Written by Sig Silber
This Article has been updated. You can access the updated article by clicking on: Saturday Night Arrival but Exactly Where? – 07Oct2017
Updated Noon CDT Oct 06, 2017: LATEST FROM NHC: “…NATE STRENGTHENING OVER THE NORTHWESTERN CARIBBEAN SEA… …HURRICANE AND STORM SURGE WARNINGS ISSUED FOR THE NORTHERN GULF COAST… ” “A HURRICANE WARNING IS NOW IN EFFECT FROM GRAND ISLE LOUISIANA TO THE ALABAMA/FLORIDA BORDER…A STORM SURGE WARNING IS NOW IN EFFECT FROM MORGAN CITY LOUISIANA TO THE ALABAMA/FLORIDA BORDER…AND FOR THE NORTHERN AND WESTERN SHORES OF LAKE PONTCHARTRAIN.”
Hurricane track appears to be shifting slightly to the East. We will update again tonight. For those who desire more frequent updates, these are available by clicking here. Flash flooding inland is now a concern including the southern Appalachians.
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In this Article we are going to focus mainly on the Atlantic and Tropical Storm Nate (formerly Tropical Depression 16) in Particular.
Here is the Track. There has been a slight shift to the east which may reduce the threat to New Orleans but the track can change.
This is also of interest.
And this:
Here is the Discussion
Tropical Storm Nate Discussion Number 9 NWS National Hurricane Center Miami FL 1000 AM CDT Fri Oct 06 2017
Reports from Air Force Reserve and NOAA Hurricane Hunter aircraft indicate that Nate lacks an inner wind core at the present time, with the maximum winds located about 50 n mi from the center. The central pressure is fluctuating near 996 mb, and the aircraft-reported winds support an initial intensity of 45 kt. This is in good agreement with the satellite intensity estimates from TAFB and SAB. Satellite imagery shows that convection associated with Nate has been increasing during the past several hours, and that the storm has good outflow in the western semicircle.
The center has moved generally northward during the past 12 hr. However, the latest recon fixes and satellite imagery suggest that a north-northwestward motion is resuming at about 18 kt. Nate is between a complex deep-layer low pressure area over the western Gulf of Mexico and Central America and a building ridge of high pressure over the western Atlantic. This combination should steer the storm quickly north-northwestward for the next 36 h or so. After that, Nate should turn northward and northeastward as it goes around the western edge of the ridge and recurves into the mid-latitude westerlies. While the guidance is in good agreement with this scenario, there has been a rightward shift to the latest guidance, likely due to the recent northward motion. The new forecast track is thus also shifted to the east of the previous forecast, and it now calls for the center of Nate to pass near or over the northeastern tip of the Yucatan Peninsula in about 12 h, followed by landfall on the northern Gulf Coast between 36-48 h. The new track is in the center of the guidance envelope in good agreement with the various consensus models.
Conditions appear favorable for strengthening up to landfall on the northern Gulf Coast, and Nate is expected to make landfall there as a hurricane. The new intensity forecast, which is an update of the previous one, lies near the upper edge of the intensity guidance. It should be noted that the Rapid Intensification Index of the SHIPS model continues to indicate an above normal chance of rapid intensification. However, the current structure of the cyclone does not favor rapid development.
KEY MESSAGES:
1. Nate could be near hurricane intensity when it approaches the Yucatan Peninsula later today bringing direct impacts from wind, storm surge, and heavy rainfall. A tropical storm warning and a hurricane watch are in effect for a portion of this area, and life-threatening flash flooding is also possible.
2. Life-threatening storm surge flooding is likely along portions of the northern Gulf Coast, and a storm surge warning has been issued from Morgan City, Louisiana, to the Alabama/Florida border. Residents in these areas should heed any evacuation instructions given by local officials.
3. A hurricane warning has been has been issued for portions of the northern Gulf Coast from Louisiana to Alabama, and preparations to protect life and property should be rushed to completion in these areas.
4. Nate will bring heavy rainfall of 3 to 6 inches with isolated totals of 12 inches from the central Gulf Coast states into the eastern Tennessee Valley and southern Appalachians through this weekend, resulting in the possibility of flash flooding in these areas.
5. Heavy rainfall from Nate will continue to be a threat in portions of Central America, with life-threatening flash flooding and mud slides possible in portions of Nicaragua, Honduras, Costa Rica, Panama, and Belize through tonight.
FORECAST POSITIONS AND MAX WINDS
INIT 06/1500Z 18.7N 85.0W 45 KT 50 MPH
12H 07/0000Z 21.3N 86.3W 50 KT 60 MPH
24H 07/1200Z 24.8N 88.3W 60 KT 70 MPH
36H 08/0000Z 28.1N 89.3W 70 KT 80 MPH
48H 08/1200Z 31.1N 88.1W 60 KT 70 MPH…INLAND
72H 09/1200Z 37.5N 80.5W 30 KT 35 MPH…INLAND
96H 10/1200Z 42.0N 70.0W 25 KT 30 MPH…POST-TROP/REMNT LOW
120H 11/1200Z…DISSIPATED
TROPICAL STORM NATE FORECAST/ADVISORY NUMBER 9 NWS NATIONAL HURRICANE CENTER MIAMI FL 1500 UTC FRI OCT 06 2017
CHANGES IN WATCHES AND WARNINGS WITH THIS ADVISORY…
A HURRICANE WARNING IS NOW IN EFFECT FROM GRAND ISLE LOUISIANA TO THE ALABAMA/FLORIDA BORDER.
A STORM SURGE WARNING IS NOW IN EFFECT FROM MORGAN CITY LOUISIANA TO THE ALABAMA/FLORIDA BORDER…AND FOR THE NORTHERN AND WESTERN SHORES OF LAKE PONTCHARTRAIN.
A TROPICAL STORM WARNING IS NOW IN EFFECT FOR METROPOLITAN NEW ORLEANS…LAKE PONTCHARTRAIN…AND LAKE MAUREPAS…AND FROM WEST OF GRAND ISLE TO MORGAN CITY LOUISIANA.
A HURRICANE WATCH IS NOW IN EFFECT EAST OF THE ALABAMA/FLORIDA BORDER TO THE OKALOOSA/WALTON COUNTY LINE.
A STORM SURGE WATCH IS NOW IN EFFECT EAST OF THE ALABAMA/FLORIDA BORDER TO INDIAN PASS FLORIDA.
A TROPICAL STORM WATCH IS NOW IN EFFECT EAST OF THE OKALOOSA/WALTON COUNTY LINE TO INDIAN PASS FLORIDA.
THE GOVERNMENT OF CUBA HAS ISSUED A TROPICAL STORM WARNING FOR THE PROVENCE OF PINAR DEL RIO AND A TROPICAL STORM WATCH FOR THE PROVENCE OF THE ISLE OF YOUTH.
THE METEOROLOGICAL SERVICE OF HONDURAS HAS DISCONTINUED THE TROPICAL STORM WARNING FOR THE COAST OF HONDURAS.
SUMMARY OF WATCHES AND WARNINGS IN EFFECT…
A HURRICANE WARNING IS IN EFFECT FOR…
* GRAND ISLE LOUISIANA TO THE ALABAMA/FLORIDA BORDER
A STORM SURGE WARNING IS IN EFFECT FOR…* MORGAN CITY LOUISIANA TO THE ALABAMA/FLORIDA BORDER * NORTHERN AND WESTERN SHORES OF LAKE PONTCHARTRAIN
A TROPICAL STORM WARNING IS IN EFFECT FOR…
* PUNTA HERRERO TO RIO LAGARTOS MEXICO
* PINAR DEL RIO
* METROPOLITAN NEW ORLEANS
* LAKE PONTCHARTRAIN AND LAKE MAUREPAS
* WEST OF GRAND ISLE TO MORGAN CITY LOUISIANA
A HURRICANE WATCH IS IN EFFECT FOR…
* PUNTA HERRERO TO RIO LAGARTOS MEXICO
* METROPOLITAN NEW ORLEANS
* LAKE PONTCHARTRAIN AND LAKE MAUREPAS
* EAST OF THE ALABAMA/FLORIDA BORDER TO THE OKALOOSA/WALTON COUNTY LINE
* WEST OF GRAND ISLE TO MORGAN CITY LOUISIANA
A STORM SURGE WATCH IS IN EFFECT FOR…
* EAST OF THE ALABAMA/FLORIDA BORDER TO INDIAN PASS FLORIDA
A TROPICAL STORM WATCH IS IN EFFECT FOR…
* EAST OF THE OKALOOSA/WALTON COUNTY LINE TO INDIAN PASS FLORIDA
* WEST OF MORGAN CITY TO INTRACOASTAL CITY LOUISIANA
* ISLE OF YOUTH
General Weather Situation
We believe that it is easier to understand what is going on with individual storms if they are put into the context of the overall weather situation.
The graphic above is particularly useful as it shows the forecasted conditions that might determine the future of a storm beyond the predictions of where the storm might be on Day 3. This graphic is updated frequently. By Day 3, Hurricane Nate is being shown in the forecast.
Below are the Sea Surface Temperature Anomalies. You can see that it is a bit warm where the storm was generated but normal along its projected track until it gets close to shore along the northern Gulf Coast and there it is just barely warmer than climatology along the shore: just barely if at all.
Additional Graphics
This is the Day 1 Forecast. You can see Hurricane Maria
This is a Day 2 Forecast. The Low over Florida may interact with this new storm.
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 very relevant as one can see both storms of most interest in this graphic. .
The explanation for the coding used in these maps, i.e. the full legend, can be found here although it includes some symbols that are no longer shown in the graphic because they are implemented by color coding.
You can see the forecast for seven days of cumulative precipitation. It is important to keep in mind that these are forecasts going forward. QPF for this new storm has now been factored in. It extends into the southern Appalachians.
The water vapor imagery is a good guide to where precipitation is occurring.You can see the impact of the current tropical wave on Florida which now seems to have moved back over Cuba.
