Dr. Jeff Masters' WunderBlog

Blog Update
Reflector site for those at work, which now also includes Weather456, daily updates


AOI #1

AOI #2

. NVM

Current Conditions
Roatan WU-Page


Updated: 27 min 27 sec ago
Partly Cloudy
88 °F
Partly Cloudy
Humidity: 62%
Dew Point: 73 °F
Wind: 9 mph from the NNE
Pressure: 29.80 in (Falling)

We have had the enormous honour of being able to interview to Mr. Masters for Cazatormentas.Net, who has nicely agreed to answer some questions formulated by Spanish Weather Enthusiasts. You could find the questions and their answers both in Spanish and in English.

Complete Interview

We want to thank him for his great effort attending to our request!

Many thanks again, Mr. Masters!! Always learning reading in your blog!

Outstanding..Jeff Masters always has something to enlighten us with,in a interview.

Thanx for the info.

hello everyone... haven't posted since last year.....building storm here in oakland park fl (n of ft laud)..... just heard 3.. loud loud and i mean loud claps of thunder

Looks heavy thunderstorm activity starting to pop...

roatangardener--- so great to see you!

Supercell initiation is about to occur in KS and NE.

wow.. the models are out to lunch, and they went a ways to get there. It seems like every model offers up a completley different solution. When I was looking at the GFS I noticed it still developed the area in the southwestern caribbean, although quite a bit weaker than previous runs, and it also seems to want to have some type, either tropical/subtropical, development off the southeast coast. The CMC doesn't even develop the caribbean area, but does develop something north of Cuba around the Bahamas and has that moving northeast. The NGPS develops an area that looks like it moves from south america northwestward to right over Jamaica? Am I crazy or this really what the computer models are saying? jw

No, your right. Models have gone from agreement a couple days ago, to conflicting.

something probably will come out of this eventually, but to what degree depends on the upper air conditions at that time...

When you see so much disparity in the Big 4,then we must assume development isnt certain,as Jeff Masters says,above,a "less than 30%" chance at Tropical Development. When you start seeing the ensemble agreeing with one another,or consensus among them,..
then Things usually follow suit.
Wouldnt be much use if every model spit out the same solution everytime.
Each model has its own High and Low points and are individually different.
For a reason,..kinda like us Humans.

Ok, I give up. I have googled, read, and looked at 4 models, all for the "Cape". Someone please tell me what the "Cape" is.

TIA

Quoting Patrap:
When you see so much disparity in the Big 4,then we must assume development isnt certain,as Jeff Masters says,above,maybe a 30% chance at Tropical Development. When you start seeing the ensemble agreeing with one another,or consensus among them,..
then Things usually follow suit.
Wouldnt be much use if every model spit out the same solution everytime.
Each model has its own High and Low points and are individually different.
For a reason,..kinda like us Humans.

A hint of sarcasm? I think so.. I understand what you said, but I was just shocked that all of them were going totally opposite ways with the forecast. I've personally never seen this much disagreement. I mean, I've seen differences but this looks whacky

Sarcasm...me?

..say it aint so.

LOL

Quoting Patrap:
When you see so much disparity in the Big 4,then we must assume development isnt certain,as Jeff Masters says,above,maybe a 30% chance at Tropical Development. When you start seeing the ensemble agreeing with one another,or consensus among them,..
then Things usually follow suit.
Wouldnt be much use if every model spit out the same solution everytime.
Each model has its own High and Low points and are individually different.
For a reason,..kinda like us Humans.

I agree, it drives me crazy how they swing from one solun to the other though. I've heard of feedback runs, but not quite sure how that happens.

Convective Available Potential Energy (CAPE)

One term you will hear when listening to NOAA Weather Radio, storm chasers, and weather experts during storm season is CAPE. Here is a little about what CAPE is and how it pertains to severe weather.

The convective available potential energy or CAPE, is used by weather officials and storm chasers to understand what the potential might be for severe weather, and how powerful those storms might become if they do materialize. The potential energy available for convection is expressed mathematically using a standard measurement of energy represented as Joules Per Kilogram. A high CAPE value might also be expressed by storm chasers and weather experts by using the term "high instability". When chasers talk about a highly unstable atmosphere, CAPE values are usually in excess of 2500 J/kg's which would supply ample energy for strong updrafts and violent storms should they develop.

CAPE value Convective potential
0 Stable
0-1000 Marginally Unstable
1000-2500 Moderately Unstable
2500-3500 Very Unstable
3500 Extremely Unstable

More specifically, CAPE represents the amount of buoyant energy available to speed up a parcel vertically, or the amount of work a parcel does on the environment. Storms require high CAPE values; the higher the CAPE value, the more energy available to promote storm growth. CAPE is especially important when air parcels are able to reach the (LFC) or Layer of Free Convection. To find CAPE from a skew-T thermodynamic diagram like the one below, simply locate the area on the diagram where the parcel sounding (Thick yellow vertical line) is farther to the right (warmer) than the atmosphere sounding (red line). The white shaded region on the sounding below is the area of CAPE.

Area forecast discussion
National Weather Service Denver Colorado
308 am MDT sun Jun 7 2009



Short term...cold front is currently backing southwest across the
forecast area. Weak outflow from thunderstorms over southern Wyoming
and northern Colorado is pushing through the Denver metropolitan area now.
The cold front runs from Fort Collins to Fort Lupton to Byers. At
its current pace the front will be through most of the metropolitan area by
sunrise. Air behind the front is very moist and cooler. Dew points
behind the front over northeast are in the middle 50s. This will result
in low clouds and fog this morning.


At the upper levels...a short wave trough over Utah will move across
northern Colorado today. The lift from the short wave combined with
the moisture behind the front should produce scattered showers and
thunderstorms. The amount of thunderstorm activity and the strength
of it will depend on how much clearing occurs late this morning and
this afternoon. Looks like it will be slow to clear out today and
afternoon heating will be slow. Lowered high temperatures to the 60s
for most locations today which will limit how unstable it will be
this afternoon. If current forecasted highs pan out convective available potential energy will
remain below a 1000 j/kg. This will make it hard for storms to
become severe but not impossible.

Thanks Pat, appreciate the explanation

I used the search engine and found that excellent explanation,,yvw


Anytime zm.

i know. i browse here all the time but dont usually post until hurricane season here starts to get busy. now we have earthquakes to deal with. since the 7.1 on may 28th we've had aftershocks in the 4.5 area almost every day. somehow we didnt have much structural damage.. just broken glass and ceramics. i was just wondering if this system in the western carib will slide over to the west and give us some badly needed rain... Helen

Yes Patrap, the Weather Channel just talking about that same cell. I think the Vortex 2 team is in the area.

A matter of searching for the right terms. When I first learned legal research there was a book just for terms - if you couldn't find what you were looking for, you searched through the "words" to find one that worked.

Obviously, I need a meterology dictionary...lol

V2 may be there..they get around pretty good,and the Front Range is a Wide open area today.

Getting wet again where they really don't need to again.

I'm interested to see what our tropical wave will bring to the WCARIB

SBCAPE (Surface-Based Convective Available Potential Energy) is a measure of instability in the troposphere. This value represents the total amount of potential energy available to a parcel of air originating at the surface and being lifted to its level of free convection (LFC). No parcel entrainment is considered. The CAPE and CIN calculations use the virtual temperature correction.

CIN (Convective INhibition) represents the "negative" area on a sounding that must be overcome before storm initiation can occur.

The NCAPE (Normalized CAPE) is CAPE that is divided by the depth of the buoyancy layer (units of m s**-2). Values near or less than .1 suggest a "tall, skinny" CAPE profile with relatively weak parcel accelerations, while values closer to .3 to .4 suggest a "fat" CAPE profile with large parcel accelerations possible. Normalized CAPE and lifed indicies are similar measures of instability.

MUCAPE (Most Unstable Convective Available Potential Energy) is a measure of instability in the troposphere. This value represents the total amount of potential energy available to the most unstable parcel of air found within the lowest 300-mb of the atmosphere while being lifted to its level of free convection (LFC). No parcel entrainment is considered. The CAPE and CIN calculations use the virtual temperature correction.

The LPL (Lifted Parcel Level) allows for the determination of the height of the most unstable parcel. This makes it easy to identify areas where the largest CAPE is "elevated."


These are from the SPC. Hope that helps...a little.

Charleston, SC yesterday

Quoting Weather456:
I'm interested to see what our tropical wave will bring to the WCARIB

Looks like the 18Z NAM is picking up on that wave at 84 hours....

Thanks Vort, Nrti, Aquak, I'm putting these on my favorites - working on reference items this week, so its a good fit.

Press - what is that bridge? Its beautiful.

Quoting zoomiami:
Thanks Vort, Nrti, Aquak, I'm putting these on my favorites - working on reference items this week, so its a good fit.

Press - what is that bridge? Its beautiful.

That's the Ravenel Bridge in Charleston.

Quoting SavannahStorm:

That low is moving on east/NE.

The trough should lift out by mid-week. Then the wave hits in the western Caribbean.

One things for certain, there is a lot of instability down the caribbean.

Quoting P451:
OT: It hit 132.8 Degrees in Afghanistan a couple of days ago:

# Past 72 Hours: 56°C (132.8°F) [KQD9:SALERNO FOB, AFGHANISTAN]

Is that a record high? Never heard of it going that high!!

Zoo...Sav is correct...it's the Ravenel Bridge...connecting the Charleston Penninsula with Mt. Pleasant...which, btw, has no mountain...and is not particularly pleasant...but the bridge is a beaut...

Patrap, didn't like the sarcasm lol, but enjoyed the link. It was very informative. Thanks