Area Forecast Discussion
Issued by NWS Jackson, MS
FXUS64 KJAN 281126
Area Forecast Discussion
National Weather Service Jackson MS
526 AM CST Tue Feb 28 2017
...ACTIVE WEATHER EXPECTED THROUGH MID WEEK...
Updated for 12Z aviation discussion
12Z TAF discussion:
IFR/LIFR conditions have prevailed this primarily due to low CIGs
as moisture streams into the region from the Gulf. Some patchy
fog has also developed throughout the region but significant
southerly winds have abated the development of dense fog.
Conditions will begin to improve after sunrise. Expect strong
gusty winds from the south to continue throughout the day and into
tonight. CIGs will once again lower to MVFR/IFR levels after
sunset. A line of TSRA will begin to approach the region from the
northwest late in the period,
Today through tonight....
Local radar scans depict increasing reflectivity returns as an axis
of shower and weak thunderstorm activity stretching from Louisiana
through the Mississippi Delta and into Tennessee continue to
increase due the interactions of an approaching upper jet max and
strong low level southerly flow pulling a significant amount of
moisture into the region. An isolated strong storm could be possible
from the Delta over into east central MS this morning, but the
window of opportunity will quickly close after 15Z. Elsewhere
through the region, expect a warm, muggy morning. Some patchy fog
has developed in the southern portions of our region but moderate
winds should prevent any dense fog from developing.
Expect temperatures to rise to nearly 20 degrees above average
throughout the region today as we mix out and some clearing occurs,
a fitting end to a February that will rank in at least the top 5
warmest on record at each climate site around the ArkLaMiss. Highs
today will be dependent on the amount and timing of clearing, which
will allow for more efficient warming. Strong WAA in the midlevels
will cause 850 temps to approach 15-16C, off the charts for this
time of the year according to climatological studies. Some MOS
guidance suggests highs approaching the upper 80s in south and west
counties and parishes, this is not out of the realm of possibilities.
Rain and storm chances today will be slim due to capping.
A line of strong, possibly severe, storms associated with an
approaching cold front and upper trough crossing the Plains should
begin to approach the ArkLaMiss Tuesday night from the west. Models
have come into better agreement with the timing of this feature with
the consensus placing the leading edge of the line of storms at our
doorstep before sunrise Wednesday morning. A severe storm or two may
be possible in our northwest counties and parishes before sunrise.
The main threat with any storms Wednesday morning will be damaging
straight line winds with a secondary threat of tornadoes. /jpm3/
Wednesday through Monday: Convection should be ongoing at the
beginning of the period over northwestern sections with a squall
line ahead of the surface cold front over AR. Capping inversion
above the boundary layer will keep convection focused in the warm
sector near the frontal boundary where forcing will be maximized.
Instability will also be maximized here as 7 C/km mid level lapse
rates, near 30 vertical totals and MLCAPES of 1000-1500 J/kg will be
coincident with the frontal boundary. Strong winds in the column
suggest the primary severe risk will be damaging winds, however, 30-
40 knots of effective bulk shear will promote some tornado risk in
any of the bowing segments along the line.
The line will clear the forecast area by early evening with clearing
skies shortly behind. Cold air advection overnight will drop
temperatures into the upper 30s and 40s by Thursday morning.
Radiational cooling Thursday night will drop temperatures even more
with mid to upper 30s and the possibility of some frost over
northeast sections early Friday morning.
Model discrepancies loom for the weekend into early next week. The
GFS/ECMWF amplify a mid level ridge over the area while the Canadian
brings a trough through. Have trended a little lower in the onset of
rain chances until a better consensus can occur./26/
.PRELIMINARY POINT TEMPS/POPS...
Jackson 84 66 78 42 / 13 17 66 11
Meridian 82 65 79 43 / 12 13 74 45
Vicksburg 84 68 77 42 / 16 25 61 8
Hattiesburg 83 66 81 44 / 11 12 57 30
Natchez 84 67 79 44 / 13 23 52 11
Greenville 80 66 74 40 / 37 41 74 7
Greenwood 81 67 76 40 / 36 27 78 7