We will be entering another wet period this weekend. It will last through the first half of next week. The moisture is a result of an Eastern Pacific hurricane named Norbert. Norbert is tracking up the west coast of Baja Mexico. This morning, Norbert is west of the southern tip of the Baja Peninsula. Below is an animated GIF of the GFS Model for the next 4 days. It shows 24-hour predicted precipitation in daily intervals. You can see Norbert in the animation. He’s bringing plenty of moisture to Arizona.
Reinforcing my post from yesterday. The Climate Prediction Center released their new September outlook. We are looking at above average precipitation. Add to this the 6-10 and 8-14 day precipitation outlooks, and they have painted a very wet picture for us this month. Moisture is already flowing our way. Look for thunderstorms to start tomorrow and go through the middle of next week. We may have dry days mixed with the wet days.
We had a wet and cool August. The National Weather Service in Flagstaff published their monthly report for August. Northern Arizona was cool and wet. The wet piece probably surprises no one. The part I find interesting is that the cool temperatures and above average precipitation prevailed in most of Northern Arizona. Too often, we have a bimodal summer. Flagstaff had 2.2 inches over the average precipitation, and 3.8 degrees below normal. I usually think +/- 2 degrees is in the normal range.
The monsoon season may have one more wet session in store for us. As tropical systems continue to march up the West Coast, they may bring more moisture to are region. This weekend is the next big chance.
On Thursday, the Climate Prediction Center released new 1-month and 3-month long-range outlooks. They point to continued above normal precipitation for September, and September to November. They are below. I think the above average temperature waters off the West Coast and the Gulf of Mexico. El Nino continues to look iffy. Currently, another slightly drier period is coming next week.
Apologies to my readers. I missed all the action last week. I was in Germany when many areas had deluges on Monday and Tuesday. The videos on YouTube are remarkable.
In my last post, I pointed out that a drier period was ahead. What I had meant, and what the models foretold, was no rain for a week or so. That has not been the case. Thursday evening, a storm moved across the west side of Flagstaff dumping heavy rain across the area. Friday evening a storm hit central Flagstaff. I got about 1/3 of an inch of rain. I got more rain on Saturday, a mere 0.03 inches. This is drier than earlier in the week when I received over an inch.
This dry trend will continue for the next few days with a 30-60% chance of rain each day through Thursday. I think that in wet years, the forecast models run on the dry side, especially at long lead times. In dry years, they run on the wet side. The result is that more is on the way for this week.
It’s hard to believe since it rained all night last night, but another break in the action is ahead. The weekend might be a bit wet, but next week is looking mostly dry.
I think this is due to the repetitive formation of hurricanes off the coast of Central America. These storms keep forming and rolling off to the west. This pattern shifts the monsoonal flow. I haven’t checked the exact numbers for Flagstaff, but we probably surpassed the average precipitation total for August with this current storm.
Last night we saw the first part of a wet week. This week, we should be inside the monsoonal flow. And, I think there is plenty of warm water to support an ongoing rainy season. The Pacific Coast of North American, all the way down to Central America is quite warm compared to normal. This can help with moisture supply to the Southwest.
Although the equatorial waters west of Peru seem warm, they have actually dropped. It still doesn’t look like the wind shift needed to support El Nino will happen. Stay tuned.
For the next four days, some of the forecasts and the computer models show as much as an 1.5-2 inches of rain for parts of Northern Arizona. This will give us a good start to August. The scope of the precipitation over the next few days isn’t reflected in every forecast. Some, like the NOAA’s Graphical forecast and the National Weather Service’s forecast seem much drier and warmer. For instance, if you are heading to Lake Powell, I expect Sunday will be cooler(everyone may not think high 80s, low 90s are cool) and wetter compared to normal.
Looking deeper into August, the 6-10 and 8-14 day outlooks have dry conditions moving into Arizona. Dry period during a reasonably wet monsoon season isn’t unusual. Later today, the Climate Prediction Center should issue a new 30-day outlook. The question is whether or not the long-range outlook will continue to forecast above average precipitation.
The monsoonal flow will shift a bit to the east for today and the weekend. This means less rain for western Arizona. As you can see in the satellite water vapor image below, an orange knuckle of dry air has moved into the state. Not to worry, next week we should see more rain.
A lot of discussion, in one-on-one conversations and on the internet, about next winter’s El Nino. Retired climate scientist Bob Tisdale has been tracking the development of the this year’s El Nino. You can visit his blog via that link to catch up on the deep details. As of his last update, the El Nino conditions seem to have not fully developed. It’s not just the temperatures that drive El Nino, it’s the winds. Currently, the trade winds haven’t shifted to sustain El Nino conditions. Stay tuned, it could still happen.
To kickoff the monsoon season in fine form, the Flagstaff Airport received a record-breaking 1.89 inches of rain on July 4, 2014. I didn’t see it reported in the Arizona Daily Sun’s website.
RECORD EVENT REPORT NATIONAL WEATHER SERVICE FLAGSTAFF, AZ 1239 AM MST SAT JUL 05 2014 ...RECORD DAILY MAXIMUM RAINFALL SET AT FLAGSTAFF AZ AIRPORT... A RECORD RAINFALL OF 1.89 INCH(ES) WAS SET AT FLAGSTAFF AZ AIRPORT YESTERDAY. THIS BREAKS THE OLD RECORD OF 1.85 SET IN 1986.
More is on the way. Considering that the airport’s normal is 2.61 inches, rainfall for this month should not find it terribly hard to hit normal. There are some dry time periods over the horizon. Also, not everyplace received that much rain. Here is the rain totals for the month so far as independently reported to Rainlog.org at the University of Arizona. The monsoon season has had a healthy start.