000
WTPZ42 KNHC 260838
TCDEP2

TROPICAL STORM IGNACIO DISCUSSION NUMBER   6
NWS NATIONAL HURRICANE CENTER MIAMI FL       EP122015
200 AM PDT WED AUG 26 2015

Ignacio continues to gradually strengthen. Deep convection has been
persisting mainly over the western half of the circulation and
recent microwave images show increased banding as well.  The Dvorak
classifications from all agencies have increased to T3.0/45 kt, and
the initial intensity is set at that value.

The tropical storm is currently in a generally favorable environment
of about 10 kt of southeasterly wind shear and over 29 deg C waters.
Since these conditions are not expected to change much during the
next few days, additional intensification appears likely.  Although
all of the intensity guidance agrees on the strengthening trend,
they disagree on the intensification rate.  The HWRF model shows
Ignacio strengthening fastest, while the SHIPS and LGEM models show
the cyclone gaining strength more gradually.  The NHC intensity
forecast is between those scenarios and in best agreement with
the intensity model consensus.  Some weakening is possible by the
end of the forecast period due to less favorable conditions.

The low-level center of the storm is difficult to locate.  Using
recent microwave images and continuity, the initial motion estimate
is 260/6 kt.  Mid-level ridging is expected to build to the north
and northeast of Ignacio during the next several days.  This pattern
should cause the cyclone to move a little faster westward today and
then west-northwestward on Thursday.  A continued west-northwestward
motion is expected through the remainder of the forecast period.
The NHC track forecast is similar to the previous one and lies close
to a consensus of the models with a little more weight on the ECMWF
solution.

FORECAST POSITIONS AND MAX WINDS

INIT  26/0900Z 12.3N 134.1W   45 KT  50 MPH
 12H  26/1800Z 12.3N 135.4W   55 KT  65 MPH
 24H  27/0600Z 12.6N 137.2W   65 KT  75 MPH
 36H  27/1800Z 13.5N 139.1W   70 KT  80 MPH
 48H  28/0600Z 14.4N 140.8W   80 KT  90 MPH
 72H  29/0600Z 15.8N 144.2W   85 KT 100 MPH
 96H  30/0600Z 17.1N 147.7W   85 KT 100 MPH
120H  31/0600Z 18.3N 151.2W   75 KT  85 MPH

$$
Forecaster Cangialosi

000
WTPZ42 KNHC 270247
TCDEP2

HURRICANE IGNACIO DISCUSSION NUMBER   9
NWS NATIONAL HURRICANE CENTER MIAMI FL       EP122015
800 PM PDT WED AUG 26 2015

Ignacio's convective cloud pattern has continued to improve and
recent passive microwave satellite imagery indicates that the
cyclone has developed a large but closed eye, which is embedded in
the center of a smooth CDO feature. Upper-level outflow is
well-defined in all quadrants and is expanding. The initial
intensity of 65 kt is based on an average of satellite intensity
estimates of T4.4/75 kt from UW-CIMSS ADT, T4.0/65 kt from TAFB,
and T3.5/55 kt from SAB. This makes Ignacio the seventh hurricane of
the 2015 eastern North Pacific season.

Microwave satellite fixes indicate that Ignacio has finally made
the expected turn toward the west-northwest, and the motion estimate
is now 290/11 kt. A west-northwestward motion is expected to
continue throughout the forecast period due to a strong subtropical
ridge to the north of Ignacio producing a deep layer of
east-southeasterly steering flow. Although the GFS and ECMWF models
differ widely on the track of the hurricane after 72 hours, the
other reliable guidance models lie between those two aforementioned
extremes. The NHC official forecast track lies close to the
previous advisory track and a blend of the various consensus models.

Environmental conditions are expected to generally be favorable for
additional strengthening throughout the forecast period. The main
hindering factor will be modest vertical wind shear for the next
24-36 hours, after which the shear is expected to decrease to less
than 10 kt. However, given the very impressive outflow pattern that
has developed, along with the aforementioned eye feature, rapid
intensification is a distinct possibility during the next 24
hours. By days 4 and 5, thermodynamic and oceanic conditions are
expected to become less favorable, and gradual weakening is
expected to occur during that time. The official intensity
forecast is similar to the previous advisory, and is close to the
consensus model IVCN.

FORECAST POSITIONS AND MAX WINDS

INIT  27/0300Z 12.2N 137.5W   65 KT  75 MPH
 12H  27/1200Z 12.8N 138.9W   75 KT  85 MPH
 24H  28/0000Z 13.8N 140.9W   85 KT 100 MPH
 36H  28/1200Z 14.6N 142.7W   95 KT 110 MPH
 48H  29/0000Z 15.4N 144.4W  100 KT 115 MPH
 72H  30/0000Z 16.7N 147.4W   95 KT 110 MPH
 96H  31/0000Z 18.1N 150.4W   85 KT 100 MPH
120H  01/0000Z 19.5N 153.5W   75 KT  85 MPH

$$
Forecaster Stewart

WTPA43 PHFO 291500
TCDCP3

HURRICANE IGNACIO DISCUSSION NUMBER  19
NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI   EP122015
500 AM HST SAT AUG 29 2015
 
THE SATELLITE PRESENTATION OF IGNACIO HAS IMPROVED DRAMATICALLY
OVER THE PAST SEVERAL HOURS...AND THE HURRICANE HAS RAPIDLY
INTENSIFIED SINCE THE PREVIOUS ADVISORY. THE EYE OF THE HURRICANE
HAS BEEN PERSISTENT AND WARMING IN INFRARED IMAGERY...WHILE
SURROUNDING COLD CLOUD TOPS NOW NEARLY ENCIRCLE THE CENTER. THE
INCREASED GRADIENT IN TEMPERATURES BETWEEN THE EYE AND EYE WALL LED
TO A SIGNIFICANT INCREASE IN SUBJECTIVE AND OBJECTIVE DVORAK DATA-T
NUMBERS. THESE SATELLITE-BASED INTENSITY ESTIMATES NOW RANGE FROM
T5.0/90 KT TO T6.0/115 KT...AND SUPPORT INCREASING THE INITIAL
INTENSITY TO 100 KT FOR THIS ADVISORY...WHICH MAKES IGNACIO A
CATEGORY 3 MAJOR HURRICANE.

THE INITIAL MOTION ESTIMATE FOR THIS ADVISORY IS 300/07 KT...WITH
THE EYE WOBBLING ALONG ON A TRACK SLIGHTLY SLOWER...AND TO THE LEFT
OF...THE PREVIOUS FORECAST. DESPITE THIS...THE TRACK FORECAST
PHILOSOPHY HAS CHANGED LITTLE...WITH IGNACIO FORECAST TO TRACK
GENERALLY NORTHWESTWARD TOWARD A BREAK IN A MID-LEVEL RIDGE THAT IS
CENTERED TO THE DISTANT NORTHEAST. THE TRACK GUIDANCE IS ONCE AGAIN
TIGHTLY CLUSTERED...BUT THE TVCN CONSENSUS HAS SHIFTED CLOSER TO THE
NEARLY UNCHANGED OFFICIAL FORECAST TRACK...AS LATEST ITERATIONS
OF BOTH THE GFS AND GFDL HAVE SHIFTED TOWARD THE LEFT.

WATER VAPOR IMAGERY...AS WELL AS UPPER-AIR AND UW-CIMSS ANALYSES...
INDICATE THAT IGNACIO CONTINUES TO TRAVERSE AN AREA OF VERY WEAK
SHEAR...IN A COL BETWEEN UPPER-LEVEL RIDGES CENTERED TO THE
EAST-NORTHEAST...AND TO THE WEST. THIS SETUP IS PROVIDING
FAVORABLE OUTFLOW CHANNELS FOR THE HURRICANE...ESPECIALLY IN THE
NORTHERN SEMICIRCLE. IN THE SHORT-TERM...SUFFICIENTLY WARM WATER
TEMPERATURES AND LIGHT SHEAR LIE ALONG THE FORECAST TRACK...AND THE
OFFICIAL FORECAST CLOSELY FOLLOWS TRENDS PRESENTED BY THE INTENSITY
CONSENSUS IVCN IN ANTICIPATING ADDITIONAL STRENGTHENING TODAY. AFTER
THE FIRST 24 HOURS...SOUTHWESTERLY SHEAR IS FORECAST TO GRADUALLY
INCREASE...WITH ONLY SMALL CHANGES IN UNDERLYING WATER TEMPERATURES
AND OCEAN HEAT CONTENT. THE FACT THAT IGNACIO MAY BECOME ANNULAR
COMPLICATES THE INTENSITY FORECAST AS IT MAY BECOME LESS PRONE TO
WEAKENING DUE TO NEGATIVE ENVIRONMENTAL FACTORS. ADDITIONALLY...
SHORT TERM FLUCTUATIONS IN INTENSITY REMAIN POSSIBLE DUE TO
DIFFICULT TO FORECAST EYE WALL REPLACEMENT CYCLES. ASIDE FROM THESE
COMPLICATING FACTORS...A GRADUAL WEAKENING TREND FORECAST TO
COMMENCE ON SUNDAY IS EXPECTED TO PERSIST THROUGH DAY 5.

WHILE THE FORECAST TRACK KEEPS THE CENTER OF IGNACIO NORTHEAST OF
THE MAIN HAWAIIAN ISLANDS...UNCERTAINTY SURROUNDING THE TRACK AND
INTENSITY FORECAST NECESSITATES THE ISSUANCE OF A TROPICAL STORM
FOR THE BIG ISLAND. ADDITIONAL ISLANDS MAY NEED TO BE ADDED TO THE
WATCH LATER TODAY.

ANOTHER RECONNAISSANCE FLIGHT BY THE HURRICANE HUNTERS IS SCHEDULED
TO INVESTIGATE IGNACIO LATER THIS MORNING...FOLLOWED BY 12 HOURLY
FLIGHTS UNTIL SUNDAY MORNING...AFTER WHICH TIME FLIGHTS WILL OCCUR
AT 6 HOURLY INTERVALS.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  29/1500Z 15.9N 146.5W  100 KT 115 MPH
 12H  30/0000Z 16.6N 147.6W  110 KT 125 MPH
 24H  30/1200Z 17.6N 149.0W  105 KT 120 MPH
 36H  31/0000Z 18.6N 150.3W  100 KT 115 MPH
 48H  31/1200Z 19.7N 151.9W   85 KT 100 MPH
 72H  01/1200Z 21.7N 154.8W   75 KT  85 MPH
 96H  02/1200Z 24.0N 157.5W   65 KT  75 MPH
120H  03/1200Z 26.5N 160.0W   60 KT  70 MPH
 
$$

FORECASTER BIRCHARD

Eric Fisher ‏@ericfisher  1 minhace 1 minuto
What does it look like inside the eye of a Cat 4 hurricane? Look at this photo of #Ignacio from @403PA! #Ignacio