Vicksburg 92 66 93 66 / 6 4 7 6
Hattiesburg 92 69 93 69 / 25 8 15 13
Natchez 90 68 91 68 / 21 7 11 8
Greenville 93 70 94 70 / 2 4 3 5
Greenwood 93 67 93 68 / 1 4 2 6
&&
Jan watches/warnings/advisories...
MS...none.
La...none.
Arkansas...none.
&&
$$
03/19
