Oct 242012
 

So, a bunch of Flagstaff Folks are in Miami this week. They are also going to try to make it home on Friday as Hurricane Sandy moves northward past the coast of Miami. I have no idea what it takes to shut down air service to an airport in such a situation. it looks like very strong winds will be buffeting the coast from Thursday night to Friday night as Sandy creeps by Miami. For situations like this, I tend to follow the US Navy’s NoGAPS models. Here is the Friday morning NoGAPS wind forecast at 10 meters height.

US Navy NoGAPS outlook for Surface (10 meter) Wind Barbs, Streamlines, Isotachs [kts]

US Navy NoGAPS outlook for Surface (10 meter) Wind Barbs, Streamlines, Isotachs [kts]

Notice that NoGAPS doesn’t forecast winds over land very well. But, the model includes strong 45 knot winds near land. The winds would probably carry inland. They get strong through the day.

The North American Mesoscale model shows 30-40 knot winds near Miami during the day on Friday. Doesn’t sound terribly bad to me. But, we expect several inches of rain with this storm in this area.
I’ll look again in the morning, but I am hoping it will only be wet.

 Posted by at 6:20 pm
Jul 172012
 

Hurricanes and tropical storms can cause changes a thousand miles away. For the next couple days, Tropical Storm Fabio will distract our monsoon season by shifting the flow of winds in the area. Currently, Fabio is off the tip of the Baja Peninsula. His forecast is to move almost straight north toward California and die along the way as he hits cooler water.

Tropical Storm Fabio 5-day forecast map from Wunderground.com. 7-17-2012

Tropical Storm Fabio 5-day forecast map from Wunderground.com. 7-17-2012

As a result, the monsoonal flow will shift eastward into New Mexico. For the next few days,  we will see a drier flow from the southwest. The monsoonal flow should shift over the weekend and possibly for much of next week, giving us a stormy pattern.

 Posted by at 6:43 am
Aug 242011
 

August started off fairly wet and near normal temperatures. But it has turned dry.

Month to date August rainfall from Rainlog.org

Month to date August rainfall from Rainlog.org

Most of the area has seen over 2 inches of rain for the month. But, in the last week, rain has been a little scarce and temperatures have been on the rise.

Rainfall for the last week. from Rainlog.org

Rainfall for the last week. from Rainlog.org

There is a good chance for thunderstorms the next few days. I think the real news for Arizona is the ongoing heat and record-breaking temperatures in Arizona.

Here is the record map from HAMWeather.com. The red dots have spread to the west from Texas. The other big news fright now is Hurricane Irene. She could end up being a huge mess. Right now, computer projections show her to take one of the worse possible paths grazing the entire Atlantic Coast of the US. This could batter the entire East coast with hurricane force winds. Time will tell.

HAMweather Climate Center - Record Events for The Past Week - Continental US

HAMweather Climate Center - Record Events for The Past Week - Continental US

 

 

 

 Posted by at 6:57 am
Jul 212011
 

As I watched the radar animation for the Southwest this morning, I was surprised to see a large cluster of thunderstorms near Tucson moving south. This is not anything like normal monsoonal activity. The answer is Hurricane Dora. She is sucking in everything around her this morning. Hurricanes effect not only the local weather in the storm, but the weather for a 1000 miles away. Dora is going to help clear us out for a couple days, then provide moisture back this weekend.

Water vapor satellite image showing Hurrican Dora on the right side. National Weather Service

Water vapor satellite image showing Hurrican Dora on the right side. National Weather Service

 Posted by at 7:04 am
Jun 092011
 

This week has been wonderfully comfortable. Maybe it has been too breezy, but the winds have been lessening. While the headlines are all about the East baking in the summer sun, the West has racked up low temperature records. For June, the daily highs have been as low as 8 degrees below normal for Flagstaff. It’s an interesting situation.

 

Record Temperatures for the week ending June 9, 2011. From HAMWeather.com

Record Temperatures for the week ending June 9, 2011. From HAMWeather.com

 

It is all about to change. Temperatures should climb closer to our normal highs by this weekend. Next week, we should see those temperatures be with in a couple degrees on the high or low side of 80. The winds should decline overall. We may still have another bout or two of breezy days. Remember, it has to get hot to fire up the monsoon.

Another interesting thing is Hurricane Adrian. Remember, hurricanes can affect the weather for a thousand miles from their core. I am afraid Adrian will impede the flow of moisture toward Arizona. This flow should be starting.

 

Hurricane Adrian - WeatherUnderground.com

Hurricane Adrian - WeatherUnderground.com

 

 

 Posted by at 6:35 am
Oct 032010
 

The National Weather Service hasn’t published their review for the month of September, yet. But, I think it’s a pretty easy month to summarize. Here is the monthly climate graph from Weather Underground.

September 2010 Climate History - Weather Underground

September 2010 Climate History - Weather Underground

There were two stormy times, from September 6-9 and September 22-23. These provided us with significantly cooler temperatures for several days. The rest of the month was absolutely beautiful. It was the best month this year to get outdoors and enjoy. As you can see the last week of the month was well above normal for temperatures and drove us firmly into an above average temperature month. Overall, according to the National Weather Service, we were 2.4deg F above normal with precipitation coming in at a meager 0.79 inches, 1.33 inches below normal. This shift in temperature represents a strong move in the departure from normal temperatures since 2004.

Departure from normal mean temperatures, 2004-2010

Departure from normal mean temperatures, 2004-2010

Temperatures have been mostly below normal since the fall of 2009.

September 1998 doesn’t match September 2010. I think this is due to the timing and rapidity of the shift from El Nino to La Nina, and the accompanied change from a warm Pacific Decadal Oscillation Index to a cool one. I think this has led to a faster return of dry, and possibly warmer conditions. Notice the large cool body of water in the Equatorial Pacific.

Global sea surface temperature anomaly - 1 October 2010 (NOGAPS)

Global sea surface temperature anomaly - 1 October 2010 (NOGAPS)

Also note the warm North Atlantic Ocean. As an aside, there are a couple cooler patches of water in the North Atlantic. One from the coast of Africa stretching north of the Caribbean towards the East Coast of United States. The other from the coast of Nova Scotia to the east. These are under the tracks of Hurricanes Earl and Danielle, and Tropical Storms Colin and Fiona. Tropical storms provide this cooling.

The warm Atlantic and the cool Pacific are going to be the drivers for our upcoming dry winter.

 Posted by at 5:34 am
Sep 222010
 

Heavy Rain is expected today. As always, some may get a little, some may get a lot. But, we have a new edition to the scenario, Tropical Depression Georgette.

Tropical Depression (Storm) Georgette

Tropical Depression (Storm) Georgette

Tropical Storm Georgette formed yesterday out of a low pressure system. As she moved north over Baja, she weakened to a Tropical Depression. She may return to tropical storm force winds as she moves during the day. She will weaken further as she rapidly continues to Arizona.

Today’s rain is not directly associated with Georgette. Many areas could still see rainfall amounts of over 0.5 inches. Some over 1 inch.

 Posted by at 4:01 am
Sep 152010
 

When the weather is this beautiful. Last week was a little chilly, but this week is near perfect. The controlled burns are destroying some of that perfection with smoke lingering around town over night.

The big question in my mind is whether we will see any precipitation in the rest of September. Enter tropical Storm Karl. Currently, there are 3 named storms in the Atlantic area. Tropical Storm Karl  is in the Caribbean.

Tropical Storm Karl Projected Path from WunderGround

Tropical Storm Karl Projected Path from WunderGround

Will Karl’s moisture and low pressure make it to the southwest? The long-term GFS Model has been vacillating between yes and no. Currently, there is a chance the moisture will make it across Northern Mexico and into Arizona around the weekend of September 25-26. However, model to model runs shows differences in the strength of the westerly flow across the state at that time. If we have strong westerly or southwesterly flow, then the moisture will be blown to the east. Something to watch.

In the mean time, enjoy the beautiful fall weather.

 Posted by at 6:48 am
Sep 042010
 

Well, La Nina isn’t looking like it will back-off in time for winter. The typical La Nina effects for Northern Arizona are slightly warmer than normal (near normal) temperatures with substantially below average precipitation.

La Nina Precipitation Effects - Winter

La Nina Precipitation Effects - Winter

La Nina Temperature Effects - Winter

La Nina Temperature Effects - Winter

1998 continues to look like a reasonable analog year. Both ENSO (El Nino Southern Oscillation) and the PDO (Pacific Decadal Oscillation) moved strongly to the cool side. They are forecast to stay cool for the winter. However, I think the move this year happened a little earlier than 1998. This gives some concern about the onset of the changes as a result.

The tropical storm season in the Atlantic got off to an earlier start this year than in 1998. Still, the number of storms could be very similar. In both years we have strong clusters of storms forming in early September. The early start makes me wonder about the precipitation in the fall in Arizona. Hurricanes and tropical storms can limit the flow of moisture to the region. At this point it looks like the Monsoon Season is over and the typical fall and winter weather pattern has begun. This pattern has storm fronts sweeping through and past Arizona.

1998 Hurricane Season - Wikipedia

1998 Hurricane Season - Wikipedia

2010 Hurricane Season - Wikipedia

2010 Hurricane Season - Wikipedia

September and October had above average and near average precipitation amounts in 1998. Right now, it doesn’t look like we will see anything for a couple weeks. I still think there is a good chance for near normal precipitation in September and October. However, the earlier transition from El Nino to La Nina could mean we will see an earlier chance to dry conditions. Temperatures in these months should be pretty close to normal, I think.

So, where does that leave us for the winter? Sorry folks. As of the start of September, it appears this winter will be near climitological normals for temperature. Now, the global outlook is for a colder than normal winter. This may cause Northern Arizona to be colder than normal. I’m just not sure. I doubt it will be warmer. This cooling trend is being driven by a very weak solar cycle among other things.

On the precipitation side, we will be dry. Probably very dry. December – February may see precipitation totals of less than 1.5 inches. I won’t be buying a season pass at Snowbowl. Then again, I never buy one. I just don’t get up there enough.

Is there a chance for change? Can I be out to lunch? Sure. Rapid changes in the sea states linked to ENSO and PDO are possible. Last year at this time, most thought El Nino would fade before winter. It didn’t, and we had a wet winter.

postscript: I installed a heated sidewalk this summer. This almost guarantees a dry winter, right?

 Posted by at 6:48 am
Aug 292010
 
North American Mesoscale Model - Jet Stream Forecast Overnight 8/29-8/30

This picture tells the tale of our weekend. But, does it foretell our future? Is the monsoon season coming to an early, wintry end?

North American Mesoscale Model - Jet Stream Forecast Overnight 8/29-8/30

North American Mesoscale Model - Jet Stream Forecast Overnight 8/29-8/30

As you can see, the jet stream has dipped far to the south in an almost winter pattern. This dried out our air and dropped our temperatures. Yesterday’s high in Flagstaff was 72F, six degrees below normal. The air is substantially drier as seen in the water vapor image below.

Satellite Water Vapor Image - August 29, 2010

Satellite Water Vapor Image - August 29, 2010

The jet stream is drawing the dry air from over the cool waters of the Pacific Ocean. This has completely shutdown the monsoonal flow. What does this mean for the long-term? I still think 1998 is the model year. The Altantic Hurricane Season is in full swing right now. Danielle and Earl are named. In the chart below, note that the names Danielle and Earl were also used in 1998. Also, note that they occurred in late August and early September. There is another area that has a high likelihood for development in the Eastern Atlantic. Behind all thosee, there is a line of disturbances across Africa that are marching to the west. Each has a good chance at developing into a hurricane. This doesn’t even count the potential for development in the Gulf of Mexico. So, 1998 still seems like a good match.

1998 Hurricane Season

1998 Hurricane Season

But, it looks like the strong southwest winds, associated with the jetstream, didn’t start until later in September. We are already there. Also, the bulk of the September precipitation came with monsoonal flow early in the month. The end of the September and early October were dry. But, but the end of October, the winter storm pattern had started. Has the 2010 timeline shifted? Are we one month ahead of 1998? We have had almost 10 inches of rain since June at the airport.

I’m still not ready to forecast for the winter, but, the winter of 1998-1999 ended up fairly dry.

 Posted by at 6:53 am
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