Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Jackson MS
508 am CST Friday Jan 30 2015
Today through Saturday night...
Cold advection will be ongoing across the forecast area today as
surface high pressure centered north of the region builds into the
forecast area during the course of the day. Stratus associated with
the middle/upper level trough swinging through the Tennessee and Ohio
River valleys will continue to skirt northeast Mississippi this
morning. As the trough continues its eastward push...stratus will
clear this area later this morning. Otherwise...look for mostly sunny
skies this afternoon with only some high clouds racing southeast
across the County Warning Area. Highs this afternoon will top out in the 50s.
Moisture aloft will be on the subtle increase tonight as the before
mentioned surface high now resides northeast of the region. A
gradual increase in clouds is expected early Saturday morning. Look
for lows tonight to range from the upper 20s in the northeast to the
middle 30s across my southwest.
Weak middle/upper ridging will build across the region Saturday and
Saturday night. Clouds will also increase during the period with
slightly warmer conditions expected. Look for partly cloudy skies
Saturday afternoon with highs ranging from the middle 50s to lower 60s.
West southwest flow aloft will increase ahead of a northern stream
shortwave beginning to swing east across the nation's mid-section.
This...in addition to low level moisture increasing across the
forecast area...will in turn result in increasing rain chances across
the forecast area from west to east late Saturday night into early
Sunday morning. Under cloudy skies...lows Saturday night will range
from the lower 40s to lower 50s. /19/
Sunday through next Friday...
It looks like thunderstorm potential could be on the increase
Sunday ahead of a strengthening cold front. After trending higher
with surface pressures over the lower MS valley region and more
suppressed with the warm sector...all guidance is now in consensus
for greater northern stream amplification aided by interaction
with the southwest Continental U.S. Trough...and this should result in surface low
development over the middle MS/Ohio valleys. This normally could spell
trouble in terms of severe weather potential given favorable forecast
hodographs...but underwhelming moisture return is expected to result
in poor low-middle level lapse rates that should make it tough to get
much deep convection.
So that there are no surprises...it should be noted that with
improved sampling of the northern stream shortwave trough...guidance may
continue to trend more amplified and pronounced with moisture return.
As it stands the GFS/European model (ecmwf) show roughly 100-300 j/kg most unstable
cape and weakly negative surface Li with surface dewpoints approaching 60 degree
f along the Highway 84 corridor. Moreover...cips guidance analogs for
this event indicate at least a very low potential for severe
weather...particularly from NE la into west central MS where models
have been signaling for the greatest frontal forcing matched up with
better instability Sunday afternoon. For now...severe probs are too low to
warrant a mention in severe weather potential statement/ graphics at this point and have just added
thunder to the official forecast...but will need to monitor trends.
Greater amplification of the trough could also draw colder air
southward Sunday night into Monday. Would not be surprised to see a
few locations along the Highway 82 corridor experience marginal hard
freeze criteria in the Monday-Tuesday time frame..but for the most part
just expect a typical middle-winter cold snap with highs struggling to
reach the upper 30s to middle 40s Monday afternoon while lows dip well
into the 20s Monday night.
Looking ahead to middle/late next week...guidance is fairly consistent
in showing that the cutoff low over the southwest Continental U.S. Will kick out
and develop a low pressure system over the northern Gulf of Mexico
while another surge of very chilly air surges south through the
central/eastern Continental U.S.. as has been consistently indicated...models do
not link the system/cold air up in time to support wintry precipitation in
the arklamiss...so expect this will be an all rain event if the
trends continue. There is quite a bit of inconsistency and model
spread in just how much cold air moves behind the system late in
the week...but the cold has the potential to be highly anomalous.
Aviation...with high clouds streaming southeast through the region
and stratus affecting northeast Mississippi this morning...VFR
conditions will continue to prevail across the forecast area.
Stratus is expected to clear east and out of northeast Mississippi
later this morning...but cirrus will continue to race southeast
overhead through much of the day. Winds today will be northerly
around 10 knots...with a few higher gusts possible through early
afternoon. Winds will subside later this afternoon...and become
more northeasterly around 5 knots overnight into early Saturday
Preliminary point temps/pops...
Jackson 55 31 59 45 / 0 0 7 39
Meridian 55 27 56 41 / 0 0 5 25
Vicksburg 55 33 59 48 / 0 0 7 51
Hattiesburg 58 31 60 46 / 0 0 6 24
Natchez 55 34 59 51 / 0 0 8 50
Greenville 50 30 55 45 / 0 0 7 45
Greenwood 51 28 56 45 / 0 0 6 44