Remnant low Karen

[GaWx]

Invest 97L is about to be officially declared Karen. Hurricane and TS watches are about to be hoisted along parts of the northern Gulf coast! In retrospect, this undoubtedly has been a TS for at least several hours.

The GFS has easily been the top model while the Euro has been absolutely awful.

This easily looks to be the biggest storm of the season to date for US impacts.

Special Advisory for TS Karen within the hour

DATA FROM AN AIR FORCE RESERVE HURRICANE HUNTER AIRCRAFT INDICATES

THAT THE AREA OF LOW PRESSURE LOCATED OVER THE SOUTHEASTERN GULF OF

MEXICO HAS BECOME A TROPICAL STORM AND IS PRODUCING WINDS OF UP TO

60 MPH IN THE EXTREME SOUTHEASTERN GULF OF MEXICO. A SPECIAL

ADVISORY WILL BE ISSUED WITHIN THE NEXT HOUR...AND HURRICANE AND

TROPICAL STORM WATCHES WILL BE ISSUED FOR PORTIONS OF THE NORTHERN

GULF COAST. THIS SYSTEM HAS A HIGH CHANCE...NEAR 100 PERCENT...OF

BECOMING A TROPICAL CYCLONE DURING THE NEXT 48 HOURS...AND A HIGH

CHANCE...NEAR 100 PERCENT...OF BECOMING A TROPICAL CYCLONE DURING

THE NEXT 5 DAYS AS IT MOVES NORTH-NORTHWESTWARD.

ADDITIONALLY...LOCALLY HEAVY RAINS COULD AFFECT PORTIONS OF CUBA AND

THE YUCATAN PENINSULA DURING THE NEXT DAY OR TWO. AN AIR FORCE

RESERVE HURRICANE HUNTER AIRCRAFT IS CURRENTLY INVESTIGATING THE

SYSTEM. ADDITIONAL INFORMATION ON THIS SYSTEM CAN BE FOUND IN HIGH

SEAS FORECASTS ISSUED BY THE NATIONAL WEATHER SERVICE.

[Marion_NC_WX]

Invest 97L is about to be officially declared Karen. Hurricane and TS watches are about to be hoisted along parts of the northern Gulf coast! In retrospect, this undoubtedly has been a TS for at least several hours.

The GFS has easily been the top model while the Euro has been absolutely awful.

This easily looks to be the biggest storm of the season to date for US impacts.

 

 

haha, you and I were both thinking the same thing...

Can the mods go ahead and delete my thread?

[Ed Lizard]

ftp://ftp.nhc.noaa.gov/atcf/tcweb/invest_RENUMBER_al972013_al122013.ren

[apm]

haha, you and I were both thinking the same thing...

Can the mods go ahead and delete my thread?

 And adjust the link?

[Ed Lizard]

My only quibble, I think recon supports 55 knot winds,,,

[phil882]

Despite the winds, this is not a well organized TC... the system is displaced eastward of the convection and the pressure is only down to 1005 hPa in the first recon pass. I'm actually quite surprised there was as much wind as observed north of the center. 

[Lindsaywx]

I still don't buy the gfs solution. Its an outlier to the east. And any westward adjustment will plow it into much drier air....

[blazess556]

Center looks displaced west of the convection... recon found lowest pressure at 21.8N 87.7W

[Guest Imperator]

I still don't buy the gfs solution. Its an outlier to the east. And any westward adjustment will plow it into much drier air....

 

Neither does the WPC:

 

CONVECTIVE LOW OVER THE YUCATAN CHANNEL

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

PREFERENCE:  NON-GFS COMPROMISE

CONFIDENCE:  AVERAGE

THE 12Z GLOBAL ENSEMBLE GUIDANCE SHOWED SOME SPREAD WITH THIS

SYSTEM AS IT MOVES UP TOWARDS/ASHORE THE GULF COAST, BUT NOTHING

EXTREME FOR THREE DAYS INTO THE FUTURE.  THE 00Z GFS WAS ON THE

EASTERN FRINGE OF THE ENSEMBLE SPREAD, WHILE THE REMAINDER OF THE

GUIDANCE SHOWS REASONABLE CLUSTERING.  A NON-GFS COMPROMISE LIES

WITHIN THE OVERALL 12Z GLOBAL ENSEMBLE SPREAD AND IS PREFERRED

WITH AVERAGE CONFIDENCE CONSIDERING THE SYSTEM'S PROGRESSIVE

NATURE.  SEE NATIONAL HURRICANE CENTER TROPICAL WEATHER OUTLOOKS

FOR THIS CYCLONE'S LATEST STATUS.

...MODEL TREND GRAPHICS AT www.wpc.ncep.noaa.gov/html/model2.shtml

ROTH

 

[DaculaWeather]

Finally a decent visible:

[phil882]

I don't think the GFS's solution is unreasonable despite being the outlier. The storm in the GoM will be in a region of relatively light steering currents. In such an environment coupled with vertical wind shear, you often see the surface circulation get tugged towards the convection when the steering flow is weak. Thats exactly what happened with Debby which was not accurately forecasted by the ECMWF (or NHC for that matter) at all. That's also what happened with Andrea earlier this year. That's what the GFS is suggesting what might happen with Karen this weekend. 

[jconsor]

Despite the winds, this is not a well organized TC... the system is displaced eastward of the convection and the pressure is only down to 1005 hPa in the first recon pass. I'm actually quite surprised there was as much wind as observed north of the center. 

 

The burst of strong convection is likely a good part of the reason for the sudden ramp-up in sfc winds.  However, I agree that it looks like a typical sheared cyclone.  As long as it moves NNW I don't see more than slow intensification, but as soon as it turns NNE and moves more with the mean flow there is a good chance that the storm-relative shear will drop considerably and provide an opportunity for significant intensification.

 

Note that the 0z AND 6z GFS and even the GFDL are significantly too weak based on the current recon obs. at 12Z.

[jconsor]

FWIW, the experimental Univ. of Wisconsin NMS ensemble (part of NHC's HFIP project to improve hurricane forecasting)

has gradually been trending more bullish w/ 97L/Karen.

 

In the 2 months that I've been using the UW-NMS ensemble, I've found it much less likely than the GFDL ensemble to overdevelop TCs and more representative of the uncertainty/spread in track and intensity.

 

The 0Z ens. mean has a good cluster a tad west of the GFS over the FL panhandle.  The ens. mean peaks just under cat 2 status by midday Fri, and then weakens but remains a solid cat 1 through landfall Sat evening.

 

 

[LakeEffectKing]

Just reposting from the other thread for Josh's entertainment.....he gets some sort of rise out of my maps...

[GaWx]

Center looks displaced west of the convection... recon found lowest pressure at 21.8N 87.7W

 

 21.8N, 87.7W is close to the latest GFS track fwiw.

[GaWx]

TROPICAL STORM KAREN SPECIAL FORECAST/ADVISORY NUMBER 1
NWS NATIONAL HURRICANE CENTER MIAMI FL AL122013
1300 UTC THU OCT 03 2013

CHANGES IN WATCHES AND WARNINGS WITH THIS ADVISORY...

A HURRICANE WATCH IS IN EFFECT FROM GRAND ISLE LOUISIANA EASTWARD TO
INDIAN PASS FLORIDA. THIS DOES NOT INCLUDE METROPOLITAN NEW
ORLEANS...LAKE MAUREPAS...OR LAKE PONTCHARTRAIN

A TROPICAL STORM WATCH IS IN EFFECT FROM WEST OF GRAND ISLE TO
MORGAN CITY LOUISIANA...METROPOLITAN NEW ORLEANS...LAKE
MAUREPAS...AND LAKE PONTCHARTRAIN.

SUMMARY OF WATCHES AND WARNINGS IN EFFECT...

A HURRICANE WATCH IS IN EFFECT FOR...
* GRAND ISLE LOUISIANA TO INDIAN PASS FLORIDA

A TROPICAL STORM WATCH IS IN EFFECT FOR...
* WEST OF GRAND ISLE TO MORGAN CITY LOUISIANA
* METROPOLITAN NEW ORLEANS
* LAKE MAUREPAS
* LAKE PONTCHARTRAIN

A HURRICANE WATCH MEANS THAT HURRICANE CONDITIONS ARE POSSIBLE
WITHIN THE WATCH AREA. A WATCH IS TYPICALLY ISSUED 48 HOURS
BEFORE THE ANTICIPATED FIRST OCCURRENCE OF TROPICAL-STORM-FORCE
WINDS...CONDITIONS THAT MAKE OUTSIDE PREPARATIONS DIFFICULT OR
DANGEROUS.

A TROPICAL STORM WATCH MEANS THAT TROPICAL STORM CONDITIONS ARE
POSSIBLE WITHIN THE WATCH AREA...GENERALLY WITHIN 48 HOURS.

TROPICAL STORM CENTER LOCATED NEAR 22.0N 87.6W AT 03/1300Z
POSITION ACCURATE WITHIN 30 NM

PRESENT MOVEMENT TOWARD THE NORTH-NORTHWEST OR 340 DEGREES AT 11 KT

ESTIMATED MINIMUM CENTRAL PRESSURE 1004 MB
MAX SUSTAINED WINDS 50 KT WITH GUSTS TO 60 KT.
50 KT....... 40NE 20SE 0SW 40NW.
34 KT....... 80NE 50SE 30SW 60NW.
12 FT SEAS.. 60NE 0SE 0SW 0NW.
WINDS AND SEAS VARY GREATLY IN EACH QUADRANT. RADII IN NAUTICAL
MILES ARE THE LARGEST RADII EXPECTED ANYWHERE IN THAT QUADRANT.

REPEAT...CENTER LOCATED NEAR 22.0N 87.6W AT 03/1300Z
AT 03/0600Z CENTER WAS LOCATED NEAR 21.5N 86.6W

FORECAST VALID 03/1800Z 23.4N 88.2W
MAX WIND 55 KT...GUSTS 65 KT.
50 KT... 40NE 20SE 0SW 40NW.
34 KT... 80NE 50SE 30SW 60NW.

FORECAST VALID 04/0600Z 25.4N 88.8W
MAX WIND 60 KT...GUSTS 75 KT.
50 KT... 40NE 30SE 0SW 40NW.
34 KT... 80NE 60SE 30SW 60NW.

FORECAST VALID 04/1800Z 27.0N 88.9W
MAX WIND 65 KT...GUSTS 80 KT.
64 KT... 20NE 0SE 0SW 0NW.
50 KT... 40NE 30SE 0SW 40NW.
34 KT... 80NE 60SE 30SW 60NW.

FORECAST VALID 05/0600Z 28.3N 88.7W
MAX WIND 60 KT...GUSTS 75 KT.
50 KT... 40NE 40SE 0SW 40NW.
34 KT... 80NE 80SE 30SW 60NW.

FORECAST VALID 06/0600Z 31.0N 87.5W...INLAND
MAX WIND 50 KT...GUSTS 60 KT.
50 KT... 20NE 60SE 0SW 0NW.
34 KT... 30NE 80SE 30SW 0NW.

EXTENDED OUTLOOK. NOTE...ERRORS FOR TRACK HAVE AVERAGED NEAR 150 NM
ON DAY 4 AND 200 NM ON DAY 5...AND FOR INTENSITY NEAR 15 KT EACH DAY

OUTLOOK VALID 07/0600Z 34.5N 83.0W...POST-TROP/EXTRATROP
MAX WIND 25 KT...GUSTS 35 KT.

OUTLOOK VALID 08/0600Z 38.5N 77.5W...POST-TROP/EXTRATROP
MAX WIND 20 KT...GUSTS 30 KT.

REQUEST FOR 3 HOURLY SHIP REPORTS WITHIN 300 MILES OF 22.0N 87.6W

NEXT ADVISORY AT 03/1500Z

$$
FORECASTER BRENNAN

[CoastalWx]

The shear axis just NW of it now is progged to move slowly NW. As that happens and Karen turns more NE it appears that is the window for intensification like Jconsor mentioned. I never like seeing such dry air to the NW of the system though.

[NavarreDon]

TROPICAL STORM KAREN SPECIAL DISCUSSION NUMBER 1

NWS NATIONAL HURRICANE CENTER MIAMI FL AL122013

800 AM CDT THU OCT 03 2013

AN AIR FORCE RESERVE HURRICANE HUNTER AIRCRAFT INVESTIGATING THE

AREA OF LOW PRESSURE JUST NORTH OF THE YUCATAN PENINSULA FOUND A

CLOSED CIRCULATION WITH A CENTRAL PRESSURE OF 1004 MB AND SURFACE

WINDS AROUND 50 KT. BASED ON THESE DATA...ADVISORIES ARE BEING

INITIATED ON TROPICAL STORM KAREN. MOST OF THE DEEP CONVECTION IS

DISPLACED NORTH AND EAST OF THE CENTER DUE TO MODERATE

SOUTHWESTERLY SHEAR. THE SHEAR IS EXPECTED TO CONTINUE AND THE

INTENSIFY IN 2 TO 3 DAYS. THIS ENVIRONMENT SHOULD ONLY SUPPORT

GRADUAL INTENSIFICATION DURING THE NEXT DAY OR SO...WITH SOME

WEAKENING EXPECTED AS KAREN APPROACHES THE GULF COAST...BUT THE

STORM COULD STILL BE NEAR HURRICANE STRENGTH AT LANDFALL.

THE INITIAL MOTION ESTIMATE IS AN UNCERTAIN 340/11 GIVEN THE RECENT

FORMATION OF THE CENTER. KAREN IS EXPECTED TO GRADUALLY TURN

NORTHWARD AROUND THE PERIPHERY OF A MID-LEVEL RIDGE AND THEN

ACCELERATE NORTHEASTWARD LATE IN THE PERIOD AHEAD OF A

MID/UPPER-LEVEL TROUGH. ALL OF THE TRACK GUIDANCE IS IN AGREEMENT

ON THIS GENERAL SCENARIO...HOWEVER THERE IS SIGNIFICANT WEST/EAST

SPREAD IN THE TRACKS...WITH THE ECMWF ON THE WEST SIDE OF THE

GUIDANCE ENVELOPE AND THE GFS FARTHEST EAST. THE NHC TRACK FORECAST

IS NEAR THE MIDDLE OF THE GUIDANCE ENVELOPE AND THE TVCA

MULTI-MODEL CONSENSUS THROUGH LANDFALL. NOTE THAT A TRACK FARTHER

EAST WOULD LIKELY RESULT IN A STRONGER STORM...WHILE KAREN WOULD

LIKELY BE WEAKER IF IT TAKES A TRACK FARTHER WEST.

GIVEN THE FORECAST...HURRICANE AND TROPICAL STORM WATCHES HAVE BEEN

ISSUED FOR PORTIONS OF THE NORTHERN GULF COAST.

FORECAST POSITIONS AND MAX WINDS

INIT 03/1300Z 22.0N 87.6W 50 KT 60 MPH

12H 03/1800Z 23.4N 88.2W 55 KT 65 MPH

24H 04/0600Z 25.4N 88.8W 60 KT 70 MPH

36H 04/1800Z 27.0N 88.9W 65 KT 75 MPH

48H 05/0600Z 28.3N 88.7W 60 KT 70 MPH

72H 06/0600Z 31.0N 87.5W 50 KT 60 MPH...INLAND

96H 07/0600Z 34.5N 83.0W 25 KT 30 MPH...POST-TROP/EXTRATROP

120H 08/0600Z 38.5N 77.5W 20 KT 25 MPH...POST-TROP/EXTRATROP

[NavarreDon]

Link to NWS-MOB OBS page.

 

http://www.srh.noaa.gov/mob/?n=observations

[wxsmwhrms]

I am going to be honest, I don't think any of the models are handling Karen very well.  The GFS is obviously a more robust solution, but not until much later in the forecast period.  None of the models have handled the intensification that has occurred to this point.  But as Phil says, that doesn't mean that the GFS won't end up being the closer solution in the end.  I really agree with NHC's last point - a track farther to the west will likely mean a weaker solution, to the east a stronger solution.

[wxmeddler]

55kts on the SFMR again, uncontaminated.

[wxmx]

I anticipated a 50 kt TS in 24 hrs, but it got to that in 12... it's definitely a sheared system, and will continue to be so for the rest of it's lifetime, but I don't think shear will be prohibitively strong... my guess would be a peak of around 70kts in about 48h...to around 55-60kts at landfall

[phil882]

FWIW, the experimental Univ. of Wisconsin NMS ensemble (part of NHC's HFIP project to improve hurricane forecasting)

has gradually been trending more bullish w/ 97L/Karen.

 

In the 2 months that I've been using the UW-NMS ensemble, I've found it much less likely than the GFDL ensemble to overdevelop TCs and more representative of the uncertainty/spread in track and intensity.

 

The 0Z ens. mean has a good cluster a tad west of the GFS over the FL panhandle.  The ens. mean peaks just under cat 2 status by midday Fri, and then weakens but remains a solid cat 1 through landfall Sat evening.

 

UWNMS_track.png

 

UWNMS_intensity.png

 

Thanks for posting this... do you have a link to the original page that you obtained these from?

[DaculaWeather]

SENIOR DUTY METEOROLOGIST NWS ADMINISTRATIVE MESSAGE
NWS NCEP CENTRAL OPERATIONS COLLEGE PARK MD
1346Z THU OCT 03 2013


12Z NCEP MODEL PRODUCTION IS ON TIME..

12Z NAM RAOB RECAP...
76805/ACA - 10142
76654/MZL - 10142
76458/MZT - 10158
76256/GYM - 10142
72645/GRB - 10142
74494/CHH - UNAVB
72520/PBZ - PURGED TEMPS/MOISTURE 717-646MB...WET BULB EFFECT

CRITICAL WEATHER DAY STATUS...
A REGIONAL CRITICAL WEATHER DAY...CWD...WILL BE DECLARED AT
1400Z THU OCT 3 2013 AND EXTEND THROUGH 0000Z MON OCT 7
2013 DUE TO TROPICAL STORM KAREN. THE FOLLOWING NWS REGIONS ARE
IMPACTED BY THIS CWD...SOUTHERN. NCEP/NWSTG AND THE NCF ARE ALSO
PARTICIPATING IN THIS CWD TO ENSURE A RELIABLE FLOW OF WEATHER
DATA. ALL SCHEDULED SOFTWARE/HARDWARE/NETWORK CHANGES FOR THE
IMPACTED OFFICES WILL BE POSTPONED UNTIL THE CWD HAS ENDED. ANY
EMERGENCY CHANGES WILL BE EVALUATED AND APPROVED BY THE LOCAL
REGIONAL MANAGEMENT OFFICIALS.  NWS OFFICES SHOULD CONTACT THEIR
REGIONAL OFFICES FOR FURTHER QUESTIONS ABOUT THIS CWD.

SHIREY/SDM/NCO/NCEP

[phil882]

Last recon fix appears to be due west of the previous fix. Not necessarily a good sign if you are thinking short term intensification. I'm pretty sure we will see an exposed circulation at some point later today.

[CoastalWx]

Thanks for posting this... do you have a link to the original page that you obtained these from?

 

 

http://cup.aos.wisc.edu/will/HFIP/ens.html

[wxmx]

Last recon fix appears to be due west of the previous fix. Not necessarily a good sign if you are thinking short term intensification. I'm pretty sure we will see an exposed circulation at some point later today.

Yep, agree...probably a wobble, but there's still a significant west component of motion.

[LakeEffectKing]

 

Last recon fix appears to be due west of the previous fix. Not necessarily a good sign if you are thinking short term intensification. I'm pretty sure we will see an exposed circulation at some point later today.

 Agree...the surface reflection developed a good deal westward than what I was anticipating last evening during/under the intense convection as depicted by IR. It renders my track map useless at the early stages, wrt track, but still think the intensity should creep up a bit more, then fall off as it approaches the GOM northern coast.

[Interstate]

Did anyone notice on the 5 day Tropical Storm Force Wind Speed Probabilities there is a tongue of possible development going up the coast?

 

[phil882]

http://cup.aos.wisc.edu/will/HFIP/ens.html

 

Thanks! Looks like the models are initialized off the GFS and GEFS grids so its not too surprising to see the intensity guidance so bullish.