ATL: BILL - Post-Tropical

[JonathanBelles]

New Post: http://jonathanbelles.com/2015/06/13/ne ... louisiana/

[underthwx]

It appears that Carlos has taken a bit of an north-northeastern track. What impact, if any, could that have on 91L and SE Texas?

I mentioned this earlier.

Those in Texas apart from what moisture 91L sends have to watch the Carlos angle to see if it makes landfall on the Mexican coast near Puerto Vallarta because the moisture would go to that state. 1-2 moisture combo possible.

C.E. can you go into a little detail about this 1-2 combo scenario?...what possible effects it could have?...and for what region?...

[Blinhart]

I also saw that the coastal regions of Louisiana are already under a Coastal Flood Advisory (not sure Watch or Warning) since the tides are already 1 to 2 feet above normal and that the Sabine River is under a Flood Warning due to it being above flood level already. So if this system pulls up around Galveston there will be some major flooding issues for South Louisiana and Southeast Texas.

[vbhoutex]

Jeff Lindner's evening update:

***Increasing threat for tropical cyclone formation over the Gulf of Mexico late Sunday into Monday with a track toward the TX coast***

Large area of showers and thunderstorms over the Yucatan, southern Gulf of Mexico, and western Caribbean Sea is showing signs of organization late this afternoon. A broad area of lower pressure is accompanying this feature over northern Belize into the Yucatan while an upper level trough is moving inland over the TX coast. The upper level trough will continue slowly westward while the surface feature over the Yucatan will move northwest and over the Gulf of Mexico late Sunday into early Monday.

Track:

91L is located to the southwest of a building ridge of high pressure over the SW Atlantic into the SE US which will result in a steering pattern toward the WNW to NNW over the next 72 hours. Global model guidance is in very good agreement with this track reasoning and is showing a strong clustering of guidance tracks toward the NW of 91L in the direction of the NW Gulf coast.

Intensity:

Conditions will be marginally favorable over the Gulf of Mexico as the tropical feature interacts with the upper level trough. Upper level winds will be somewhat conducive for development and there is a large mass of dry air over the east coast of MX that may become entrained into any circulation. However tropical systems have before formed in less than ideal conditions especially when upper level divergence on the east side of the upper trough help vent the surface low…this appears to be what models are keying on for development and this can already be seen in the satellite data with the expansive cloud shield arcing out toward the east suggesting decent upper level outflow on the eastern side of the feature. Model intensity guidance generally is in fair agreement on bringing a 40mph tropical storm across the NW Gulf.


Timing:

Track guidance is in good agreement on the track and timing of the system. Most guidance brings the center of a surface low into the TX coast around 72 hours from 600am (12Z) this morning which would be around 600am (12Z) on Tuesday morning. Some of the global models are slightly slower and have a landfall later in the day on Tuesday.

Impacts:

High PWS air mass is already in place and was clearly showing its capabilities this morning where 5-7 inches of rainfall fell over northern Galveston County including 5.32 inches at the NWS office in League City. PWS are near 2.1 inches and will remain at this level into Monday before the onset of a more significant surge of moisture associated with 91L. Forecast models show moisture levels surging to a very impressive 2.6 inches on Tuesday which is well over +2SD above normal for June and .20 of an inch above TS Allison levels. Such moisture levels if they are to verify would be extremely dangerous and support “incredible” rainfall rates of 4-6 inches per hour.

Rainfall:

Forecast models are very aggressive with rainfall totals and much of this is due to the very high moisture levels. Global models are showing a strong signal for a large band of sustained excessive rainfall along the eastern flank of the low level circulation as it moves inland…currently right across SE TX. Totals within this banding would be significant. For now will go with widespread rainfall amounts of 3-5 inches with isolated totals of 5-10 inches possible. It is possible that totals as high as 20 inches could occur near and to the east of the center of circulation given the extremely high moisture levels that will be in place. Where this happens will be highly dependent on the exact track of the low level center and could be anywhere from the TX coastal bend to SC LA….but will be devastating.

Winds:

Will await NHC wind guidance once advisories are initiated on the system, but based on model guidance a large swath of sustained 40-50mph winds appear likely across the NW Gulf of Mexico. Will have to adjust wind speeds upward over the coastal waters starting early Monday and likely onset tropical storm force gusts by late Monday across the Gulf waters and bays/coastline early Tuesday. Inland winds will increase out of the ENE and E starting Monday and peak on Tuesday in the 25-35mph range with gusts of 40-45mph along the coast. Again, better wind grids will be available from NHC once the system is upgraded.

Tides/Storm Surge:

Tides are already running .5-1.0 ft above normal and will continue to increase with onshore flow in progress. Increasing winds will start wave and tidal run-up as early as Monday morning with tides continuing to increase into Tuesday. Could see tide levels near the critical 4.0 ft water level by late Monday into Tuesday especially on the Gulf facing beaches. This could result in overwash of western Galveston Island and Bolivar and coastal flooding around Seabrook and Kemah. Will need to make adjustments on tides once a good defined center develops. Tides could certainly become an issue and coastal residents should begin to prepare for high coastal water levels.

Forecast Confidence:

Overall confidence in formation of a tropical system in the western Gulf of Mexico in the next 72 hours in moderate to high. NHC currently has a 50% chance of development over the next 5 days.

Track: moderate

Intensity: moderate

Rainfall: moderate to high

Winds: low

Tides: moderate


A USAF aircraft is planned to fly this system Sunday afternoon followed by multiple aircraft flights on Monday.

Residents along the TX coast should pay close attention to the weather over the next few days as significant forecast changes are likely.

Starting Sunday a morning and evening update will be issued on this situation and this will likely increase to at least three updates on Monday.

[Dean4Storms]

One thing is almost a certainty, whatever becomes of this it looks like most of the weather will be on the eastern side of the system.

[Ntxw]

One thing is almost a certainty, whatever becomes of this it looks like most of the weather will be on the eastern side of the system.

For the time being due to shear. Eventually as the ridging builds into the Southeast US convection will go further west in the BOC and stream N/NW around the building ridge and a more marginally conducive environment over the western gulf.

[Hurricaneman]

Another good analog for this system may be 1993 Arlene

[tolakram]

Live IR:

http://wwwghcc.msfc.nasa.gov/cgi-bin/get-goes?satellite=GOES-E%20CONUS&lat=20&lon=-90&info=ir&zoom=2&width=1000&height=800&quality=92&type=Animation&palette=ir1.pal&numframes=10&mapcolor=gray

[Hammy]

Looks like a massive shear wall slamming into the western side, and there doesn't appear to have been any movement since the afternoon which makes me wonder if the circulation ever exits the Yucatan at all.

[Rgv20]

Special Weather Statement from the NWS in Brownsville

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE BROWNSVILLE TX
957 PM CDT SAT JUN 13 2015

TXZ248>257-141200-
ZAPATA-JIM HOGG-BROOKS-KENEDY-STARR-HIDALGO-INLAND WILLACY-
INLAND CAMERON-COASTAL WILLACY-COASTAL CAMERON-
INCLUDING THE CITIES OF...ZAPATA...HEBBRONVILLE...FALFURRIAS...
SARITA...RIO GRANDE CITY...ROMA...MCALLEN...EDINBURG...PHARR...
MISSION...WESLACO...RAYMONDVILLE...BROWNSVILLE...HARLINGEN...
PORT MANSFIELD...PORT ISABEL...SOUTH PADRE ISLAND...
LAGUNA HEIGHTS...LAGUNA VISTA
957 PM CDT SAT JUN 13 2015

...TROPICAL DISTURBANCE APPROACHING THE SOUTHERN GULF OF MEXICO...

THE TROPICAL DISTURBANCE OVER THE YUCATAN PENINSULA HAS BECOME A
BIT MORE ORGANIZED TODAY AS THE WINDS ALOFT HAVE ABATED ALLOWING
FOR AN INCREASE IN THUNDERSTORM ACTIVITY. CONDITIONS FAVOR FOR
SOME ADDITIONAL DEVELOPMENT AS THE LOW PRESSURE TROUGH MOVES NORTH
TO NORTHWEST THE NEXT 24-48 HOURS. FORECAST MODELS AND NATIONAL
HURRICANE CENTER PROJECTIONS CONTINUES TO SHOW THE CENTER OF THE
DISTURBANCE MOVING TOWARDS THE MIDDLE TO UPPER TEXAS COAST BY
TUESDAY. ON THIS CURRENT PROJECTED PATH THE LOWER TEXAS COAST AND
RIO GRANDE VALLEY REMAINS ON THE WESTERN SIDE OF ANY POTENTIAL
TROPICAL CYCLONE DEVELOPMENT LIMITING IMPACTS MORE OVER THE
COASTAL WATERS AND FARTHER NORTH ALONG THE TEXAS COASTAL BEND.

MAIN IMPACTS THAT CAN BE EXPECTED AT THIS TIME WILL BE A
CONTINUING OF DANGEROUS RIP CURRENTS AND POSSIBLE HIGH SURF ALONG
THE BEACH OF SOUTH PADRE ISLAND AND BOCA CHICA. A HIGH RISK OF RIP
CURRENTS IS CURRENTLY OBSERVED AND LIKELY TO CONTINUE THROUGH
MONDAY. A COASTAL FLOOD ADVISORY MAY BE NEEDED IF SURF OVERWASH
APPROACHES THE SAND DUNES...MAKING DRIVING ALONG THE BEACH
DIFFICULT AND POSSIBLY AFFECTING SOME BEACH ACCESS POINTS.

MARINE IMPACTS...A SMALL CRAFT ADVISORY CONTINUES THROUGH SUNDAY
FOR THE OFFSHORE COASTAL WATERS MAINLY DUE TO THE HIGH SWELL AND
SEAS. THIS IS LIKELY TO BE CONTINUE INTO MONDAY AS THE
DISTURBANCE MAKES ITS CLOSEST APPROACHES LATER MONDAY INTO
TUESDAY.

SHOWERS AND THUNDERSTORMS ALTHOUGH ON THE INCREASE ARE LIKELY TO
REMAIN WIDESPREAD OVER THE COASTAL WATERS AND NORTHEAST OF THE
TROUGH OR TROPICAL LOW CENTER. CAN NOT RULE OUT HEAVY RAIN AND
NUISANCE FLOODING ANYTIME FROM SUNDAY MORNING THROUGH AT LEAST
TUESDAY AS ABUNDANT TROPICAL MOISTURE FEEDS INTO DEEP SOUTH TEXAS.

STAY TUNED FOR LATER UPDATES AS THIS TROPICAL DISTURBANCE MOVES
INTO THE GULF OF MEXICO.


$$

GB

[Blinhart]

Looks like a massive shear wall slamming into the western side, and there doesn't appear to have been any movement since the afternoon which makes me wonder if the circulation ever exits the Yucatan at all.

We hear this everytime a weak system is over the Yucatan Peninsula at night.

[LaBreeze]

So is this going to be a mid to south TX coast hit or upper Mexico? Sabine eastward in the clear for now? (I do know that things can and will change).

[Blinhart]

So is this going to be a mid to south TX coast hit or upper Mexico? Sabine eastward in the clear for now? (I do know that things can and will change).

I don't think anyone can say for sure about anything right now. Maybe by Monday morning we will have a better idea.

[LaBreeze]

So is this going to be a mid to south TX coast hit or upper Mexico? Sabine eastward in the clear for now? (I do know that things can and will change).

I don't think anyone can say for sure about anything right now. Maybe by Monday morning we will have a better idea.

Agreed, Blinhart - I'm south of you in Vermilion Parish and I'm keeping an eye on this as well. Just seems like models are falling into agreement rather early.

[cycloneye]

TROPICAL WEATHER OUTLOOK
NWS NATIONAL HURRICANE CENTER MIAMI FL
800 AM EDT SUN JUN 14 2015

For the North Atlantic...Caribbean Sea and the Gulf of Mexico:

A sharp trough of surface low pressure across the Yucatan Peninsula,
in combination with an upper-level low over the Gulf of Mexico,
continues to produce showers and thunderstorms over portions of
Guatemala, Belize, the Yucatan, and adjacent waters. Upper-level
winds are expected to become more favorable for some development
over the next day or two as the system moves northwestward into the
western Gulf of Mexico, and an Air Force Reserve Hurricane Hunter
aircraft is scheduled to investigate the system this afternoon.
Heavy rains are expected to continue over these areas today, along
with winds to near gale force over portions of the northwestern
Caribbean Sea and the southeastern Gulf of Mexico. Additional
information on this system can be found in High Seas Forecasts
issued by the National Weather Service.
* Formation chance through 48 hours...medium...60 percent
* Formation chance through 5 days...medium...60 percent

&&
High Seas Forecasts can be found under AWIPS header NFDHSFAT1 and
WMO header FZNT01 KWBC.

$$
Forecaster Franklin

[wxman57]

So is this going to be a mid to south TX coast hit or upper Mexico? Sabine eastward in the clear for now? (I do know that things can and will change).

What? I don't see anything to suggest mid to south TX. More like upper Texas coast. Heavy rain may occur 200 miles east of where the center crosses the coast. Louisiana is definitely "under-the-gun" as far as heavy rain potential. Heaviest rain may be from the Houston/Galveston area eastward from what I'm seeing this morning.

This situation reminds me very much of Allison (2001) as far as it's appearance - large, deep plume of tropical moisture heading north toward the Gulf Coast.

My eye is drawn to the area between 22.5N-23N and 90W this morning. There may not be a surface low there yet, but I think it may form there later today. That's a lot farther north than the models initialized, and that would increase the threat farther east along the Gulf Coast (LA).

[NDG]

Yeah I agree with you wxman57, just off the northern coast of the Yucatan P, north of Merida, is where I think low pressure will take shape later today.

[cycloneye]

Recon slips a few hours to late afternoon.

NHC Atlantic Ops ‏@NHC_Atlantic · 7m7 minutes ago
The reconnaissance mission for the system near the Yucatan has been slipped from 2 PM to 5 PM.

[cycloneye]

12z Best Track:

AL, 91, 2015061412, , BEST, 0, 205N, 890W, 30, 1008, DB

[wxman57]

12z Best Track:

AL, 91, 2015061412, , BEST, 0, 205N, 890W, 30, 1008, DB

I think it's going to form much farther to the north, maybe 23 to 23.5N and 90W. This increases the threat farther east (into SW LA). Do a Google search of Allison in the Gulf 2001 and look at the image of Allison when it neared Galveston. Note where the center is within the cloud pattern. Look there for 91W in the satellite today.

Note that there may be a couple of low center at first - one farther south and one north where I'm looking. I think that the northern low will be the one to watch.