August 16th, 2013
Tropical Storm Erin officially became the 5th named storm of the 2013 N. Atlantic Hurricane season, forming just west of Cape Verde off the coast of Africa. However the official NHC update for 11 AM on Friday 8/16 downgraded Erin to a depression. This is do in most part to cooler sea surface temperatures, and a stable atmosphere that is suppressing convection.
Most of the models are predicting a NW curvature in the near term, and the intensity forecasts keep Erin at the depression/TS cut-off line for the next 5 days.
The Capital Weather Gang blog has a nice write-up about the likelihood of Erin, an August named storm developing so far east, of making its way to the US as a hurricane.
Another system, probably of much more interest, is INVEST92, which is a modestly organized area of convection over the Yucatan Peninsula. The morning model runs still have a lot of disagreement as to where 92 (which would be named Fernand if it strengthens) will go.
The intensity forecasts do indicate that 92/Fernand should develop in the next 48 hours. There is also a good fetch of warm SST’s in the Gulf of Mexico (GOM) which could play a big role, as this system, TS or not, will bring moderate-to-heavy precipitation to the TX/LA region.
We will continue to monitor Erin and 92/Fernand over the weekend and provide updates as necessary.
August 7th, 2013
Both Klotzbach and Gray (of CSU) and Tropical Storm Risk (TSR) have released updated N. Atlantic seasonal activity forecasts for August onward. K&G dropped their hurricane and major hurricane (cat-3 or greater) count by 1, down to 18 named storms, 8 ‘canes, and 3 major ‘canes. TSR is predicting 15/7/3 for the season.
And although despite the early seasonal start (Andrea June 5) followed by a prolonged quiet period (short lived Chantal and Dorian), we are still slightly AHEAD of pace when comparing against the 1966 – 2009 averages.
On average we dont observe our 4th named storm until August 23rd, with our first hurricane August 10th, and our first major hurricane September 3rd. The temporal “peak” of hurricane activity in the N. Atlantic is September 10th, with observed activity quickly ramping up in August. The image below shows the expected area of formation for most August hurricanes.
It’s also worth noting that the US is 41% BELOW tornado count average when compared to 2005 – 2011 counts (with hail down 16% and wind down 8%). And this is the quietest year for tornadoes since 2005, which produced $3.6B in industry insured loss (inflation adjusted). 2013 is at just over $8B at present.
July 26th, 2013
The 1100 AM EST report from the National Hurricane Center indicated weakening in the system to 50 mph max sustained winds. Satellite recon shows a lack of banding and disorganized cloud structure.
11:00 AM AST Fri Jul 26
Location: 17.7°N 43.4°W
Moving: WNW at 21 mph
Min pressure: 1006 mb
Max sustained: 50 mph
Dorian is forecasted to remain in this shear setup for the next couple of days, which will inhibit any further organization, and could potentially downgrade the system to a tropical wave. Movement is still forecated due West over the next 5 days. Early model runs show strong agreement on the path, but diverge widely on the intensity, with half indicating a moderate-to-weak tropical storm, and others showing weakening to a wave.
The NHC is keeping its forecast at ~50% chance of maintaining Tropical Storm strength (sustained winds of 35 mph) over the next 5 days.
Worth noting: Dr. Masters has a great article on tropical cyclone steering currents for those that are interested over at Wunderground. It speaks to some basic indicators of predicting storm motion using deep layer wind streamlines.
Tropical Storm Dorian officially became the 4th tropical cyclone Wednesday late morning. The latest forecast indicates that Dorian will not affect land until sometime Monday at the earliest, when the NHC cone takes her towards Puerto Rico.
Here is the latest from the NHC:
5:00 PM AST Thu Jul 25
Location: 16.5°N 37.8°W
Moving: WNW at 18 mph
Min pressure: 999 mb
Max sustained: 60 mph
The short term forecast is mixed for Dorian. NHC Discussions note that there is some dryer air to the northwest that could impede any further devlopment. The main convective region has survived an area of lower sea surface temperatures over the past 24 hours, and the system is now in a more favorable development region, as wind shear will soon subside and the system moves into more unstable air.
The models are in decent agreement in terms of path over the next 5 days with a consensus W/NW track. This is also the case with intensity with most maintaining Dorian as a Tropical Storm though the next 120 hours. Some of the late-model runs do show a chance of strengthening late in the forecast period. Additionally the 12Z run of the HWRF model shows Dorian as a category 1 storm north of the Dominican Republic in 126 hours.
It’s extremely early, but the ECMWF model, which was lauded for it’s Sandy accuracy so far out in advance in 2012, shows a 850-mb vorticity maxima moving into the Gulf of Mexico in the middle of next week. But we will keep our eye on all the models as they are updated regularly in the coming days.
Dr. Masters noted on Wunderblog that Dorian is the only the 2nd named storm to form this far east so early in the season. Only Berth in 2008 was further east.
And Paul Douglas had a few interesting tidbits in terms of storm climatology; It’s July 25th and the N. Atlantic is already on its 4th named storm. Climatologically, the 4th storm usually isn’t designated until late August (8/23 to be exact). Also of note from Douglas;
“By my calculations 76 hurricane names have been retired so far. 61 of the retired names were A thru K in the alphabet, only 15 names from K-Z. The storms in the first half of the hurricane season have a greater probability of being severe enough to be retired”
In their June updated forecast, Klotzbach and Gray identified 5 analog season (since 1949) which compared similarly to 2013 (as it was setting up). These are the dates of the earliest and 4th storm from each year;
1961 Anna (7/20) Debbie (9/7)
1996 Aurthur (6/19) Dolly (8/19)
2005 Arlene (6/8)* Dennis (7/4)*
2007 Andrea (5/9) Dean (8/13)
2011 Arlene (6/28) Don (6/27)
* US Landfalling Storm
Thus far the analogs look very accurate compared to 2013.
We will continue to monitor this system in the coming days.
June 28th, 2013
Only 11 years after the severe flooding in 2002, Germany and other central European countries (Austria, Czech Republic, Poland, and Switzerland among others) were hit by another devastating flood. In Germany, the spatial extent of the flooding has been larger than for any event occurring after 1950. At many gauges within the Elbe and Danube catchments record-breaking values of water level and river discharge were measured. In the city of Passau at the confluence of the rivers Danube and Inn, a historical maximum water level of 12.75 meters (41.8′) was reached on 03 June 2013.
Due to several dike breaches along rivers, large-scale flooding of the back-country occurred, resulting in fatalities, evacuation of entire villages, and intensive damage to residential and commercial property. Catastrophe Modeling vendor AIR estimates insured losses in a range from 4 to 5.8 billion Euros. Total economic loss may climb to 12 billion Euros according to the rating agency Fitch.
The severity of the flooding was driven by a combination of heavy rainfall and extremely wet antecedent conditions. The amount of precipitation in May 2013 was 178 percent of the long-term monthly rainfall for Germany. By the end of May, a large area of Germany experienced the wettest soil conditions in several hundred years.
Extreme values of soil moisture on 16.05.2013
0= no maximum exceeded
1= third-highest value of soil moisture exceeded since 1961
2= second-highest value of soil moisture exceeded since 1961
2= highest value of soil moisture exceeded – new absolute maximum since 1961
A stable meteorological depression coming from north-east brought very moist air and lead to excessive rainfall. In some areas as much as 400 liters of rainfall per square meter (15.7″) fell within a few days. Through trapping of air masses due to mountain ranges (orographic effect) heavy rainfall was reinforced. Since the water retention capacity of the soil was very low, most of the incoming rainfall was quickly routed to streams as surface runoff.
Even though the water level of most rivers has normalized now, a cold front in late June with thunderstorms, hail, and heavy rainfall continues to keep people on alert.
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