GFS Indicates Potential Hurricane Off Florida Coast Days 11-15

T.S. Mindy Weakens Inland. Heavy Rains Ahead for Texas/Louisiana.
09/09/2021, 5:39 am EDT
Tropical Storm Likely Southwest Gulf of Mexico later Weekend/Early Next Week
09/10/2021, 8:18 am EDT
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Highlight: East not quite as hot in medium-range. Day 11-15 major hurricane!

Fig. 1-2: 12Z GFS temperature anomaly forecast and 12-hour change.

Fig. 3-4: 12Z GFS percent of normal rainfall forecast and 12-hour change.

Discussion: At midday, the 12Z GFS was not quite as warm across the eastern half of the U.S. although the forecast still remains quite warm (Fig. 1-2). The bulk of the hot weather is biased toward the West-central U.S. The western states trended warmer at midday. The precipitation outlook is mostly dry across the U.S. the next 15 days with notable exceptions including the Texas Coast and parts of the Interior Northwest (Fig. 3). The 12Z GFS was wetter across Southern Texas and the Upper Midwest (Fig. 4). A major hurricane causes wetter changes in the Southeast States (Fig. 5).

Fig. 5: 12Z GFS indicates a major hurricane heading toward Florida/Georgia in the 11-15-day period.

DatesCDD Forecast12-Hr Change24 Hours Ago10-year NML30-year NML
Sep 3-955.6+0.155.461.756.0
Sep 10-1661.5+0.762.352.647.1
Sep 17-2359.7+8.956.343.037.9

Table 1: The 12Z GFS population weight CDD forecast compared to the 30-year/10-year normal and 12 and 24 hours ago.