Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Mobile Alabama
437 am CST sun Nov 23 2014
..squall line approaches and moves east across the area today and
brings potential of damaging winds and isolated tornadoes...
Short term [today and tonight]...vigorous middle level storm system was
moving across eastern Texas this morning with an area of cold cloud
tops indicated on infrared satellite imagery from coast southwest Louisiana
to off the Louisiana coast. Colder clouds/concentrated lightning
data is positioned in the more established...high level diffluent
flow as the middle level system will soon begin lifting northeast. A
strongly defined negative tilt appearance and diffluent flow to the
middle/upper level heights will move across the central Gulf Coast by
the noon hour. This will cause enhanced ascent in a developing warm
and moist sector as a warm front surges northward across
Alabama/Mississippi. Low level wind profiles veer with 850 mb
southwesterly low level jet streak increasing to 50 to 60 knots
during the late morning to middle afternoon. Latest short range
mesoscale models indicate hodographs becoming strongly curved with
0-1 km storm relative helicity values ranging from 150 to 300 m2/s2.
This supports rotating storm updrafts and isolated tornadoes in
discrete cells that form out ahead of main squall line that is
prognosticated to make eastward progress over the central Gulf Coast. Latest
high resolution weather models indicate timing of this line across
southeast MS between 9 am and noon...moving into southwest Alabama around
the noon hour and moving across the western Florida Panhandle between
1 and 3 PM. In addition to the isolated tornado threat will be the
potential of localized damaging wind gusts in any bowing line
segments. Locally heavy rains also possible...but the rapid eastward
progression of the line...is expected to mitigate widespread flooding
issues. Looks like wet weather will be moving east of the local area
by and after 3 PM. Clouds look to linger longer as low level cyclonic
curvature in height field aloft remains in place. High temperatures
in the lower half of the 70s with overnight lows in the Lower/Middle 50s
interior to Lower/Middle 60s beach areas.
Latest radar velocity wind profiles in the lowest 3 kft show
southeast winds at 25 to 35 knots. These winds are forecast to
continue to veer and trend higher through the day as the upper level
storm system makes a closer approach. Good mixing should allow for a
windy day with east northeast winds this morning becoming south to
southwest through the course of the afternoon...ranging from 20 to 30
miles per hour with frequent higher gusts. A Wind Advisory has been issued
beginning at middle morning and continuing through the afternoon.
An increase in southerly component in winds in combination with
Spring tidal cycles and an increase in higher period swell results in
continued high risk of dangerous to potentially deadly rip currents
along the beaches today. /10
[monday and tuesday]...a cold front sweeping through our southeast
Mississippi and inland southwest Alabama counties Monday morning
will move quickly southeastward through the rest of the forecast
area by middle afternoon. A few lingering showers ahead of the front
across the extreme southeast portion of our forecast area will
quickly exit eastward by noon Monday. A massive upper level longwave
trough will cradle much of North America Monday morning. A 150 knot
300 mb jet diving southeast over the northwest Continental U.S. Will carve out
a highly amplified upper trough from the upper Midwest to south
Texas by Tuesday afternoon. This upper trough will then advance
eastward over the Mississippi River valley by late Tuesday night.
Cold surface high pressure will be in place across the northwest
Gulf of Mexico and the lower Mississippi River valley as a surface
low developing over the Bay of Campeche lifts northeast over the
eastern Gulf by Tuesday evening...and then across the Florida
Peninsula after midnight. Prior to the arrival of the upper
system...high temperatures across the northern Gulf will be in the
near 60 with overnight lows falling into the middle to upper 30s...so
expect a cold rain Tuesday night. /22
Long term [wednesday through sunday]...upper zonal flow will resume
on Thursday as the upper trough moves east over the western
Atlantic. Surface high pressure building in from the west will
settle across the Gulf of Mexico and southeast states through the
remainder of the long term. Dry and cool conditions will persist
with high temperatures expected to range from the upper 50s to middle
60s...and low temperatures expected to range from the middle 30s to the
middle 40s Wednesday night through Friday night...warming into the middle
40s to middle 50s Saturday night. /22
23.12z kmob/kbfm and kpns taf cycle
convective line is forecast to move across mob/bfm between 17 and
19z and pns between 18 and 20z. Ahead of the line...winds turn south
and range from 15 to 25 knots with higher gusts. Stronger winds
expected with passing convection. IFR/LIFR ceilings and visibility possible in
Marine...a strengthening surface low pressure system moves into the
lower to middle Mississippi River valley today. As this occurs...strong
east to southeast winds will become south to southwest and increase.
Frequent wind gusts to gale force are likely through most of the day
today over the open Alabama and northwest Florida coastal waters.
Small craft advisories remain up across bays and sounds. High seas
continue. Data collection platforms at 23.09z indicate seas of 8 feet
at buoy 42012 and 42040. As squall line of storms move east
today...winds...waves and seas will be locally higher. Mariners
should be alert to severe storms which will likely bring instances of
wind gusts in excess of 50 knots. Isolated tornadoes also possible.
Frequent cloud to water lightning and locally heavy...visibility
reducing rains will be common in strong to severe marine storms
today. Low pressure responsible for unsettled weather conditions
today...lifts quickly northeast...up across the Great Lakes on Monday
with high pressure building across the southern states into the
middle of the week. Winds decrease and seas subside into the middle
of the week. /10
Preliminary point temps/pops...
Mobile 74 58 70 41 59 / 100 10 10 05 20
Pensacola 75 63 72 46 59 / 100 10 10 05 40
Destin 72 64 72 49 59 / 100 20 20 05 40
Evergreen 73 55 71 40 59 / 100 10 10 05 20
Waynesboro 74 51 66 38 59 / 100 10 10 05 05
Camden 72 53 68 39 58 / 100 10 10 05 10
Crestview 73 61 74 42 59 / 100 20 10 05 40
Alabama...high rip current risk until 6 am Monday for the following zones:
lower Baldwin...lower Mobile...
Wind Advisory from 9 am Sunday to 6 PM Sunday for the following
Crenshaw...Escambia...lower Baldwin...lower Mobile...
Monroe...upper Baldwin...upper Mobile...Washington...
Florida...Wind Advisory from 9 am Sunday to 6 PM Sunday for the following
zones: coastal Escambia...coastal Okaloosa...coastal Santa
Rosa...inland Escambia...inland Okaloosa...inland Santa
High rip current risk until 6 am Monday for the following zones:
coastal Escambia...coastal Okaloosa...coastal Santa Rosa...
MS...Wind Advisory from 9 am Sunday to 6 PM Sunday for the following
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 Warning until 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 60
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...