Basement-dwelling pseudo-otaku with a thrill for forecasting on the side.
By: KoritheMan , 5:57 AM GMT on July 06, 2013
Erick continues to strengthen, and is just under hurricane strength according to the latest NHC advisory:
Wind: 70 mph, with higher gusts
Location: 17.0°N 103.8°W
Movement: NW at 10 mph
Pressure: 991 mb
Erick is sporting a satellite signature that is typical of tropical storms on the verge of intensifying to hurricanes; the deep convection has taken on tightly-wound banding, and conventional satellite fixes throughout the last 12 hours have showed hints of a developing eye. A timely 0230 UTC SSMI pass showed a well-defined ring of convection surrounding a primitive eye feature; incidentally, the pass also showed that the mid-level eye feature was displaced a little northwest of the low-level one, which likely signals that there is still a little bit of southeasterly shear over Erick.
Figure 1. Latest infrared satellite image of Tropical Storm Erick. Image credit: NOAA's Satellite Services Division (SSD).
Environmental conditions appear supportive of continued intensification, with very warm sea surface temperatures and low to moderate vertical wind shear. Most of the guidance makes Erick a hurricane over the next 24 hours, with the 0z intensity consensus currently suggesting a peak near 70 kt. I will go along with this. Beyond 24 hours, the cyclone will be approaching cooler water; waters which rapidly cool subsequent to that time. Thus, my forecast shows Erick weakening rather quickly after 36 hours, and the tropical cyclone is expected to lose that nominal status in about 96 hours, although it could occur a little sooner, particularly if Erick moves north of the forecast track.
While satellite and microwave fixes suggest that Erick continues moving northwest gravitating toward a residual weakness in the mid-level ridge to the north, water vapor imagery suggests that the mid-level flow is beginning to amplify as a slow-moving mid-level trough departs the Texas coastal region. This is causing the ridge to rebuild to the north of the tropical cyclone, which seems to be occurring a little faster than indicated by the majority of the guidance; this leads me to the conclusion that Erick will turn westward quicker than indicated by the guidance or the NHC. My forecast track is generally along the southern edge of the model consensus, especially beyond day two, and is quite a bit south of the 0300 UTC National Hurricane Center forecast.
Regardless, there is a wide enough margin for error that Erick could still reasonably make landfall along the southwestern coast of Mexico, and it is possible a hurricane watch will be issued later this morning. Interests in the tropical storm warning area should take the necessary precautions to prepare for Erick's potential arrival.
Even if Erick does not make landfall, it is expected to produce tropical storm force winds (especially gusts) in squalls, along with very heavy rainfall capable of causing flash flooding and mudslides, which will be capable of causing loss of life. Treacherous sea conditions in the form of strong rip currents, locally high storm surge, and large battering waves will also accompany Erick as it parallels the coast.
5-day intensity forecast
INITIAL 07/06 0500Z 60 KT 70 MPH
12 hour 07/06 1200Z 65 KT 75 MPH
24 hour 07/07 0000Z 70 KT 80 MPH
36 hour 07/07 1200Z 65 KT 70 MPH
48 hour 07/08 0000Z 55 KT 65 MPH
72 hour 07/09 0000Z 30 KT 35 MPH
96 hour 07/10 0000Z 25 KT 30 MPH...POST-TROPICAL/REMNANT LOW
120 hour 07/11 0000Z...DISSIPATED
5-day track forecast
Figure 2. My 5-day forecast track for Erick.
NHC storm information
WTPZ35 KNHC 060538
TROPICAL STORM ERICK INTERMEDIATE ADVISORY NUMBER 7A
NWS NATIONAL HURRICANE CENTER MIAMI FL EP052013
1100 PM PDT FRI JUL 05 2013
...ERICK STILL JUST BELOW HURRICANE STRENGTH...
SUMMARY OF 1100 PM PDT...0600 UTC...INFORMATION
ABOUT 155 MI...250 KM SSE OF MANZANILLO MEXICO
ABOUT 565 MI...910 KM SE OF THE SOUTHERN TIP OF BAJA CALIFORNIA
MAXIMUM SUSTAINED WINDS...70 MPH...110 KM/H
PRESENT MOVEMENT...NW OR 315 DEGREES AT 9 MPH...14 KM/H
MINIMUM CENTRAL PRESSURE...991 MB...29.26 INCHES
WATCHES AND WARNINGS
CHANGES WITH THIS ADVISORY...
SUMMARY OF WATCHES AND WARNINGS IN EFFECT...
A TROPICAL STORM WARNING IS IN EFFECT FOR...
* ZIHUATANEJO TO CABO CORRIENTES
A TROPICAL STORM WARNING MEANS THAT TROPICAL STORM CONDITIONS ARE
EXPECTED SOMEWHERE WITHIN THE WARNING AREA WITHIN 36 HOURS.
FOR STORM INFORMATION SPECIFIC TO YOUR AREA OUTSIDE OF THE
UNITED STATES...PLEASE MONITOR PRODUCTS ISSUED BY YOUR NATIONAL
DISCUSSION AND 48-HOUR OUTLOOK
AT 1100 PM PDT...0600 UTC...THE CENTER OF TROPICAL STORM ERICK WAS
LOCATED NEAR LATITUDE 17.0 NORTH...LONGITUDE 103.8 WEST. ERICK IS
MOVING TOWARD THE NORTHWEST NEAR 9 MPH...14 KM/H. A GENERAL
NORTHWEST TO WEST-NORTHWEST MOTION IS EXPECTED OVER THE NEXT COUPLE
OF DAYS. ON THE FORECAST TRACK...THE CORE OF ERICK SHOULD MOVE
PARALLEL TO...BUT REMAIN OFFSHORE OF...THE COAST OF SOUTHWESTERN
MAXIMUM SUSTAINED WINDS ARE NEAR 70 MPH...110 KM/H...WITH HIGHER
GUSTS. ERICK IS FORECAST TO BECOME A HURRICANE AT ANY TIME.
TROPICAL STORM FORCE WINDS EXTEND OUTWARD UP TO 105 MILES...165 KM
FROM THE CENTER PRIMARILY IN THE NORTHEAST QUADRANT.
THE ESTIMATED MINIMUM CENTRAL PRESSURE IS 991 MB...29.26 INCHES.
HAZARDS AFFECTING LAND
RAINFALL...ERICK IS EXPECTED TO PRODUCE TOTAL RAIN ACCUMULATIONS
OF 3 TO 5 INCHES OVER SOUTHWESTERN OAXACA...SOUTHERN GUERRERO...
SOUTHERN MICHOACAN...COLIMA...AND SOUTHERN JALISCO MEXICO...WITH
POSSIBLE ISOLATED MAXIMUM AMOUNTS OF 8 INCHES. THESE RAINS COULD
CAUSE LIFE-THREATENING FLASH FLOODS AND MUD SLIDES.
WIND...TROPICAL STORM CONDITIONS ARE LIKELY TO SPREAD WESTWARD
ACROSS THE WARNING AREA TONIGHT AND SATURDAY.
NEXT COMPLETE ADVISORY...200 AM PDT.
A large area of showers and thunderstorms over the western and central Gulf of Mexico is associated with a surface trough interacting with an upper-level trough along the northern Gulf Coast. Looking agonizingly tonight for evidence of any sort of circulation pattern, I'm just not seeing it. Shortwave infrared satellite images indicate that there could be a mid-level circulation near 25.5N 90.5W, but this was not supported at all by CIMSS 500 mb vorticity data over the last six hours. In addition, there has not been a center fix or any model runs on what's actually supposed to be 94L -- in the southwestern Gulf -- since 18z Friday (2:00 PM). Looking at that area now, there is literally no evidence of even a faint mid-level rotation, and I expect that any surface center which did form in the southwestern Gulf has long since dissipated.
There is still about 30 kt of westerly shear over the disturbance associated with the south side of the upper-level trough moving through Louisiana, but the tendency has been for the shear to slowly decrease over the last 24 hours. The global models continue to indicate that the upper tropospheric flow could relax considerably over the next 24-48 hours, but how much the system can take advantage of this forecast depends largely on how fast a surface circulation can develop underneath the convection south of the Louisiana coast, and also how long the system remains over water; if a center reformation is indeed occurring in the aforementioned convective mass, there could be fits and wobbles in the track over the day on Saturday as the low-level center attempts to get tucked underneath the convection and avoid the shear. If that were to happen, the system could have a little more time over water than currently forecast.
In any event, I do not think the system has either the time nor the patience to become a tropical cyclone before moving ashore the northern Gulf Coast in the next 24-36 hours, but it will spread heavy rains capable of causing flooding in short bursts; flash flood watches are already in effect for a large portion of the northern Gulf Coast in anticipation of this threat. Strong gusty winds, particularly along the coast, will also be a factor, which could produce some coastal flooding, especially if the low decides to meander.
Upper air data over the Gulf Coast region shows that winds are backing over Texas and western Louisiana, suggesting that a low- to mid-level ridge is attempting to rebuild in the wake of the trough moving through Louisiana; this would tend to discourage any significant westward component of motion from the disturbance. Since the trough appears to be moving through Louisiana, albeit slowly, I would expect that any system which develops amidst the convection south of the Louisiana coast would move generally northward, with a possible turn to the northeast after landfall occurs along the southeastern Louisiana coast. I'm favoring a landfall near Grand Isle at the moment, but it could come in a little farther east if the trough begins to move a little quicker.
Surface pressures are not falling, and any development is expected to be slow.
Probability of development in 48 hours: 20%
Eastern Atlantic tropical wave
Another vigorous tropical wave unseasonable for the month of July is located in the far eastern Atlantic about 700 miles southwest of the Cape Verde Islands. Scatterometer data earlier on Friday suggested a broad surface circulation that was elongated from west-northwest to east-southeast. This system and its associated surface low are still trapped in the ITCZ, and development cannot occur in that situation. The system is also rather far to the south, at about 7N, which also argues against significant development since low pressure centers that far south can't successfully leverage the Earth's spin.
Interestingly, there's not a lot of shear over the disturbance, and the models keep it fairly light over the next several days. This wave is expected to move westward to west-northwestward.
Probability of development in 48 hours: 10%
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