Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Jackson MS
420 am CST Wednesday Nov 25 2015
Today through Thursday night...
A deep longwave trough over the western Continental U.S. Will induce an
anomalous downstream ridge over the central Gulf Coast region as we
move into latter portions of the week. Strong middle level subsidence
will greatly limit rain chances...but low level moisture transport
could be sufficient to produce isolated shower activity over NE la/SW
MS this afternoon per recent hrrr and other high res near term guidance.
This pattern will bring much milder low temperatures to the
arklamiss with readings expected to be ~ 15 degree f above climate
normals. High temperatures will be warmer than recently
observed...but the warmth should be tempered some by increasing
stratocumulus coverage and east-southeast flow emanating from a slightly cooler
airmass wedging around the southern Appalachians. Still expect highs
to be 5 to 10 degree above climatology on average...but a few cooler
pockets will be possible where cloud cover is more persistent...
especially over east central MS. /Ec/
Long term (friday through next tuesday)...the primary concern in the
extended is precipitation timing for late this week into next week.
At the beginning of the period, an upper trough extending from
Hudson Bay into the northern plains will be in the process of
cutting off an upper low over California/Nevada. A slow moving cold
front will be positioned from the Great Lakes through the middle
Mississippi Valley to the Red River valley, with considerable rain
ongoing in those areas.
Heading into the weekend, considerable timing/pattern incongruities
remain among op/ensemble model guidance, thus did not stray far from
ensemble mean and model blend probability of precipitation. At this time it appears
elongated middle level ridging and (at least in the eastern half of the
area) wedging surface high pressure will help deflect precipitation largely
to the northwest through Friday - meaning dry conditions for Post-
Thanksgiving bargain hunters. Subtle impulses embedded within an
upper level southwesterly flow regime will ultimately act to lower
heights into the weekend. As a result, rain chances will begin to
climb, especially in the northwest by Saturday with more widespread
coverage possible Sunday as a stronger disturbance is expected to
Through the weekend into early next week, the cutoff upper low will
migrate into the upper plains. As the upper jet remains north of the
region almost parallel to the surface front, the front will only
meander into the area through early next week, gradually weakening
with the loss of upper support. However, above average precipitable water in the 1
to 1.5 inch range will still exist across the area, keeping the
possibility for scattered showers around into early next week.
Throughout the entire period, only isolated to lower end chance probability of precipitation
will be included across the Pine belt as the front looks to remain
farthest away from this area. Guidance continues to show little to
no instability with this system, thus we will continue to keep
thunder out of the forecast. /Dl/
Aviation...increasing moisture transport is bringing an end to a
long streak of mostly clear skies with 4000-5000 feet ceilings already
developing over the hbg-mei corridor early this morning...but still
expect mainly VFR category ceilings as we go through today into this
evening. This should change early Thursday morning when the potential
for 1000-1500 feet ceilings increases during the pre-dawn hours.
Preliminary point temps/pops...
Jackson 67 54 70 57 / 7 2 5 4
Meridian 66 48 70 52 / 1 1 3 4
Vicksburg 69 55 74 59 / 8 4 6 7
Hattiesburg 71 53 72 55 / 3 4 7 4
Natchez 69 57 73 60 / 12 4 6 7
Greenville 66 54 70 59 / 5 3 9 9
Greenwood 65 52 70 57 / 6 2 10 4