Scientific Forecaster Discussion
Area forecast discussion...updated
National Weather Service Mobile Alabama
552 PM CST Sat Nov 22 2014
00z issuance update...
a mix of MVFR ceilings begin the period except for occasionally LIFR
near the immediate coast. IFR ceilings are expected to prevail by 03z
with then lower to LIFR conditions as a squall line moves through
early Sunday morning into early afternoon with MVFR ceilings in the
wake of the squall line by 18-20z. Showers and thunderstorms are
expected to increase in coverage overnight ahead of the approaching
squall line. Easterly winds near 10 knots switch to the southeast
near 14-15 knots and gusty by near 12z Sunday then become southwest
by 18-20z. /29
Previous discussion... /issued 416 PM CST Sat Nov 22 2014/
A risk of severe storms expected Sunday morning...
Short term [tonight through Sunday night]...still appears to be be
a threat of severe weather across the forecast area late tonight through
midday or early afternoon Sunday. The Storm Prediction Center has
backed off of the enhanced threat overall...but we still feel locally
that there could be a smaller area of enhanced threat over our
area...especially along and south of Highway 84.
Models still in good agreement in moving a warm front toward the
coast overnight and into the Florida Panhandle and coastal Alabama
by around sunrise Sunday. Will probably see some overrunning rain or
elevated showers tonight...mainly after midnight to the north of
this warm front...with showers and thunderstorms increasing and
becoming more surface based along and south of the front as it moves
ashore. Most of this stronger surface based convection will be over the
southern portion of the forecast area mainly between 3am-6am Sunday.
Damaging winds and isolated tornadoes will be possible with these
storms as the move in off the Gulf. During the morning hours on
Sunday...the warm front is expected to surge rapidly northward
through our forecast area...with the entire area under the influence of
the warm sector of the system. Still a little uncertain as to how
far inland the better instabilities make it...but we feel pretty
confident that it will be at least as far inland as the Highway 84
corridor. As the instability increases...we are still looking at the
sufficient dynamics and shear to warrant mention of severe storms in
the warm sector. Models still in good agreement with 850mb jet of 50
to 60 knots over the forecast area around midday Sunday. In the upper
levels...negatively tilted trough ejects energy northeast across the
region Sunday. This and the upper level divergence east of the trough
will help produce ample vertical lift.
By around 12z (6 am sunday) we expect a squall line that will likely
develop in association with the approaching upper dynamics to be
moving into our southeast MS counties...moving east into southwest
Alabama by around 10 am...then along and just east of the I-65 corridor
and across the western Florida Panhandle noon to 1 PM. By around 2
PM...most of the stronger active weather is expected to be east of
our forecast area.
Isolated tornadoes...some potentially long tracked given shear
profiles...possible in isolated cells in the warm sector out ahead
of the squall line as well as embedded within the squall line
itself. Damaging straight line winds also possible...especially with
the passage of the squall line. Individual storm cells will likely
be moving rather quickly...40 to 50 miles per hour toward the northeast.
Some heavy rainfall possible with the passage of the system...but
the progressive movement and current dry conditions across the area
will help to suppress any widespread flash flooding issues. 1 to 3
inches of rainfall possible...up to 4 inches along and south of the
I-65 corridor. Some locally higher amounts possible. Main threat
from heavy rains will be minor...temporary urban flooding.
[monday and Monday night]...cold front will move through our region
from the west early Monday morning with reinforcing cool air behind
it. The front will start moving in early Monday morning...and with
the 850 mb trough clearing US by Monday afternoon we expect clearing
skies with high temperatures on Monday in the low 70s in the
east...and middle 60s behind the front generally in the western half.
Lows upper 30s inland and lower 40s coastal. Dry conditions through
the period. 77/blowing dust
Long term [tuesday through saturday]...expect a slight chance of
showers along and east of a line from near Crestview to Pensacola
Tuesday night as a fast moving upper disturbance moves along a
northeastward track now further south and east of our area. Cool
conditions with minimal rain chances continuing through the long
term...with highs expected to range from the middle 50s to lower
60s...and lows expected to range from the low 30s to the low 40s.
Marine...a strong area of surface high pressure extending from the
western Atlantic...westward to east of the Mississippi River valley
this evening will result in a moderate to strong east southeast flow
tonight. The high moves eastward on Sunday as a strengthening area of
surface low pressure pivots northeast across the middle south on Sunday.
As this occurs...winds turn more onshore from the south to southwest
and remain strong. Wind gusts could approach gale force through most
of the day on Sunday over the Gulf coastal waters of Alabama and
northwest Florida. Seas will trend much higher. Small craft
advisories are in effect tonight through early Monday...with a gale
watch in effect for Gulf coastal waters on Sunday. 12/ds
23/00z taf issuance...clouds increased this afternoon and have
steadily lowered...to MVFR. Becoming IFR to LIFR overnight and
continuing through noon Sunday. Scattered showers developing and
becoming more numerous late...then thunderstorms increasing after
about 23/09z. Between 23/12z-23/18z a squall line will likely be
moving east across the forecast area with LIFR conditions prevailing.
Preliminary point temps/pops...
Mobile 61 76 58 67 40 / 90 90 05 10 05
Pensacola 62 73 62 71 43 / 90 90 20 10 05
Destin 64 73 64 72 52 / 90 90 20 20 05
Evergreen 58 73 58 70 38 / 90 90 05 10 05
Waynesboro 58 77 52 65 38 / 90 90 05 10 05
Camden 56 74 54 68 37 / 90 90 05 10 10
Crestview 62 73 61 71 41 / 90 90 20 10 05
Alabama...high rip current risk until 6 am Monday for the following zones:
lower Baldwin...lower Mobile...
Florida...high rip current risk until 6 am Monday for the following zones:
coastal Escambia...coastal Okaloosa...coastal Santa Rosa...
GM...Small Craft Advisory until noon Monday for the following zones:
Choctawhatchee Bay...Mississippi Sound...northern Mobile
Bay...Pensacola Bay system...Perdido Bay...southern Mobile
Gale watch from 6 am Sunday to 6 PM Sunday for the following
zones: coastal waters from Destin to Pensacola Florida out 20
nm...coastal waters from Pensacola Florida to Pascagoula MS out
20 nm...waters from Destin to Pensacola Florida from 20 to 60
nm...waters from Pensacola Florida to Pascagoula MS from 20 to
Small Craft Advisory until 6 am Sunday for the following zones:
coastal waters from Destin to Pensacola Florida out 20 nm...
coastal waters from Pensacola Florida to Pascagoula MS out 20
nm...waters from Destin to Pensacola Florida from 20 to 60 nm...
waters from Pensacola Florida to Pascagoula MS from 20 to 60
Small Craft Advisory from 6 PM Sunday to noon Monday for the
following zones: coastal waters from Destin to Pensacola Florida
out 20 nm...coastal waters from Pensacola Florida to Pascagoula
MS out 20 nm...waters from Destin to Pensacola Florida from 20
to 60 nm...waters from Pensacola Florida to Pascagoula MS from
20 to 60 nm...