# Presentation: 335967

**The Time for Special Marine Warnings****                     An exercise focused on the marine **
**            ****customer–oriented perspective on lead times**

**	**

**          ****Pete Wolf ****	****        ****                  ****Andrew Shashy**
**Science/Operations Officer****	****   ****	****   Sr. Forecaster/Marine Focal Pt.**
**     ****NWS Jacksonville FL****	****  ****	****             NWS Jacksonville FL**
**    ****Peter.Wolf@noaa.gov****	****                       Andrew.Shashy@noaa.gov**

**Notes:**
This exercise focuses on the necessary lead time for Special Marine Warnings needed to allow mariners to seek safe shelter (or to secure craft to ride out significant weather).

## Exercise

- Examine the next 5 slides (A through E), showing base reflectivity data across southern GA and northern FL.  Active severe t-storm warnings are shown in magenta.
- Focus on the developing bow echo over southern GA, moving rapidly eastward at 40-45 kts. Outflow winds of 40-60 kts are likely along the length of the bow.
- In this exercise, we will ignore the convection that exists off the coast. Focus only on the bow echo.
- For which slide (A through E) do you feel a **Special Marine Warning** should be issued for the southeast GA coastal waters, due to the wind threat from the bow echo (assuming we expect the bow echo to maintain itself)?
- Assume that some uncertainty exists as to whether the bow echo will make it to the coastal waters before weakening.

**Notes:**
Exercise instructions. Be sure to read them closely before starting the exercise. 

## 2245zAn hour prior to arrival on coastline, and prior to SVRs for adjacent coastal counties

- Magenta polygons indicate
- existing SVRs.

## B. 2300z45 minutes prior to arrival along coastline...and just prior to issuance of coastal county SVR.

- Magenta polygons indicate
- existing SVRs.

## C. 2315z30 minutes prior to arrival along coastline...and just after issuance of coastal county SVR.

- Magenta polygons indicate
- existing SVRs.

## D. 2325z20 minutes prior to arrival along coastline...but well after coastal county SVR is issued.

- Magenta polygons indicate
- existing SVRs.

## E. 2345zwithin 5 minutes of arrival along coastline, when the threat of strong winds becomes imminent for the coastal waters.

- Magenta polygons indicate
- existing SVRs.

## Decision-Time

- For choices A to E just shown, which do you think is best with regard to a **Special Marine Warning** issuance for the southeast Georgia coastal waters?
- The best answer is shown on the next slide.

**Notes:**
At which time (based on slide choice) would you issue a Special Marine Warning for the southeast Georgia coastal waters based on the advancing bow echo?

## Best Answer:  A (1-hr lead time)

- The best option is choice **A**, providing a 1-hr lead time before the strong winds
- (along the leading edge of the bow echo) reach the coastline.

**Notes:**
Best option, despite any existing uncertainty as to whether or not the threat reaches the coastal waters before diminishing.

## ALTERNATIVE CHOICES:B. 2300z (left) or C. 2315z (right)providing 30-45 minutes lead time prior to arrival along coast. 

- Magenta polygons indicate
- existing SVRs.

- Magenta polygons indicate
- existing SVRs.

- These choices would be acceptable **if **Marine Weather Statements (MWS) were
- issued with at least an hour lead time indicating potential for dangerous weather
- conditions over the coastal waters. Both SMWs and MWSs are likely broadcast to
- mariners.

**Notes:**
Alternative options.

## Discussion

**Special Marine Warnings** are tailored to marine customers. Required lead times to take protective action depends on the action required.
- If the required action is to seek port ahead of the threat, then the required lead time is considerably longer than if the required action is to prepare to ride out the threat (for lesser threats).

## Discussion

- Recreational vessels travel 20-30 kts on average.
- Sailboats travel more slowly, usually 5-10 kts.
- A minimum of an hour may be required to seek shelter in a     coastal harbor.
- Coastal zone :  0 to 20 nm width
- Offshore zone: 20 to 60 nm width

## Discussion

- Once the threat reaches the coastline, the chance to take cover ends, and mariners are left to “ride it out”.
- Assuming the decision is to “ride out” the threat, it can still take 30 minutes or longer to prepare a boat to handle the expected conditions.

## Discussion

- In this example, the radar image below shows the bow echo an hour before arrival at the coast. Even if warnings are not yet issued for coastal counties, an **SMW** may be needed now, given the greater amount of lead time required.
- If uncertain that the bow echo will reach the coast before falling apart, at minimum, a **Marine Weather Statement** should be issued to indicate what the potential is during the next 1-2hr period.

**Notes:**
In addition, the Hazardous Weather Outlook (HWO) product could be used to provide further advanced notice when the potential for significant weather over the marine area evolves, even before the thunderstorms develop.

Also note with Choice C, when an SMW is issued a the same time as a SVR for coastal counties, that with the latest version of AWIPS, both SVR and SMW can be issued simultaneously with the same WarnGen display and polygon (covering both coastal counties and marine area).

## Conclusion

- For mariners, think ahead an hour. Special marine warnings (or at least Marine Weather Statements) should be issued, when possible, at least an hour ahead of the threat.
- Sometimes, customer needs may come ahead of the meteorology.
- An accurate warning for extreme weather conditions, with a 20 minute lead time, while excellent for land warnings, is insufficient for marine customers. Thus, in this exercise, choices D and E would provide insufficient lead time to take appropriate action.
- While choices D and E would lead to greater confidence decisions (and perhaps more accurate warning decisions), the needs of marine customers make choices A-C better, even at the risk of a false alarm.

**Notes:**
It is important to keep the customers needs in mind. Longer lead times are needed for mariners compared to people on land.

## THE END

**THE END**