Opti Forecast 7/22

Sailing Weather Forecast

Optimist Nationals

Lake Minnetonka, MN

Issued: 0700LT Sunday, 22 JULY 2007

 

REQUEST: Feedback is an important part of the process toward improving weather forecasts. Please send daily weather notes and feedback to msanders@sailwx.com. Thanks!

 

WEATHER RISKS: 1) There are no active weather warnings or advisories for the sailing area.

2) An increased risk of thunderstorms exists from this evening through the overnight. These should be garden variety storms with a low probability of sever weather but they may contain heavy downpours.  

Please tune your VHF to NOAA Weather Radio for the latest official warnings and advisories.

 

Synopsis: The forecast went well yesterday as the wind speed and direction remained on the predicted track. During the morning a SSE breeze blew at 09-14 kts as anticipated. The predicted shift to a southerly flow occurred near noontime and then the wind increased as expected to 10-15 kts during the afternoon.   

 

Today Minnesota resides on the edge of high pressure located over the central Great Lakes. Meanwhile an area of low pressure currently over the Dakotas will die out as it tracks just north of the Lake Minnetonka area. The nearby low brings clouds to sky and the possibility of an afternoon shower or thunderstorm. The better shot at some precipitation occurs overnight and tomorrow morning.   

 

Current Conditions: A southerly flow has been in place since yesterday afternoon. Surface observations, including the MYC weather station, continue to show this is the case as an 08-11 kt S wind blows at 0630 this morning.

 

Satellite images show that Lake Minnetonka is on the edge of an area of clouds that extends to the west into the Dakotas. Rain and thunderstorms associated with these clouds is indicated by radar over the far western part of Minnesota. Visibility remains unrestricted at 10 miles or greater across the region.  

 

Forecast Discussion: The southerly flow that has been in place since yesterday will continue to blow at a steady rate across Lake Minnetonka today. This morning a S wind at 08-10 kts persists through 1100. A slight increase in wind speed to 09-12 kts occurs near noontime as the wind remains out of the S. Late in the afternoon, after 1700, the southerly wind should decline by a few knots to 08-11 kts. Wind gusts should top out at 17 kts during the mid afternoon.      

 

Weather: Skies are going to remain rather cloudy today, though the sunshine will break through from time to time. There is a low possibility of a shower or thunderstorm from midday through the afternoon. Temperatures reach a high of 86 F and it will feel more humid than yesterday. The UV index is moderate at 7 today.   

 

Seas: A slight chop is likely to persist as a steady breeze continues through the day.

 

Detailed Wind Forecast for Today (07/22/2007):

Time(LT)  Wind Speed    Wind Direction 

1000      08-10         SSE-S

1100      08-11         S           …slight build in speed underway

1200      09-11         S          

1300      09-12         S          

1400      09-12         S           …max winds of the day, gusts to 17 kts

1500      09-12         S          

1600      09-11         S    

1700      08-11         S           …declining wind late in the day

1800      07-10         S

 

Hedge: 1) Forecast confidence is AVERAGE today. Showers and thunderstorms may develop this afternoon but I think most, if any, precipitation holds off until tonight, specifically after midnight. However, if a shower occurs it will likely produce a temporary wind shift. Winds tend to blow out of an approaching shower with a several knot increase in wind speed.    

 

2) A steady southerly wind will continue through the day. However, breaks in the clouds should provide an opportunity for pockets of increased wind speed. This means that winds may be stronger, but shiftier, under sunny areas and weaker, but less shifty, beneath the clouds.    

 

Monday (23 JULY 2007): Tomorrows forecast is tricky as a small area of low pressure crosses Minnesota and this places Lake Minnetonka very near a wind shift. At the moment it appears that the morning will be dominated by a SSW wind at 02-06 kts. Approaching noon the low passes nearby and this likely flips the wind for several hours to the NNE at 04-08 kts. Then during the late afternoon the wind backs to the SSE and declines to 03-07 kts. Sailing will be challenging in this light air even if the midday wind shift does not occur.

 

Detailed Wind Forecast for Monday (07/23/2007):

Time(LT)  Wind Speed    Wind Direction

1000      02-06         SSW

1200      04-08         SSW to NNE

1400      04-08         NNE

1600      03-07         NNE-E

1800      03-07         ESE-SSE

 

Weather: Showers and thunderstorms from the overnight may remain across the area tomorrow morning. Any precipitation should exit the area by noontime but more clouds than sunshine cover the sky through the day. Temperatures will again be warm with a muggy high of 90.

 

LONG RANGE OUTLOOK

 

Tuesday (24 JULY 2007): An ESE wind at 03-07 kts during the morning, turning SE and increasing to 06-09 kts by 1300 and though the afternoon. Sunshine with a few clouds and a high near 92 F.

 

Wednesday (25 JULY 2007):  A SE wind at 04-08 kts becoming S and building to 06-10 kts after 1100. The wind eases to 04-07 kts and turns SSW after 1700. Continued hot and muggy with a high of 93 F under sunshine.   

 

Thursday (26 JULY 2007): Expect a persistent S-SSW flow building from 04-08 kts early to 08-12 kts by midday. A high near 92 with mostly sunny skies.