Tropical weather analysis - October 21, 2013

By: KoritheMan , 5:40 AM GMT on October 21, 2013

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Raymond

Potentially dangerous Hurricane Raymond is intensifying not too far off the southern coast of Mexico. As of the latest NHC advisory, the following information was posted on the hurricane:

Wind: 100 mph, with higher gusts
Location: 15.9°N 102.0°W
Movement: N at 6 mph
Pressure: 975 mb
Category: 2 (Saffir-Simpson Hurricane Wind Scale)

While the 06z satellite estimates from TAFB and SAB have yet to be released, a recent CIMSS ADT estimate gave an intensity of 100 kt using the raw numbers, or the bottom of major hurricane strength. The satellite presentation of Raymond is impressive, with a 15 to 20 mile wide eye surrounded by a ring of deep convection. Upper-tropospheric outflow is well-defined with the hurricane, particularly to the west and north, where the subtropical jet appears to be energizing and amplifying the poleward outflow. A 0348 UTC AMSU microwave pass suggests that the tight inner core continues to become better defined.



Figure 1. Latest infrared satellite image of Hurricane Raymond. Image credit: NOAA's Satellite Services Division (SSD).

Raymond appears to be undergoing a classic rapid intensification episode, and the hurricane is likely to get stronger; I am certainly not going to deify myself and assert with any certainty just how strong, however. Since ocean temperatures are around 30°C and the vertical shear is low, there should be nothing to deter or prevent this episode from continuing. My forecast is well above the intensity consensus, explicitly showing Raymond becoming a Category 4 hurricane in about 36 hours. Given current trends, there exists the possibility that Raymond could actually get a little stronger than even this. Beyond that time, while the waters will stay quite warm along the projected path of the hurricane, interaction with the mountains of southern Mexico and possible inner core fluctuations will likely cause Raymond to weaken. In addition, water vapor imagery shows increasing westerly shear near the longitude Raymond is expected to be by days four and five, which, while not quite shown in the GFS as of now, could cut a sizable chunk of Raymond's health. There is also a drier airmass to the west of the hurricane, and Raymond will likely ingest this subsident flow once it begins to accelerate westward at longer ranges. I should note that I don't have much confidence in my intensity forecast, particularly during the weakening portion.

Recent satellite fixes suggest that Raymond has jogged a little west of due north, but the general motion has been, for the most part, nearly due northward. Water vapor imagery shows a gradually amplifying trough along the southern United States, which is expected to pick up Raymond and turn it toward the coast. Although the models agree with the actual scenario, there are considerable differences in regards to the timing and sharpness of the northeastward turn, as well as how far to the right Raymond gets before a mid-level ridge builds to the north behind the departing trough and forces a westward motion. The ECMWF and GFS continue to keep Raymond offshore, but the latter has trended toward the right between 18z and 0z, bringing Raymond within just miles of the coast before the westward turn commences. The GFDL and HWRF continue to exhibit a more northward-moving hurricane, which runs into the coast and ultimately dissipates over the mountains. CIMSS real-time steering data suggests that the trough is a little stronger the higher you get in the troposphere, which is typical. Hence, Raymond's ultimate track depends largely on its intensification. Since the degree of intensification appears to be quite sizable at the moment, I am going to go to the right of the current NHC forecast during the first 48 hours, but slowly blend in thereafter. My forecast takes the core of a dangerous Category 4 hurricane within miles of the coast; if that were to verify, the northern eyewall may lash the immediate coastal areas, delivering sustained winds of 115 to 135 mph to the region.

Although Raymond still appears to be a fairly small hurricane, scatterometer data over the last 24 hours suggest that the wind field has steadily increased. If Raymond intensifies, the wind field is likely to increase further. Because of this possibility, hurricane warnings have been issued for a portion of the coast by the government of Mexico. Interests in the warned area should carefully monitor the progress of Raymond, which has the potential to be a very dangerous hurricane for the area.

Intensity forecast and positions

INITIAL 10/21 0600Z 16.0°N 102.1°W 85 KT 100 MPH
12 hour 10/21 1800Z 16.4°N 102.0°W 100 KT 115 MPH
24 hour 10/22 0600Z 16.7°N 101.9°W 105 KT 120 MPH
36 hour 10/22 1800Z 17.1°N 101.8°W 115 KT 135 MPH
48 hour 10/23 0600Z 17.5°N 101.7°W 105 KT 120 MPH
72 hour 10/24 0600Z 17.3°N 103.5°W 85 KT 100 MPH
96 hour 10/25 0600Z 17.1°N 106.1°W 75 KT 85 MPH
120hour 10/26 0600Z 16.8°N 109.7°W 70 KT 80 MPH

NOTE: The initial position given above is my estimate of where the center is. Initial time was rounded off to 6z.

Track forecast



Figure 2. My forecast track for Raymond.

NHC storm information


000
WTPZ32 KNHC 210254
TCPEP2

BULLETIN
HURRICANE RAYMOND ADVISORY NUMBER 5
NWS NATIONAL HURRICANE CENTER MIAMI FL EP172013
800 PM PDT SUN OCT 20 2013

...RAYMOND CONTINUES TO RAPIDLY STRENGTHEN...
...HURRICANE WARNING ISSUED FOR A PORTION OF SOUTH-CENTRAL MEXICO...


SUMMARY OF 800 PM PDT...0300 UTC...INFORMATION
----------------------------------------------
LOCATION...15.9N 102.0W
ABOUT 125 MI...205 KM SSW OF ZIHUATANEJO MEXICO
ABOUT 155 MI...250 KM WSW OF ACAPULCO MEXICO
MAXIMUM SUSTAINED WINDS...100 MPH...160 KM/H
PRESENT MOVEMENT...N OR 350 DEGREES AT 6 MPH...9 KM/H
MINIMUM CENTRAL PRESSURE...975 MB...28.79 INCHES


WATCHES AND WARNINGS
--------------------
CHANGES WITH THIS ADVISORY...

THE GOVERNMENT OF MEXICO HAS ISSUED A HURRICANE WARNING FROM TECPAN
DE GALEANA WESTWARD TO LAZARO CARDENAS.

SUMMARY OF WATCHES AND WARNINGS IN EFFECT...

A HURRICANE WARNING IS IN EFFECT FOR...
* TECPAN DE GALEANA TO LAZARO CARDENAS

A HURRICANE WATCH IS IN EFFECT FOR...
* ACAPULCO TO TECPAN DE GALEANA

A TROPICAL STORM WARNING IS IN EFFECT FOR...
* ACAPULCO TO TECPAN DE GALEANA

A HURRICANE WARNING MEANS THAT HURRICANE CONDITIONS ARE EXPECTED
SOMEWHERE WITHIN THE WARNING AREA. A WARNING IS TYPICALLY ISSUED
36 HOURS BEFORE THE ANTICIPATED FIRST OCCURRENCE OF TROPICAL-
STORM-FORCE WINDS...CONDITIONS THAT MAKE OUTSIDE PREPARATIONS
DIFFICULT OR DANGEROUS. PREPARATIONS TO PROTECT LIFE AND PROPERTY
SHOULD BE RUSHED TO COMPLETION.

A HURRICANE WATCH MEANS THAT HURRICANE CONDITIONS ARE POSSIBLE
WITHIN THE WATCH AREA...IN THIS CASE WITHIN THE NEXT 48 HOURS.

A TROPICAL STORM WARNING MEANS THAT TROPICAL STORM CONDITIONS ARE
EXPECTED SOMEWHERE WITHIN THE WARNING AREA WITHIN 36 HOURS.

FOR STORM INFORMATION SPECIFIC TO YOUR AREA...PLEASE MONITOR
PRODUCTS ISSUED BY YOUR NATIONAL METEOROLOGICAL SERVICE.


DISCUSSION AND 48-HOUR OUTLOOK
------------------------------
AT 800 PM PDT...0300 UTC...THE CENTER OF HURRICANE RAYMOND WAS
LOCATED NEAR LATITUDE 15.9 NORTH...LONGITUDE 102.0 WEST. RAYMOND IS
MOVING TOWARD THE NORTH NEAR 6 MPH...9 KM/H. A GENERAL NORTHWARD
MOTION WITH A DECREASE IN FORWARD SPEED IS EXPECTED TONIGHT AND
EARLY MONDAY...FOLLOWED BY A SLOW AND ERRATIC MOTION ON TUESDAY. ON
THE FORECAST TRACK...RAYMOND IS EXPECTED TO APPROACH THE COAST OF
MEXICO WITHIN THE HURRICANE WARNING AREA LATE MONDAY OR TUESDAY.

MAXIMUM SUSTAINED WINDS HAVE INCREASED TO NEAR 100 MPH...160 KM/H...
WITH HIGHER GUSTS. ADDITIONAL STRENGTHENING IS EXPECTED DURING THE
NEXT DAY OR SO...AND RAYMOND IS FORECAST TO BECOME A MAJOR
HURRICANE LATER TONIGHT OR MONDAY.

RAYMOND IS A SMALL HURRICANE. HURRICANE FORCE WINDS EXTEND OUTWARD
UP TO 15 MILES...30 KM...FROM THE CENTER...AND TROPICAL STORM FORCE
WINDS EXTEND OUTWARD UP TO 60 MILES...95 KM.

THE ESTIMATED MINIMUM CENTRAL PRESSURE IS 975 MB...28.79 INCHES.


HAZARDS AFFECTING LAND
----------------------
WIND...TROPICAL STORM CONDITIONS ARE EXPECTED TO BEGIN IN PORTIONS
OF THE WARNING AREA BY LATE MONDAY. HURRICANE CONDITIONS ARE
EXPECTED IN PORTIONS OF THE HURRICANE WARNING AREA BY LATE MONDAY
NIGHT OR EARLY TUESDAY. HURRICANE CONDITIONS ARE POSSIBLE IN THE
WATCH AREA BY LATE MONDAY NIGHT OR TUESDAY.

STORM SURGE...A STORM SURGE IS EXPECTED TO PRODUCE SIGNIFICANT
COASTAL FLOODING IN AREAS OF ONSHORE WIND WITHIN THE WARNING AREAS.
NEAR THE COAST...THE SURGE WILL BE ACCOMPANIED BY LARGE AND
DESTRUCTIVE WAVES.

RAINFALL...RAYMOND IS EXPECTED TO PRODUCE RAINFALL AMOUNTS OF 2 TO 4
INCHES WITH ISOLATED AMOUNTS UP TO 8 INCHES OVER THE MEXICAN STATE
OF GUERRERO. RAINFALL AMOUNTS OF 1 TO 3 INCHES WITH ISOLATED AMOUNTS
UP TO 5 INCHES WILL BE POSSIBLE IN THE ADJACENT BORDERING STATES OF
OAXACA AND MICHOACAN.

SURF...SWELLS GENERATED BY RAYMOND ARE AFFECTING PORTIONS OF
THE SOUTH-CENTRAL COAST OF MEXICO. THESE SWELLS ARE LIKELY TO CAUSE
LIFE-THREATENING SURF AND RIP CURRENT CONDITIONS. FOR MORE
INFORMATION...PLEASE CONSULT PRODUCTS FROM YOUR LOCAL WEATHER
OFFICE.


NEXT ADVISORY
-------------
NEXT INTERMEDIATE ADVISORY...1100 PM PDT.
NEXT COMPLETE ADVISORY...200 AM PDT.

$$
FORECASTER BROWN/BERG

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2. WunderAlertBot (Admin)
7:03 AM GMT on October 22, 2013
KoritheMan has created a new entry.
1. EstherD
5:56 AM GMT on October 21, 2013
Good read! You write well. Keep it up. Thanks...
-- EstherD
Member Since: November 10, 2009 Posts: 2 Comments: 146

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About KoritheMan

I'm just a 22 year old with an ardent passion for weather. I first became aware of this interest after Tropical Storm Isidore struck my area in 2002.