Ask a Pro Met

[isohume]

I mean by backwards becuase don't it run the evening run first and then the rest of the runs?

 

No, it's continuous. There is no "first" model run.  The 00Z designation just means the model is initialized off the 00Z data...the same goes for the 06Z, 12Z, and 18Z runs.   

[weatherbob1234]

cool thanks!!!

[Quixotic1]

Dumb question:  Do folks blizzard chase?  I ask because I have never been in one in my life.  The proximity of the current one in the Texas Panhandle makes me wonder if I should try it sometime, however I'd prefer not to get my stupid self smoked by getting stranded out in the open. 

[Ellinwood]

Dumb question:  Do folks blizzard chase?  I ask because I have never been in one in my life.  The proximity of the current one in the Texas Panhandle makes me wonder if I should try it sometime, however I'd prefer not to get my stupid self smoked by getting stranded out in the open. 

There are blizzard chasers... most are just off-season storm chasers. Just make sure you've got a vehicle that can handle it and that you know what you're getting into (closed roads, power outages, biting wind chills, possibility of getting stuck in the cold and snow for many hours, etc.).

[Festus]

In the Regional forums, medium range forecasts occasionally involve terms like ENSO, PNA, MJO, AO, NAO, etc. 

 

Could someone provide a brief description of each (and maybe some I missed) and what they means in terms of sensible weather to the Northeast U.S.?

[Quixotic1]

There are blizzard chasers... most are just off-season storm chasers. Just make sure you've got a vehicle that can handle it and that you know what you're getting into (closed roads, power outages, biting wind chills, possibility of getting stuck in the cold and snow for many hours, etc.).

 

Thanks for the response.  My goal was to hole up somewhere in the path before it gets there and chase if it shucks and jives. 

[Quixotic1]

In the Regional forums, medium range forecasts occasionally involve terms like ENSO, PNA, MJO, AO, NAO, etc. 

 

Could someone provide a brief description of each (and maybe some I missed) and what they means in terms of sensible weather to the Northeast U.S.?

I'm not a met, but this is a good place to get started.  All the teleconnections links are on the left side of the page.

 

http://www.cpc.ncep.noaa.gov/

 

There are probably better sites that mets would know, but it couldn't hurt to get started there. 

[weatherbob1234]

Where can i find some map making software or soemthing to make weather map graphics with?

 

thanks,

bobby

[GrumpyRainbow]

Where can i find some map making software or soemthing to make weather map graphics with?

 

thanks,

bobby

 

I'm not sure how familiar you are with programming, but I would recommend learning Python and using Basemap.

 

You can do a lot of cool things with Python and Matplotlib.  There are certainly other ways to make weather graphics, but Python is a great language to know, especially if you plan on doing any sort of data analyses.

 

http://matplotlib.org/basemap/users/examples.html

[weatherbob1234]

i'm not to big on programming, but i've heard of python, i have gempak, but i could try python, i didn't know you could do things like that with it.

 

thanks,

bobby

[NCsandhills]

What is a Miller A and Miller B?  Do Miller B's every produce snow for the SE?  I noticed not many people are fond of it.

 

I might be completely off base with this next one but thats what this forum is for right? lol.  If there is a strong Nino, does that make for a more active STJ, which would bring more stormy weather?

 

With measuring the NAO/AO, I see it written as -3.75 or 2 etc.  How are these numbers gotten?

[ohleary]

i'm not to big on programming, but i've heard of python, i have gempak, but i could try python, i didn't know you could do things like that with it.

 

thanks,

bobby

 

If you have gempak, I assume you're in a Linux/Unix environment, shell scripts are really all you need to manipulate gempak.

[Jim Marusak]

thanks

one other thing to keep in mind though when you have the spin-up and broadening out of vorticity. not to go too much into the calc-side dynamics (because they can get more than a bit ugly), but as part of the dynamics of changing the spin, you also end up with an equatorial directional movement to the area of vorticity at the surface level.

 

how this is best shown on the east coast is when you have the low marching across between i-80 and US 6 in western PA, but it appears to jump to the southeast towards the Chesapeake and the Delmarva. as late as the early and mid-90's, the weather models had a big problem allowing for this equator-bound direction to the jump and as a forecaster you always had to correct by moving the low the models depict southwards by 1-2 degrees latitude. these days, the models do a much better job producing the needed jump southeastwards that the lee-side cyclo-genesis produces.

[Ed Lizard]

ENSO and trough orientation- does a warm ENSO/negative troughs more likely correlation extend beyond cold season. (KU book has an ENSO section).

 

And non-met level but not TWC explanation, how does the ENSO affect trough orientation?

[isohume]

ENSO and trough orientation- does a warm ENSO/negative troughs more likely correlation extend beyond cold season. (KU book has an ENSO section).

 

And non-met level but not TWC explanation, how does the ENSO affect trough orientation?

 

 

I haven't seen any studies that correlate ENSO phase with mlvl trough orientation. I have seen a non-peer reviewed paper that discusses the the possible connection btw the combined phases of a maritime MJO and an ENSO cooling phase to the frequency of cut-off lows across the NE CONUS. This is only a general relationship statistically speaking, however, and does not account for individual variability. Thus, operationally, there is no significant statistical correlation or relationship to be had. This isn't to say there aren't studies out there claiming otherwise, it just means I'm not aware of any.  

http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&cad=rja&ved=0CC8QFjAA&url=http%3A%2F%2Fcstar.cestm.albany.edu%2FCAP_Projects%2FProject16%2FMPayer%2F10Payer_Ch3.doc&ei=bAlTUdT1G4rO9ATj3oDgDA&usg=AFQjCNFCqY-D3Pnrf0GobtQj79ME9RT3Tw

[Eskimo Joe]

Where can i find some map making software or soemthing to make weather map graphics with?

 

thanks,

bobby

 

 

I'm not sure how familiar you are with programming, but I would recommend learning Python and using Basemap.

 

You can do a lot of cool things with Python and Matplotlib.  There are certainly other ways to make weather graphics, but Python is a great language to know, especially if you plan on doing any sort of data analyses.

 

http://matplotlib.org/basemap/users/examples.html

 

 

i'm not to big on programming, but i've heard of python, i have gempak, but i could try python, i didn't know you could do things like that with it.

 

thanks,

bobby

Quantum GIS is another open-source solution.  A quick Google search will provide you with all the information you need.  

[dvcavall]

Question regarding the use of commonly available indicators from weather service providers to determine the degree of "moisture per volume" in the air?

 

As you can probably tell from the phrasing of my question, I am not educated in meteorology or weather, so please forgive me.  I hope I can still get an answer?

 

My reason for asking is this. I have started a small business that uses a portable air compressor to power what is called a soda blaster, much like a sandblaster, but uses a salt mineral similar to epson salt.  It is a highly hygroscopic material. Even though we use moisture separators/dryers on our equipment which are devices meant to remove water from the compressed air, on days where there is a good amount of moisture in the air moisture still gets into the system (air is be compressed around 150 PSI) and causes the media to jam the hoses and valves and stops the work. So, I am trying to understand if I can use "RH" and "Dew Point" or any other indicators I can get on a cell phone App, to tell me when there is either a "Low/Med/High" volume  of moisture in the air?  My understanding so far is that RH  indicates the amount of "water saturation" in the air per  a given pressure and temperature?  And "Dew Point" indicates the temperature at which water vapor will condensate?  If those definitions are generally accurate, RH would seem like the indicator, but I have read it really doesn't indicate the amount of moisture per volume of air, which I think is what matters since I am compressing air volume at a 150 PSI?

 

I would like to schedule this type of work on days when the amount of moisture in the air is low.  Can you help me understand what I should be looking at to make that determination?

 

Also, I have more than one weather App on my phone, and none of them are ever in synch on the data? One might show a RH of 36% and another can say 69%? Is there a weather App for Android that is thought to be accurate?  I live in Southern California,

 

Thank you for the help.

 

Dave C

[ohleary]

You're right about RH, not very telling if you want to know how much water vapor is actually in the air. 

 

Mixing ratio tells you the ratio of the weight of water vapor in a specified volume of air to the weight of dry air in that same volume.  You have to calculate mixing ratio but if you're always working at about the same pressure level, i.e. near sea level, then just use dew point, which with pressure is used to find mixing ratio. 

 

If you sometimes have to go up to 2500 feet to work then it gets trickier, as you have to know the pressure at that level to calculate the mixing ratio from the dew point.  See:

 

Surface: 1000mb...dew point 15C...mixing ratio - 10.78 grams/kilogram

2500 ft: about 920mb...dew point 15C...mixing ratio - 11.73 grams/kilogram

Denver, CO: about 840mb...dew point 15C...mixing ratio - 12.87 grams/kilogram

 

So after trial and error you know that over 11 grams/kilogram is no good, it's fine at the surface but not at 2500 ft.

 

Mixing ratio calculator:

 

http://www.srh.noaa.gov/epz/?n=wxcalc_mixingratio

 

That's my two cents.

 

[dvcavall]

Thank you for the reply. Now I need to figure out "saturated" vs "actual" mixing ratio, and why they are so different?  My WeatherPro app showed 85 degrees F, Dewpoint 56 degrees F,Pressure 1009hPa, and a RH of 37. The calculator shows 26.34 grams saturated, and 9.57 grams actual. Can you explain the difference and which I should use?  Thanks again.  Dave

[ohleary]

The saturation mixing ratio is the amount of water vapor in the air at that temp and pressure if the air were saturated, i.e. 100% RH.  You don't want to use that. 

[dvcavall]

Thanks again ohleary!

 

Having tracked the "actual mixing ratio" for my area (Santa Clarita, CA 91390), and listening to the weather broadcasts on the news stations, I must say I am not as clear on all this as I would like to be, so just a few more questions please? 

 

When the Power House fire was active ( a big fire near where I live), the news folks were always reporting on RH, which I know isn't what I want to use, but the inference was that "humidity was low" which was not helping the fire fighters. As I calculated the "actual mixing ratio" during those days it was consistently at 9.XXX grams per kilogram.  We are now having cooler temps, and higher humidity reported. The RH is 70% today.

 

However, when i calculate the "actual mixing ratio" using the reported pressure of 1015hPa, and a Dew Point of 53 degrees, I get 8.51grams per kilogram which I think should indicate there is actually LESS moisture in the air, not more?  So, how can we be having  higher humidity when there is less water vapor in the air?  

 

Thanks in advance for clarifying.

 

Dave

[NeffsvilleWx]

However, when i calculate the "actual mixing ratio" using the reported pressure of 1015hPa, and a Dew Point of 53 degrees, I get 8.51grams per kilogram which I think should indicate there is actually LESS moisture in the air, not more?  So, how can we be having  higher humidity when there is less water vapor in the air?  

 

I'm no met, but doesn't the "carrying capacity" of air change with the temperature? If I remember correctly, hot air has more capacity than hot air, and I think relative humidity is the percentage of saturation of the air.

 

So, when air is cooler, it requires less moisture to reach saturation, resulting in higher relative humidity levels for less actual moisture.

 

For instance (using arbitrary numbers) if saturation (100% RH) at 70 degrees is 10 g/kg, at 100 degrees, it might be 20 g/kg, which means RH would be 50%.

[dvcavall]

Hmmm. So for my purposes (identifying days where my compressor will have less moisture in the air it compresses), all I need to focus on is the "actual mixing ratio", and if that ratio calculates to 8.XXX as opposed to 9.XXX, there is LESS moisure per kg of air on the 8.XXX day than on the 9.XXX day ..period. Correct?

 

My other question is... what Android App is most accurate for things like dew point and pressure...assuming there is a consensus of opinion? I have several apps on my phone, and they all seem to give different numbers?  I realize weather is a point-in-time thing which may account for the differences, but can I rely on a particular service more often than others?  I am currently looking at WeatherPro most often, then calculating the "actual mixing ratio" with another app..

[dvcavall]

OK. Now I know to use the "actual or absolute" mixing ratio to find out the amount of water in the air that will need to be filtered out of my compressors air supply if I want "dry" air delivered.  However, what I can't seem to find on the web or here, is any kind of scale that says if the reading indicates high moisture or low moisture? In other words, what reading range would typically be expected on a low moisture day, as opposed to a high moisture (humid) day?  I live in So Cal, so a historical or typical range for this area would be great.  I can calculate the ratio every day, but have no reference to know if 9.5g/kg is considered dry or not?

 

Thanks,

Dave

[Snowball]

A BS in Meteorology from Miss State is the same thing as a BS in Meteorology from Penn State. No one is going to make any hiring decision based on your undergrad location. Other things like good grades and educational diversity are much much more important. If you are talking about their certification program, that's a different story.

Are you kidding? The program is VERY important. If a PSU and Miss State grad came walking in the door, I would hire the PSU person hands down.

[ctsnowstorm628]

Are you kidding? The program is VERY important. If a PSU and Miss State grad came walking in the door, I would hire the PSU person hands down.

Being a senior undergrad at Lyndon State and having spent a lot of time with undergrads at PSU this past summer and now this fall, it really just depends on the person (specific skills and diversity). There are a lot of capable people from all over. Institution isn't everything, but every program is different (see below).

I know at SUNY Oswego, people majoring in meteorology didn't have to take an atmospheric thermodynamics class...like, are you kidding me? Probably the most important meteorology class in my opinion. Some programs aren't "up to snuff", but many are just as good as others.

[heavy_wx]

Being a senior undergrad at Lyndon State and having spent a lot of time with undergrads at PSU this past summer and now this fall, it really just depends on the person (specific skills and diversity). There are a lot of capable people from all over. Institution isn't everything, but every program is different (see below).

I know at SUNY Oswego, people majoring in meteorology didn't have to take an atmospheric thermodynamics class...like, are you kidding me? Probably the most important meteorology class in my opinion. Some programs aren't "up to snuff", but many are just as good as others.

 

Who told you that? I graduated from SUNY Oswego last spring and we were required to take a year of dynamic meteorology; thermodynamics in the fall and fluids in the spring semester.

[ctsnowstorm628]

Who told you that? I graduated from SUNY Oswego last spring and we were required to take a year of dynamic meteorology; thermodynamics in the fall and fluids in the spring semester.

My co-intern (and room mate) last summer is a senior and did not take it, and said he is not taking it. I was really surprised... 

 

At Lyndon we take Atmospheric Thermo in the spring of sophomore year, then two semesters of Atmoshperic Dynamics junior year along with Synoptic for two semesters and radiation/cloud microphysics. I assumed Oswego did the same, provided the talent that comes out of there.

[heavy_wx]

My co-intern (and room mate) last summer is a senior and did not take it, and said he is not taking it. I was really surprised... 

 

At Lyndon we take Atmospheric Thermo in the spring of sophomore year, then two semesters of Atmoshperic Dynamics junior year along with Synoptic for two semesters and radiation/cloud microphysics. I assumed Oswego did the same, provided the talent that comes out of there.

 

I guess Lyndon has another semester of dynamics then. We generally have the same requirements otherwise.

 

http://catalog.oswego.edu/preview_program.php?catoid=26&poid=2618

[ctsnowstorm628]

I guess Lyndon has another semester of dynamics then. We generally have the same requirements otherwise.

 

http://catalog.oswego.edu/preview_program.php?catoid=26&poid=2618

I figured. I don't know what my room mate was talking about then.