WRUF Weather

10-Day Tropical Outlook for Florida (6/21)

The first two named storms of the 2013 Atlantic Hurricane Season are already in the book, but it may be several weeks before the next tropical cyclone of our projected “active” season forms.  Several meteorological factors will likely prevent the development of a closed area of low pressure in the coming days, none of which are unusual for this time of year.  Statistics show that a tropical storm or hurricane typically only develops one out of every two years during the month of June, and the second named storm of the year doesn’t usually form until around August 1st.

THE BOTTOM LINE

  • June 22-July 2:  NO CURRENT RISK
  • Upper-level conditions are not favorable for approaching storms from the Atlantic
  • Marginal conditions for a developing nearby storm in the southern Gulf or western Caribbean develop around the first week of July
Gulf of Mexico and Caribbean
Over the past 40 years, most of the storms that form during the period of June 20 to July 10 form in the Gulf of Mexico, western Caribbean, or northern Atlantic.

The overall weather pattern that delivered a cool and wet finish to the spring season for much of the eastern half of the United States will re-emerge by the end of the month, possibly sending an unusually strong cold front off the East Coast by July 1st.  This would be a significant deterrent to any approaching tropical cyclone from the Atlantic Ocean as the upper-level winds would be too strong.  This same front is forecast to stall over the Gulf of Mexico and the state of Florida around the first week of July, and stalled fronts do have to be watched closely for possible tropical development this time of year.  However, there is relatively low skill in forecasting development of these waves this far in advance.  Elsewhere, unsettled weather is likely to continue in the southwest Caribbean near the coastline of Central America due to interactions of deeper tropical moisture and upper-level pieces of energy moving across the continent from the Eastern Pacific.  Long range forecast data suggests that tropical cyclone formation could occur near the Yucatan Peninsula around the first week of July, but confidence in this scenario is very low at the time.

Atlantic Ocean
The Atlantic Hurricane Season peaks in early September, when storm development occurs at a rate nearly four times the rate in June or July.

The rest of the Tropical Atlantic Basin is forecast to remain quiet and relatively convection (or thunderstorm) free.  The ITCZ (Intertropical Convergence Zone), where clusters of storms are common near the Equator, is forecast to remain too far to the south to allow westward moving waves of energy to develop closed circulations, which is also quite common this time of year.  A large and very strong ridge of high pressure is dominating most of the ocean north of 20°N and only near the end of the next ten days does it show signs of possibly weakening.  Water temperatures are also just a bit too cool to support robust tropical development in these same regions.  We are likely two to three weeks away from the first tropical wave being capable of surviving the trip off of west Africa into this ridge of higher pressure.  The global wave of higher energy and convection, referred to in the meteorology community as the Madden Julian Oscillation (or MJO), is not forecast to move back into the Caribbean and western Atlantic region until around this time as well.  Considering all of the aforementioned factors, we are reasonably confident that tropical activity in the Atlantic basin will be largely quiet over the next ten days.

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