Five disturbances in a confused pressure pattern today
Gerneral picture 1500Z 6th July 2013
Satellite images this morning show the skies above the Gulf of Mexico to be rather confused. We will try to provide a simple outline.
There are two large upper level systems impacting on the Gulf of Mexico. An area of upper level low pressure over northern Texas is creating a wide band of clockwise wind shear. This is holding disturbance ten at bay, which is centred roughly speaking 350 miles south- sou'west of Galveston. This disturbance is still making way but at little more than walking pace and is expected to creep ashore somewhere in the direction Brownsville in the next 36 hours. It is unlikely now that this do more than cause widespread heavy rain and isolated strong thunderstorms from northeastern Mexico into southwestern Louisiana.
The second upper level formation of interest is a high altitude low in the western Atlantic, which is creating a clockwise sweep of wind shear. The sheer from system has taken the wind out of the sails of disturbance twelve which has opened into a low pressure wave extending from Alabama into the central Gulf of Mexico and moving north-nor'east at around 5 knots - little more than walking pace too. This is continuing to interact with an upper-level trough of low pressure causing widespread showers and thunderstorms across much of the central Gulf Coast and the deepwater and coastal lease blocks south of Louisiana and Mississippi with occasional enthusiastic squalls.
The maverick disturbance fourteen is centred around 800 miles east of the Florida Straits and is moving west near 10 knots and will move across southern Florida and the Florida Straits in 3 to 4 days, then, egged on by the sweep of clockwise winds from the upper level high mentioned in the previous paragraph, will turn northwest over the eastern Gulf of Mexico and move into the western Florida panhandle or north-central Gulf Coast next weekend. One or two modellers still favour this to impress at some stage, but their numbers are dwindling to the usual one or two catastrophists and chances are only slight.
Disturbance thirteen is a tropical wave centred around 400 miles north of the Amazon delta and still drifting to the north of the convergence zone at 10 knots. As this moves away from the fertile development latitudes, the chances of developement are reducing however, it will produce enhanced showers and thunderstorms across the eastern Caribbean Sea over the next couple of days, including the Lesser Antilles.
Disturbance fifteen is now mid-Atlantic, moving west at 10 knots and closely tracing the convergence zone, which may provide some strengthening on passage. This morning's satellite images showed some circulation which may be an early signal of enthusiasm. We will see.
I'm still not certain if that is as clear as I would wish, but at least I can end with customary reassurance for the forthcoming days at least, to say stand easy.Back