Today, Tropical Storm Dolly remains the top news. Let’s start with her vitals:
24.0N, 94.5W; moving NW @ 11mph; maximum sustained winds of 70mph; minimum pressure of 991mb.
Just a little more sustained wind speed and Dolly will become a Category 1 hurricane. In fact, she is expected to do so by sundown tonight. She is moving over very warm Gulf of Mexico waters and has upper-air support in the form of a 200mb anticyclone, which aids her outflow of rising air.
The biggest change from yesterday is with her forecasted track. The two models indicating a more southerly landfall appear now to have been correct. Thus, the eyewall should come over land very near the Texas-Mexico border, right around Brownsville. I’ll repeat what I wrote yesterday: more importantly, hurricane force and tropical storm force winds will extend for many miles away from the eyewall. Those are the features that folks need to pay attention to as Dolly comes ashore. She should do so as a Category 1, then weaken back to Tropical Storm strength for about a day before degrading to a Tropical Depression again. Her weakening won’t reduce her potential lethality as torrential rains will be the main characteristic of the storm as she moves across Mexico. The extended track is very uncertain: some model solutions show her moving across all of Mexico, while one turns her northwestward and over western Texas and southeastern New Mexico in five plus days.
Aesthetically, Dolly looks good on satellite imagery. A clear eye is forming, and has been measured to be about 20nm across, which is pretty big. Concentric rings of convective clouds are swirling into the middle of the storm.
[Update 3:20P MDT]:
Dolly has strengthened to a Category 1 hurricane. Hurricane hunter aircraft data measured winds at flight level than when extrapolated to the surface, pass the threshold for hurricane strength. Additionally, Dvorak estimates confirm Dolly’s strength. Her updated vitals:
24.6N, 95.3W; maximum surface winds of 75mph; minimum surface pressure of 985.0mb.
Some further strengthening is expected before Dolly makes official landfall, probably as a strong Category 1 storm. That landfall is still expected to occur somewhere near the Texas-Mexico border, near Brownsville, TX sometime Wednesday afternoon. Thereafter, weakening back to Tropical Storm status should occur ~24 hours after landfall and to Tropical Depression statues ~24 hours after that. Heavy rains and strong winds will be the main problems associated with this storm.
More after the fold.
Onto Tropical Storm Cristobal. Vitals include: located at 40.9N, 65.9W; moving NE @ 25mph; maximum sustained winds at 65mph (not bad!); minimum pressure of 1000mb.
Contrary to yesterday, TS Cristobal is forecasted to stay south of Newfoundland while continuing to move to the northeast. He should reach his furthest northward extent Wednesday morning before turning back to the southeast. He should slowly weaken the entire time, and be downgraded to a Tropical Depression by Friday morning. Beyond that, the models disagree some. Most keep Cristobal moving generally eastward between 40N and 45N. One curves Cristobal back to the south and west at around 35N. At this point, I’m thinking the eastward solution is more likely. If this happens, Cristobal could affect the Azores.
The tropical wave I discussed yesterday has been designated Invest-97. This system, at this early point in time, looks more like Bertha did at the beginning of her life-cycle. By that, I mean it has come off Africa at about 15N, which is more northerly than Dolly did. It could form as a Cape Verde storm, as Bertha did. I can find three model solutions for I-97. One predicts movement like Bertha – WNW for a couple of days, then NW. The other two predict more NW movement earlier, then a turn to the north and even north-east, curling back at about 25N-30N, just at different days.
[Update]: A fourth model solution became available after posting. It emphasizes there is no consensus for I-97′s possible future track. This model has I-97 moving WSW, then WNW for the next few days, then moving NW and finally N about 55W. The pattern displayed by all model solutions at this point indicates that I-97 is likely to curve north into the central Atlantic well away from land. That could change, of course, but that’s the current trend.
I-97′s current intensity is estimated to be 22mph sustained winds. One advantage I-97 has at such a relatively high latitude is it has clear cyclonic motion because of the Coriolis force. One disadvantage I-97 has is a large region of dry air to its west, air that it is ingesting as it moves into and across the Atlantic. The NHC is giving it a 20-50% chance of developing into a Tropical Depression. If it organizes further, it would be called Edouard.