CPC And Hope

For the weather illiterate, what does CPC stand for??

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I think we and the CPC would get along quite well!!... unless they are thinking, like, ice and stuff.

Yeah, what does CPC stand for?

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I believe it stands for "Climate Prediction Center". Notice they continue to edge the eastern portion of the pink shading a little further north. A slight change from this morning.

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Tks, Russ

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CPS

Can PREDICT SNOW>>>>>


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Can Possibly Snow??? LOL.... J/K!!!!


Keep HOPE Alive

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BTW.... how accurate is CPC? I hope very!!

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Ice cubes went down the tiolet....getting desperate!

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Ice cubes went down the toilet....getting desperate!

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LOL Everyone - spoon is under all pillow except eli's. he dont have a pillow, and would use the spoon as a drumstick in the middle of the night

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Does anyone remember how the storm in the early 90's came about? Was it phased or a result of dynamic cooling? I was really young and didnt care then, i just enjoyed the snow. Maybe James or J.B. remember

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Ok snow fans , we can give up hope, but I am naming the next one , and it is going to be called Steph.... She has put so much work into the dancing , I am giving this one up to her... NOw the 18 z run has got interesting, but we all knwo what that means .. If you dont, ask greg... but here we go ...Lets look at what we have now... lets start off with the QPF..Now this is the updated qpf off of the 00z run for 17 dec... so this is the latest thinking :

http://www.hpc.ncep.noaa.gov/qpf/p120i00.gif

as you can see, the moisture is being shunted to the south with bob... we may get a few sprinkles, but the moisture will be limited.. Here are some additional graphics for bob... Lets look at the latest from our friend the GFS... here we are, tonight, with the high really moving down over N. mississippi, and to be honest, this really decreases the chances of the moisture moving to far north ...

http://www.nco.ncep.noaa.gov/pmb/nwprod/analysis/namer/gfs/18/ima
ges/gfs_slp_006s.gif

Now lets move out to Sat morning and you can see the moisture beginning to build in the gulf

http://www.nco.ncep.noaa.gov/pmb/nwprod/analysis/namer/gfs/18/ima
ges/gfs_slp_018s.gif

As we move along in the day , you can see the bulk of the rain still moving south ..

http://www.nco.ncep.noaa.gov/pmb/nwprod/analysis/namer/gfs/18/ima
ges/gfs_slp_030s.gif

Now lets look at some of the critical snow values for BOB late tomorrow night.. as you can see from the last graphic ..the 540 line is all the way up in tennessee, so the surface temp will be to warm for anything but light rain here.... NOw lets talke a look at the 850mb and see the freezing line at 5000 ft. now this is off the Nam 18z run :

http://www.nco.ncep.noaa.gov/pmb/nwprod/analysis/namer/nam/18/ima
ges/nam_850_030s.gif

As you can see, the freezing line is all the way up into tennessee again.. so The confidence that we will even see any winter mix is all but gone... Ther is a chance that we could see some dynamic cooling that could casue a little sleet or a few flakes on the northern edge of the precip, but unlikely., and as sunday rolls around, Bob is history, and we have a dry sunny day on sunday:

http://www.nco.ncep.noaa.gov/pmb/nwprod/analysis/namer/gfs/18/ima
ges/gfs_slp_042s.gif


Now on to hope... and Im sorry , but all hope is lost here on the 18z run of the GFS.. Lets look at the following week on a day by day basis... :

Monday

http://www.nco.ncep.noaa.gov/pmb/nwprod/analysis/namer/gfs/18/ima
ges/gfs_slp_066s.gif

Tuesday

http://www.nco.ncep.noaa.gov/pmb/nwprod/analysis/namer/gfs/18/ima
ges/gfs_slp_090s.gif

Wednesday:
http://www.nco.ncep.noaa.gov/pmb/nwprod/analysis/namer/gfs/18/ima
ges/gfs_slp_114s.gif

Thursday:

http://www.nco.ncep.noaa.gov/pmb/nwprod/analysis/namer/gfs/18/ima
ges/gfs_slp_138s.gif

And Friday.. :
http://www.nco.ncep.noaa.gov/pmb/nwprod/analysis/namer/gfs/18/ima
ges/gfs_slp_162s.gif

Now we have moderated quite a bit by friday, now lets look at the bigh upcomming Christmas Weekend...

Christmas EVE:
http://www.nco.ncep.noaa.gov/pmb/nwprod/analysis/namer/gfs/18/ima
ges/gfs_slp_192s.gif

Good and dry...That will work well for ol Santa, I hear he has a trampoline that has to be put together that night in my back yard... Thats going to be fun

NOw for the big Day ..CHRISTMAS DAY::And what do my wandering eyes see, but storm steph moving in from the North...
http://www.nco.ncep.noaa.gov/pmb/nwprod/analysis/namer/gfs/18/ima
ges/gfs_slp_216s.gif

Now this is a Polar Express , and will not be working with much moisture, most commonly or big snow storms come from moisture out of the gulf , riding up and over the cold air .. This is moving in from the North and not tapping into the gulf moisture, so moisture would be verry limited.

Now we know the chances of us getting a white Christmas are limmited, but lets look at those who will ... Lets look at the snow cover for North America....

http://www.ssd.noaa.gov/PS/SNOW/DATA/cursnow_usa.gif

At leaste santa will be able to pull that sleigh thru the snow , most of the way down....

Well there we have it folks... The 18z run of the GFS. and thats what we have to work with .. dont forget to flush some ice cubes and put those Pajamas on backwards, and put that spoon under the pillow... and remember one thing... Merry Christmas, and God Bless....




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Now lets take a look at some effects that could be used to determine evaporational cooling... Now we have all heard James talk about evaporational cooling, but do we truly understand what he is talking about?? Well let me use this demonstration.. Now .. Put your hand out in front of your face and blow on it..Now it feels a little cooler, now wet that hand an dblow on it.. The hand gets much cooler.. That is becase the moisture is evaperating off the hand and is cooling the skin as it does so... YOu ever wonder why, when you put alcohol on your skin, it feels like it reallly cools your skin down, well the alchohol evaporates much faster, removing the heat from your hand as it does.. This is evaperational cooling, and the same thing can hapen in the atmosphere. Now there are products used on football sidelines in the early season that uses this same principal... Here is a part of one of their adds"We produce this cooling effect by what is referred to as evaporational cooling. This is achieved by pumping high pressure water through the nozzles which turns the water into tiny droplets. When these droplets hit the air they evaporate which, in turn cools the air by extracting the heat from it" so evaporational cooling is very impoertant when forcasting temperatures , when you are close to the Rain snow line... The potential for the greatest rate of evaporational cooling occurs when temperatures are warm and the dewpoint depression is large. As temperatures warm, the potential to evaporate moisture in the air increases exponentially. As dewpoint depression increases, the relative humidity decreases and the evaporational potential increases. Evaporational cooling potential is found by calculating the wetbulb depression. The wetbulb depression is the difference between the temperature and the wetbulb temperature. The wetbulb temperature is found by cooling the initial temperature as much as possible by evaporational cooling.

Now this is one of the possibilities that can cause havoc on a weatherman during the winter season...Now one of the meathods that we can use to forcast the potential is by using a skew-t.. Skew-T's are handy forecasting tools for predicting winter precipitation type. If temperatures from a 1000 meters above the surface to the top of the troposphere are below freezing, precipitation type is likely to be snow. It may, for a short period, fall as a cold rain or a wintry mix, but through evaporational cooling the precipitation type will change to snow (unless low level warm air advection is occurring or inadequate evaporation cooling occurs in the boundary layer). In some cases, temperatures in the PBL will be below freezing but an inversion just above the PBL will have above freezing temperatures. This inversion could be the top of a shallow cold front or a layer of warm air advection. This situation is conducive to producing sleet. If the below freezing temperatures near the surface are fairly deep are are capped with above freezing temperatures further aloft, precipitation type will likely be sleet. Precipitation type will be freezing rain if the warm air aloft is well above freezing and/or deep. The set up for freezing rain is similar to that of sleet except the below freezing temperatures extend only a short distance above the surface (ranging from below freezing temperatures just at the surface or extending to as high as 500 or so meters above the surface). An inversion of above freezing temperatures will cap the below freezing low level temperatures, but the inversion will be closer to the ground than inversions associated with sleet. Only two balloon soundings are launched each day, therefore soundings can change rapidly in just a few hours. From studying the analysis and forecast panels, gain an insight into thermal and moisture advections that will change the soundings. A slight change in thermal advection can change the precipitation type from one to the other (i.e. warm air advection... snow to rain, freezing rain to rain, sleet to freezing rain;;;; cold air advection. ... rain to snow, freezing rain to sleet, freezing rain or sleet to snow). Sometimes the vertical depth of cold air and the inversion of above freezing temperatures will be near the cusps of a change in precipitation type. This produces a wintry mix, precipitation type changes from one type to another or even sleet, snow, and cold rain all falling at the same time. Evaporational cooling also plays a key role. Monitor the wet bulb temperatures from the surface to the top of the inversion to monitor possible changes in precipitation type (if wet bulb is at or below freezing at all levels, precipitation type will eventually change to all snow, until or unless warm air advection again changes it back to another type.
Remember that winter precipitation is "elevated convection". Parcels of air will begin their ascent from the top of the inversion. Calculate indices using the top of the inversion as a base for the convection or lift.

Now there is the weather lesson for the night... My head is spinning, as is yours, unless you are greg, HAHAH just kidding..... well now we are all just a little more educated...


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POP quiz on tonights lesson:

How does our bodies use evaperational cooling?

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When we sweat it evaporates off our skin cooling it down. Am I close?

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Hey Rusty, are you a Science teacher by chance? LOL

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Brandon, You are right , about the evaporational cooling that is... Not abut the science teacher, my mother in law is a Biology teacher at Hewitt.... I am just a weather Junkie...


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Cool. I want snow for the prize. But i guess I'll settle for the A. =)

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Now we must move on .. James is always talkign about Dynamic cooling as well as evaporational cooling, now these two are different , now both cool the different layers of the atmosphere, but the method they do it is different .. Now as we have learned evaporational cooling is when precipitation evaporates before reaching the ground, each evaporative snowflake, or raindrop takes heat out of the atmosphere, cooling it , now , lets look at Dynamic cooling. Now when heavy precipitation creates downdrafts that bring cold air from the upper atmospheres to the surface , this cols the surface temperature, and thus when you have an 850 mb chart with freezing temperatures over an area that has surface temperature just above freezing , this can cause a headach for James and the crew.... So now we have covered the dynamic and evaporational cooling that james uses on a regular basis... Hopefully this will make some of the charts make more sense...

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Brandon , A + for you my friend...

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Hey Rusty I guess I get a F+;(since I did not get to class in time alt="!)" /> alt="!)" />

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Hey I guess my F+ got worse(;

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Hey Stephanie why did you not tell me to come to class;(

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Hey,there was some misty type stuff coming down just north of Jasper a little bit ago,I do not seem to remember ant precip being mentioned for tonight,I've got 37 on the ole thermometer right now.

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P.T.after the class tonight , tell me was that a wet bulb temp, or a dry bulb temp????YOu know you can get a wet bulb temp by wetting a piece of cheese cloth and wrapping your dry bulb thermometer in it ...It wil give you a wet bulb temp...

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everyone will get an a in this class.... A for Absent... there will be a test next week

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Rusty you do an excellant job. Thanks for your time. James will have to let you sit with them at some of the Storm Alert Tours. All have a good night & weekend.

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Hey Stephanie made me miss class just kidding

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Hey I missed class too :-) Christmas dance at TMS........ was sitting in a very long carpool line sorry!!

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