Updraft: August 20, 2012 Archive

Potential "Hurricane Isaac" near Florida for RNC next week? GFS model upgrades

Posted at 6:30 PM on August 20, 2012 by Paul Huttner
Filed under: Hurricanes

79 degrees high temp at MSP Airport Monday (at 2:59pm)

-1.6 degrees temps at MSP Airport vs. average this month

May 2011 - last cooler than average month in Minnesota

Growing Florida & RNC threat? Still too early to say, but worth watching next 7 days

Hurricane Isaac? Growing chance of a new Hurricane in the Atlantic next 72 hours

500+ miles - average model track error on hurricanes 7 days out

Picture perfect?

Does the weather get any better than Monday in Minnesota?

In my experience as a forecaster, a sun soaked sky and temps in the upper 70s make for what many consider to be "perfect weather." San Diego with lakes? Why not? Minnesota with lakes is plenty good enough for me.

Our winning streak of low humidity and warm temps will run through Wednesday. Summer warmth builds Tuesday & Wednesday as 80 returns.

Source: Twin Cities NWS

Let's face it; it just doesn't get any better than this in Minnesota.

State Fair 2012: Big Smiles, full bellies & umbrellas?

I only wish the Fair started Monday....3 days of "perfect weather" with low humidity, no rain and comfy temps might have made for record crowds.

Right now the first weekend of the Fair looks fairly good, but potentially a little wet at times.

The latest GFS runs (still) suggest a slow moving low pressure system that could bring scattered showers & T-Storms Thursday (possibly favoring Thursday night) into Friday morning.

Source: NOAA via College of DuPage Weather Lab

Low #1 slides east for a nicer Friday, then a second wave brings the threat of more scattered rain Saturday & Sunday.

Temps look a bit warmer than I thought last week...with highs in the 80s Thursday through Saturday.

Eyeing "Isaac?" Potential Hurricane "Isaac" threat to SE USA & RNC next week?

Future "Hurricane Isaac?"
Source: NOAA via WxUnderground

This falls under the category of "way too early to say for sure" with any meteorological credibility.

Keep in mind that average model errors for hurricane tracks are 500+ miles 7 days out.

That said, there is a growing trend in the forecast models that suggest we may see "Hurricane Isaac" forming n the next 3 days, and that the system may pose a threat to the southeast USA by next week.

Source: https://my.sfwmd.gov/sfwmd/common/images/weather/plots/storm_94.gif

A couple of the models (including the GFS) suggest a hurricane near or over Florida by next Monday-Tuesday.

GFS Modle: Hurricane near Florida early next week?
Source: NOAA/NCEP

With average track errors of 500+ miles 7 days out, "Isaac" could end up anywhere from the Gulf of Mexico to the Carolina's next week.

WxUnderground hurricane expert Jeff Masters elaborates.

This storm is a long-range threat to the U.S., as historically, 16% of storms in 94L's location have gone on to hit the U.S., with North Carolina the preferred target (10% chance.) A trough of low pressure capable of pulling 94L to the north enters Western Canada Thursday night, and the exact timing and amplitude of this trough will determine the ultimate landfall location of 94L.

The long range 7 - 14 day runs of the GFS model over the past three day have all predicted an eventual landfall for 94L in the U.S., though these long-range runs are notoriously unreliable. The predicted landfall locations have ranged from New England to Texas--which isn't much help. The past three runs beginning on Sunday afternoon have all taken 94L over Florida during the August 27 - 29 time frame, which I'm sure is making organizers of the Republican National Convention uncomfortable, since the convention is in Tampa August 27 - 30. However, 94L could miss Florida completely, as the average error in model forecasts going out 7 days is in excess of 500 miles.

We can't rule out a North Carolina landfall, but the pattern we've seen so far this year is for landfalls in Mexico's Yucatan Peninsula, so a more southwards path for 94L into the Yucatan is definitely a possibility. Also, we have that huge drought region in the Midwest, which tends to create its own high pressure bubble, which reduces the odds of storms making the turn and hitting the Central or Western Gulf Coast. If 94L makes it to the Western Caribbean, I see the two most likely options as a landfall in Mexico's Yucatan Peninsula (and then westwards into Mexico south of the Texas border), or recurvature into the Florida Gulf Coast.

The RNC kicks off next Monday in Tampa. No doubt they'll be keeping a close eye on what could be Hurricane Isaac.

GFS Model upgrades:

File this under "not a moment too soon."

NOAA's NCEP has recently made some upgrades to the Global Forecast System models. (GFS)

The GFS is NOAA's primary "medium range" forecast model that goes out to 16 days.

Here are the (welcome) details from NOAA:

Significant Improvement Ahead for Weather and Climate Forecast Accuracy

The National Centers for Environmental Prediction - a division of NOAA's National Weather Service - recently upgraded the operational Global Forecast System, which is run four times per day and produces forecasts up to 16 days in advance. The GFS is the backbone of the National Weather Service's global weather and climate forecasting capability.

On May 22, the upgrade provided a new method for assimilating the billions of pieces of atmospheric data collected daily from Earth observations and satellites. These data are used to describe the current state of the atmosphere, the important first step to running any weather forecast model.

During extensive preoperational testing, the new system produced more accurate forecasts out to 16 days. It also improved hurricane track forecast accuracy, general global weather predictions, and forecasts of stratospheric ozone, which affects the amount of skin‐damaging radiation that hits Earth's surface and also affects climate.

The new hybrid system is the result of an intensive, three‐year collaboration between scientists at NCEP, the NOAA Earth System Research Laboratory (ESRL), NASA and the University of Oklahoma. Further system improvements will be developed over the next few years through continued collaboration between NCEP and ESRL, the University of Maryland and the University of Oklahoma.

Source: NOAA

The GFS and the European Model are the primary "competitors" in medium range forecast that extend out 1-2 weeks. I've worked with the Euro model since the 1990s during my days at WGN-TV with Tom Skilling, We both agree the Euro has some advantages in certain seasonal situations over the GFS.

Let's hope the GFS upgrades will be as good as advertised.

PH