Tropical storm Cristobal to intensify, Gulf coast on watch for rain & surge

Tropical storm Cristobal is expected to emerge back over the Gulf of Mexico later today and head generally northwards towards the United States, with strengthening forecast and still a chance that the storm could be named hurricane Cristobal prior to landfall.

In general the warm waters of the Gulf of Mexico are strong enough to support intensification of tropical storm Cristobal, but just how much is uncertain and the forward-speed of the storm may be a factor, as it dictates how long it will have over the warmer seas to gain additional structure and strength.

In addition, some wind shear has been forecast, although most seem to think this won’t significantly hinder the development of Cristobal as it moves north.

With forecasts for the 2020 Atlantic hurricane season still pointing to a particularly active season ahead, Cristobal is the first U.S. landfall prospect, so has alerted insurance, reinsurance and insurance-linked securities (ILS) market participants.

However, at this stage it does look like rainfall and some coastal storm surge are the major threats, although intensification to hurricane force winds cannot be ruled out yet.

Earlier this week, tropical storm Cristobal formed over the Bay of Campeche and headed south for a landfall in Mexico. Since then the storm has weakened back to a depression but has dropped enormous amounts of rainfall in the Central American region, with storm totals as high as 35 inches reported.

Now, Cristobal is ready to regain tropical storm characteristics and expected to head out over the Gulf of Mexico tonight. Tropical storm Cristobal’s current position can be seen below.

Update, Sunday June 7th, pre-landfall from the NHC:

SUMMARY OF 700 AM CDT…1200 UTC…INFORMATION
———————————————-
LOCATION…28.2N 89.9W
ABOUT 70 MI…110 KM S OF GRAND ISLE LOUISIANA
ABOUT 75 MI…125 KM SSW OF THE MOUTH OF THE MISSISSIPPI RIVER
MAXIMUM SUSTAINED WINDS…50 MPH…85 KM/H
PRESENT MOVEMENT…N OR 360 DEGREES AT 12 MPH…19 KM/H
MINIMUM CENTRAL PRESSURE…994 MB…29.35 INCHES

SUMMARY OF WATCHES AND WARNINGS IN EFFECT:

A Storm Surge Warning is in effect for…
* Mouth of the Mississippi River to Ocean Springs Mississippi
* Lake Borgne

A Storm Surge Watch is in effect for…
* East of Morgan City Louisiana to the mouth of the Mississippi
River

A Tropical Storm Warning is in effect for…
* Intracoastal City Louisiana to the Okaloosa/Walton County
Florida line
* Lake Pontchartrain and Lake Maurepas

DISCUSSION AND OUTLOOK
———————-
At 700 AM CDT (1200 UTC), the center of Tropical Storm Cristobal was located by an Air Force Reserve reconnaissance aircraft near latitude 28.2 North, longitude 89.9 West. Cristobal is moving toward the north near 12 mph (19 km/h) and this general motion is expected to continue today, followed by a gradual turn toward the north-northwest late today or tonight. On the forecast track, the center of Cristobal will approach the northern Gulf of Mexico coast
this afternoon, then move inland across Louisiana late today through Monday morning, and northward across Arkansas and Missouri Monday afternoon into Tuesday.

Data from NOAA Doppler weather radars indicate that maximum sustained winds remain near 50 mph (85 km/h) with higher gusts. Little change in strength is forecast before landfall, and weakening will begin once Cristobal moves inland.

Tropical-storm-force winds extend outward up to 205 miles (335 km) mainly to the east of he center. A National Ocean Service station at the Southwest Pass of the Mississippi River recently reported a sustained wind of 43 mph (69 km/h) and a gust to 51 mph (82 km/h) at an elevation of 78 feet (24 m).

The minimum central pressure recently measured by the reconnaissance aircraft was 994 mb (29.35 inches).

STORM SURGE: 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…

Mouth of the Mississippi River to Ocean Springs MS including Lake Borgne…3-5 ft
Morgan City LA to Mouth of the Mississippi River…2-4 ft
Ocean Springs MS to Marco Island FL including Mobile Bay, Pensacola Bay, and Tampa Bay…1-3 ft

The deepest water will occur along the immediate coast in areas of onshore winds and will likely extend along the coast well to the east of the center. Surge-related flooding depends on the relative timing of the surge and the tidal cycle, and can vary greatly over short distances. For information specific to your area, please see products issued by your local National Weather Service forecast office.

WIND: Tropical storm conditions are expected within the Tropical Storm Warning area along the northern Gulf coast today and tonight.

RAINFALL: Cristobal is expected to produce total rainfall accumulations of 4 to 8 inches across portions of the central Gulf Coast into the Lower Mississippi Valley, with isolated amounts to 12 inches. Rainfall totals of 2 to 4 inches with local amounts to 6 inches are expected across portions of the eastern Gulf Coast, along with the Mid to Upper Mississippi Valley and Northern Plains near and in advance of Cristobal. This rainfall may lead to flash
flooding and widespread flooding on smaller streams across portions of the central Gulf Coast into the Lower Mississippi Valley. New and renewed significant river flooding is possible along the central Gulf Coast and into the Mississippi Valley.

TORNADOES: A few tornadoes are possible today and tonight across eastern Louisiana, southern Mississippi, southern Alabama, and northern Florida.

Original article:

Tropical storm Cristobal is still a depression at the moment, with winds just below storm strength, but is expected to regain that status later today then head into the Gulf travelling northwards at around 12 mph.

Cristobal is expected to near the U.S. Gulf Coast by Sunday and could make landfall Sunday night or perhaps into Monday morning.

The National Hurricane Center warns of a storm surge threat quite widely to the Gulf Coast, of 1 to 5 feet:

– Aripeka to Marco Island including Tampa Bay…1-3 ft
– Grand Isle to Ocean Springs including Lake Borgne…2-4 ft
– Indian Pass to Aripeka…2-4 ft
– Ocean Springs to Indian Pass including Mobile Bay and Pensacola Bay…1-3 ft

Tropical storm force winds from Cristobal are expected on the Gulf Coast as of Sunday morning.

Rainfall could be a significant threat, with NOAA forecasting up to 10 inches in some areas of the eastern and central Gulf Coast and the lower Mississippi Valley.

Now, that is nothing compared to the rainfall experienced in some parts of Central America, as Southern Guatemala, coastal portions of Chiapas in Mexico and El have seen isolated storm total amounts of as much as 35 inches dating back to Saturday, May 30th from Cristobal and the Pacific storm Amanda it formed from the remnants of.

So Cristobal is known to carry a lot of moisture and there is every chance it could absorb much more on its way across the Gulf of Mexico, so rainfall totals will be something to watch and localised flooding is certainly possible.

In terms of potential landfall location, Louisiana seems to be the models favourite, but some put the storm closer to the Florida Panhandle by Sunday.

Forecasters at a number of weather monitoring services warn that there is a chance that hurricane Cristobal forms, as they see time for intensification as the storm tracks across the Gulf and believe the waters are warm enough to support that.

But ultimately, with Cristobal, it is rainfall and also the chance of tropical storm force winds extending inland for some distance, with the storm becoming particularly large as it crosses the Gulf, that seem the main threats.

As a result, it shouldn’t pose any significant threat to reinsurance or ILS interests, although insurance carriers could face elevated claims levels due to the storm.

You can view a recent forecast model run showing the GFS predicted track for tropical storm Cristobal below, sourced from TropicalTidbits.com.

You can view a recent forecast model run showing the intensity guidance for tropical storm Cristobal below, sourced from TropicalTidbits.com.

It clearly shows there remains some potential for steady intensification of tropical storm Cristobal’s winds as it moves across the warm waters of the Gulf of Mexico towards the United States.

However, it’s worth reiterating that Cristobal may be a rain bringer, rather than wind. Even if it does manage to gain hurricane status, it is unlikely to pose a significant reinsurance market threat.

Track the 2020 Atlantic tropical storm and hurricane season on our dedicated page and we’ll update you as new information emerges of relevance to insurance, reinsurance and ILS markets.