Hurricane Nate and Dangerous Storm Surge Heading for the Northern Gulf Coast Saturday (Updated at 2 pm CDT)

Update at 2 pm CDT:

Hurricane Nate is likely to be a Cat 1 or 2 at landfall (thinking NHC forecast of 2 as high-end). It is leveling off based on current satellite presentation as well as air force reconnaissance observations. STORM SURGE REMAINS THE GREATEST HAZARD. The asymmetric structure…a product of Nate’s forward motion, may intensify/focus surge/battering waves from Mouth of Mississippi River to the MS/AL border.¬†9-11 ft surge with battering waves expected Mouth of Miss. River to MS/AL border as center passes nearby. 6-9 ft east to AL/FL border. Dangerous.¬†High tide along Gulf Coast of MS around midnight, passage of center may be 8-10 pm CDT…partial enhancement could exacerbate flooding.

Probability of Cat 1 at initial landfall: 90%

Probability of Cat 2 at initial landfall: 10%

Landfall should be between 5-7 pm in far Southwest Louisiana.

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Hurricane Nate is headed for a likely landfall with the northern Gulf Coast of the US this evening. The hurricane is blasting north-northwestward very fast for a tropical cyclone…26 mph at the moment. This is under the influence of an approaching upper-level trough of low pressure which will eventually turn it northeastward after landfall. The system has continued to organize as expected over the warm waters (83-84 degrees F) and favorable low wind shear. The storm (at 10 CDT) is a Category 1 hurricane with maximum sustained winds of 90 mph with gusts to 110 mph.

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Visible imagery of Nate showing its rapid forward motion toward the coast.

The waters atmospheric and oceanic conditions should remain favorable for intensification up until landfall. Landfall is likely between 6-8 pm in far southwest Louisiana. My assessment based on this on trends, is that Nate is likely (65%) to make landfall as Category 2 (100-110 mph sustained) with a moderate chance (10%) to make landfall as a Category 3 (115 mph+), if more rapid intensification occurs during the next 7-8 hrs. There is also a 25% chance of a landfall as a Category 1.

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National Hurricane Center track forecast at 10 am CDT Saturday.

Heavy rainfall (lessened by the storm’s forward speed) is most likely over southern Mississippi into Alabama. Much of Louisiana will miss the worst of the storm, including New Orleans, however points east will face potentially significant surge. Surge may reach 7-11 ft along the mouth of the Mississippi River to the Mississippi/Alabama border; 6-9 ft from the MS/AL border to the AL/FL border, including Mobile Bay.

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Potential Storm Surge Flooding by Nate Saturday night. Orange and Red colors represent potential for 6-9+ feet of surge.

If you know anyone in these areas, please tell them to evacuate NOW!! This storm is moving FAST and storm surge will, BY FAR be the greatest danger from Nate. Far more than the wind or even inland flooding. I do have some concern that the combination of the relatively recent development of this system, its fast forward movement, and resulting shorter lead time, in addition to the system being relatively weaker in terms of maximum sustained winds that people may not leave or leave fast enough. People need to leave and be safe.

I will have updates when possible this afternoon and evening.

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Potential Impacts by Tropical Storm Nate this Weekend

Tropical Storm Nate, which developed as a depression yesterday, made landfall in Nicaragua this morning and is moving over eastern Nicaragua and Honduras this evening. Very heavy rainfall and flash flooding has already resulted in 22 deaths in Nicaragua and Costa Rica.

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Heavy showers and thunderstorms producing heavy rain over portions of Central America from Tropical Storm Nate this evening and into tonight. (image valid at 5:15 pm CDT).

Nate is progressing generally northward and will emerge over the Northwest Caribbean Sea late tonight where it will have an opportunity to reorganize. The waters over that region are running in the range of 84-86 degrees F (29-30 degrees C), more than sufficient for re-intensification. With that said, the inner core will likely be badly “gutted” by the mountainous terrain of Nicaragua and Honduras and with a second landfall possible Friday evening, time will likely be limited for more robust intensification. With that said, minimal hurricane strength is possible, with a lower chance that the storm may get stronger if it’s inner core can re-organize quickly Friday.

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National Hurricane Center forecast (issued 5 pm EDT Thursday) showing a likely landfall on the Yucatan Peninsula of Mexico Friday evening and likely US impacts on the northern Gulf Coast beginning Saturday evening.

A Hurricane Watch and Tropical Storm Warning is in effect for much of the coastal Yucatan Peninsula. Again, the major threats will be from water…heavy rain and freshwater flooding and also modest (although still hazardous) storm surge and high wave action.

Potential Impacts for Central Gulf Coast of US-

While many details are still in need of being honed in for the Central Gulf Coast…it is highly likely a tropical storm or minimal hurricane will approach the region Saturday evening with landfall early morning Sunday. The biggest threats will be from water (flooding/surge) with wind producing damage from falling trees and power outages.

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NWS Weather Prediction Center 5 day accumulative rainfall forecast (valid beginning 7 pm CDT Thursday) showing heavy rainfall along the track of Nate and its remnants expected, particularly Saturday afternoon into early next week. Very heavy rainfall possible in Greater New Orleans area which is prone to freshwater flooding.

Sea surface temperatures are slightly cooler along the northern Gulf Coast north of the Loop Current (82-84 degrees F/28-29 degrees C). Still more than warm enough for intensification if the system can remain over the current (a slightly farther west track may leave it over slightly cooler waters longer).

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Analysis of Sea Surface Temperatures and the Loop Current. Nate will track along the Loop Current much of its track over water, providing with fuel to re-intensify. (Analysis by Earth Nullschool).

Also, given the shear currently over the Central Gulf will relax over the next couple of days (as an area of upper-level high pressure over Texas shifts westward and weakens), Nate will have an opportunity to re-intensify over the Gulf after leaving the Yucatan Peninsula. Computer models have some variability in timing of an upper trough which will move over the US Central Plains during the day Saturday. This will ultimately influence the exact track of the center of Nate. However both deterministic and ensemble members of the various models depict a likely landfall of the center somewhere from Southeast Louisiana to coastal Mississippi/Alabama. Regardless, widespread heavy rain (particularly near and east of the center), moderate storm surge flooding and high wind conditions will be likely over the coastal areas of these states by Saturday afternoon, spreading inland Saturday night and Sunday. Tropical storm force winds (sustained 39 mph+) will likely arrive on the LA Coast Saturday evening.

 

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Earliest Reasonable Arrival Time for Tropical Storm-Force (issued 5 pm EDT). Folks along the Central Gulf Coast should have preparations for stormy conditions completed by Saturday afternoon.

Tropical cyclone watches will likely be issued for portions of Louisiana, Mississippi and Alabama late tonight or early tomorrow morning.

Climatology Update-

The Atlantic Hurricane Season is currently running above normal (1966-2010 norms in parenthesis): 14 named storms (9), 8 hurricanes (6) and 5 major hurricanes (2). In terms of Accumulated Cyclone Energy (a function of maximum sustained winds over time), 2017 ranks (as of this post) as the 6th most active season on record for the North Atlantic Basin. The average temperature of the North Atlantic Main Development region (open tropics west of Africa) exceeded 83 degrees F (~28 degrees C) for the 9th time since 2002 (had never done so in the record prior going back to 1981). The MDR is the 3rd warmest on record overall.

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My God…

Estimated 5-day total rainfall from Hurricane Harvey. In most tropical events, the light blue on this color scheme (12-16 inches) would be highly significant. And for many of subregions on this map, the bulk of rainfall fell in just 3 days. Again that would be significant alone. Here a wide swath of land was doused in in up 1 1/3 ft of rain from San Marcos, TX south to the coast and east of Lake Charles, LA. Within that rainfall totals turn into something nightmares are made of. Again much fell in subregions within 3 days. Beaumont, TX received nearly 2 feet of rain in 24 hrs yesterday where catastrophic flooding is in progress.

By Jordan Tessler for Capitol Weather Gang.

Flooding in Port Arthur this morning as witnessed by @MayorofPA on Twitter.
Flooding in Port Arthur as seen by @OliverTerry on Twitter.

–Meteorologist Nick Humphrey 

After Days of Agony…

The continuous rainfall in Houston…is over.



Unfortunately, Harvey remains a 45 mph tropical storm. Although its center has moved east, ending rain in Houston, the torrential rain is spreading into far SE Texas with increasing concerns in Southwest and southern Louisiana as well.

Heavy rain cause by thunderstorm activity north Harvey’s center to circulation. Far southeast TX into Southwest LA have been hard hit today with flash flooding.

Harvey is expected to make landfall on the Southwest LA Coast Wed morning. No further strengthening is expected as the system is too disorganized and in a high vertical wind shear environment to support rapid intensification (thankfully). It will move across western LA Wed-early Thurs, being heavy rain to much of the state and spreading into Arkansas.

New Record-

Today, Harvey (preliminarily) set the Continential US record for highest storm total rainfall for a tropical cyclone at 51.88 inches at Cedar Bayou in the Houston area. The previous record was Hurricane Amelia in 1978 with 48 inches (also in TX). Almost all of this rain fall in the 72 hr period with Saturday night-Sunday morning being the absolute worst with 15- 25 inches of rain in 12-15 hrs, initially the catastrophic urban flood event in Houston. One automated rain gauge which captured rainfall per min saw an equivalent rainfall rate ~12 inches/hr very briefly late Saturday night!


And additional 15-25 inches fell Sunday-Monday worsening the situation and conditions for those waiting for rescue miserable.

Storm totals ending Tuesday morning.

As of this post, 31 people are reported to have died as a result of Harvey in the US…one in Rockport who died in a house fire at the height of the storm; and 30 in the Houston area, most flood-related.

See photos of the disaster and human response by tve New York Times: HERE

Photo of flooded Houston street Sunday taken by a relative who lives there. She is safe.

(Title image is courtesy of Alyssa Schukar of the New York Times).

–Meteorologist Nick Humphrey

Monday Analysis on Tropical Storm Harvey and Outlook for Texas/Louisiana

This continues to be, by far the main weather story in the US. Harvey continues to produce historic catastrophic flash flooding in the Houston Metro area as well as other parts of Southeast Texas and now intensifying in Southwest Louisiana as the center of the tropical cyclone drifts offshore.

11 am CDT radar showing center of circulation moving offshore and rain bands continuing to circulate and pound Houston and the surrounding communities with moderate to heavy rainfall.
Main feeder band stretched out far from Harvey’s center pounding Lafayette and surrounding SW Louisiana with rainfall rates of up to 3+ inches/hr. Flash flooding is likely as the band somewhat “trains” shifting slowly north-northeast as it forms off the Gulf.(11:05 am CDT)

Massive amounts of rain have fallen as a result of Harvey.

Storm total precipitation from Harvey as of 7 am CDT Monday. (NWS)

Observed maximum precipitation since Friday ranges from 25-40 inches! The Houston Metro has been the center of the bullseye, resulting in catastrophic flooding, thousands recused by police and US Coast Guard and so many more still in need of help as waters are still expected to rise. Another 15-25 inches. Yes…the potential for over 50 inches of storm total rainfall exists. Over 30 inches may fall in parts of Southwest LA when all is said and done.
NWS Weather Prediction Center graphic on Harvey issued after 11 am CDT.

As you can see, the center of Harvey will continue to shift more offshore before pulling back for a historic *third* landfall on the Texas Coast near Galveston Wednesday. Because of the current structure of Harvey (lack of inner core) it’s not expected to rapidly intensify over the open coastal waters, however it will likely strengthen some and a 45-50 mph intensity is possible by Wed.

Thunderstorm activity (the brighter yellow in this image) recently firing up near center of circulation as Harvey begins to gain greater heat energy the open Gulf waters offshore SE Texas. Image at 11:15 am CDT

In the end, the maintenance or mild intensification of winds within the cyclone matter not so much as the structural survival of the system and its position as a “pump” from which to machine gun Southeast TX and Southwest LA with intense to horrific amounts of rain causing significant to catastrophic flooding the rest of the week until the system finally gets the steering currents to come far inland. This will be a major problem for awhile.

And if that wasn’t enough we have a potential new system initiating tropical storm watches for North Carolina and continued high heat and dryness out West and on the Northern High Plains. I’ll have more on the drought situation later today or tomorrow.

Photos from Houston this weekend…


From Rockport, TX where Harvey made landfall as a Category 4 hurricane-

-Meteorologist Nick Humphrey

Catastrophic freshwater flood event in progress Houston Metro/SE Texas

I could put so much into words what’s happening. Major flow of moistue from Tropical Storm Harvey has led to incredible rainfall totals and a devastating flood event for now ongoing in Houston and Southeast Texas. Damage is being done and lives are being lost while others are being rescued. It’s a horrible tragedy unfolding. This may very well rival HURRICANE KATRINA as one of the worst flooding disasters in US history. I do not say that lightly…but with around two FEET of rain fallen and another foot or more expected today, and more likely overnight…and tomorrow. This is simply a grotesque act of Motger Nature we are witnessing.

Follow my Twitter (@wxclimonews) or FB (Meteorologist Nick Humphrey) more constant news throughout the day. But…it’s just awful what’s happening there. Been up most of the night watching in absolute horror. Wish it would stop raining in Texas….
5 deaths this morning in Houston Metro so far from the flooding. 





Harvey Makes Historic Landfall in Texas; only beginning of Disastrous Several Days

Hurricane Harvey has made landfall on the Texas coast as a Category 4 storm with maximum sustained winds of 130 mph and gusts possibly as high as 145 mph around 10 pm CDT Friday night. It did so between Port Aransas and Port O’Conor. 

Hurricane Harvey making landfall in Texas tonight.

The eye of the hurricane moving ashore at 10:20 pm CDT. Destructive surge also in progress under and just north of the eye in addition to damaging winds in the eyewall surrounding the calmer eye.

As the system very slowly moves inland overnight it will gradually weaken. With that said, it’s damaging wind field will spread inland somewhat as it does so. However the biggest and most dangerous threat will continue to be (as it’s already begun) its heavy rainfall. As it stalls out “thanks” to VERY strong upper-level high pressure over The Western US, Harvey will literally sit over Southeast TX for 4-5 days dumping copious amounts of rain in bands of thunderstorms and tropical downpours. The result will likely be this:

National Hurricane Center forecast rainfall from Harvey tonight through next Wednesday. Up to 30 inches possible with isolated amounts up to 40 inches in “greater than 20 inch” coverage.

These rainfall totals will come with rainfall rates of perhaps 4-6 inches/hr, capable of producing catastrophic flash flooding. 

Track forecast for Harvey showing the terrible “weak steering” forecast in which the system has no steering current to shift it out of the area. It will produce prolific amounts of rain in short order.

Global Forecast System Model forecast valid 7 pm CDT Saturday showing sea level pressure and heights at 500 millibars (mid-levels of the atmosphere). The mid-level heights extending northward into the Western US/Canada associated with a ridge of the high pressure will prevent the low level circulation of Harvey in TX from advancing far inland.

On a historic note. Hurricane Harvey is the first major hurricane (Cat 3+) to make landfall in the US since Wilma in 2005 and the first Category 4 to do so since Charley in 2004. It is the first major for Texas since 1999 Bret and first Category 4 for that state since 1961 Carla.