Humberto

Update, September 22, 3:14 p.m., Eastern: My schedule got very crazy and I couldn’t follow this tropical cyclone. Fortunately, it stayed out to sea for most of its life cycle, only causing some heavy rain in the Cape Verde Islands early on as a new tropical storm.

September 11, 5:55 a.m., Eastern: As of 5 a.m., we’ve got a hurricane, per the NHC:

ZCZC MIATCDAT4 ALL
TTAA00 KNHC DDHHMM

HURRICANE HUMBERTO DISCUSSION NUMBER 11
NWS NATIONAL HURRICANE CENTER MIAMI FL AL092013
500 AM AST WED SEP 11 2013

CENTRAL CONVECTION HAS BEEN ON THE INCREASE WITH HUMBERTO DURING THE
LAST FEW HOURS…WITH A LARGE CURVED BAND WRAPPING AROUND THE
CYCLONE ALSO BECOMING BETTER DEFINED. THE DVORAK ESTIMATES AT 6Z
SUPPORTED ANYTHING FROM 55-65 KT…AND GIVEN THE NOTABLE
STRENGTHENING OF THE CENTRAL DEEP CONVECTION AND OVERALL INCREASE
IN ORGANIZATION…THE INITIAL WINDS ARE RAISED TO 65 KT. HUMBERTO
HAS ABOUT A DAY TO STRENGTHEN BEFORE AN INCREASE IN SHEAR AND
COOLER WATERS SHOULD CAUSE A WEAKENING TREND. IN A FEW DAYS…
ALTHOUGH WATER TEMPERATURES BEGIN TO RISE…STRONG WESTERLY SHEAR
AND ENTRAINMENT OF DRIER AIR WILL PROBABLY KEEP THE CYCLONE
GRADUALLY WEAKENING. THE INTENSITY GUIDANCE SEEMS TO BE WELL
CLUSTERED…SO THE LATEST NHC WIND SPEED PREDICTION IS CLOSE TO THE
PREVIOUS FORECAST AND THE MODEL CONSENSUS.

HUMBERTO APPEARS TO BE TURNING TO THE RIGHT…NOW MOVING 330/7. THE
CYCLONE SHOULD TURN TO THE NORTH SOON AND ACCELERATE SOME WHILE IT
MOVES BETWEEN A RIDGE OVER NORTHWESTERN AFRICA AND A TROUGH OVER
THE CENTRAL ATLANTIC OCEAN. IN A COUPLE OF DAYS…HUMBERTO IS
LIKELY TO TAKE A HARD LEFT TURN DUE TO IT RUNNING AGAINST A RATHER
STOUT RIDGE IN THE SUBTROPICAL EASTERN ATLANTIC. WITH HUMBERTO
BECOMING A MORE SHALLOW SYSTEM IN THE LONGER RANGE…IT MAKES SENSE
TO STAY ON THE SOUTHERN SIDE OF THE GUIDANCE ENVELOPE GIVEN THE
STRONG LOW-LEVEL RIDGE FORECAST. THE LATEST NHC FORECAST IS
BASICALLY AN UPDATE OF THE PREVIOUS ONE…STAYING EQUATORWARD OF
THE MODEL CONSENSUS IN THE MEDIUM RANGE.

FORECAST POSITIONS AND MAX WINDS

INIT 11/0900Z 16.0N 28.9W 65 KT 75 MPH
12H 11/1800Z 17.2N 29.2W 70 KT 80 MPH
24H 12/0600Z 19.0N 29.3W 75 KT 85 MPH
36H 12/1800Z 20.9N 29.6W 70 KT 80 MPH
48H 13/0600Z 22.5N 30.3W 65 KT 75 MPH
72H 14/0600Z 23.8N 33.9W 50 KT 60 MPH
96H 15/0600Z 24.2N 39.1W 45 KT 50 MPH
120H 16/0600Z 25.5N 44.0W 40 KT 45 MPH

$$
FORECASTER BLAKE

*************************

September 10, 11:09 a.m. Eastern: Humberto is still doing its thing out at sea. The GFS again shows it holding together through 180 hours, though pulsing up and down a little bit in intensity during the later part of the period. The NHC isn’t so impressed. In their 11 a.m. discussion, they note the cyclone will be running into stronger wind shear and “a more hostile thermodynamic environment” (presumably cooler waters.

*************************

September 9, 11:10 a.m. This morning, the NHC decided to name the storm Humberto. It currently is drenching the Cape Verde Islands with heavy rain and looks rather majestic for a tropical storm on the GOES water vapor channel:

Humberto at 1100 Sept 9

The Cape Verdes may be the only land this tropical system affects and only now, very early in its life cycle. That’s good. I’m only following the GFS computer model and it forecasts Humberto to become a long-lived major hurricane…but luckily for humanity, one that stays out to sea – a “fish,” as enthusiasts call such storms.

The meteorologists at the NHC, of course, have to follow all the models and here is what they have to say about it in their 11 a.m. forecast discussion.

THE EAST-NORTHEASTERLY SHEAR AFFECTING HUMBERTO IS EXPECTED TO ABATE
WITHIN THE NEXT 12 HOURS…AND THE THERMODYNAMICS APPEAR
SUFFICIENTLY CONDUCIVE TO SUPPORT ADDITIONAL INTENSIFICATION DURING
THE NEXT 72 HOURS. THE SHIPS AND LGEM MODELS CONTINUE TO SHOW THE
MOST AGGRESSIVE STRENGTHENING…BUT THAT IS COUNTERED BY THE
HWRF…GFDL…AND FLORIDA STATE SUPERENSEMBLE WHICH EITHER DO NOT OR
JUST BARELY MAKE HUMBERTO A HURRICANE. THE OFFICIAL FORECAST STILL
LIES BETWEEN THESE TWO SCENARIOS AND IS JUST A TAD HIGHER THAN THE
INTENSITY CONSENSUS.

Their forecast cone in graphical form:

Humberto five day cone Sept 9

*************************

At 5 p.m. Eastern today (2 hours ago), the NHC identified Tropical Depression 9:

Proto Humberto

000
WTNT44 KNHC 082042
TCDAT4

TROPICAL DEPRESSION NINE DISCUSSION NUMBER 1
NWS NATIONAL HURRICANE CENTER MIAMI FL AL092013
500 PM AST SUN SEP 08 2013

SATELLITE IMAGES INDICATE THAT THE LOW PRESSURE SYSTEM BETWEEN THE CAPE VERDE ISLANDS AND THE WEST COAST OF AFRICA HAS DEVELOPED ENOUGH CONVECTIVE ORGANIZATION TO BE DESIGNATED AS A TROPICAL DEPRESSION. THE INITIAL INTENSITY IS SET AT 25 KT BASED ON DVORAK ESTIMATES OF T2.0 FROM TAFB AND T1.5 FROM SAB. THE LOW-LEVEL CENTER APPEARS TO BE ON THE EASTERN EDGE OF THE DEEP CONVECTION DUE TO A LITTLE BIT OF NORTHEASTERLY SHEAR.

THE INITIAL MOTION ESTIMATE IS 270/9 KT. THE DEPRESSION IS LOCATED TO THE SOUTH OF A LARGE MID-TROPOSPHERIC ANTICYCLONE CENTERED NEAR THE AZORES…AND THE CURRENT WESTWARD MOTION IS EXPECTED TO CONTINUE FOR ANOTHER 36 HOURS OR SO. AFTER THAT TIME…THE ANTICYCLONE IS FORECAST TO WEAKEN WHILE A CLOSED MID/UPPER-LEVEL LOW DEVELOPS NEAR THE CANARY ISLANDS AND A RIDGE BUILDS WESTWARD FROM AFRICA. THIS PATTERN WILL ALLOW THE DEPRESSION TO TURN RATHER SHARPLY TO THE NORTH-NORTHWEST AFTER 48 HOURS AND CONTINUE THAT TRAJECTORY THROUGH THE END OF THE FORECAST PERIOD. SURPRISINGLY…THE LARGEST SPREAD AMONG THE TRACK GUIDANCE OCCURS WITHIN THE FIRST 48 HOURS OR SO…BUT THE MODELS SEEMS TO CONVERGE BY 72 HOURS. THE NHC OFFICIAL TRACK FORECAST IS CLOSE TO THE MODEL CONSENSUS FOR
MUCH OF THE FORECAST.

A MOIST AIR MASS…WARM WATERS…AND RELATIVELY LIGHT SHEAR SHOULD ALLOW THE DEPRESSION TO STRENGTHEN AT LEAST GRADUALLY DURING THE NEXT FEW DAYS. HOWEVER…SOME OF THE MODELS …MAINLY THE STATISTICAL-DYNAMICAL GUIDANCE…ARE FAIRLY AGGRESSIVE WITH THE INTENSIFICATION RATE AFTER 24 HOURS. SHIPS AND LGEM HAVE TENDED TO HAVE A HIGH BIAS THIS HURRICANE SEASON…SO THE OFFICIAL FORECAST IS KEPT A BIT LOWER. THE FORECAST DOES…HOWEVER…ANTICIPATE THE CYCLONE BECOMING A HURRICANE BY 72 HOURS.

GIVEN THE FORECAST…AND THE UNCERTAINTY WITH HOW BIG THE WIND FIELD WILL GET ONCE THE DEPRESSION BECOMES A TROPICAL STORM…A TROPICAL STORM WARNING HAS BEEN ISSUED FOR THE SOUTHERN CAPE VERDE ISLANDS.

FORECAST POSITIONS AND MAX WINDS

INIT 08/2100Z 13.1N 20.7W 25 KT 30 MPH
12H 09/0600Z 13.2N 22.1W 30 KT 35 MPH
24H 09/1800Z 13.5N 24.3W 35 KT 40 MPH
36H 10/0600Z 13.9N 26.5W 40 KT 45 MPH
48H 10/1800Z 14.5N 27.9W 55 KT 65 MPH
72H 11/1800Z 17.5N 29.5W 70 KT 80 MPH
96H 12/1800Z 21.0N 31.0W 70 KT 80 MPH
120H 13/1800Z 23.5N 32.5W 65 KT 75 MPH

$$
FORECASTER BERG

The GFS still shows development and a track northwards now a little west of the -30 longitude line. Amazingly, it still shows Humberto intact and going fairly strong in 180 hours. As mentioned, the models can’t be trusted at all that far out, but the GFS certainly has been consistent with this.

Humberto, not a quitter, according to the GFS.

Humberto, not a quitter, in 180 hours, according to the GFS today.



Categories: Weather

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