I'm just a 23 year old with an ardent passion for weather. I first became aware of this interest after Tropical Storm Isidore struck my area in 2002.
By: KoritheMan , 5:40 AM GMT on September 07, 2013
Tropical Depression Eight
The area of low pressure in the southern Bay of Campeche became a tropical depression just as it was crossing the coast around 1800 UTC Friday. As of the 0300Z NHC advisory, the following information was available on the storm:
Wind: 30 mph, with higher gusts
Location: 21.7°N 98.8°W
Movement: SW at 8 mph
Pressure: 1009 mb
The cloud pattern has become increasingly disorganized since landfall, with satellite data suggesting that the circulation has become ill-defined. However, a burst of convection has recently erupted near and along the coastal waters near Tampico, which will continue to cause a heavy rain threat there, along with perhaps some locally gusty winds.
Figure 1. Latest infrared satellite image of Tropical Depression Eight. Image credit: NOAA's Satellite Services Division (SSD).
I don't have much to say about the depression. It appears to be moving pretty much due southwest under a deep-layer ridge located over the central United States. The residual circulation should disintegrate shortly, and the cyclone is expected to become a remnant low very soon, and then completely dissipate in about 24 hours or less. Nevertheless, there is still a vigorous mid-level circulation which will pose a threat for very heavy rainfall and flash flooding over portions of Veracruz, San Luis Potosi, and Tamaulipas even for a couple of days succeeding dissipation.
Any remaining strong winds along the coast and offshore should quickly subside over the next few hours as the circulation moves farther inland and the convection loses its support.
Intensity forecast and positions
INITIAL 09/07 21.7°N 98.8°W 0300Z 25 KT 30 MPH...INLAND
12 hour 09/07 21.1°N 99.5°W 1200Z 20 KT 25 MPH...POST-TROPICAL/REMNANT LOW
24 hour 09/08 0000Z...DISSIPATED
Figure 2. My forecast track for Tropical Depression Eight.
Lorena weakens to a tropical depression while it moves just off the coast of southwestern Baja. As of the latest NHC advisory, the following information was available on the storm:
Wind: 35 mph, with higher gusts
Location: 23.1°N 111.5°W
Movement: WNW at 9 mph
Pressure: 1007 mb
Lorena is rapidly becoming disorganized, with satellite and radar data showing a significant deterioration of the convective cloud pattern. Satellite estimates from TAFB and SAB barely support a tropical storm, and the latest CIMSS ADT estimates have been even lower. The remaining convection, quite shallow, is confined to a broken cloud band about 35 to 40 miles southeast of the exposed low-level center. Surface observations and radar data suggest that the center of Lorena is located not far southwest of La Paz, and that the circulation is becoming elongated.
Figure 3. Latest infrared satellite image of Tropical Storm Lorena. Image credit: NOAA's Satellite Services Division (SSD).
Water vapor imagery shows a very dry airmass just ahead of Lorena, which could be partly responsible for the cyclone's rather abrupt decay this evening. In addition, sea surface temperatures are cooling along the forecast track, and the circulation is interacting with land, even with it being just offshore. These factors should continue to weaken Lorena, and the GFS and SHIPS even suggest that southwesterly shear could increase in a couple of days, which will likely be a moot point since Lorena is forecast to be long deceased by that point.
My forecast track is similar to the one from the National Hurricane Center, with the primary steering mechanism for Lorena being the southwestern extent of the strong ridge located over the central United States, the same one steering what's left of Tropical Depression Eight.
Surface observations have not suggested much in the way of strong winds this evening, and Lorena did not make landfall as I had originally predicted. Thus, any remaining tropical storm force winds should stay offshore, probably even in the mountains; the continued lack of convection will also assist in weakening the surface winds.
Locally heavy rainfall and possible isolated flooding will continue over portions of southern and central Baja for the next couple of days, as Lorena is not expected to move much as it enters a region of weak steering currents. This is consistent with the GFS and ECMWF, which both indicate little motion of the dying tropical storm.
Intensity forecast and positions
INITIAL 09/07 0300Z 23.2°N 111.0°W 35 KT 40 MPH
12 hour 09/07 1200Z 23.5°N 111.6°W 30 KT 35 MPH
24 hour 09/08 0000Z 23.7°N 111.8°W 25 KT 30 MPH...POST-TROPICAL/REMNANT LOW
36 hour 09/08 1200Z 23.8°N 112.1°W 20 KT 25 MPH...POST-TROPICAL/REMNANT LOW
48 hour 09/09 0000Z...DISSIPATED
Figure 4. My forecast track for Lorena.
NHC storm information
NHC storm information
WTPZ32 KNHC 070532
TROPICAL DEPRESSION LORENA INTERMEDIATE ADVISORY NUMBER 8A
NWS NATIONAL HURRICANE CENTER MIAMI FL EP122013
1100 PM PDT FRI SEP 06 2013
...LORENA WEAKENS TO A TROPICAL DEPRESSION NEAR THE SOUTHERN BAJA
SUMMARY OF 1100 PM PDT...0600 UTC...INFORMATION
ABOUT 100 MI...160 KM W OF CABO SAN LUCAS MEXICO
ABOUT 120 MI...195 KM SSE OF CABO SAN LAZARO MEXICO
MAXIMUM SUSTAINED WINDS...35 MPH...55 KM/H
PRESENT MOVEMENT...WNW OR 295 DEGREES AT 9 MPH...15 KM/H
MINIMUM CENTRAL PRESSURE...1007 MB...29.74 INCHES
WATCHES AND WARNINGS
CHANGES WITH THIS ADVISORY...
THE GOVERNMENT OF MEXICO HAS DISCONTINUED ALL TROPICAL STORM WATCHES
SUMMARY OF WATCHES AND WARNINGS IN EFFECT...
THERE ARE NO COASTAL WATCHES OR WARNINGS IN EFFECT.
FOR STORM INFORMATION SPECIFIC TO YOUR AREA...PLEASE MONITOR
PRODUCTS ISSUED BY YOUR NATIONAL METEOROLOGICAL SERVICE.
DISCUSSION AND 48-HOUR OUTLOOK
AT 1100 PM PDT...0600 UTC...THE CENTER OF TROPICAL DEPRESSION LORENA
WAS LOCATED NEAR LATITUDE 23.1 NORTH...LONGITUDE 111.5 WEST. LORENA
IS MOVING TOWARD THE WEST-NORTHWEST NEAR 9 MPH...15 KM/H. A
DECREASE IN FORWARD SPEED AND A TURN TO THE NORTH-NORTHWEST ARE
EXPECTED OVER THE WEEKEND. ON THE FORECAST TRACK...THE CENTER OF
LORENA SHOULD REMAIN NEAR THE SOUTHERN BAJA CALIFORNIA PENINSULA
DURING THE NEXT COUPLE OF DAYS.
MAXIMUM SUSTAINED WINDS HAVE DECREASED TO NEAR 35 MPH...55 KM/H...
WITH HIGHER GUSTS. ADDITIONAL WEAKENING IS EXPECTED...AND LORENA
IS FORECAST TO BECOME A REMNANT LOW ON SATURDAY.
THE ESTIMATED MINIMUM CENTRAL PRESSURE IS 1007 MB...29.74 INCHES.
HAZARDS AFFECTING LAND
RAINFALL...LORENA IS EXPECTED TO PRODUCE ADDITIONAL RAINFALL
ACCUMULATIONS OF 1 TO 2 INCHES OVER THE SOUTHERN PORTION OF THE
BAJA CALIFORNIA PENINSULA...WITH ISOLATED MAXIMUM AMOUNTS OF 4
INCHES POSSIBLE THROUGH SATURDAY. THESE RAINS COULD PRODUCE
LIFE-THREATENING FLASH FLOODS AND MUD SLIDES.
NEXT COMPLETE ADVISORY...200 AM PDT.
African tropical wave a threat to develop
A tropical wave over west Africa has the potential to become a tropical depression over the next few days. In fact, the GFS and ECMWF both actually support development in about two or three days. While rare, tropical cyclogenesis with systems just emerging from Africa does happen, with Hurricane Julia in 2010, Tropical Depression Ten in 2011, and Tropical Storm Florence in 2012 being three recent examples. Environmental conditions favor intensification, but the system will be moving northwestward through a latitude where it is statistically unlikely for an impact to the United States.
Heavy rains and gusty winds will likely overspread much of the Cape Verde Islands over the next couple of days as the well-defined wave axis moves off the coast.
Probability of development in 48 hours: 20%
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