Written by Sig Silber
Note: This article has been updated – Go to Tracking Irma while also Assessing Storm Impacts – 09 Sep2017
2PM EDT Sept 8: Storm Track for Sunday seems to have shifted just a bit west but a new Discussion will not be released until 5PM. But there is an updated Bulletin which contains similar information and it can be accessed here. The Forecast Advisory has also been updated. If we are reading the updated Track correctly, the storm has been forecast to be downgraded to a Tropical Depression by the time it reaches Northwest Georgia which means an end to special updates at that time. This article is updated every evening or more frequently when the situation is changing rapidly which is today and tomorrow for sure and possibly Sunday. There is a big difference between the strength of this storm while it will be in Southern Florida compared to when it will be further north but it can still be very dangerous there also.
Irma is now considered to be an imminent threat to CONUS.
Part A will be the current weather forecasts as they involve Irma.
Part BÂ will be the physical and human impacts of Harvey and Irma.
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Part A. Here we focus on the Meteorological Aspects of the Storms impacting or potentially impacting CONUS. We attempt to keep this information up to date. We will update this information frequently and one can also access some of this information directly from NOAA here if it has Hurricane status or potential or here if it has been downgraded to a Tropical Storm. It is our goal to provide in this continually updated report the information that readers will find most useful. But those links have additional information.
For some purposes, you might want to consult our Monday Weather and Climate report as that report has additional information on the overall weather situation. You can always find the location of all of our reports by clicking here.
Let’s Focus on Irma.
Latest Reported Track Forecast
Latest Irma Discussion
Hurricane Irma Discussion Number 36 NWS National Hurricane Center Miami FL 1100 PM EDT Thu Sep 07 2017
Microwave images and data from an Air Force Reserve Hurricane Hunter aircraft indicate that Irma is developing a concentric eyewall structure, and the plane reported an elliptical eye. The highest flight-level and SFMR winds measured by the aircraft were 146 kt and 139 kt, respectively, so the initial intensity is lowered slightly to 145 kt. Irma’s central pressure has fallen a bit despite the slight reduction in winds, counterbalanced by an expansion of the hurricane-force wind field as observed by the plane.
If Irma has developed concentric eyewalls, then some additional gradual weakening or fluctuations in intensity are possible over the next day or two, despite a seemingly favorable atmospheric and oceanic environment. The intensity models depict a very gradual decrease in Irma’s maximum winds up until a possible landfall in Florida, but the hurricane is nonetheless expected to still be at or near category 4 strength at that time. After landfall, a fairly quick decay in maximum winds is expected due to land interaction and increased shear, although Irma’s large wind field is likely to still produce hurricane-force winds over a large area.
Irma continues to move west-northwestward at 290/14 kt, steered by the western extent of the subtropical ridge. Irma should maintain this trajectory but slow down during the next 36 hours, and then turn north-northwestward toward a break in the ridge by 72 hours. Although there was a westward shift in the 18Z GFS, this model’s new track puts it very close to the previous NHC forecast.  As such, no major changes to the NHC track were required on this forecast through 72 hours, and the projected path lies between the GFS and ECMWF, closest to the TVCN consensus and HCCA. After 72 hours, the models are showing a more pronounced turn toward the northwest when Irma interacts with a shortwave diving southeastward from the Central Plains, and the NHC forecast has been adjusted accordingly at the end of the forecast period.
KEY MESSAGES:
1. Irma is a potentially catastrophic category 5 hurricane and will continue to bring life-threatening wind, storm surge, and rainfall hazards to the Turks and Caicos Islands and the Bahamas through Saturday. Heavy rainfall is still possible across portions of Hispaniola through Friday. Hurricane conditions will also spread over portions of the north coast of Cuba, especially over the adjacent Cuban Keys through Saturday.
2. Severe hurricane conditions are expected over portions of the Florida peninsula and the Florida Keys beginning late Saturday. Irma could make landfall in southern Florida as a dangerous major hurricane, and bring life-threatening storm surge and wind impacts to much of the state. A Hurricane Warning is in effect for southern Florida, the Florida Keys, Lake Okeechobee, and Florida Bay, while Hurricane Watches have been issued northward into central Florida.
3. A Storm Surge Warning is in effect for southern Florida and the Florida Keys. A Storm Surge Warning means there is a danger of life-threatening inundation, from rising water moving inland from the coastline, during the next 36 hours in the indicated locations. For a depiction of areas at risk, please see the National Weather Service Storm Surge Watch/Warning Graphic, available at hurricanes.gov. This is a life-threatening situation. Persons located within these areas should take all necessary actions to protect life and property from rising water and the potential for other dangerous conditions. Promptly follow evacuation and other instructions from local officials. A Storm Surge Watch has been issued north of the Storm Surge Warning for portions of the central Florida coast.
4. There is a chance of direct impacts in portions of Georgia, South Carolina, and North Carolina, but it is too early to specify the magnitude and location of these impacts.
FORECAST POSITIONS AND MAX WINDS
INITÂ 08/0300Z 21.3NÂ 72.4WÂ 145 KT 165 MPH
12HÂ 08/1200Z 21.8NÂ 74.4WÂ 145 KT 165 MPH
24HÂ 09/0000Z 22.3NÂ 76.7WÂ 140 KT 160 MPH
36HÂ 09/1200Z 22.9NÂ 78.6WÂ 135 KT 155 MPH
48HÂ 10/0000Z 23.7NÂ 79.9WÂ 135 KT 155 MPH
72HÂ 11/0000Z 27.2NÂ 81.1WÂ 100 KT 115 MPH…INLAND
96HÂ 12/0000Z 32.0NÂ 83.5WÂ Â 50 KTÂ 60 MPH…INLAND
120HÂ 13/0000Z 35.5NÂ 86.5WÂ Â 30 KTÂ 35 MPH…INLAND
Those impacted should consult their local sources of information. The Public Advisories and other information that is available from the NOAA National Hurricane Center can be found here.
And right behind Irma: Jose which appears to be forecast to turn out to sea.
And over in the Western Gulf of Mexico: Katia which clearly is a threat to Mexico
Current Conditions and Short-Term Forecast. The Above Information was Provided by the National Hurricane Center. Now I Present information from Other Parts of NOAA.Â
Additional Graphics
This is a national animation of weather fronts and precipitation forecasts with four 6-hour projections of the conditions that will apply covering the next 24 hours and a second day of two 12-hour projections the second of which is the forecast for 48 hours out and to the extent it applies for 12 hours, this animation is intended to provide coverage out to 60 hours. This graphic is now very relevant. Irma early impacts are shown. Irma is shown. Notice how the weather is moving southeast into Florida in the early part of this animation and then it suddenly turns around and moves to the north as Irma arrives.
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Part B. The Human and Economic Impacts of Recent Storms
B1. Irma Impacts
First Saint Martin especially the French portion of the Island.
Hurricane Irma destroys ‘95%’ of French part of St Martin
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Saint Martin September 6, 2017Â Photo Credit. Lionel Chamoiseau/AFP/Getty Images
B2. Harvey Meteorological Summary (For Analysis Purposes Mainly)
Final NOAA Harvey Advisory.
POST-TROPICAL CYCLONE HARVEY ADVISORY NUMBER 53 NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 1100 AM EDT SAT SEP 02 2017
POST-TROPICAL CYCLONE HARVEY CONTINUES TO WEAKEN…
SUMMARY OF 1100 AM EDT…1500 UTC…INFORMATION
LOCATION…38.1N 84.9W ABOUT 20 MILES…30 KM…WNW OF LEXINGTON KENTUCKY ABOUT 60 MILES…100 KM…ENE OF FORT KNOX KENTUCKY MAXIMUM SUSTAINED WINDS…15 MPH…25 KM/H PRESENT MOVEMENT…NE OR 045 DEGREES AT 5 MPH…8 KM/H MINIMUM CENTRAL PRESSURE…1013 MB…29.92 INCHES
WATCHES AND WARNINGS
FLOOD WARNINGS AND ADVISORIES ARE ONGOING SCATTERED THROUGHOUT EASTERN TEXAS…THE LOWER MISSISSIPPI VALLEY…TENNESSEE VALLEY…AND THE LOWER OHIO VALLEY.
DISCUSSION AND 48-HOUR OUTLOOK
AT 1100 AM EDT…1500 UTC…THE CENTER OF POST-TROPICAL CYCLONE HARVEY WAS LOCATED NEAR LATITUDE 38.1 NORTH…AND LONGITUDE 84.9 WEST. HARVEY CONTINUES TO WEAKEN AND IS EXPECTED TO DISSIPATE OVER THE MID-UPPER OHIO VALLEY BY TONIGHT ALONG WITH ANY LINGERING HEAVY RAIN AND RUNOFF THREAT DIRECTLY RELATED TO THE CIRCULATION. HOWEVER, A SEPARATE AREA OF LOW PRESSURE DEVELOPING OVER THE MID-ATLANTIC REGION AHEAD OF HARVEY WILL INTERACT WITH ITS REMNANT MOISTURE PLUME TO PRODUCE AS MUCH AS 1 TO 2 INCHES OF RAIN OVER THE NORTHEAST THROUGH SUNDAY.
HAZARDS AFFECTING LAND
RAINFALL…RESIDUAL FLOODING WILL CONTINUE IN AND AROUND HOUSTON, BEAUMONT/PORT ARTHUR/ORANGE, AND EASTWARD AROUND THE LOUISIANA BORDER THROUGH THE WEEKEND. DO NOT ATTEMPT TO TRAVEL IN THE AFFECTED AREA IF YOU ARE IN A SAFE PLACE. DO NOT DRIVE INTO FLOODED ROADWAYS.
NEXT ADVISORY
THIS IS THE LAST PUBLIC ADVISORY ISSUED BY THE WEATHER PREDICTION CENTER FOR THIS SYSTEM. PLEASE REFER TO YOUR LOCAL NATIONAL WEATHER SERVICE OFFICE FOR FURTHER INFORMATION ON THIS STORM.
FORECAST POSITIONS
INITIAL 02/1500Z 38.1N 84.9W
12HR VT 03/0000Z 39.8N 82.3W…POST-TROP/EXTRATROP
24HR VT 03/1200Z…DISSIPATED
Harvey Final Reported Precipitation Totals as of 11AM EDT September 2, 2017. There is no longer a separate site that I know of that provides update totals and they will no longer be in the WPC Updates so most likely this will be the final update of this information. We may add local updates if significant.
And then Additional States were Impacted.
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New States being Impacted
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Second Set of States Impacted (This data is as reported on Thursday 10 PM August 31.
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Initial States Impacted (These totals are no longer being updated so they were correct as of 10 AM CDT Wednesday August 30).
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Below is the last reported Track. There are no further updates of the track but you can tell the track by other graphics that I have included. Also the track is describe in the discussion which is up to date. We are now at the end of the reported track so this graphic is mostly of historical significance now.
Interesting way to view the precipitation pattern in the Houston area.
B2: Harvey Impacts
Economic Impacts.
The usual impacts of a disaster are first very negative and later very positive and essentially reflect Keynesian Economics. Unfortunately the first phase comes first and it can be very heartbreaking. One clue to how this might work out is provided by this excellent article.
More Than 50 Percent Of Properties In Houston At High And Moderate Risk Of Flood Are Not In Designated Flood Zones
First Report on number of homes damaged. Source: Market Watch
About 100,000 homes were damaged by Hurricane Harvey, President Donald Trump’s Homeland Security Adviser Tom Bossert told reporters on Thursday. Speaking at the White House, Bossert said the administration would soon ask Congress for an initial round of emergency funding to aid relief efforts. He said a second request would be made after getting more information.
Total Residential Insured And Uninsured Flood Loss For Hurricane Harvey Between $25 Billion And $37 Billion Approximately 70 Percent Of Flood Damage Is Uninsured
Oil Refinery Impacts
At the Beaumont-Port Arthur Airport, 26.03†of rain fell on Tuesday, which is more than double Beaumont’s previous calendar-day record of 12.76″ on May 19, 1923, in records going back to 1901. Between 10 pm last night and 1 am this morning, 11.86†fell. So far on Wednesday, 4.71†has been reported (as of 11 am CDT), bringing their 5-day storm total rainfall to a staggering 47.98â€. The intense rains caused extreme flash flooding that inundated all of Port Arthur, according to Mayor Freeman, who showed a video this morning of the inside of his flooded house on his Facebook page. Port Arthur is the site of the nation’s largest oil refinery, which was forced to shut down due to the floods. The nation’s second-largest refinery, in Baytown, TX, was also forced to shut down yesterday, due to flooding-induced roof damage. In all, at least 12 refineries are currently offline due to Harvey. Source: Weather Underground Category 6 Click to Read Full Article
From this Geopolitical Futures article
The following is from our initial assessment Saturday afternoon. We will attempt to provide an organized assessment rather than streaming news reports as they come it. There is so much reporting that streaming these reports would mostly duplicate the traditional news services. So we will attempt to consolidate the information and provide a somewhat comprehensive analysis.Â
Concern about Facilities that Depend on Cooling.
Arkema: No way to prevent explosion at flooded Texas chemical plant Click to read more
Well it seems the report unfortunately was timely as this chemical plant has had explosions. You may be able to read about it here (you may hit a paywall not sure).
This is what we reported Saturday afternoon. There are many pictures showing flooding and other damage that we could show now.
Some of the graphics are very disturbing. But first we want to put this storm into perspective. This graphic was sent in by the NWS in Jackson Kentucky but was probably originally prepared by PBS.
It shows that very wet events are not unknown to Texas so we hope they are prepared to deal with this one.
This is a photo shown on the Blog Category 6; Image Credit is Joe Raedle/Getty Images.
Rockport is about 40 miles Northeast of Corpus Christi and presumably exposed to the strongest winds which are often in the NE quadrant of the storm. Harvey’s winds declined rapidly so we should expect that wind damage now will be restricted to tornadoes which can be very deadly. The main story here will be the flooding.
Another Rockport photo
More photo coverage of Rockport can be found here. For some reason the photo credit that is on the photo in the article does not show up when I display the photo separately. It is Brian Emfinger/LSM
We should expect that damage reports may come in slowly since may areas have been evacuated and the media may not be allowed in until the areas are deemed to be save from down power lines etc.
Tornadoes will cause a lot of damage. Right now they seem to be happening in the Cypress Area Northwest of Houston while in Houston flooding has been significant.
Source: Houston News KHOU
Same source for photos below: KHOU with the first photo credited to Kyra Respress.
and one more.
So far the reports of injured and deaths are amazingly low. That might change.
This is an excellent report from the Daily Mail in the UK – Lots of photos.
What Happens Next
It is important to understand that natural disasters often occur over a period of time, not instantaneously.
A good example is the rising of rivers which then overflow their banks and cause damage many hours and even days after the advent of a widespread storm. It takes time for this to happen and with Harvey we have a storm that is likely to provide the time for such subsequent events. Below, from NOAA, is a forecast for the San Bernard River. It is already at flood stage. Not sure how the river can rise to 35 feet once the level is so high that it can no longer be confined by the river banks but the graphic may be intended to show the severe level that is predicted. (If the normal level is x feet below the average river bank height, then all land within 35-x feet in elevation above normal water level will be flooded.)