September 29, 2011
Ophelia now a hurricane!
It took a while - but after meandering around a bit, Ophelia is a hurricane. It is forecast to head north and away from the Caribbean - we'll see! This could be an issue for Bermuda however...
HURRICANE OPHELIA DISCUSSION NUMBER 29
NWS NATIONAL HURRICANE CENTER MIAMI FL AL162011
500 PM AST THU SEP 29 2011
SATELLITE IMAGES AND MICROWAVE DATA INDICATE THAT THE CLOUD PATTERN
HAS CONTINUED TO ACQUIRE ORGANIZATION. THERE IS A CYCLONICALLY
CURVED CONVECTIVE BAND WRAPPING AROUND THE CENTER AND THE
UPPER-LEVEL OUTFLOW HAS EXPANDED IN ALL QUADRANTS. THERE HAS BEEN
AN EYE FEATURE INTERMITTENTLY APPEARING ON VISIBLE IMAGES...BUT
THERE IS DEFINITELY A DISTINCT ONE AT THE MID-LEVELS ON EARLIER
MICROWAVE DATA. T-NUMBERS FROM TAFB AND SAB HAVE INCREASED TO 4.0
ON THE DVORAK SCALE AND ON THIS BASIS...OPHELIA HAS BEEN UPGRADED
TO HURRICANE STATUS...THE FOURTH OF THE 2011 SEASON.
OPHELIA HAS KICKED OUT THE SHEAR AND GLOBAL MODELS INSIST ON KEEPING
AN UPPER-LEVEL RIDGE OVER THE CYCLONE. THIS PATTERN SHOULD ALLOW
SOME ADDITIONAL STRENGTHENING DURING THE NEXT DAY OR SO. THE
OFFICIAL FORECAST CONTINUE TO BE VERY SIMILAR TO THE STATISTICAL
LGEM...ALTHOUGH SOME MODELS FORECAST A STRONGER HURRICANE.
BEYOND 72 HOURS THE SHEAR IS FORECAST TO INCREASE SIGNIFICANTLY...
AND THE SEA SURFACE TEMPERATURES WILL DECREASE. THIS SHOULD RESULT
IN WEAKENING...AND MOST LIKELY OPHELIA WILL BECOME POST-TROPICAL BY
96 HOURS OR SOONER.
OPHELIA HAS BEEN MOVING TOWARD THE NORTH-NORTHWEST OR 340 DEGREES AT
8 KNOTS. THERE HAS BEEN NO CHANGE IN THE STEERING TO REPORT. THE
OFFICIAL FORECAST REMAINS UNCHANGED AND CONTINUES IN THE MIDDLE OF
THE GUIDANCE ENVELOPE IN BETWEEN THE GFS AND THE ECMWF FOR THE NEXT
2 TO 3 DAYS. OPHELIA SHOULD GRADUALLY TURN TO THE NORTH BY FRIDAY
AND THEN RECURVE NEAR THE LATITUDE OF BERMUDA IN ABOUT 48 HOURS.
THE WESTERN EDGE OF THE GUIDANCE ENVELOPE BARELY REACHES BERMUDA
AT THIS TIME.
September 27, 2011
Remnants of Ophelia, Tropical Storm Philippe UPDATE
This is an update - as Ophelia looks like it may in fact become a named storm again and could produce heavy rains for the Leeward islands:
1. A LOW PRESSURE SYSTEM...THE REMNANTS OF OPHELIA...CENTERED A COUPLE
OF HUNDRED MILES EAST-NORTHEAST OF THE NORTHERN LEEWARD ISLANDS...
IS PRODUCING A LARGE AREA OF SHOWERS AND THUNDERSTORMS. SURFACE
AND SATELLITE OBSERVATIONS INDICATE THAT THE SYSTEM HAS A BROAD
CIRCULATION...AND UPPER-LEVEL WINDS APPEAR SOMEWHAT CONDUCIVE FOR
ADDITIONAL REDEVELOPMENT AS THE LOW MOVES SLOWLY NORTHWESTWARD
DURING THE NEXT DAY OR TWO. THIS SYSTEM HAS A HIGH CHANCE...80
PERCENT...OF REGENERATING INTO A TROPICAL CYCLONE DURING THE NEXT
48 HOURS. LOCALLY HEAVY RAINS ARE POSSIBLE OVER PORTIONS OF THE
NORTHERN LEEWARD ISLANDS THROUGH WEDNESDAY.
ELSEWHERE...TROPICAL CYCLONE FORMATION IS NOT EXPECTED DURING THE
NEXT 48 HOURS.
The remnants of Tropical Storm Ophelia are still hanging around north of the Leeward Islands, and Tropical Storm Philippe is out in the Atlantic meandering northward. Neither system looks at this point to be a risk to the Caribbean region.
September 21, 2011
Tropical Storm Ophelia Open Thread
Use this post to ask questions or leave comments about Tropical Storm Ophelia.
Tropical Storm Ophelia 5 Day Track
Tropical Storm Ophelia
Tropical Storm Ophelia has formed in the Atlantic and looks like it will be another storm that tracks through the Leeward Islands. It is not forecast to become a hurricane any time soon, but you should keep and eye on it if you are in the region:
TROPICAL STORM OPHELIA DISCUSSION NUMBER 2
NWS NATIONAL HURRICANE CENTER MIAMI FL AL162011
500 AM EDT WED SEP 21 2011
CURVED CONVECTIVE BANDS OVER THE NORTHERN AND SOUTHERN PORTIONS OF
THE LARGE CIRCULATION HAVE BECOME A LITTLE BETTER DEFINED THIS
MORNING...HOWEVER THERE IS STILL A LACK OF DEEP CONVECTION NEAR
THE CENTER OF THE TROPICAL STORM. THE INITIAL INTENSITY OF THE
CYCLONE HAS BEEN INCREASED TO 40 KT...BASED ON DATA FROM A SHIP
LOCATED TO THE NORTH OF THE CENTER AND AN EARLIER ASCAT PASS.
THE UPPER-LEVEL WIND PATTERN AHEAD OF OPHELIA DOES NOT FAVOR
SIGNIFICANT STRENGTHENING. MODERATE SOUTHWESTERLY SHEAR CURRENTLY
OVER THE CYCLONE IS EXPECTED TO BECOME MORE WESTERLY AND INCREASE
IN A FEW DAYS AS AN UPPER-LEVEL LOW FORMS NORTH OF PUERTO RICO.
MOST OF THE INTENSITY GUIDANCE AGREES WITH THIS SCENARIO AND CALLS
FOR ONLY A LITTLE ADDITIONAL STRENGTHENING. THE NHC FORECAST IS IN
GOOD AGREEMENT WITH THE SHIPS/LGEM GUIDANCE AND IS VERY SIMILAR TO
THE PREVIOUS ADVISORY.
THE INITIAL MOTION ESTIMATE REMAINS RATHER UNCERTAIN...HOWEVER
IT APPEARS THAT OPHELIA IS MOVING A LITTLE FASTER THAN BEFORE. THE
TRACK FORECAST REASONING IS UNCHANGED FROM THE PREVIOUS NHC
ADVISORY. OPHELIA IS EXPECTED TO MOVE WESTWARD DURING THE NEXT
COUPLE OF DAYS TO THE SOUTH OF THE SUBTROPICAL RIDGE. AFTER 72
HOURS...THE WESTERN PORTION OF THE RIDGE IS EXPECTED TO WEAKEN AS A
LARGE MID/UPPER-LEVEL LOW DEVELOPS OVER THE EASTERN UNITED STATES.
THIS SHOULD RESULT IN THE CYCLONE TURNING TOWARD THE WEST-NORTHWEST
WITH SOME REDUCTION IN FORWARD SPEED. THE UPDATED NHC FORECAST
LIES BETWEEN THE TYPICALLY RELIABLE GFS AND ECMWF MODELS...AND IS
VERY CLOSE TO THE PREVIOUS ADVISORY.
September 9, 2011
TROPICAL STORM MARIA DISCUSSION NUMBER 11
The only good news about this storm is that it is not a hurricane - it is looking like it will track directly over the Virgin Islands, which will likely see a lot of rain and winds of about 40 to 50 MPH:
TROPICAL STORM MARIA DISCUSSION NUMBER 11
NWS NATIONAL HURRICANE CENTER MIAMI FL AL142011
500 AM AST FRI SEP 09 2011
THERE HAS BEEN AN INCREASE IN THE CONVECTION DURING THE PAST SEVERAL
HOURS BUT SATELLITE INTENSITY ESTIMATES HAVE NOT CHANGED. SURFACE
PRESSURES ARE FALLING...AS INDICATED BY BUOY 41101 WHICH RECENTLY
REPORTED A MINIMUM PRESSURE OF 1003.7 MB. THE INITIAL INTENSITY IS
KEPT AT 35 KNOTS AT THIS TIME...AND A RECONNAISSANCE PLANE WILL
CHECK MARIA AROUND 1200 UTC. THE UPPER-LEVEL WIND ENVIRONMENT IS
NOT AS HOSTILE AS IT WAS 12 TO 24 HOURS AGO...AND THE INTENSITY
GUIDANCE SHOWS SOME SLIGHT STRENGTHENING AS THE CYCLONE MOVES
ACROSS THE EXTREME NORTHEASTERN CARIBBEAN SEA...AND IT IS SOMEWHAT
MORE AGGRESSIVE BY THE END OF THE FORECAST PERIOD. THE NHC FORECAST
FOLLOWS SUCH GUIDANCE.
MARIA IS MOVING TOWARD THE WEST-NORTHWEST OR 290 DEGREES AT 17
KNOTS. THE LATEST TRACK GUIDANCE HAS SHIFTED TO THE RIGHT AS GLOBAL
MODELS NOW FORECAST A WEAKER SUBTROPICAL RIDGE TO THE NORTH OF THE
CYCLONE. ON THAT BASIS...THE OFFICIAL FORECAST HAS ALSO BEEN
SHIFTED TO THE NORTH BUT IT IS ON THE SOUTHERN EDGE OF THE NEW
GUIDANCE ENVELOPE IN CASE MODELS SHIFT BACK TO THE SOUTH IN THE
NEXT CYCLE. GIVEN THE TRACK AND INTENSITY FORECAST...A TROPICAL
STORM WARNING HAS BEEN ISSUED FOR A LARGE PORTION OF THE
NORTHEASTERN CARIBBEAN ISLANDS.
FORECAST POSITIONS AND MAX WINDS
INIT 09/0900Z 13.8N 56.2W 35 KT 40 MPH
12H 09/1800Z 14.5N 58.5W 35 KT 40 MPH
24H 10/0600Z 16.0N 61.3W 35 KT 40 MPH
36H 10/1800Z 17.5N 63.5W 40 KT 45 MPH
48H 11/0600Z 19.0N 65.5W 45 KT 50 MPH
72H 12/0600Z 22.0N 69.5W 55 KT 65 MPH
96H 13/0600Z 24.0N 71.5W 65 KT 75 MPH
120H 14/0600Z 27.0N 73.5W 70 KT 80 MPH
September 8, 2011
Tropical Storm Maria
Tropical Storm Maria is the latest in a fast and furious September so far for named storms. Katia is now an Atlantic hurricane and not a threat to the region, and Nate is a Gulf of Mexico/Central America storm - but Maria, although not forecast to become a hurricane in the Caribbean, looks to be tracking right over the Leeward Islands. It is packing 50 mph winds and plenty of rain, so while it shouldn't be a disastrous storm as currently forecast, it can certainly ruin your vacation and trigger local flooding and heavy surf in the next several days.
TROPICAL STORM MARIA DISCUSSION NUMBER 7
NWS NATIONAL HURRICANE CENTER MIAMI FL AL142011
500 AM AST THU SEP 08 2011
MARIA CURRENTLY HAS A RATHER DISORGANIZED APPEARANCE ON SATELLITE
IMAGES...AND CONSISTS PRIMARILY OF A RATHER SHAPELESS CLUSTER OF
DEEP CONVECTION WITH A FEW THUNDERSTORMS TO THE WEST-SOUTHWEST OF
THE CLUSTER. THERE IS LITTLE...IF ANY...EVIDENCE OF BANDING
FEATURES. AN ASCAT PASS FROM SEVERAL HOURS AGO INDICATED THAT THE
MAXIMUM WINDS REMAIN NEAR 45 KT. HOWEVER...DATA FROM THIS PASS ALSO
CAST SOME DOUBT AS TO WHETHER THE SYSTEM HAS A CLOSED CIRCULATION
AT THIS TIME. VISIBLE IMAGERY AND AN AIRCRAFT MISSION LATER TODAY
SHOULD GIVE MORE INFORMATION ON THE STATUS OF MARIA.
NO CHANGE IS MADE TO THE INTENSITY FORECAST. AN UPPER-LEVEL LOW OR
TROUGH TO THE NORTHWEST OF THE STORM HAS BEEN IMPARTING ABOUT 20 KT
OF SOUTH-SOUTHWESTERLY SHEAR OVER THE TROPICAL CYCLONE...AND
INHIBITING STRENGTHENING. GLOBAL MODELS INDICATE THAT THIS
LOW/TROUGH WILL MOVE MORE OR LESS IN TANDEM WITH MARIA THROUGH
ABOUT 72 HOURS...AND CONTINUE TO PRODUCE SIGNIFICANT SHEAR ON THE
SYSTEM. THE OFFICIAL FORECAST SHOWS NO STRENGTHENING THROUGH 72
HOURS FOLLOWED BY SOME INCREASE IN INTENSITY AS THE IMPACT OF THE
AFOREMENTIONED UPPER-LEVEL LOW IS EXPECTED TO LESSEN. THE NHC WIND
SPEED FORECAST IS ROUGHLY BETWEEN THE LATEST LGEM GUIDANCE AND THE
INTENSITY MODEL CONSENSUS.
THE CENTER IS QUITE DIFFICULT TO FIND...BUT IT IS PRESUMED THAT
MARIA HAS BEEN MAINTAINING A MOTION OF 275/20. A CONTINUED WESTWARD
MOTION IS LIKELY FOR ANOTHER DAY OR SO AS THE STORM MOVES ON THE
SOUTHERN SIDE OF A SUBTROPICAL RIDGE. SOME DECELERATION IS
PREDICTED AS THE RIDGE WEAKENS A LITTLE WITH TIME. IN 48 TO 72
HOURS...MARIA SHOULD BE NEARING A WEAKNESS IN THE RIDGE AND TURN
WEST-NORTHWESTWARD. AS USUAL...THERE IS A FAIR AMOUNT OF
UNCERTAINTY IN THE TRACK 4 TO 5 DAYS FROM NOW. A BROAD 500 MB
TROUGH...MOVING OFF THE U.S EAST COAST...IS SHOWN BY THE GLOBAL
MODELS TO WEAKEN THE RIDGE ENOUGH TO CAUSE MARIA TO TURN
NORTHWESTWARD BY 96 HOURS. IF THE TROUGH TURNS OUT TO BE WEAKER
THAN CURRENTLY PREDICTED...IT COULD DELAY THE NORTHWESTWARD TURN.
THE OFFICIAL FORECAST IS VERY CLOSE TO THE PREVIOUS ONE AND ROUGHLY
IN THE MIDDLE OF THE TRACK GUIDANCE ENVELOPE...BRACKETED BY THE
U.K. MET OFFICE MODEL ON THE LEFT AND BY THE GFS AND HWRF MODELS ON
THE RIGHT.
FORECAST POSITIONS AND MAX WINDS
INIT 08/0900Z 13.5N 48.2W 45 KT 50 MPH
12H 08/1800Z 13.8N 51.2W 45 KT 50 MPH
24H 09/0600Z 14.5N 54.7W 45 KT 50 MPH
36H 09/1800Z 15.3N 57.8W 45 KT 50 MPH
48H 10/0600Z 16.7N 60.8W 45 KT 50 MPH
72H 11/0600Z 19.5N 65.5W 45 KT 50 MPH
96H 12/0600Z 23.0N 69.0W 50 KT 60 MPH
120H 13/0600Z 26.0N 72.0W 60 KT 70 MPH
Tropical Storm Maria Open Thread
Use this post to ask questions or leave comments about Tropical Storm Maria.
Tropical Storm Maria 5 Day Track
September 2, 2011
Katia regains hurricane status
The forecast remains mixed and unclear, but it should cause rough surf conditions for many Caribbean Islands:
HURRICANE KATIA DISCUSSION NUMBER 18
NWS NATIONAL HURRICANE CENTER MIAMI FL AL122011
1100 AM AST FRI SEP 02 2011
THE CONVECTIVE DEPICTION OF KATIA HAS IMPROVED THIS MORNING AS BOTH
MICROWAVE IMAGERY FROM SSMIS AND CONVENTIONAL VISIBLE SATELLITE
IMAGERY INDICATE THAT AN EYE MAY BE FORMING. BECAUSE OF THE
IMPROVED STRUCTURE...BOTH TAFB AND SAB DVORAK CLASSIFICATIONS CAME
IN AT A 4.0...OR 65 KT...AS DID A 1053Z CIMSS AMSU INTENSITY
ESTIMATE. THUS KATIA HAS REGAINED HURRICANE STATUS.
THE HURRICANE IS MOVING TOWARD THE WEST-NORTHWEST AT ABOUT 12
KT...AS IT IS BEING ADVECTED AROUND THE SOUTHWEST PERIPHERY OF A
DEEP-LAYER RIDGE. KATIA SHOULD MOVE TOWARD THE WEST-NORTHWEST OR
NORTHWEST FOR THE NEXT FEW DAYS AT A SLIGHTLY SLOWER RATE OF SPEED.
ALL OF THE RELIABLE GUIDANCE...WITH THE EXCEPTION OF THE UKMET WHICH
HAS A MUCH MORE EQUATORWARD SOLUTION DUE TO A SHORT-WAVE TROUGH OFF
OF THE U.S. EAST COAST LIFTING OUT TO THE NORTHEAST MORE QUICKLY...
IS IN EXCELLENT AGREEMENT. THE TRACK FORECAST IS VERY SIMILAR TO
THE PREVIOUS ADVISORY AND THE CONSENSUS OF THE GLOBAL AND HURRICANE
MODELS LESS THE UKMET MODEL.
DESPITE BECOMING A HURRICANE AGAIN...KATIA FACES A RELATIVELY
HOSTILE ENVIRONMENT WITH SOUTHWEST VERTICAL SHEAR OF 15-20 KT
SUGGESTED FOR THE NEXT DAY OR TWO. BEYOND 48 HOURS...THE SHEAR
FROM THE GLOBAL MODELS IS ANTICIPATED TO DECREASE...BUT THE
THERMODYNAMICS MAY NOT BE IDEAL WITH LOW HUMIDITIES AND A MORE
STABLE ENVIRONMENT ANTICIPATED. SOME OF THE UPPER-LEVEL
TEMPERATURE INCREASES ANALYZED IN THE SHIPS/LGEM STATISTICAL
MODELS...HOWEVER...MAY BE SPURIOUS...AS THE STRONGER VORTEX FROM
THE GFS MAY BE THE CAUSE OF THESE VALUES RATHER THAN THE
ENVIRONMENT. THUS THE SHIPS/LGEM GUIDANCE MAY BE TOO LOW AT DAYS
THREE TO FIVE. THE INTENSITY PREDICTION IS SLIGHTLY LOWER THAN A
SHIPS/LGEM/HWRF BLEND BUT HIGHER THAN THE PREVIOUS ADVISORY DURING
THE NEXT TWO DAYS.
