Tropical Storm Mario Discussion Number 2
NWS National Hurricane Center Miami FL EP142019
300 PM MDT Tue Sep 17 2019
Thunderstorm activity continues to grow over the center of the
cyclone, with a banding feature trying to form in the western
semicircle. While the subjective estimates are unchanged from
earlier, the objective estimates are rising, which matches the
increased convective organization trend on satellites. Thus the
initial wind speed is bumped up to 35 kt on this advisory.
Mario is moving northwestward, with that general motion anticipated
for the next two days due primarily to a mid-latitude ridge centered
over northwestern Mexico. A slow west-northwest track is forecast
at long-range due to the orientation of the weakening ridge. Global
models have come into much better agreement overall, and the new NHC
track forecast is shifted to the west during the next few days since
the models suggest little-to-no interaction with Tropical Storm
Lorena.
With the guidance showing less interaction with Lorena, it seems
probable that further strengthening will occur in a low-shear,
warm-water environment. Interestingly, the guidance is actually
lower than this morning, although it is difficult to pinpoint any
reasons for the change. I've elected to let the morning forecast
ride for one more advisory to see if the guidance comes back
upward, and the latest wind speed prediction is at the upper end of
the guidance envelope.
Tropical Depression Fourteen-E Discussion Number 1
NWS National Hurricane Center Miami FL EP142019
900 AM MDT Tue Sep 17 2019
Deep convection has intensified over the small area of low pressure
that NHC has been monitoring for several days. Both SAB and TAFB
estimates indicate that there is now enough organized thunderstorm
activity to initiate advisories on a tropical depression, and the
initial wind speed of 30 kt matches the overnight scatterometer
data and the subjective Dvorak estimates.
The initial motion is an uncertain 335/8 kt, with steering provided
by a distant low-level ridge to the east. The cyclone is forecast
to gradually turn toward the northwest and west-northwest during the
next several days as it runs into the southwestern side of a mid-
latitude ridge centered over northwestern Mexico. The biggest
complication is Tropical Storm Lorena to the northeast, which some
of the model guidance, such as the 6Z GFS, shows a binary
interaction with at longer term, which could induce a more northward
motion. While I can't rule that out, the forecast will stay closer
to the models that show less interaction, such as the more westward
HWRF and ECMWF solutions, and the NHC forecast is close to a blend
of those models.
While almost all of the guidance indicates strengthening of this
depression into a hurricane in a few days, this forecast is
problematic because of the proximity to Lorena. Convective outflow
from Lorena could induce more easterly shear than is currently
forecast if the tracks get closer together. For now, since the
cyclones are forecast to remain a fair distance from one another,
this wind speed prediction assumes that the low-shear environment in
most of the models materializes, and the forecast follows the
corrected-consensus intensity guidance HCCA.
1. A small area of low pressure centered several hundred miles
south-southwest of Manzanillo, Mexico, continues to become better
organized. Any significant increase in organized thunderstorm
activity will likely result in the formation of a tropical
depression tonight or tomorrow. Beyond mid week, strong upper-level
winds from the system to the east could inhibit further development
while the low moves slowly west-northwestward or northwestward.
* Formation chance through 48 hours...high...80 percent.
* Formation chance through 5 days...high...80 percent.
WTPN21 PHNC 161600
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE FORMATION ALERT (INVEST 91E)//
RMKS/
1. FORMATION OF A SIGNIFICANT TROPICAL CYCLONE IS POSSIBLE WITHIN
160 NM EITHER SIDE OF A LINE FROM 9.7N 106.8W TO 15.6N 111.7W
WITHIN THE NEXT 12 TO 24 HOURS. AVAILABLE DATA DOES NOT JUSTIFY
ISSUANCE OF NUMBERED TROPICAL CYCLONE WARNINGS AT THIS TIME.
WINDS IN THE AREA ARE ESTIMATED TO BE 25 TO 30 KNOTS. METSAT
IMAGERY AT 161200Z INDICATES THAT A CIRCULATION CENTER IS LOCATED
NEAR 10.5N 107.5W. THE SYSTEM IS MOVING WESTWARD AT 09 KNOTS.
2. REMARKS: AN AREA OF CONVECTION (INVEST 91E) HAS PERSISTED NEAR
10.5N 107.5W, APPROXIMATELY 545 NM SOUTH-SOUTHWEST OF MANZANILLO,
MEXICO. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY AND A 161219Z
91GHZ SSMIS MICROWAVE IMAGE DEPICT FLARING CONVECTION TAKING ON SOME
MIDLEVEL ROTATION ABOVE AN ELONGATED LOW LEVEL CIRCULATION (LLC).
THE ENVIRONMENT IS OVERALL MARGINAL, WITH LOW-MODERATE (15-20KT)
VERTICAL WIND SHEAR, NEUTRAL UPPER LEVEL DIVERGENCE OVER THE LLC,
AND WARM (29-31C) SEA SURFACE TEMPERATURES. GLOBAL MODELS GENERALLY
AGREE ON INVEST 91E TRACKING NORTHWEST AS IT CONTINUES TO DEVELOP,
WITH THE POSSIBILITY OF ABSORBING INVEST 92E WHICH IS LOCATED TO THE
EAST. MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED AT 25 TO 30
KNOTS. MINIMUM SEA LEVEL PRESSURE IS ESTIMATED TO BE NEAR 1000 MB.
THE POTENTIAL FOR THE DEVELOPMENT OF A SIGNIFICANT TROPICAL CYCLONE
WITHIN THE NEXT 24 HOURS IS HIGH.
3. THIS ALERT WILL BE REISSUED, UPGRADED TO WARNING OR CANCELLED BY
171600Z.//
NNNN
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