Alabama’s Coastal Monsoon: Variability in Sea Breeze Thunderstorm Rainfall

Jason C. SenkbeilDepartment of Geography

Data Difficulties

Hourly Precipitation (NOAA)• Complete records available

for only 3 stations

South Alabama Mesonet• Since 2008 for most stations

How do sea-breeze thunderstorms

form?

FH

MOB

AtmoreBM

RD

Coden

DI

Sea Breeze Rainfall Belt?

Station Total Days

Dry Days % Dry Mean Daily rainfall

Mean daily rainfall (excluding dry days)

Atmore 3908 2329 59.6 4.90 mm 10.87 mm

Bay Minette 5823 3426 58.8 5.72 mm 12.68 mm

Robertsdale 5850 3327 56.9 5.98 mm 12.75 mm

Fairhope 5875 3407 58.0 5.84 mm 12.57 mm

MOB 5872 3293 56.1 5.61 m 11.58 mm

Coden 4770 2993 62.7 5.61 mm 14.27 mm

Dauphin I 2 3483 2214 63.6 5.37 mm 13.12 mm

df F p

6 2.46 .02

Station Pair p

FAIRHOPE and Atmore

.04

ROBERTSDALE and Atmore

<.01

df F p

6 5.46 <.01

Station Pair p

ROBERTSDALE and Atmore

.04

CODEN and Mobile

<.01

CODEN and Atmore

<.01

DI2 and Atmore

<.01

1 Way ANOVA all days

1 Way ANOVA precip days only

4.5

5

5.5

6

6.5

7

50s 60s 70s 80s 90s 00s

Bay MinetteFairhopeMobileRobertsdale

Mean decadal daily precip (mm)

Station r2

Atmore 0.48

Bay Minette 0.13

Robertsdale 0.46

Fairhope 0.31

MOB 0.10

Coden 0.49

Mean afternoon sst 2 – 6 pm and

cumulative seasonal precipitation

FH

MOB

Atmore

BM

RD

Coden

DI

Wettest summers sea level pressure anomaly (mb)

Mobile Bay Minette

Fairhope Robertsdale

Wettest summers geopotential height anomaly 500mb

Fairhope Robertsdale

Bay MinetteMobile

1982, RD, BM, MOB

Sea level pressure

500 mb

• Chaos Theory wins• Future research

– USA mesonet with Nexrad Level III Radar

• Sea Breeze belt appears to exist– Atmore, Coden, Dauphin Island different

• Decadal trends?• Correlation between sst and seasonal rainfall• Microscale disturbances

Conclusions