Monitoring Weather - SailNet Community

   Search Sailnet:

 forums  store  


Quick Menu
Forums           
Articles          
Galleries        
Boat Reviews  
Classifieds     
Search SailNet 
Boat Search (new)

Shop the
SailNet Store
Anchor Locker
Boatbuilding & Repair
Charts
Clothing
Electrical
Electronics
Engine
Hatches and Portlights
Interior And Galley
Maintenance
Marine Electronics
Navigation
Other Items
Plumbing and Pumps
Rigging
Safety
Sailing Hardware
Trailer & Watersports
Clearance Items

Advertise Here






Go Back   SailNet Community > Contributing Authors > Seamanship Articles
 Not a Member? 


Closed Thread
 
LinkBack Thread Tools
  #1  
Old 05-13-2001
Contributing Authors
 
Join Date: Jan 2000
Posts: 57
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 15
Michael Carr is on a distinguished road
Monitoring Weather

In the Northern hemisphere, without the benefit of instruments, how can we be relatively certain that the winds we are currently in are the result of a high-pressure system and not the leading edge of a low-pressure system? 
 
Michael Carr responds:
Great question! It's interesting that you should ask because this is something that always comes up in mariner weather courses, in fact it's a topic that I covered recently in a seminar on Using Ocean Currents and Weather to Win.
 
Here is how you tell the difference between winds associated with low pressure or high pressure:
 
1. Monitor surface pressure readings. Normal sea level pressure is 1013 mb. If pressure is lower than 1013 and falling, a low is approaching; if it's above 1013 and rising then a high is approaching.
2. Cloud cover. Clouds thicken and lower with an approaching low, while they dissipate and provide clear skies with high pressure.
3. Relate the present weather you're seeing to the weather pattern. If you have been under the influence of  good weather, i.e. high pressure, for the past several days and winds have been SW (we are talking about any venue on the US East Coast), then a shift of winds to NE, accompanied by increasing cirrus clouds, a lowering barometer and increasing winds, is no doubt a developing area of low pressure. The reverse is true of a high-pressure system approaching. If the conditions are clearing and you experience a dissipation of clouds and a shift in the wind to a northerly direction, that shows the arrival of high pressure from the west.
 
The very best way to keep tuned in and maintain good situational awareness of the weather is to look at the Marine Prediction Center surface and 500-mb charts each day. These are available via weatherfax and the Internet. 
 
Without some instruments you will always have a difficult, if not impossible time sorting our the differences between local weather (sea breezes, etc.) and larger (synoptic scale) weather events. At a minimum you need a reliable and calibrated barometer, and at the high end you need satellite imagery, and easy access to charts via weatherfax or satcom systems. I hope this helps.
Closed Thread


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools

 
Posting Rules
You may post new threads
You may post replies
You may post attachments
You may edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On



All times are GMT -4. The time now is 12:45 AM.

Add to My Yahoo!         
Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
SEO by vBSEO 3.6.1
(c) Marine.com LLC 2000-2012

The SailNet.com store is owned and operated by a company independent of the SailNet.com forum. You are now leaving the SailNet forum. Click OK to continue or Cancel to return to the SailNet forum.