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).

SSTs
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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Florida Peninsula Forecast for Hurricane Irma (Sat night update)

EDIT AT 8 PM EDT:

Hurricane Irma made landfall in the coastal keys of Cuba last night as a Category 5 hurricane with maximum sustained winds of 160-165 mph. Since then, it has continued to batter Cuba all day, but is now slowly pulling away from Cuba toward it’s final approach to Florida.

I cannot stress how serious this storm is. The track has shifted toward a more west coast track (SW FL landfall, track northward up the Peninsula). However, because of the sheer massive size of this storm it is likely to produce significant wind damage across the state of Florida (catastrophic near the eye in SW FL) as well as potentially significant to catastrophic storm surge impacting much of the central and southwest FL coasts. For the city of Tampa, this may be the most destructive hurricane in many decades. In addition, very heavy rain is expected (in progress) capable of producing flash flooding as well as an elevated tornado threat (in progress). I will update this page further and will be sharing more frequent info via Twitter and Facebook.


This is forecast information for the Florida Peninsula related to Hurricane Irma. I will update and repost this page periodically through Sunday. I have LOTS of friends in Florida even though I have never stepped foot in the state, so I have much concern for them and their families. If you know anyone in evacuation areas or who haven’t prepared for the storm’s impacts, tell them to do so now. The time is running out. Irma will likely make landfall with maximum sustained winds of at least Category 4 strength (130 mph+).

8 pm EDT-

Maximum Sustained Winds: 120 mph, gusts up to 150 mph. (Category 3)

Hurricane-Force Wind Field (74 mph+ sustained): 70 miles from center.

Tropical Storm-Force Wind Field (39 mph+ sustained): 195 miles from center.

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Impacts-

Storm Surge-

Surge could reach up to 10-15 feet in some portions of Southwest Florida. Other areas may be up to 4-10 feet of surge. Of note, Tampa Bay may see 5-8 feet of surge and the Naples area may see the 10-15 ft water rise above dry ground (if at high tide). The storm surge threat is potentially significant and life-threatening. The risk is extensive surge is high over both SW and SE FL. I list storm surge first because it is the number one greatest killer in hurricanes. For Storm Surge Guidance see the NHC. (great interactive map I highly recommend): HERE

Wind-

South Florida (Map):

Timing: Tropical storm conditions (sustained winds) overspreading the region from the south this evening. Hurricane conditions (sustained winds) will arrive from the south beginning early Sunday morning. Wind gusts will exceed well over 100 mph across Southwest FL (over 85 mph Southeast), with stronger winds from onshore flow along the coastal areas. Winds will be stronger in SE FL if the center makes landfall even a few tens of miles farther east than forecast. The highest winds will be in the eye wall which is expected to move over portions of SW FL. At Category 4 intensity, gusts will exceed 150 mph in the eyewall.

Central Florida (Map):

Timing: Tropical storm conditions expected to overspread region from the south beginning midday Sunday. Hurricane conditions are likely from the south beginning as early as Sunday evening. Wind gusts will exceed 100 mph particularly in western areas (up to 85 mph over central and 75 mph over eastern locations), with the most intense gusts (115 mph+) in areas within the eyewall of the northward advancing hurricane.

North Florida Peninsula and far South Georgia (Map):

Timing: Tropical storm conditions expected to overspread region from the south beginning late-Sunday night. Hurricane conditions are possible on the Florida side, to the south and west (northwest of Gainesville, southeast of Tallahassee) early-Monday morning. Wind gusts will exceed 75 mph, with (in Florida) isolated gusts to 90 mph in any remaining organized eyewall of Irma in western areas (up to 65 mph over the eastern locations).

Tornado Threat- 

The tornado threat related to the advance of Hurricane Irma is in progress and will continue to spread from south to north across the Florida Peninsula through Sunday. Tropical cyclone tornadoes can spin up quickly and move fast. Be ready to take shelter when warnings are issued in the rain bands. See the Storm Prediction Center for additional info.

Rainfall-

Much of South Florida is expecting 15-20 inches of storm total rainfall from Irma. The rest of the peninsula can expect 6-15 inches of rainfall. Flash flooding and urban flooding will be problems from Irma.

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Please keep track of the latest forecasts from your local TV meteorologists, local National Weather Office, as well as the National Hurricane Center.

–Meteorologist Nick Humphrey

Violent Hurricane Irma direct threat to Florida Sunday

Violent Hurricane #Irma direct threat to #Florida Sunday. #FLwx

The following is an analysis of the situation related to the potential landfall of Hurricane Irma this weekend in the United States. Let’s take a look at things currently (as of 5 pm CDT Thursday)-

Hurricane Irma is a violent Category 5 hurricane with maximum sustained winds at 175 mph (150 knots). Numerical models have been struggling on the exact path of the hurricane, but the general scenario is clear; there appears to be high confidence that the hurricane will make landfall in South Florida early-Sunday morning. The National Hurricane Center has the hurricane intensity forecast as a high-end Category 4 hurricane near landfall (max winds 150-155 mph with gusts up to 180-190 mph). This is after the hurricane impacts the southern Bahamas and the north Coast of Cuba with hurricane-force winds Friday-Saturday. After landfall either near or just north or south of Miami (this has been fluctuating in forecasts), the system is expected to advance northward spreading destructive winds, heavy rain, and (along the coast) damaging surf/surge northward up the Peninsula of Florida.

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Track forecast and current wind extent for Hurricane Irma by the National Hurricane Center as of 5 pm EDT Thursday.
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Category 5 Hurricane Irma plowing its way through the Turks and Caicos Islands at this time. Maximum sustained winds up to 175 mph with gusts to 210 mph in the inner eye wall surrounding the eye.
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Close up view of eyewall of Hurricane Irma impacting the Turks and Caicos Islands this afternoon.

I will not sugar coat this. This is most one of the most serious hurricanes Florida has faced in a very long time. Certainly since Charley in 2004 (Category 4) and perhaps since Andrew in 1992 (Category 5). Enhanced locally by issues such as sea-level rise (climate change) and especially land use changes and urban population growth and land cover changes (geographic changes). In addition sea-surface temperatures (SSTs) were the 3rd highest on record globally for the month of August behind 2016 and 2015 (extraordinary considering no El-Nino in the tropical Pacific…much of the Atlantic basin is running above normal; in the long term trend, SSTs are warming because of climate change, however, shorter term climate variability, including the continued shorter multi-decadal cycle for enhanced SSTs and hurricane activity in the Atlantic contributing). The enhanced SSTs and deep warm waters (oceanic heat content) are leading to Irma having ample fuel to remain extremely powerful for a very long period of time. In fact, it became the longest tropical cyclone ever observed in the satellite era (since 1966) to have a strength of 160 knots (185 mph for 37 hrs straight). It has been a category 5 storm operationally since 8 am EDT Tuesday Sept 5th (now third longest streak on record in the Atlantic Basin as of this post, being out 2004 Hurricane Ivan). All this is from warm SSTs, low wind shear not sufficient to disrupt the circulation and low land interaction with the terrain of Hispaniola, which it managed to largely avoid last night (minus minor inflow of drier air off the mountainous terrain to south of the eye, lowering its intensity slightly).

A HURRICANE WATCH has been issued for much of the coastal areas, including the Keys and Lake Okeechobee (see NHC advisories for updates). Hurricane warnings will likely be issued by tomorrow night as the hurricane continues to approach. Evacuations have been called for portions of the Keys and for Miami-Dade County and other areas. If you are in South Florida and in an evacuation area for storm surge and haven’t evacuated, I would highly suggest you do so or call 311 for aid if you are disabled and have difficulty leaving your home. Surge in portions of South Florida from this hurricane could reach 10 ft or more. This is simply not survivable if you’re along the open ocean coast. It is twice as high as my height (I am 5′ 6″ tall). Surge is dependent upon the track and strength of the storm as well as the tidal heights…and if you stay, you basically put your life in the hands of a lifeless beast…

StormSuge
NHC storm surge guidance (with intertidal layer included to neglect surge flooding in those areas). Based on current forecast track and subject to change (see NHC for updates).

In addition, I do have serious concern Irma could make landfall in South Florida stronger than forecast. The system currently has much going for it. Thus far, the hurricane has exhibited INCREDIBLE resilience. It’s been unable to be significantly impacted by outside forces (weak vertical wind shear which would hamper weaker systems) or internal fluctuations in the inner core region surrounding the eye where the strongest winds are located. This is why Irma has remain so powerful for so long. In addition, beginning basically tonight into tomorrow, it will be entering a region of increasing sea surface temperatures and oceanic heat content (increasing heat with greater depth) and at the same time, the relatively modest vertical wind shear which has attempted to disrupt (largely unsuccessfully) the “inertially stable” inner core will remain modest or even weaken. This means, unless the system moves farther west than forecast and hits Cuba (which would be a catastrophe for them) before turning north, it would will likely (in my opinion) be a Category 5 hurricane as it approaches South Florida last Saturday night-early Sunday. So at least 160 mph sustained with gusts perhaps over 175 mph within the inner eyewall. The surge would be higher than currently forecast and as a result more lethal along the coast, extending farther inland. The winds would also be more destructive at landfall and with greater extent farther inland.

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Sea Surface Temperature Analysis for Sept. 6th showing waters of 29-30 degrees C (84-86 degrees F) under Irma currently and waters of 30-31 degrees C (86-88 degrees F) in its path between Cuba and the Bahamas. (NOAA/AOML)
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Tropical Cyclone Heat Potential showing oceanic heat of 70-90 kilojoules per sq cm under Irma. It increases up to 100-120 kJ/sq cm between Cuba and the Bahamas.
Analysis
Shear Analysis showing favorable conditions for vertical wind shear for Irma as it is forecast to move between Cuba and the Bahamas Friday. (CIMSS)

With that said, regardless, of Category 4 or 5, the south-to-north track up the peninsula as a violent hurricane moving at a relative speedy clip (over 15 mph) is a worst-case scenario at it exposes many significant populations to hurricane-force high wind event. A category 4 hurricane at landfall is a catastrophic storm for all hazards as well. Obviously if you are inland and far from the potential surge areas, be ready for days of outages with the necessary supplies and gas (which is quickly running low in many areas!).

If you are in parts of Georgia and South Carolina…keep track of Irma’s track…while there was some talk of it actually making its first landfall in those states, it appears the Florida chances of first landfall are increasing. However, damaging wind gusts (as well as very heavy rain and inland flooding) associated with the landfalling hurricane may spread northward into these states Sunday night-Monday. Track the latest forecasts and be ready for deteriorating weather conditions by the end of the weekend.

I will continue to have frequent updates on things on Twitter and Facebook. I’ll see about more extensive updates on the blog in the coming few days. Hopefully all this writing is wrong and this system misses Florida completely. There has already been incredible damage in Barbuda, Anguilla, the British Virgin Islands, as well as extensive impacts in the US Virgin Islands and Puerto Rico. The Turks and Caicos Island are suffering a direct hit this afternoon/evening. A truly awful storm we can all hope comes to a conclusion soon. But unfortunately the US may be the last on the list of targets folks in the path must be prepared to action to protect life and property.

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–Meteorologist Nick Humphrey

EDIT at 7:50 pm CDT: Excuse the typo in the shear analysis graphic. That should say “Hurricane Irma”.

Catastrophic Hurricane Irma heading for Leeward Islands. Florida must get ready.

Category 5 Hurricane Irma bearing down on the Leeward Islands at 8:45 am CDT Tuesday.

If you’re in South Florida or the Florida Keys…you need to know what you’ll to once watches and warnings are issued BEFORE they are issued. I do have enough confidence in the path of Hurricane Irma to state that Florida is in a very serious situation based on forecast data and so folks need to 1) track the forecast 2) know your plan, especially if you live in coastal evacuation zones 3) have emergency supplies ready. This storm already has the potential to be devastating for many people all week as it buzzsaws its way through the northern Leeward Islands, close approach to US and British Virgin Islands, then the US territory of Puerto Rico with 3.5 million people, the Dominican Republic, then portions of the Bahamas, before a close passage of the coast of Cuba. And it could do this as a large Category 4-5 hurricane. 
Most likely time of arrival of tropical storm force winds overlay 7 am CDT probability of those winds during 5 day forecast period. Note South Florida is most likely to see winds arrive by Saturday morning and they could arrive overnight Fri-Sat, with the eye not expected near Florida until Sat night-Sun morning.

Get ready, be ready to act if/when watches/warnings are issued and keep track of the latest forecast. Also, hope the best for our friends facing Irma right now.

I’ll updates on Irma throughout the week and you can follow me on Facebook and Twitter.

EDIT AT 10:20 am CDT: Winds in Hurricane Irma increased to 180 mph, making it the most powerful hurricane (by wind) ever observed in the North Atlantic outside the Gulf of Mexico and Caribbean Sea.

–Meteorologist Nick Humphrey

Hurricane Irma threatening the Lesser Antilles; landfall risk increasing for US late week

PHurricane warnings have been issued for the northern islands of the Lesser Antilles as Hurricane Irma – as of this post, a Category 3 Hurricane with maximum sustained winds of 115 mph – approaches after days of crossing the tropical Atlantic from its birthplace over West Africa.


Enhanced infrared satellite image of Irma.

The hurricane is expected to intensify into at least a Category 4 hurricane as it approaches the Lesser Antilles Tuesday. This will be as a result of a combination of reduced vertical wind shear and gradually warming sea surface temperatures along the track. Areas near center will face destructive winds, highest storm surge/surf, and torrential rain. 

In addition to the Lesser Antilles, Puerto Rico, the Dominican Republic, and the Bahamas will need to be ready to make preparations if and when watches and warnings are issued. If trends in the forecast continue, they will likely be required in the next 48-72 hrs.

As for the United States…the risk of landfall by Irma is increasing as models indicate the possibility of either landfall somewhere along the East Coast (particularly the Southeast to Mid-Atlantic) or an offshore recurvature ultimately heading out to sea. Obvious, the implications for damage potential are dramatically different for either grouping of scenarios. Stay up to update on the latest forecast. We should continue to know more over the next few days.

Expected onset of tropical storm force winds and the probability of tropical storm force winds as of the advisory time.

Probability of hurricane force winds.

–Meteorologist Nick Humphrey 

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.

JPL 2017 Eclipse Simulator

Anyone want to know what the 2017 Eclipse will look like at your location with nice graphics and all? Check out this excellent simulator put together by NASA’s Jet Propulsion Laboratory. You’ll be able to animate the eclipse for any given location in the US from beginning to end and find out what to expect. I made a collection of some of the locations which will experience partial eclipses (all at their time of maximum eclipse). All these location were in areas of 75% or greater obscuration of the solar disk. Optical and atmospheric effects begin to take hold with 75% obscuration as incoming shortwave radiation from the sun is significantly reduced. Read more about that in my previous July post HERE if you haven’t already. Remember, however, that even with 99% obscuration, the sun will still be too bright and therefore too dangerous too look at directly without certified eclipse glasses. Direct viewing of the sun for multiple minutes can blind you, any amount can cause eye injury!

Seattle
Seattle, WA. My home city! 92% Obscuration.
Portland
Portland, OR. 99% Obscuration. So close to totality, yet so far!
San Francisco
San Francisco, CA. 75.5% Obscuration.
Denver
Denver, CO. 92% Obscuration.
Brookings
Brookings, SD. The location of my undergraduate alma mater South Dakota State University. 89% Obscuration.
Minneapolis
Minneapolis, MN. My Mom and much of my extended family lives here. They’ll take in the show. 83% Obscuration.
Dallas
Dallas, TX. 75% Obscuration.
Atlanta
Atlanta, GA. 97% Obscuration.
DC
Washington, DC. 81% Obscuration.
Jacksonville
Jacksonville, FL. 90.5% Obscuration.

Additional eclipse info for this post (such as max eclipse time) is courtesy of Xavier Jubier’s 2017 Total Eclipse Interactive Map.