Dry air to the rescue!
Cristobal continues to move north across the Gulf of Mexico but is also interacting with a lot of dry air and a little bit of shear. That is limiting its growth, organization and intensity. All good news. While it may not look like the typical tropical system, it will still produce very heavy rain, very gusty wind, and have the potential to produce brief tornadoes.
The latest from the National Hurricane Center puts Cristobal making landfall Sunday afternoon or evening along the central/eastern Louisiana Coast. Leaving sections of Louisiana, Mississippi and Alabama on the east side of the storm. And Cristobal’s east side has the heaviest rain, gustiest wind and will have the potential to produce tornadoes.
From the NHC
SUMMARY OF 1000 AM CDT…1500 UTC…INFORMATION
———————————————–
LOCATION…24.2N 90.1W
ABOUT 345 MI…555 KM S 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…29.36 INCHES
Cristobal’s satellite presentation continues to lack the appearance of a classic tropical cyclone, with a large curved band over the northern semicircle and little deep convection near the center. The latest flight-level and SFMR-observed surface wind observations from an Air Force Hurricane Hunter aircraft support a current intensity of 45 kt. Based on the poorly-organized state of the system, some dry air entrainment, and interaction with an upper-level low, only some slow strengthening is forecast, as in the previous advisories. The NHC intensity forecast remains in good agreement with the model consensus.
The storm is moving northward at a slightly slower 10 kt. There has not been much change in the track forecast or forecast reasoning. Cristobal should continue northward through a weakness in the subtropical ridge until tomorrow evening, bringing the center to the northern Gulf coast in about 36 hours. Later, a turn to the north-northwest, and then back to the north is forecast as the cyclone moves between a mid-level ridge and a trough approaching the central United States. In 3-4 days, the post-tropical system should accelerate north-northeastward on the east side of the trough and move into Canada.
Cristobal is likely to remain a broad and asymmetric storm when it makes landfall. Therefore, users are urged to not focus on the exact forecast path as the associated winds, storm surge, and rainfall will extend well to the east of the center.
Key Messages:
1. There is a danger of life-threatening storm surge outside of the Hurricane and Storm Damage Risk Reduction System from the Mouth of the Mississippi River to Ocean Springs, Mississippi, and a Storm Surge Warning is in effect for those areas. Life-threatening storm surge remains possible in other portions of southern and southeastern Louisiana where a Storm Surge Watch is in effect. Residents in these locations should follow advice given by local emergency officials.
2. Tropical storm force winds are expected by late tonight along the northern Gulf Coast from central Louisiana to the western Florida Panhandle, including metropolitan New Orleans, and a Tropical Storm Warning is in effect for this area. These winds will arrive well in advance of and extend well east of Cristobals center.
3. Heavy rainfall will continue across west and north Florida today, spreading from east to west across the eastern and central Gulf Coast from the Florida Panhandle into Louisiana today into Sunday. This heavy rain will move into the Lower Mississippi Valley on Monday. Significant flooding will be possible on smaller streams, especially where heavier rainfall occurs over portions of the Gulf Coast and Lower Mississippi Valley.
4. Damaging and deadly flooding was already occurring in portions of Mexico and Central America. Additional rainfall from Cristobal will continue to slowly subside, however life-threatening flash floods and mudslides will still be possible through today. Refer to products from your local weather office for more information.
Extra forecast details:
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 beginning late tonight or Sunday morning.
RAINFALL: Cristobal is expected to produce total rainfall accumulations of 4 to 8 inches across the eastern and central Gulf Coast into the Lower Mississippi Valley, with isolated amounts to 12 inches. Isolated significant river flooding is possible along the central Gulf Coast. Rainfall totals of 2 to 4 inches, with local amounts to 6 inches, are expected across the Mid-Mississippi Valley. This rainfall may lead to flash flooding and widespread flooding on smaller streams across the Lower to Mid-Mississippi Valley.
Additional rainfall totals of 1 to 3 inches are expected across the Mexican states of Quintana Roo and Yucatan, bringing isolated storm totals to 25 inches. This will continue the threat of life-threatening flash floods and mudslides.
TORNADOES: A few tornadoes may occur on Sunday across southern Louisiana, southern Mississippi, southwest Alabama and the western Florida Panhandle.
SURF: Swells generated by Cristobal will affect portions of the northern and eastern Gulf coast during the next few days. These swells are likely to cause life-threatening surf and rip current conditions. Please consult products from your local weather office.
On satellite
The satellite presentation of Cristobal is not as “pretty” as a Major Hurricane, sure. But I think most everyone would prefer the former to the latter.
This morning you can see on the “mesoscale floater” imagery, the exposed center of Cristobal. The exposed, elongated center is making it difficult for Cristobal to get better organized.
Flipping between visible satellite, infrared and water vapor, you can also see that the stronest convection is on the east side, while the west side of the storm is almost non-existent.
For those who have lived along the Gulf Coast fo a while may remember Hurricane Nate. Nate was a very one-sided system, too. The eastern side had the rain, wind, tornadoes and storm surge. The west side was a gusty of wind and a passing shower.
Inland Impacts
Flooding
– Major rainfall flooding may prompt many evacuations and rescues.
– Rivers and tributaries may rapidly overflow their banks in multiple places. Small streams, creeks, canals, and ditches may become dangerous rivers. Flood control systems and barriers may become stressed.
– Flood waters can enter many structures within multiple communities, some structures becoming uninhabitable or washed away. Many places where flood waters may cover escape routes. Streets and parking lots become rivers of moving water with underpasses submerged. Driving conditions become dangerous. Many road and bridge closures with some weakened or washed out.
Winds
– Some damage to roofing and siding materials, along with damage to porches, awnings, carports, and sheds. A few buildings experiencing window, door, and garage door failures. Mobile homes damaged, especially if unanchored. Unsecured lightweight objects become dangerous projectiles.
– Several large trees snapped or uprooted, but with greater numbers in places where trees are shallow rooted. Several fences and roadway signs blown over.
– Some roads impassable from large debris, and more within urban or heavily wooded places. A few bridges, causeways, and access routes impassable.
– Scattered power and communications outages, but more prevalent in areas with above ground lines.
Tornadoes
– The occurrence of isolated tornadoes can hinder the execution of emergency plans during tropical events.
– A few places may experience tornado damage, along with power and communications disruptions.
– Locations could realize roofs peeled off buildings, chimneys toppled, mobile homes pushed off foundations or overturned, large tree tops and branches snapped off, shallow-rooted trees knocked over, moving vehicles blown off roads, and small boats pulled from moorings.
Model Data and Analysis
The 500mb map does a good job at highlighting the problems facing Cristobal.
It also explains why there is so much dry air on the west side of the storm. The system is caught downstream from a ridge of high pressure. That leads to the air piling up on the west side of the storm. More air, more convergence, more pressure. More pressure, higher pressure. Higher pressure, fewer clouds.
Fewer clouds? That makes Rapid Intensification difficult.
The SHIPS model continues to try to paint Cristobal with a chance for Rapid Intensification. However, given the dry air, I find that to be unlikely. Unless it can somehow wrap itself up and shield the center, it won’t rapidly intensify.
It also needs to stack the lower and middle areas of low pressure, too. But that also seemed unlikely.
During the next few days, the ridge will transition tot the east side of Cristobal and that will nudge the storm back to the west a bit, and may allow it to fill in on the west side shortly, but this will happen as the storm makes landfall, so it is unlikely to really matter in the long run.
Model data is also struggling to nail down where – specifically – the heaviest stripe of rain will be. Yesterday, models seem to come into a reasonable agreement that it would be along the Mississippi coast and the eastern sections of the Louisiana boot. But today, the European model has shifted the heaviest rain back to the west.
That said, the GFS computer model continues to show the original area of concern as being pegged with the highest rainfall totals.
Either way, all model guidance shows a pretty sharp cut-off from the heaviest rain to a very manageable amount of rain – going from 8″ to 3″ pretty quickly along the eastern side. This may make it difficult to accurately predict specifics with respect to rainfall totals for some.
Timeline and Bottom Line
Cristobal will make landfall Sunday afternoon or evening along the Louisiana Coast. This will bring heavy rain, gusty wind and the potential for brief tornadoes to Louisiana, Mississippi and Alabama on Sunday and Monday. Rainfall totals of up to 12″ will be possible, wind gusts up to 60mph will be possible, and up to EF-1 tornadoes will be possible.
The clouds have already started to increase over the region. The rain bands will begin to move onshore Sunday morning with heavy rain and gusty wind.
By Sunday afternoon rain bands will increase in coverage and intensity. Rainfall rates may approach 2″ per hour in the heaviest downpours. Wind gusts will start to pick up along the coast.
By Sunday evening, some of the heaviest rain will begin to enter the region with rainfall rates up to 3″ to 4″ per hour in the heaviest downpours, wind gusts to 60mph will be possible – especially along the coast – and the threat for brief tornadoes will begin.
Those conditions will continue through the overnight hours and into Monday morning.
By Monday late morning and into the afternoon conditions will begin to improve, but rain may continue to fall.
Right now
Right now would be a good time to make sure you have all of the supplies you need in your Hurricane Preparedness Kit. It would also be a good time to look around the exterior of your home to inspect any trees or shrubs for dead branches or branches that may cause damage to your home. Check the storm drains and creeks near your hour to make certain there are no “obstructions” blocking the water’s path. And clean out your gutters, too, to make certain all of that water can flow freely away from your home.
Thank you for the update!
Thank you so much. At least one thing remains great right now and that is science. And none better I prefer to deliver that ONLY science of weather than you. It’s appreciated more than you know!