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Area forecast discussion 
National Weather Service Mobile Alabama
503 am CST Sat Dec 27 2014

..locally heavy rains may lead to instances of flash flooding over
the northwest zones this weekend...

Short term [today and tonight]...a highly amplified pattern is
observed on weather maps this morning with a deep upper level trough
positioned from the northern High Plains to across The Four Corners
of the Desert Southwest. To the southeast...quasi-stationary upper
level ridge was analyzed over Cuba and Hispaniola. Between these large
scale weather active upper level southwest flow will be
in place over the central Gulf Coast today and tonight as a series of
middle level impulses traverse the area. A strong upper level jet streak from
the Texas Panhandle to Iowa is prognosticated to continue to intensify to
some 150 to 180 knots as it lifts northeast up across Missouri to the
Great Lakes. Strong upper level forcing in the favored right rear
quadrant of this jet itself...supports a large swath of
rainfall organizing from the Upper Texas coast to th middle south in the
near term. Radar shows rains breaking out over southeast
Mississippi/southwest Alabama and will be tracking across the western
zones this morning. Gulf moisture has opened up with 27.00z soundings over
the central Gulf Coast showing precipitable water (pwat) values
having gained an inch in 24 hours. Precipitable water values are forecast to
continue to rise...settling around 1.8 inches across
Louisiana/central Mississippi/central Alabama through the course of
the day and into tonight. These values are anomalously high for late
December...being nearly 2 Standard deviations above the mean.
Considering amount of available moisture...deep layer
lift...orientation of upper level southwest flow and approach of a
slow eastward moving frontal zone/waves of low pressure along
it...appears to be setting the stage for the potential of locally
heavy rains over a portion of the Gulf Coast. At this time...the
favored area is along and southwest of a line from Camden/Monroeville
Alabama to Leakesville and Lucedale Mississippi. This is where the
higher event total rains are forecast this weekend and considering
the recent heavy rains (3 to 5 inches) observed earlier in the week
over interior southeast Mississippi...a Flash Flood Watch will be
issued on this package beginning at noon today. As assessment of
instability suggests that the risk of severe weather will be low.
Daytime highs to range from 63 to 68. Overnight lows mild with
middle/upper 50s interior to lower 60s coast. /10

[sunday through Monday night]...the large upper high pressure system
centered over the Bahamas will gradually shift south-southwest over
the southern Gulf of Mexico through the remainder of the short term.
The upper trough will move east over the Southern Plains on Sunday
and deamplifies before reaching the southeast Continental U.S. Sunday night.
A weak surface low centered over northern and central Alabama will
shift east...while a cold front approaching the region from the
northwest on Sunday moves slowly southeast across the forecast area
Sunday night.

Ongoing numerous to widespread showers with embedded thunderstorms
will occur Sunday across the Flash Flood Watch area over the
northwest portion of the forecast area...with scattered coverage to
the southeast. The bulk of the precipitation will then pass east
across the forecast area Sunday night...with the precipitation coming
to an end northwest of I-65 by late Sunday night. Isolated to
scattered showers will persist into Monday morning southeast of
I-65...and then move east of the area with the departing cold front.

MLCAPE will remain below 100 j/kg on Sunday with 0-1km helicity
values remaining below 100 m2/s2 as well. So we are only expecting
general thunderstorms on Sunday.

It will be warm Sunday with high temperatures ranging from 70 to 75
degrees. Lows Sunday night will range from the middle 40s behind the
cold front to around 60 degrees near Destin Florida. High
temperatures Monday will range from the low to middle 60s across
southeast Mississippi and southwest Alabama...with upper 60s to
around 70 degrees across the western Florida Panhandle and south
central Alabama. /22

Long term [tuesday through saturday]...a very large surface high
pressure area will extend southeast all the way to the eastern
Seaboard and northern Gulf of Mexico from a strong 1055mb pressure
centered over Montana Tuesday morning. The center of the high will
migrate south-southeast through midweek...becoming centered over
Oklahoma Wednesday night. The center will then move east over the
southeast Continental U.S. By Thursday afternoon. This will keep the region
rain-free through midweek. The center of the high pressure will then
move very quickly over the western Atlantic...setting up a return flow
and increasing moisture across the region on the backside of the
departing high late in the week. Upper Cutoff low centered over Nevada move south over
the southwest Continental U.S. Wednesday night and Thursday...before ejecting
east over the Southern Plains by Saturday. Impulses rounding the
base of the upper low will eject east-northeast across the
region...bringing scattered showers into the forecast area...mainly
Thursday night into Saturday.

High temperatures will be near normal on Tuesday...and below normal
Wednesday and Thursday. The air mass will modify considerably Friday
and Saturday with the return flow...with highs rebounding back above
normal. /22


27.12z kmob/kbfm and kpns taf cycle
starting off with VFR conditions with high based lower to a
blend of MVFR/IFR levels through the day. A light east northeast wind
early becomes southeasterly 10-13 knots through the course of the
day. Passing light rains early...with moderate rain showers by 18z and a few
thunderstorms mixing in by/near 21z. 10/29


Marine...high pressure over the southeast breaks down over the
weekend while a cold front approaches the lower Mississippi River
valley. With the front unsettled weather pattern
sets up over the marine area this weekend as showers increase in
coverage along with embedded storms. Frontal passage and associated
wind shift is forecast late Sunday night. Rains end with the frontal
passage. A large and strong area of surface high pressure expands
across the southern United States next week...resulting in a light to
moderate north to northeast flow and moderate seas late in the


Preliminary point temps/pops...
Mobile 68 62 74 56 67 / 90 80 40 70 10
Pensacola 67 61 74 60 69 / 70 30 30 60 30
Destin 65 61 73 62 69 / 60 30 20 60 30
Evergreen 66 56 73 56 69 / 80 70 50 70 20
Waynesboro 63 59 67 47 62 / 100 100 80 70 10
Camden 63 55 72 52 66 / 100 100 80 70 10
Crestview 68 55 75 60 71 / 60 30 30 60 30


Mob watches/warnings/advisories...
Alabama...Flash Flood Watch from noon Saturday to midnight Monday for the
following zones: Choctaw...Clarke...Monroe...Washington...

MS...Flash Flood Watch from noon Saturday to midnight Monday for the
following zones: George...Greene...Perry...stone...Wayne...

GM...Small Craft Advisory until 6 am Saturday for the following
zones: coastal waters from Pensacola Florida to Pascagoula MS
out 20 nm...waters from Pensacola Florida to Pascagoula MS from
20 to 60 nm...



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