WTNT43 KNHC 192049
TCDAT3
TROPICAL STORM CRISTOBAL DISCUSSION NUMBER   4
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL032008
500 PM EDT SAT JUL 19 2008
 
THE AIR FORCE HURRICANE HUNTER HAS FOUND MAXIMUM FLIGHT LEVEL WINDS
OF 58 KT AT 2500 FT...CORRESPONDING TO ABOUT 45 KT AT THE SURFACE.
HOWEVER...SFMR DATA AT THAT SAME LOCATION SHOWED ONLY 35 KT AND
CONVECTION HAS BEEN WEAKENING NEAR THE CENTER. THE INITIAL
INTENSITY IS A COMPROMISE BETWEEN THESE VALUES AND IS SET TO 40 KT.
FURTHER INTENSIFICATION IS POSSIBLE AS THE SYSTEM MOVES OVER WARM
GULF STREAM WATERS AND EXPERIENCES LIGHT SHEAR. THE OFFICIAL
FORECAST IS INCREASED FROM THE PREVIOUS ONE AND IS CLOSE TO A
SHIFOR/SHIPS CONSENSUS. STRANGELY...THE GFDL/HWRF STILL REFUSE TO
INTENSIFY THIS SYSTEM.
 
THE INITIAL MOTION ESTIMATE IS 050/6.  THERE IS NO CHANGE TO THE
PREVIOUS SYNOPTIC REASONING. A WEAK MID-TROPOSPHERIC RIDGE TO THE
SOUTHEAST OF THE STORM SHOULD CONTINUE TO MOVE THE SYSTEM AT ABOUT
THE SAME HEADING AND SPEED DURING THE NEXT DAY OR SO. MODEL
GUIDANCE REMAINS IN GOOD AGREEMENT ON TAKING THE SYSTEM NEARLY
PARALLEL TO THE NORTH CAROLINA COAST DURING THE NEXT DAY OR SO.
THEREAFTER...THE DEPRESSION WILL MOVE FASTER TO THE NORTHEAST
BETWEEN A BUILDING RIDGE TO THE EAST AND A DEEPENING MIDDLE-
LATITUDE TROUGH OVER EASTERN NORTH AMERICA. THE MODELS DO DIVERGE A
LITTLE ON WHETHER THE STORM WILL BE TURN A LITTLE MORE TO THE LEFT
IN RESPONSE TO THE TROUGH OR STAY MORE SEPARATE FROM THAT FEATURE.
THE OFFICIAL FORECAST IS A TAD FASTER AND A LITTLE LEFT OF THE
PREVIOUS ONE AFTER 36 HR...NEAR THE CENTER OF THE GUIDANCE
ENVELOPE.
 
  
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      19/2100Z 33.0N  77.9W    40 KT
 12HR VT     20/0600Z 33.7N  77.0W    45 KT
 24HR VT     20/1800Z 34.7N  75.6W    50 KT
 36HR VT     21/0600Z 35.9N  73.9W    55 KT
 48HR VT     21/1800Z 38.0N  71.3W    55 KT
 72HR VT     22/1800Z 43.5N  64.0W    45 KT...EXTRATROPICAL
 96HR VT     23/1800Z...ABSORBED
 
$$
FORECASTER BLAKE/KNABB
 

WTNT43 KNHC 200251
TCDAT3
TROPICAL STORM CRISTOBAL DISCUSSION NUMBER   5
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL032008
1100 PM EDT SAT JUL 19 2008
 
SATELLITE...RADAR...AND SURFACE OBSERVATIONS SHOW NO INDICATION THAT
CRISTOBAL HAS STRENGTHENED THIS EVENING.  CURRENTLY THE STORM IS
CONVECTIVELY CHALLENGED...WITH THE COLD TOPS LIMITED TO A COUPLE OF
BANDS TO THE SOUTHEAST OF THE CENTER.  THE INITIAL INTENSITY IS
HELD AT 40 KT PENDING THE ARRIVAL OF THE NEXT AIRCRAFT AROUND 06Z. 
THE MORE OBVIOUS ENVIRONMENTAL FACTORS DO FAVOR SOME STRENGTHENING
OVER THE NEXT DAY OR SO...THESE BEING LIGHT SHEAR AND ANTICYCLONIC
FLOW ALOFT...AND WARM WATERS BELOW.  THE OFFICIAL FORECAST
PRIMARILY FOLLOWS THE SHIPS/LGEM GUIDANCE.  AT PRESENT THE WIND
FIELD IS VERY ASYMMETRIC.  HOWEVER...IF THE FORECAST STRENGTHENING
OCCURS...CRISTOBAL COULD WRAP SOME OF THE TROPICAL STORM FORCE
WINDS AROUND TO THE WEST SIDE OF THE CIRCULATION. 

THERE HAS BEEN NO MAJOR CHANGE TO THE TRACK FORECAST.  THE INITIAL
MOTION IS 045/5.  CRISTOBAL IS EXPECTED TO MOVE NORTHEASTWARD...
VERY CLOSE TO THE COASTLINE...AROUND THE PERIPHERY OF THE
SUBTROPICAL RIDGE...WITH SOME ACCELERATION AS IT ENTERS THE
WESTERLIES.  ONLY THE NOGAPS AND GFNI TAKE CRISTOBAL CLOSE TO
EASTERN MASSACHUSETTS.   GLOBAL MODELS SUGGEST THAT CRISTOBAL WILL
BECOME ABSORBED AHEAD OF AN APPROACHING COLD FRONT IN ABOUT 48
HOURS...ALTHOUGH I'VE ELECTED TO SHOW THE SYSTEM AS A SEPARATE
ENTITY A LITTLE BIT LONGER.

 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      20/0300Z 33.4N  77.5W    40 KT
 12HR VT     20/1200Z 34.1N  76.6W    45 KT
 24HR VT     21/0000Z 35.2N  75.1W    50 KT
 36HR VT     21/1200Z 36.8N  73.0W    55 KT
 48HR VT     22/0000Z 39.0N  70.0W    45 KT
 72HR VT     23/0000Z 45.0N  63.0W    35 KT...EXTRATROPICAL
 96HR VT     24/0000Z...ABSORBED
 
$$
FORECASTER FRANKLIN
 

WTNT43 KNHC 200858
TCDAT3
TROPICAL STORM CRISTOBAL DISCUSSION NUMBER   6
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL032008
500 AM EDT SUN JUL 20 2008
 
THE SATELLITE PRESENTATION OF CRISTOBAL REMAINED UNIMPRESSIVE-
LOOKING OVERNIGHT.  THERE HAS BEEN VERY LITTLE DEEP CONVECTION NEAR
THE CENTER WITH THE PRIMARY BANDS OF THUNDERSTORMS WELL DISPLACED
TO THE SOUTH AND SOUTHEAST.  FLIGHT-LEVEL WINDS FROM AIR FORCE
HURRICANE HUNTER DATA INDICATE THAT THE MAXIMUM WINDS REMAIN NEAR
40 KT.  SOME SFMR READINGS FROM THE AIRCRAFT GAVE HIGHER SURFACE
WINDS BUT THESE APPEAR TO BE ERRONEOUS DUE TO INTERFERENCE.
ALTHOUGH SURFACE OBSERVATIONS SHOW LITTLE EVIDENCE OF DRY
AIR...WATER VAPOR IMAGERY SHOWS SOME EVIDENCE OF MID-LEVEL
SUBSIDENCE OVER THE NORTHEASTERN PORTION OF THE CIRCULATION AND
UPPER-LEVEL OUTFLOW IS BEING SHUNTED OVER THE NORTHERN SEMICIRCLE.   
200 MB WIND FORECASTS FROM THE GFS SUGGEST A MORE FAVORABLE
UPPER-LEVEL ENVIRONMENT WITHIN THE NEXT DAY OR SO...AND SOME
INTENSIFICATION IS FORECAST AS IN THE PREVIOUS ADVISORIES.  THE
OFFICIAL WIND SPEED FORECAST IS A LITTLE HIGHER THAN THE INTENSITY
FORECAST MODEL CONSENSUS.  WITHIN 2-3 DAYS THE SYSTEM IS EXPECTED
TO LOSE STRENGTH DUE TO RAPIDLY INCREASING SOUTHWESTERLY
SHEAR...AND LOSE TROPICAL CHARACTERISTICS.

THE INITIAL MOTION IS SLOWLY NORTHEASTWARD...040/5.  CRISTOBAL IS
EXPECTED TO GRADUALLY INCREASE ITS FORWARD SPEED AS IT BECOMES
PICKED UP IN THE FLOW AHEAD OF A BROAD MID-TROPOSPHERIC TROUGH.  BY
72-96 HOURS OR SOONER THE SYSTEM IS EXPECTED TO MERGE WITH A LARGER
EXTRATROPICAL CYCLONE NEAR THE CANADIAN MARITIMES.  THE OFFICIAL
TRACK FORECAST IS ABOUT IN THE MIDDLE OF THE MODEL GUIDANCE AND
SIMILAR TO THE PREVIOUS NHC TRACK.

FORECAST POSITIONS AND MAX WINDS
 
INITIAL      20/0900Z 33.9N  77.2W    40 KT
 12HR VT     20/1800Z 34.7N  76.0W    45 KT
 24HR VT     21/0600Z 35.8N  74.4W    50 KT
 36HR VT     21/1800Z 37.5N  72.0W    55 KT
 48HR VT     22/0600Z 40.2N  69.0W    45 KT
 72HR VT     23/0600Z 47.0N  61.0W    35 KT...EXTRATROPICAL
 96HR VT     24/0600Z...ABSORBED
 
$$
FORECASTER PASCH
 

WTNT43 KNHC 201500
TCDAT3
TROPICAL STORM CRISTOBAL DISCUSSION NUMBER   7
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL032008
1100 AM EDT SUN JUL 20 2008

EARLIER THIS MORNING...THE AIR FORCE PLANE REPORTED MAXIMUM FLIGHT
LEVEL WINDS OF 54 KT...WITH SFMR MEASURMENTS OF ABOUT 45 KT. SINCE
THEN...THERE HAS BEEN LITTLE CHANGE IN SATELLITE IMAGES SO THE
MAXIMUM WINDS WILL REMAIN 45 KT FOR THIS ADVISORY. DRY AIR IN THE
MIDDLE TO UPPER LEVELS HAS SEEMINGLY PREVENTED CRISTOBAL FROM
DEVELOPING MUCH CONVECTION NEAR THE CENTER. THE GFS SUGGESTS A MORE
FAVORABLE UPPER-LEVEL ENVIRONMENT IS POSSIBLE WITHIN THE NEXT DAY
OR SO...AND A LITTLE BIT OF INTENSIFICATION IS FORECAST AT THAT
TIME. THE OFFICIAL WIND SPEED FORECAST IS CLOSE TO THE SHIPS MODEL. 
 
THE INITIAL MOTION IS SLOWLY NORTHEASTWARD...040/5. MODEL GUIDANCE
IS TIGHTLY CLUSTERED ON AN ACCELERATING TRACK TO THE NORTHEAST AS
CRISTOBAL BECOMES PICKED UP IN THE FLOW AHEAD OF A BROAD
MID-TROPOSPHERIC TROUGH. THE OFFICIAL TRACK FORECAST IS CLOSE TO
THE MIDDLE OF THE MODEL GUIDANCE AND SIMILAR TO THE PREVIOUS NHC
TRACK.  IN ABOUT TWO DAYS THE STORM IS EXPECTED TO START TO BECOME
ABSORBED BY THE MIDDLE-LATITUDE TROUGH...AND BE FULLY ABSORBED BY 3
DAYS. 
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      20/1500Z 34.5N  76.4W    45 KT
 12HR VT     21/0000Z 35.2N  75.3W    45 KT
 24HR VT     21/1200Z 36.7N  73.2W    50 KT
 36HR VT     22/0000Z 38.9N  70.2W    50 KT
 48HR VT     22/1200Z 42.5N  65.9W    45 KT
 72HR VT     23/1200Z...ABSORBED
 
$$
FORECASTER KNABB/BLAKE
 

WTNT43 KNHC 202044
TCDAT3
TROPICAL STORM CRISTOBAL DISCUSSION NUMBER   8
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL032008
500 PM EDT SUN JUL 20 2008
 
THUNDERSTORM ACTIVITY HAS BEEN SIGNIFICANTLY INCREASING IN THE
SOUTHERN PORTION OF THE STORM.  HOWEVER...THE FLIGHT-LEVEL WINDS AT
5000 FT HAVE BEEN NO HIGHER THAN 46 KT RECENTLY...NORMALLY
CORRESPONDING TO ABOUT 35 KT AT THE SURFACE.  THE SFMR DID MEASURE
46 KT IN DEEP CONVECTION SOUTHEAST OF THE CYCLONE.  GIVEN THE LACK
OF PERSISTENCE IN THE CONVECTION DURING THE LAST DAY OR SO...WE'RE
GOING TO USE A COMPROMISE INITIAL INTENSITY ESTIMATE OF 40 KT. 
SOME INTENSIFICATION IS POSSIBLE AS THE SYSTEM FIGHTS THE DRY AIR
ALOFT AND REMAINS OVER THE WARM GULF STREAM WATERS.  THE OFFICIAL
FORECAST IS A LITTLE LOWER THAN BEFORE...BUT ABOVE MOST OF THE
GUIDANCE.  

THE INITIAL MOTION CONTINUES NORTHEASTWARD AT 7 KT...A LITTLE FASTER
THAN BEFORE.  THIS GENERAL TRACK SHOULD CONTINUE WITH AN INCREASING
FORWARD DUE TO FASTER STEERING CURRENTS BETWEEN A MID-TROPOSPHERIC
HIGH TO THE EAST AND AN APPROACHING MIDDLE-LATITUDE TROUGH. IN A
COUPLE OF DAYS...A COMBINATION OF SSTS BELOW 20C AND A LARGE
INCREASE IN VERTICAL WIND SHEAR SHOULD FACILITATE AN EXTRATROPICAL
TRANSITION OF THE STORM.  THE APPROACHING TROUGH WILL PROBABLY
ABSORB CRISTOBAL IN ABOUT THREE DAYS...THOUGH A FEW MODELS DO KEEP
IT MORE SEPARATE FROM THE TROUGH. THERE HAS BEEN LITTLE CHANGE TO
THE GUIDANCE...AND THE OFFICIAL FORECAST IS CLOSE TO THE PREVIOUS
ONE. 
 
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      20/2100Z 34.7N  75.8W    40 KT
 12HR VT     21/0600Z 35.9N  74.3W    45 KT
 24HR VT     21/1800Z 37.9N  71.6W    45 KT
 36HR VT     22/0600Z 40.8N  68.0W    45 KT
 48HR VT     22/1800Z 44.0N  63.5W    45 KT...EXTRATROPICAL
 72HR VT     23/1800Z...ABSORBED
 
$$
FORECASTER BLAKE/KNABB
 

WTNT43 KNHC 210244
TCDAT3
TROPICAL STORM CRISTOBAL DISCUSSION NUMBER   9
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL032008
1100 PM EDT SUN JUL 20 2008
 
AIR FORCE RESERVE RECONNAISSANCE SFMR DATA INDICATED SURFACE WINDS
OF 45 KT IN THE EAST AND SOUTHEAST QUADRANTS. CONVENTIONAL
SATELLITE IMAGERY ALSO SUGGESTS AN INCREASE IN DEEP CONVECTION OVER
THIS PARTICULAR AREA. AS A RESULT...THE INITIAL INTENSITY IS
INCREASED SLIGHTLY. NO CHANGES ARE MADE TO THE INTENSITY
FORECAST...WITH CRISTOBAL HOLDING ON TO THE CURRENT INTENSITY
DURING THE NEXT 3 DAYS...EVEN WHEN THE CYCLONE COMPLETES AN
EXTRATROPICAL TRANSITION AROUND THE 48 HOUR PERIOD. 
 
THE INITIAL MOTION IS AGAIN SLIGHTLY FASTER...BUT ON A SIMILAR
HEADING...045/8.  CRISTOBAL SHOULD CONTINUE TO GRADUALLY INCREASE
FORWARD SPEED IN RESPONSE TO AN APPROACHING MID-LATITUDE
TROUGH...WITH FURTHER ACCELERATION AS IT MOVES INTO THE UPPER
WESTERLIES.  DYNAMICAL MODELS ARE NOW INDICATING THAT CRISTOBAL WILL
REMAIN A SEPARATE ENTITY A LITTLE BIT LONGER BEFORE BEING
ABSORBED BY A BAROCLINIC SYSTEM...AND THIS IS REFLECTED IN THE NEW
FORECAST TRACK.  THE OFFICIAL FORECAST IS BASED ON A CONSENSUS OF
THE DYNAMICAL MODELS. 
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      21/0300Z 35.2N  75.0W    45 KT
 12HR VT     21/1200Z 36.5N  73.3W    45 KT
 24HR VT     22/0000Z 38.9N  70.3W    45 KT
 36HR VT     22/1200Z 41.9N  66.3W    45 KT
 48HR VT     23/0000Z 44.7N  61.7W    45 KT...EXTRATROPICAL
 72HR VT     24/0000Z 46.0N  55.0W    45 KT...EXTRATROPICAL
 96HR VT     25/0000Z...ABSORBED
 
$$
FORECASTER ROBERTS/FRANKLIN
 

WTNT43 KNHC 210901
TCDAT3
TROPICAL STORM CRISTOBAL DISCUSSION NUMBER  10
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL032008
500 AM EDT MON JUL 21 2008
 
THIS EVENING'S RECONNAISSANCE SFMR DATA INDICATED 40 KT IN THE EAST
QUADRANT AND 51 KT AT 850 MB.  OF 45 KT IN THE EAST AND SOUTHEAST
QUADRANTS. ADDITIONALLY...SFMR RECORDED 59 KT ON AN INBOUND LEG OVER
THE NORTHEAST PORTION OF THE CYCLONE.  THIS ANOMALOUS WIND APPEARS
TO HAVE BEEN DUE TO A LARGE CLUSTER OF THUNDERSTORMS WITH AN
ASSOCIATED WELL DEFINED OUTFLOW BOUNDARY...THAT EARLIER DETACHED
FROM THE LARGE ARE OF DEEP CONVECTION OVER THE EASTERN SIDE. 
CONSEQUENTLY...THE INITIAL INTENSITY IS KEPT AT 45 KT AS A
COMPROMISE.  THE INTENSITY FORECAST REMAINS UNCHANGED...WITH THE
CYCLONE HOLDING ON TO THE CURRENT INTENSITY DURING THE NEXT 3
DAYS...INCLUDING WHEN THE SYSTEM COMPLETES AN EXTRATROPICAL
TRANSITION AROUND THE 48 HOUR PERIOD.
 
THE INITIAL MOTION IS ESTIMATED AT 045/11...SLIGHTLY FASTER.  THE
CYCLONE SHOULD CONTINUE TO GRADUALLY INCREASE IT'S SPEED OF ADVANCE
IN RESPONSE TO AN APPROACHING MID-TROPOSPHERIC TROUGH...WITH
FURTHER INCREASE IN SPEED AS IT MOVES INTO THE UPPER WESTERLY FLOW.  
THE LARGE-SCALE MODELS KEEP CRISTOBAL AS A SEPARATE ENTITY DURING
THE NEXT 72 HOURS BEFORE BECOMING ABSORBED BY THE BAROCLINIC ZONE.
A FEW OF THE MODELS ARE SUGGESTING THAT A WEAK SURFACE CIRCULATION
WILL SURVIVE AND DRIFT SOUTHEASTWARD AROUND THE NORTHEAST PERIPHERY
OF THE SUBTROPICAL HIGH...WHICH COULD HAPPEN.  THE OFFICIAL
FORECAST IS A BIT SLOWER THAN THE PREVIOUS FORECAST AND FOLLOWS A
BEND OF THE DYNAMICAL MODELS.
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      21/0900Z 36.1N  73.9W    45 KT
 12HR VT     21/1800Z 37.2N  72.1W    45 KT
 24HR VT     22/0600Z 39.7N  69.0W    45 KT
 36HR VT     22/1800Z 42.5N  65.0W    45 KT...EXTRATROPICAL
 48HR VT     23/0600Z 44.4N  61.0W    45 KT...EXTRATROPICAL
 72HR VT     24/0600Z 45.0N  52.0W    45 KT...EXTRATROPICAL
 96HR VT     25/0600Z...ABSORBED
 
$$
FORECASTER ROBERTS/PASCH
 

WTNT43 KNHC 210955
TCDAT3
TROPICAL STORM CRISTOBAL DISCUSSION NUMBER  10...CORRECTED
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL032008
500 AM EDT MON JUL 21 2008

...CORRECTED TEXT...
 
THIS EVENING'S RECONNAISSANCE SFMR DATA INDICATED 40 KT IN THE EAST
QUADRANT AND 51 KT AT 850 MB.  ADDITIONALLY...THE SFMR RECORDED 59
KT ON AN INBOUND LEG OVER THE NORTHEAST PORTION OF THE CYCLONE. 
THIS ANOMALOUS WIND APPEARS TO HAVE BEEN DUE TO A LARGE CLUSTER OF
THUNDERSTORMS WITH AN ASSOCIATED WELL-DEFINED OUTFLOW
BOUNDARY...THAT EARLIER DETACHED FROM THE LARGE AREA OF DEEP
CONVECTION OVER THE EASTERN SIDE.  SINCE THE WINDS ASSOCIATED WITH
THIS EVENT SHOULD NOT BE CONSIDERED REPRESENTATIVE OF THE INTENSITY
OF THE TROPICAL CYCLONE'S CIRCULATION...THE INITIAL INTENSITY IS
KEPT AT 45 KT.  THE INTENSITY FORECAST REMAINS UNCHANGED...WITH THE
CYCLONE HOLDING ON TO THE CURRENT INTENSITY DURING THE NEXT 3
DAYS...INCLUDING WHEN THE SYSTEM COMPLETES AN EXTRATROPICAL
TRANSITION AROUND THE 48 HOUR PERIOD.
 
THE INITIAL MOTION IS ESTIMATED AT 045/11...SLIGHTLY FASTER.  THE
CYCLONE SHOULD CONTINUE TO GRADUALLY INCREASE ITS SPEED OF ADVANCE
IN RESPONSE TO AN APPROACHING MID-TROPOSPHERIC TROUGH...WITH
FURTHER INCREASE IN SPEED AS IT MOVES INTO THE HIGHER-LATITUDE
WESTERLY FLOW.  THE LARGE-SCALE MODELS KEEP CRISTOBAL AS A SEPARATE
ENTITY DURING THE NEXT 72 HOURS BEFORE BECOMING ABSORBED BY THE
BAROCLINIC ZONE.  A FEW OF THE MODELS ARE SUGGESTING THAT A WEAK
SURFACE CIRCULATION WILL SURVIVE AND DRIFT SOUTHEASTWARD AROUND THE
NORTHEAST PERIPHERY OF THE SUBTROPICAL HIGH...WHICH COULD HAPPEN. 
THE OFFICIAL FORECAST IS A BIT SLOWER THAN THE PREVIOUS FORECAST
AND FOLLOWS A BLEND OF THE DYNAMICAL MODELS.
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      21/0900Z 36.1N  73.9W    45 KT
 12HR VT     21/1800Z 37.2N  72.1W    45 KT
 24HR VT     22/0600Z 39.7N  69.0W    45 KT
 36HR VT     22/1800Z 42.5N  65.0W    45 KT...EXTRATROPICAL
 48HR VT     23/0600Z 44.4N  61.0W    45 KT...EXTRATROPICAL
 72HR VT     24/0600Z 45.0N  52.0W    45 KT...EXTRATROPICAL
 96HR VT     25/0600Z...ABSORBED
 
$$
FORECASTER ROBERTS/PASCH
 

WTNT43 KNHC 211457
TCDAT3
TROPICAL STORM CRISTOBAL DISCUSSION NUMBER  11
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL032008
1100 AM EDT MON JUL 21 2008

SATELLITE IMAGES INDICATE THAT CONVECTION REMAINS QUITE STRONG IN
THE SOUTHERN PORTION OF THE STORM.  ON THE LAST PASS THROUGH THE
STORM...THE AIR FORCE PLANE FOUND A FALLING PRESSURE AND SOME
EVIDENCE OF A CENTER REFORMATION TO THE SOUTH. A QUIKSCAT PASS FROM
THIS MORNING SUGGESTS THE MAXIMUM WINDS WERE 50-55 KT...WHICH ISN'T
TOO FAR FROM THE SFMR DATA COLLECTED BY THE PLANE.  THE INITIAL
INTENSITY IS INCREASED TO 55 KT FOR THIS ADVISORY.  SOME
INTENSIFICATION IS POSSIBLE WHILE THE CENTER MOVES ACROSS THE GULF
STREAM AND THE SHEAR REMAINS LOW DURING THE NEXT 24 HR OR SO. 
THEREAFTER...CRISTOBAL IS FORECAST TO MOVE NORTH OF THE GULF STREAM
AND INTO A STRONGER SHEARING ENVIRONMENT...WHICH SHOULD BEGIN THE
WEAKENING PROCESS.  THE OFFICIAL FORECAST IS IN GOOD AGREEMENT WITH
THE SHIPS/LGEM MODELS WHICH SHOW THIS SYSTEM STAYING JUST BELOW
HURRICANE STRENGTH.

THE INITIAL MOTION IS A LITTLE UNCERTAIN DUE TO TO CENTER
REFORMATION BUT IS ESTIMATED AT 055/11.  A TRACK TO THE NORTHEAST
WITH INCREASING FORWARD SPEED IS LIKELY IN RESPONSE TO AN
APPROACHING MID-TROPOSPHERIC TROUGH.  THIS SYSTEM SHOULD TURN MORE
TO THE EAST WITH TIME AS IT MOVES INTO MORE WESTERLY FLOW.  THE
BIGGEST CHANGE FROM THE LAST ADVISORY IS THAT MORE MODELS SUGGEST
THAT THE STORM WON'T BE FULLY ABSORBED BY A TROUGH OVER NORTH
AMERICA AND INSTEAD ROTATE AROUND THE SOUTHERN END OF THE TROUGH.  
THE OFFICIAL FORECAST IS SHIFTED SOUTHWARD AT THE END OF THE PERIOD
AND IS EXTENDED TO 96 HR IN LINE WITH THE GUIDANCE.  
  
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      21/1500Z 36.6N  72.6W    55 KT
 12HR VT     22/0000Z 37.9N  70.6W    60 KT
 24HR VT     22/1200Z 40.5N  67.5W    60 KT
 36HR VT     23/0000Z 43.3N  63.5W    55 KT...BECOMING EXTRATROPICAL
 48HR VT     23/1200Z 45.0N  59.0W    45 KT...EXTRATROPICAL
 72HR VT     24/1200Z 45.0N  47.0W    40 KT...EXTRATROPICAL
 96HR VT     25/1200Z 41.0N  40.0W    35 KT...EXTRATROPICAL
120HR VT     26/1200Z...DISSIPATED
 
$$
FORECASTER BLAKE
 

WTNT43 KNHC 212046
TCDAT3
TROPICAL STORM CRISTOBAL DISCUSSION NUMBER  12
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL032008
500 PM EDT MON JUL 21 2008

A LARGE BALL OF CONVECTION REMAINS ON THE SOUTH SIDE OF THE TROPICAL
CYCLONE.  MICROWAVE AND CONVENTIONAL SATELLITE IMAGERY SUGGESTS THE
CENTER IS IN THE NORTHERN PORTION OF THE DEEP CONVECTION.  THERE
HAS BEEN LITTLE CHANGE TO INTENSITY ESTIMATES...SO THE INITIAL
INTENSITY WILL REMAIN 55 KT.  IT IS POSSIBLE THAT CRISTOBAL COULD
BE CLOSE TO HURRICANE STRENGTH BEFORE MOVING OVER THE COOLER WATERS
NORTH OF THE GULF STREAM TOMORROW.  THE INTENSITY FORECAST IS VERY
SIMILAR TO THE PREVIOUS AND IS CLOSE TO A CONSENSUS OF THE
STATISTICAL MODELS.  PHASE SPACE DIAGRAMS FROM FLORIDA STATE
SUGGEST THAT A RAPID EXTRATROPICAL TRANSITION SHOULD START TOMORROW
AND BE COMPLETED BY WEDNESDAY.  

THE INITIAL MOTION ESTIMATE IS 055/12...A LITTLE FASTER THAN
EARLIER. GLOBAL MODELS ARE IN EXCELLENT AGREEMENT ON AN
ACCELERATING NORTHEASTWARD TRACK DURING THE NEXT DAY OR SO.
THEREAFTER...THE STORM IS NOW FORECAST TO AVOID ANY TROUGHING OVER
NORTH AMERICA AND INSTEAD RIDE ALONG THE WESTERLIES TO THE NORTH OF
A SUBTROPICAL RIDGE OVER THE CENTRAL ATLANTIC OCEAN. IN A COUPLE
DAYS...A NEW TROUGH IS FORECAST TO AMPLIFY TO THE EAST OF THE
STORM...WHICH SHOULD STEER THE CYCLONE MORE TO THE SOUTHEAST. THE
OFFICIAL FORECAST IS SHIFTED TO THE SOUTH AND IS NOT TOO FAR FROM
THE GFS BY 96 HOURS. MOST OF THE MODELS SUGGEST NO BAROCLINIC
REINTENSIFICATION WILL OCCUR AND INSTEAD CRISTOBAL MAY DISSIPATE
OVER THE COLD NORTH ATLANTIC WATERS IN ABOUT 120 HOURS.
  
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      21/2100Z 37.1N  71.4W    55 KT
 12HR VT     22/0600Z 38.9N  68.7W    60 KT
 24HR VT     22/1800Z 41.7N  64.7W    60 KT
 36HR VT     23/0600Z 44.0N  60.0W    50 KT...EXTRATROPICAL
 48HR VT     23/1800Z 45.0N  55.0W    40 KT...EXTRATROPICAL
 72HR VT     24/1800Z 42.5N  45.0W    35 KT...EXTRATROPICAL
 96HR VT     25/1800Z 38.5N  40.5W    25 KT...EXTRATROPICAL
120HR VT     26/1800Z...DISSIPATED
 
$$
FORECASTER BLAKE
 

WTNT43 KNHC 220248
TCDAT3
TROPICAL STORM CRISTOBAL DISCUSSION NUMBER  13
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL032008
1100 PM EDT MON JUL 21 2008
 
CRISTOBAL APPEARS TO BE SUCCUMBING TO THE COOLER SSTS AS DEEP
CONVECTION HAS SIGNIFICANTLY DECREASED DURING THE LAST 6 HOURS. THE
INITIAL INTENSITY IS LOWERED TO 50 KT BASED ON A RECENT QUIKSCAT
PASS.  GIVEN THE EXTREMELY COLD SSTS THAT CRISTOBAL WILL ENCOUNTER
ALONG THE FORECAST TRACK...FURTHER WEAKENING APPEARS LIKELY.  THE
FLORIDA STATE UNIVERSITY CYCLONE PHASE SPACE DIAGRAM INDICATES THE
SYSTEM WILL BE EXTRATROPICAL IN ABOUT 36 HOURS.  HOWEVER...IF THE
PRESENT TREND IN CONVECTION CONTINUES...CRISTOBAL COULD BECOME A
REMNANT LOW PRIOR TO ITS TRANSITION TO AN EXTRATROPICAL CYCLONE.  
REGARDLESS...SIGNIFICANT RESTRENGTHENING DOES NOT APPEAR LIKELY AT
THIS TIME DUE TO LACK OF BAROCLINIC FORCING. 
 
CRISTOBAL CONTINUES TO ACCELERATE EAST-NORTHEASTWARD WITHIN THE
DEEP-LAYER SOUTHWESTERLY FLOW AHEAD OF A TROUGH OVER THE EASTERN
UNITED STATES...AND THE INITIAL MOTION ESTIMATE IS NOW 060/14.
TRACK MODELS ARE IN GOOD AGREEMENT ON A GRADUAL TURN EASTWARD AT
DAY TWO AS CRISTOBAL MOVES AROUND THE NORTH SIDE A RIDGE OVER THE
CENTRAL ATLANTIC.  THEREAFTER...GUIDANCE DIVERGES DUE TO DIFFERING
FORECASTS OF A TROUGH...AND ITS ASSOCIATED SURFACE FRONT...WHICH
AMPLIFIES SOUTHWARD OVER THE NORTHEAST ATLANTIC.  CONSIDERING THE
UNCERTAINTY...THE OFFICIAL FORECAST LIES NEAR THE CENTER OF THE
DYNAMICAL MODEL CONSENSUS AT DAYS 3 AND 4. 
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      22/0300Z 37.7N  69.8W    50 KT
 12HR VT     22/1200Z 39.8N  67.1W    45 KT
 24HR VT     23/0000Z 42.5N  62.7W    40 KT
 36HR VT     23/1200Z 44.0N  57.9W    35 KT...EXTRATROPICAL
 48HR VT     24/0000Z 44.0N  52.8W    35 KT...EXTRATROPICAL
 72HR VT     25/0000Z 41.0N  44.5W    30 KT...EXTRATROPICAL
 96HR VT     26/0000Z 37.5N  41.0W    25 KT...EXTRATROPICAL
120HR VT     27/0000Z...DISSIPATED
 
$$
FORECASTER RHOME
 

WTNT43 KNHC 220842
TCDAT3
TROPICAL STORM CRISTOBAL DISCUSSION NUMBER  14
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL032008
500 AM EDT TUE JUL 22 2008
 
THE OVERALL SATELLITE PRESENTATION HAS NOT CHANGED MUCH SINCE AN
EARLIER QUIKSCAT PASS WHICH INDICATED PEAK WINDS AROUND 50 KT.
ACCORDINGLY...THE INITIAL INTENSITY IS HELD AT 50 KT FOR THIS
ADVISORY.  CRISTOBAL'S FORECAST TRACK TAKES THE CYCLONE OVER MUCH
COOLER SSTS AS IT CROSSES THE NORTH WALL OF THE GULF STREAM DURING
THE NEXT DAY OR SO.  PHASE SPACE DIAGRAMS FROM FLORIDA STATE
UNIVERSITY INDICATE CRISTOBAL WILL TRANSITION TO AN EXTRATROPICAL
SYSTEM WITHIN THE NEXT 24 HOURS.  HOWEVER....SINCE THERE WILL BE
LIMITED BAROCLINIC FORCING...WEAKENING APPEARS LIKELY. 
 
CRISTOBAL CONTINUES TO ACCELERATE NORTHEASTWARD WITH AN INITIAL
MOTION ESTIMATE OF 055/18.  THIS GENERAL MOTION IS EXPECTED TO
CONTINUE FOR THE NEXT DAY OR SO FOLLOWED BY A TURN EASTWARD BETWEEN
24-48 HOURS...THEN SOUTHEASTWARD AT DAY 3 AS THE CYCLONE MERGES
WITH A FRONTAL BOUNDARY PUSHING SOUTHWARD OVER THE EASTERN
ATLANTIC.  TRACK GUIDANCE IS IN REASONABLY GOOD AGREEMENT THROUGH
ABOUT 48 HOURS BUT DIVERGES QUITE A BIT AT DAY 3.  THE NEW OFFICIAL
FORECAST IS ESSENTIALLY AN UPDATE TO THE PREVIOUS ONE. 
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      22/0900Z 39.1N  68.2W    50 KT
 12HR VT     22/1800Z 41.0N  65.2W    45 KT
 24HR VT     23/0600Z 43.4N  60.6W    40 KT...EXTRATROPICAL
 36HR VT     23/1800Z 44.0N  55.7W    35 KT...EXTRATROPICAL
 48HR VT     24/0600Z 43.3N  50.6W    35 KT...EXTRATROPICAL
 72HR VT     25/0600Z 40.0N  43.0W    30 KT...EXTRATROPICAL
 96HR VT     26/0600Z...ABSORBED
 
$$
FORECASTER RHOME
 

WTNT43 KNHC 221440
TCDAT3
TROPICAL STORM CRISTOBAL DISCUSSION NUMBER  15
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL032008
1100 AM EDT TUE JUL 22 2008
 
A 1013 SSMIS MICROWAVE PASS SHOWED A BANDED EYE STRUCTURE WITH
CRISTOBAL...THOUGH IT ALSO INDICATED THE SURFACE CENTER WAS ON THE
NORTHWESTERN EDGE OF THE DEEP CONVECTION. BUOY 44011 ALSO SUGGESTS
THE SURFACE CIRCULATION IS ELONGATED FROM SOUTHEAST TO NORTHWEST.
HOWEVER...BECAUSE OF THE IMPROVING SATELLITE PRESENTATION...THE
WINDS ARE INCREASED CONSERVATIVELY TO 55 KT. THIS SHOULD BE THE
LAST HURRAH FOR CRISTOBAL AS THE CYCLONE HAS PASSED NORTH OF THE
GULF STREAM INTO COOLER WATERS. A RAPID EXTRATROPICAL TRANSITION IS
FORECAST BY ALL MODELS AND IS INDICATED BELOW. STEADY WEAKENING AS
AN EXTRATROPICAL CYCLONE IS FORECAST DUE TO A STRONG SHEARING
ENVIRONMENT AND NO BAROCLINIC FORCING.
 
CRISTOBAL IS REALLY START TO MOVE AND THE INITIAL MOTION ESTIMATE IS
050/22.  THERE IS NO CHANGE TO THE SYNOPTIC REASONING FROM THE
PREVIOUS FORECAST.  THE CYCLONE IS EXPECTED TO MOVE TOWARD THE
NORTHEAST TODAY AND THEN EAST TOMORROW AS IT ROUNDS THE NORTHERN
PORTION OF THE SUBTROPICAL RIDGE IN THE CENTRAL ATLANTIC.  A TURN
TOWARD THE SOUTHEAST IS FORECAST DUE TO AN APPROACHING
MIDDLE-LATITUDE TROUGH AND THE SYSTEM SHOULD EITHER DISSIPATE
AROUND 4 DAYS OR BE ABSORBED BY A FRONTAL BOUNDARY.  THE OFFICIAL
FORECAST IS BASICALLY AN UPDATE TO THE PREVIOUS ONE AND IS SLIGHTLY
SOUTH OF AND FASTER THAN THE DYNAMICAL MODEL CONSENSUS.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      22/1500Z 40.9N  65.9W    55 KT
 12HR VT     23/0000Z 42.9N  62.6W    50 KT...BECOMING EXTRATROPICAL
 24HR VT     23/1200Z 44.5N  57.0W    40 KT...EXTRATROPICAL
 36HR VT     24/0000Z 44.0N  51.5W    35 KT...EXTRATROPICAL
 48HR VT     24/1200Z 42.5N  46.5W    30 KT...EXTRATROPICAL
 72HR VT     25/1200Z 39.0N  41.5W    25 KT...EXTRATROPICAL
 96HR VT     26/1200Z...DISSIPATED
 
$$
FORECASTER BLAKE
 

WTNT43 KNHC 222049
TCDAT3
TROPICAL STORM CRISTOBAL DISCUSSION NUMBER  16
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL032008
500 PM EDT TUE JUL 22 2008
 
VISIBLE SATELLITE IMAGES INDICATE THAT THE MID-LEVEL CENTER OF
CRISTOBAL IS RAPIDLY BECOMING DECOUPLED FROM THE LOW-LEVEL CENTER.
WINDS ARE DECREASED TO 45 KT ON THIS ADVISORY AND SHOULD DIMINISH
AS THE SYSTEM BECOMES EXTRATROPICAL OVERNIGHT. A STEADY DECREASE IN
STRENGTH IS SHOWN BY ALL GUIDANCE AND THE OFFICIAL FORECAST IS
ADJUSTED DOWNWARD. STEADY WEAKENING AS AN EXTRATROPICAL CYCLONE IS
ALSO FORECAST DUE TO A STRONG SHEARING ENVIRONMENT AND NO
BAROCLINIC FORCING.
 
CRISTOBAL HAS CONTINUED TO ACCELERATE AND IS MOVING NORTHEAST AT
ABOUT 24 KT.  MOST OF THE MODELS SHOW A DECREASE IN FORWARD SPEED
AS THE SYSTEM TRANSITIONS INTO AN EXTRATROPICAL CYCLONE. THE
REMNANT OF CRISTOBAL ARE EXPECTED TO TURN TOWARD THE EAST TOMORROW
AS IT MOVES ACROSS THE NORTHERN PERIPHERY OF A SUBTROPICAL RIDGE IN
THE CENTRAL ATLANTIC. GLOBAL MODELS TURN THE CYCLONE TOWARD THE
SOUTHEAST DUE TO AN APPROACHING MIDDLE-LATITUDE TROUGH.  THIS
SYSTEM SHOULD EITHER OPEN UP INTO A TROUGH OR BE ABSORBED BY A COLD
FRONT IN ABOUT 3 DAYS. TRACK GUIDANCE IS IN EXCELLENT AGREEMENT AND
THE OFFICIAL FORECAST IS CLOSE TO THE PREVIOUS ONE.

CANADIAN BUOY 44137 WAS VERY HELPFUL IN DETERMINING THE WIND RADII.  
 
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      22/2100Z 42.2N  62.9W    45 KT
 12HR VT     23/0600Z 44.0N  58.5W    40 KT...EXTRATROPICAL
 24HR VT     23/1800Z 45.0N  53.5W    35 KT...EXTRATROPICAL
 36HR VT     24/0600Z 44.0N  48.0W    30 KT...EXTRATROPICAL
 48HR VT     24/1800Z 42.0N  43.0W    25 KT...EXTRATROPICAL
 72HR VT     25/1800Z...DISSIPATED
 
$$
FORECASTER BLAKE
 

WTNT43 KNHC 230242
TCDAT3
TROPICAL STORM CRISTOBAL DISCUSSION NUMBER  17
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL032008
1100 PM EDT TUE JUL 22 2008
 
WHILE THE SATELLITE SIGNATURE ASSOCIATED WITH CRISTOBAL HAS DEGRADED
SIGNIFICANTLY DURING THE PAST 6 HOURS...NEARBY BUOY AND SHIP REPORTS
INDICATE THE SYSTEM IS STILL PRODUCING WINDS OF AT LEAST 40-45 KT.
ACCORDINGLY...THE INITIAL INTENSITY IS HELD AT 45 KT FOR THIS
ADVISORY.  NOW THAT THE EARLIER BURST OF DEEP CONVECTION HAS
DISSIPATED...WEAKENING SHOULD RESUME.  CRISTOBAL IS EXPECTED TO
TRANSITION INTO AN EXTRATROPICAL CYCLONE WITHIN THE NEXT 24
HOURS.  HOWEVER...SINCE THERE WILL NOT BE ANY SIGNIFICANT BAROCLINIC
FORCING...THE EXTRATROPICAL CRISTOBAL IS EXPECTED TO WEAKEN AND
EVENTUALLY BE ABSORBED BY A FRONTAL SYSTEM.
 
CRISTOBAL CONTINUES TO ACCELERATE NORTHEASTWARD AND IS NOW MOVING AT
AN ESTIMATED SPEED OF 30 KT.  GLOBAL MODELS...SAVE THE UKMET...
SUGGEST A DECREASE IN FOREWARD SPEED BUT THEY DID NOT ADVERTISE THE
CURRENT ACCELERATION.  ACCORDINGLY...THE OFFICIAL FORECAST IS
FASTER THAN AND NORTH OF THE DYNAMICAL MODEL CONSENSUS OUT OF
RESPECT FOR THE RECENT PERFORMANCE OF THE UKMET.
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      23/0300Z 44.0N  59.0W    45 KT
 12HR VT     23/1200Z 45.1N  54.8W    40 KT...EXTRATROPICAL
 24HR VT     24/0000Z 45.0N  49.0W    35 KT...EXTRATROPICAL
 36HR VT     24/1200Z 43.3N  44.0W    30 KT...EXTRATROPICAL
 48HR VT     25/0000Z...ABSORBED
 
$$
FORECASTER RHOME
 

WTNT43 KNHC 230848
TCDAT3
TROPICAL STORM CRISTOBAL DISCUSSION NUMBER  18
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL032008
500 AM EDT WED JUL 23 2008
 
ALL OF THE DEEP CONVECTION NEAR THE CENTER OF CIRCULATION HAS
DISSIPATED AND CRISTOBAL NO LONGER HAS THE APPEARANCE OF A TROPICAL
CYCLONE.  THE FLORIDA STATE UNIVERSITY PHASE SPACE DIAGRAMS USING
GLOBAL MODEL OUTPUT ALSO SUGGEST THAT CRISTOBAL HAS TRANSITIONED
INTO AN ASYMMETRIC COLD CORE LOW...I.E. AN EXTRATROPICAL CYCLONE.
WITH THAT...CRISTOBAL IS DECLARED EXTRATROPICAL AND THIS WILL BE
THE LAST ADVISORY ON THIS SYSTEM ISSUED BY THE NATIONAL HURRICANE
CENTER.  ADDITIONAL INFORMATION ON CRISTOBAL CAN BE FOUND IN HIGH
SEAS FORECASTS ISSUED BY THE NATIONAL WEATHER SERVICE...UNDER AWIPS
HEADER NFDHSFAT1 AND WMO HEADER FZNT01 KWBC.
 
THE DEGRADATION OF THE SATELLITE APPEARANCE SUGGEST CRISTOBAL HAS
WEAKENED SO THE INITIAL INTENSITY IS SET AT 40 KT.  SINCE DYNAMICAL
MODELS INDICATE A LACK OF BAROCLINIC FORCING...CONTINUED WEAKENING
IS EXPECTED DURING THE NEXT DAY OR SO PRIOR TO CRISTOBAL MERGING
WITH OR BEING ABSORBED BY A FRONTAL SYSTEM OVER THE NORTH ATLANTIC.
  
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      23/0900Z 44.7N  55.9W    40 KT...EXTRATROPICAL
 12HR VT     23/1800Z 45.3N  51.0W    35 KT...EXTRATROPICAL
 24HR VT     24/0600Z 44.4N  44.8W    35 KT...EXTRATROPICAL
 36HR VT     24/1800Z 42.6N  38.7W    30 KT...EXTRATROPICAL
 48HR VT     25/0600Z...ABSORBED
 
$$
FORECASTER RHOME
 

