KoritheMan's WunderBlog

Tropical weather analysis - June 18, 2013

Posted by: KoritheMan, 03:21 AM GMT on Juni 19, 2013

Tropical Depression Two

Tropical Depression Two continues to pose a rainfall threat for Mexico. As of the 11:00 PM advisory from the NHC, the following information was available on the cyclone:

Wind: 30 mph, with higher gusts
Location: 18.9°N 92.7°W
Movement: WNW at 12 mph
Pressure: 1007 mb

Some bands of deep convection are redeveloping over the Bay of Campeche to the north of the center, which suggests the system is still hanging on from a convective standpoint. There have been no recent scatterometer passes over the circulation, but a blend of surface observations, satellite imagery, and radar data suggests the circulation is over water near Ciudad del Carmen; however, there is a lot of uncertainty in this estimate given the broad nature of the circulation.

Figure 1. Latest infrared satellite image of Tropical Depression Two. Image credit: NOAA's Satellite Services Division (SSD).

There is excellent agreement amongst the dynamical models as to where the depression will track throughout the remainder of its existence, which should be about two to three days. The current narrow mid-level trough over the northern Gulf Coast is in the process of lifting out as per 0z soundings, with backing noted above 500 mb. There is still some southwesterly flow below that level, but extrapolation of current trends on water vapor imagery suggest that this temporal weakness should quickly fill. In the meantime, there appears to be enough of a weakness in the Gulf of Mexico ridge to keep the cyclone moving with at least a semblance of a northerly component, but a more solid and definite westward turn is forecast over the next 12-24 hours as the ridge to the north of the tropical cyclone strengthens.

While the global models suggest a slowing of the forward speed prior to landfall, this seems a little unrealistic to me given current trends, and it is not immediately clear what would cause such a change. My forecast is thus a little faster than the model consensus. After landfall, the cyclone is forecast to slow down as it gets stuck over the Sierra Madre mountain range.

There is the potential for the system to become a tropical storm prior to landfall, although the upper flow over the Bay of Campeche is one that consists of at least modest southwesterly shear, which may inhibit significant intensification. Then again, the normally enhancing effect of the mountains in this area is generally unappreciated, so there's always that little bit.

Regardless of whether or not the cyclone strengthens, the primary concern is heavy rainfall and flash flooding, particularly over areas of elevated/mountainous terrain.

5-day intensity forecast

INITIAL 06/19 0300Z 25 KT 30 MPH...OVER WATER
12 hour 06/19 1200Z 30 KT 35 MPH
24 hour 06/20 0000Z 35 KT 40 MPH...APPROACHING THE COAST
36 hour 06/20 1200Z 25 KT 30 MPH...INLAND
48 hour 06/21 0000Z 20 KT 25 MPH...INLAND
72 hour 06/22 0000Z...DISSIPATED

5-day track forecast

Figure 2. My 5-day forecast track for Tropical Depression Two.

NHC storm information

000
WTNT32 KNHC 190248
TCPAT2

BULLETIN
TROPICAL DEPRESSION TWO ADVISORY NUMBER 7
NWS NATIONAL HURRICANE CENTER MIAMI FL AL022013
1000 PM CDT TUE JUN 18 2013

...TROPICAL DEPRESSION MOVES OVER THE SOUTHERN BAY OF
CAMPECHE...
...TROPICAL STORM WATCH ISSUED FOR A PORTION OF SOUTHERN MEXICO...

SUMMARY OF 1000 PM CDT...0300 UTC...INFORMATION
-----------------------------------------------
LOCATION...18.9N 92.7W
ABOUT 60 MI...100 KM WNW OF CIUDAD DEL CARMEN MEXICO
ABOUT 120 MI...195 KM ENE OF COATZACOALCOS MEXICO
MAXIMUM SUSTAINED WINDS...30 MPH...45 KM/H
PRESENT MOVEMENT...WNW OR 300 DEGREES AT 12 MPH...19 KM/H
MINIMUM CENTRAL PRESSURE...1007 MB...29.74 INCHES

WATCHES AND WARNINGS
--------------------
CHANGES WITH THIS ADVISORY...

THE GOVERNMENT OF MEXICO HAS ISSUED A TROPICAL STORM WATCH FROM
PUNTA EL LAGARTO WESTWARD TO BARRA DE NAUTLA.

SUMMARY OF WATCHES AND WARNINGS IN EFFECT...

A TROPICAL STORM WATCH IS IN EFFECT FOR...
* PUNTA EL LAGARTO TO BARRA DE NAUTLA MEXICO

A TROPICAL STORM WATCH MEANS THAT TROPICAL STORM CONDITIONS ARE
POSSIBLE WITHIN THE WATCH AREA...IN THIS CASE WITHIN 24 TO 36 HOURS.

FOR STORM INFORMATION SPECIFIC TO YOUR AREA...PLEASE MONITOR
PRODUCTS ISSUED BY YOUR NATIONAL METEOROLOGICAL SERVICE.

DISCUSSION AND 48-HOUR OUTLOOK
------------------------------
AT 1000 PM CDT...0300 UTC...THE CENTER OF TROPICAL DEPRESSION TWO
WAS LOCATED NEAR LATITUDE 18.9 NORTH...LONGITUDE 92.7 WEST. THE
DEPRESSION IS MOVING TOWARD THE WEST-NORTHWEST NEAR 12 MPH...19
KM/H. A TURN TOWARD THE WEST AND A DECREASE IN FORWARD SPEED ARE
EXPECTED DURING THE NEXT 24 HOURS. ON THE FORECAST TRACK...THE
CENTER OF THE DEPRESSION WILL MOVE OVER THE SOUTHERN BAY OF
CAMPECHE TONIGHT AND WEDNESDAY AND REACH THE COAST IN THE
STATE OF VERACRUZ WEDNESDAY NIGHT.

MAXIMUM SUSTAINED WINDS ARE NEAR 30 MPH...45 KM/H...WITH HIGHER
GUSTS. SOME SLIGHT STRENGTHENING IS POSSIBLE DURING THE NEXT DAY
OR SO...AND THE DEPRESSION COULD BE NEAR TROPICAL STORM STRENGTH
WHEN IT APPROACHES THE COAST OF MEXICO.

THE ESTIMATED MINIMUM CENTRAL PRESSURE IS 1007 MB...29.74 INCHES.

HAZARDS AFFECTING LAND
----------------------
RAINFALL...THE DEPRESSION IS EXPECTED TO PRODUCE TOTAL RAINFALL
ACCUMULATIONS OF 3 TO 5 INCHES WITH MAXIMUM AMOUNTS OF 10 INCHES
ACROSS PORTIONS OF GUATEMALA...THE YUCATAN PENINSULA AND SOUTHERN
MEXICO. THESE RAINS COULD CAUSE LIFE-THREATENING FLASH FLOODING AND
MUDSLIDES...ESPECIALLY IN MOUNTAINOUS AREAS.

WIND...TROPICAL STORM FORCE WINDS ARE POSSIBLE IN THE WATCH AREA
BY LATE WEDNESDAY.

NEXT ADVISORY
-------------
NEXT INTERMEDIATE ADVISORY...100 AM CDT.
NEXT COMPLETE ADVISORY...400 AM CDT.

$$
FORECASTER BROWN

Categories:2013 Atlantic hurricane season Tropical Depression Two

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Tropical weather analysis - June 7, 2013

Posted by: KoritheMan, 07:42 AM GMT on Juni 07, 2013

Andrea

Tropical Storm Andrea made landfall in the Florida Big Bend region just south of Steinhatchee early Thursday evening. At the time of landfall, Andrea was a 55 kt tropical storm. It has since weakened as it's moved overland, and the following information was available on the tropical cyclone on the latest NHC intermediate advisory:

Wind: 45 mph, with higher gusts
Location: 31.3°N 81.7°W
Movement: NE at 19 mph
Pressure: 99...

Categories:2013 Atlantic hurricane season Tropical Storm Andrea Invest 92L

Updated: 07:52 AM GMT on Juni 07, 2013

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Tropical weather analysis - June 6, 2013

Posted by: KoritheMan, 05:30 AM GMT on Juni 06, 2013

Andrea

Tropical Storm Andrea formed in the east-central Gulf of Mexico today from what was previously Invest 91L. As of the latest NHC advisory, pending the upcoming intermediate update, the following information was available on the cyclone:

Wind: 40 mph, with higher gusts
Location: 26.0°N 86.3°W
Movement: N at 6 mph
Pressure: 1002 mb

Andrea is a typical early June tropical cyclone, with much of the associated weath...

Categories:2013 Atlantic hurricane season Tropical Storm Andrea

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Tropical weather analysis - June 5, 2013

Posted by: KoritheMan, 06:15 AM GMT on Juni 05, 2013

Invest 91L

A weak area of low pressure over the central Gulf of Mexico continues to produce widespread disorganized showers and thunderstorms to the east of the low.

Convection continues to wax and wane, with a current burst going off about two degrees east of the estimated center location. However, CIMSS analyses diagnoses about 25 kt of westerly shear over the disturbance, which in combination with a very subsident airmass over the western Gulf of Me...

Categories:2013 Atlantic hurricane season

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Tropical weather analysis - June 4, 2013

Posted by: KoritheMan, 05:35 AM GMT on Juni 04, 2013

Invest 91L

A large area of disturbed weather extending from the southern Gulf of Mexico into the Florida Straits continues in association with Invest 91L. While areal surface observations indicate that the circulation associated with this system is better defined than yesterday, it is still broad and poorly-defined. The biggest change since yesterday is that the cyclonic envelope encompassing the system appears to have shrunk a little, and I am not being ...

Categories:2013 Atlantic hurricane season Invest 91L

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