1. Tropical storm conditions are expected in the Cayman Islandsbeginning late today, and a Tropical Storm Warning is in effect.

2. Dangerous storm surge and hurricane conditions are possible inportions of western Cuba and the Isle of Youth by Tuesdayafternoon, and a Hurricane Watch is in effect.

3. Heavy rainfall will affect portions of Jamaica, the Cayman Islands, and western Cuba during the next few days. This rainfall could lead to significant flash flooding and mudslides.

4. The system is forecast to approach the northern Gulf Coast latethis week as a hurricane. While there is large uncertainty in thetrack and intensity forecasts at these time ranges, there is a riskof dangerous storm surge, wind, and rainfall hazards along the coastfrom Louisiana to the western Florida Panhandle. Residents in theseareas should monitor the progress of the system and check forupdates to the forecast during the week.

CHANGES WITH THIS ADVISORY:

None.

SUMMARY OF WATCHES AND WARNINGS IN EFFECT:

A Hurricane Watch is in effect for...
- Cuban provinces of Pinar del Rio and Artemisa
- Isle of Youth

A Tropical Storm Warning is in effect for...
- Cayman Islands including Little Cayman and Cayman Brac

A Tropical Storm Watch is in effect for...
- Cuba province of La Habana

A Hurricane Watch means that hurricane conditions are possible within the watch area, generally within 48 hours.

A Tropical Storm Warning means that tropical storm conditions are expected somewhere within the warning area within 36 hours.

A Tropical Storm Watch means that tropical storm conditions are possible within the watch area, generally within 48 hours.

For storm information specific to your area, please monitor products issued by your national meteorological service.

Key messages for Tropical Depression TwentySix can be found in the Tropical Cyclone Discussion under AWIPS header MIATCDAT1, WMO header WTNT41 KNHC, and on the web at www.hurricanes.gov/text/MIATCDAT1.shtml.

STORM SURGE: A dangerous storm surge will raise water levels by as much as 3 to 5 feet above normal tide levels along the immediate coast of the Isle of Youth and along the south coast of western Cuba near and to right of where the center makes landfall. Near the coast, the surge will be accompanied by large and dangerous waves.

RAINFALL: Through midweek, this system is expected to produce 3 to 5 inches of rain with isolated maximum totals of 8 inches across Jamaica and western Cuba. This rainfall could lead to significant flash floods and mudslides. Over the Cayman Islands, 2 to 4 inches of rainfall will be possible with this system.

WIND: Tropical storm conditions are expected in the Cayman Islands beginning late today. Hurricane conditions are possible within the Hurricane Watch area by Tuesday afternoon, with tropical storm conditions possible by early Tuesday. Tropical Storm conditions are possible in the Tropical Storm Watch area in Cuba by early Tuesday.

At 500 AM EDT (0900 UTC), the center of Tropical Depression TwentySix was located near latitude 17.0 North, longitude 78.2 West. The depression is moving toward the westnorthwest near 9 mph (15 km/h), and this general motion should continue for the next day or so. A faster northwestward motion is expected on Tuesday and Wednesday. On the forecast track, the center of the depression is expected to move away from Jamaica through this morning, move near or over the Cayman Islands later tonight, and approach the Isle of Youth and western Cuba Tuesday afternoon or evening. The tropical cyclone is forecast to move into the southeastern Gulf of Mexico Tuesday night or early Wednesday.

Maximum sustained winds are near 35 mph (55 km/h) with higher gusts. Strengthening is expected during the next few days, and the depression is forecast to become a tropical storm when it nears the Cayman Islands later today, and be a hurricane when it moves near or over western Cuba on Tuesday.

The estimated minimum central pressure is 1006 mb (29.71 inches).

Deep convection has been steadily improving in both vertical depth and structure, with the cloud pattern becoming more circular with upper-level outflow now having become established in all quadrants. However, there are still some indications in satellite imagery that the low-level and the mid-/upper-level circulations are not yet vertically aligned, with the low-level center still located just inside the northern edge of the convective cloud shield. For now, the initial intensity remains at 30 kt based on Dvorak satellite classifications from TAFB and SAB and also UW-CIMSS ADT. However, SATCON estimates suggest that the cyclone is close to tropical storm status.

The initial motion estimate is an uncertain 290/08 kt. Even after maintaining some continuity with the previous forecast, the initial position had to be adjusted a little farther to the south and west based on satellite animation, and the current position may have to be adjusted farther south on the next forecast cycle due to possible redevelopment of the center into the deep convective cloud mass. Otherwise, the previous forecast track reasoning remains essentially unchanged. The cyclone is expected to move west-northwestward to northwestward along the southern side of a deep-layer ridge for the next few days. By day 4 and beyond, a broad mid- to upper-level trough is forecast to develop across northern Mexico and Texas, which is expected to create a break in the ridge and turn the cyclone northward toward the north-central Gulf coast. The steering flow pattern becomes a little complex on days 2-3 due to expected binary interaction with Tropical Storm Gamma or its remnants, which could result in a sharp westward jog, after which a sharp turn back toward the northwest could occur. However, the latest NHC model guidance is in fairly good agreement that the cyclone will make a sharp northward turn between 90W-92W longitude around 96 hours or so. Thereafter, acceleration toward the north-northeast or northeast ahead of the approaching trough and frontal system is anticipated. The new NHC forecast track is a little to the left of the previous track through 72 hours, mainly to account for the more westward initial position, and lies down the middle of the tightly packed model guidance envelope.The northeasterly deep-layer vertical wind shear that has been plaguing the cyclone is finally showing signs of abating. The GFS- and ECMWF-based SHIPS model guidance shows the shear decreasing to near zero in the 24-48 hour period, which allow for some robust intensification to occur, assuming that the inner-core wind field becomes better defined later today. By 96 hours and beyond, the SHIPS models are forecasting the shear to increase 20-30 kt from the southwest, which would be expected to induce rapid weakening. However, the SHIPS models appear to be creating too much shear over the cyclone's center by incorporating jetstream winds of about 60 kt across Texas, whereas the 200-mb model fields only show winds of 10-15 kt over the center by 96 hours. As a result, the new intensity forecast calls for the cyclone to reach its peak intensity in the 72-96 hour period, followed by weakening due to likely cold upwelling of shallow cool shelf waters offshore the southwest coast of Louisiana and Mississippi. The new NHC intensity forecast is similar to the previous advisory, and lies near the upper end of the intensity guidance, similar to the corrected-consensus model HCCA.

Users are reminded that the average 4- and 5-day NHC track forecasterrors are about 160 to 200 miles at those time periods,respectively.