At 2am EDT today, the National Hurricane Center (NHC) issued an update on a potential tropical cyclone headed toward Louisiana. Maximum sustained winds at this time are 30mph. The NHC predicts the disturbance will become a tropical storm by tonight.
At this moment, it looks like the storm will make landfall east of the Houston area, putting us on the dry side of the storm. However, the NHC also warns that the forecast track could vary by more than 170 miles and that the width of the storm may exceed the cone of uncertainty shown below. This will increase our rainfall chances significantly later in the week.
SUMMARY OF WATCHES AND WARNINGS IN EFFECT
A Storm Surge Watch is in effect for the Mississippi-Alabama border westward to the Mouth of the Mississippi River
A Tropical Storm Watch is in effect reaching from the Alabama-Florida border westward to east of Morgan City, Louisiana, including Lake Pontchartrain and Lake Maurepas.
DISCUSSION AND OUTLOOK
The system is moving near 15 mph, and this general motion is expected to continue through Wednesday. On the forecast track, the disturbance will pass over the Florida Keys or the southern portion of the Florida peninsula today, move over the southeastern Gulf of
Mexico by this evening, and reach the central Gulf Coast by late Tuesday or Tuesday night.
Maximum sustained winds are near 30 mph with higher gusts. Gradual strengthening is forecast during the next 48 hours, and the disturbance is forecast to become a tropical storm by tonight.
- Formation chance through 48 hours is high at 80 percent.
- Formation chance through 5 days remains high at 80 percent.
- The estimated minimum central pressure is 1012 mb (29.89 inches).
HAZARDS AFFECTING LAND
The combination of a dangerous storm surge and the tide will cause normally dry areas near the coast to be flooded by rising waters moving inland from the shoreline. The water could reach the following heights above ground somewhere in the indicated areas if the peak surge occurs at the time of high tide…
- Destin Florida to the Mississippi-Alabama border…1 to 2 ft.
- Mississippi-Alabama border to the Mouth of Mississippi River…2 to
- Mouth of the Mississippi River to the Louisiana-Texas border…1 to
The deepest water will occur along the immediate coast near and to the east of the landfall location, where the surge will be accompanied by large waves. Surge-related flooding depends on the relative timing of the surge and the tidal cycle, and can vary greatly over short distances.
The disturbance is expected to produce heavy rainfall along the central Gulf Coast by the middle of the week.
Tropical storm conditions are possible within the watch area by late Tuesday. Winds should reach 40mph by 9/4 and 50 mph by 9/5. Maximum winds inland should reach 30 knots with gusts to 40.
NOTE: Errors for track have averaged 150 nautical miles (NM) on day 4, 175 NM on day 5, and near 15 KT each day for intensity. So stay alert and check forecasts several times each day. The current (unrelated) low pressure disturbance moving onshore is expected to bring widespread rainfall of 1 to 3 inches with 5 to 6 inches likely closer to the coast. If #7 stays on the current track, expect another 1 to 4 inches of rain. If it tracks more westward and slows down, we could see quite a bit more than that, according to Space City Weather. However, current forecasts predict rainfall toward the lower end of that spectrum.
LOCAL IMPACT FROM CURRENT STORM
As of 7pm Sunday night, Jeff Lindner, meteorologist for Harris County Flood Control predicted that the greatest impact from the current storm would be concentrated near the coast. He predicts street flooding is the largest threat. “Most creeks and bayous will be able to handle this amount of rainfall as long as it does not all fall in an hour or two. I think the biggest threats will be street flooding with hourly rates of 2-3 inches where any banding or training develops.”
Posted by Bob Rehak on 9/3/2018 @2:48 am.
370 Days since Hurricane Harvey