Monday, September 5, 2011

Valid Time: Monday, September 5 until Monday September 12, 2011

Feature(s) of Interest:

The features of interest this week are the motion of hurricane Katia in the western Atlantic, the vigorous tropical wave in the tropical Atlantic SW of the Cape Verde Islands and a surface disturbance projected to develop on the tail-end of a cold front in the Bay of Campeche later this week. Also, in the upper levels, an upper low will favour moderate to heavy convection over Belize through Tuesday, but will be replaced by a diffluent NE’ly airflow by midweek and an inverted trough through the weekend. These upper level patterns will all support low level convergence of moist, unstable air over the southern Gulf of Mexico, Yucatan and Belize this working week through the upcoming, holiday weekend.

At 3:00 pm local time hurricane Katia was located near latitude 25.2N… longitude 63.9W. Katia was moving NW at 12 mph, and this general motion with a slight decrease in forward speed is expected through Wednesday. Maximum sustained winds have increased to near 115 mph with higher gusts. Katia is a Category III hurricane, and some additional strength is forecast through Tuesday, followed by little change in strength on Wednesday. Meanwhile, the NHC is giving the vigorous tropical wave in the eastern Atlantic, SW of the southernmost Cape Verde Islands, a 60% chance of developing into a tropical cyclone during the next 48 hours (See Fig. 1 below). This disturbance will continue to move westward at 15 mph during the next couple of days, then it is projected to shift WNW, skirting the NE tip of the northernmost Leeward Islands by Saturday of this week (See Fig. 4 and Fig. 5 below). This TC is expected to continue along a WNW track towards the Bahamas.

The unstable conditions will persist over the NW Caribbean and Belize this working week, and thunderstorm activity will increase later on Wednesday and Thursday as an active cold front move into the eastern Gulf of Mexico and induce a vigorous area of low pressure in the Bay of Campeche. The unsettled weather will persist through Saturday and Sunday, resulting in heavy rainfall activity over western and northern areas of Belize.

Daily rainfall totals will range from 0.50–1.00 inch in the heavier showers or thunderstorms over the hilly areas of the interior during the afternoon hours and along some areas of the coast and the sea in the morning. Daily rainfall rates will increase from 2–3 inches especially over the hilly interior on Thursday through the weekend, and on Monday according to the GFS model projections. Associated runoff will lead to more flooding in the west and north of Belize. River monitors should remain vigilant as we head for the holiday weekend!

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