Friday, October 31, 2008
Our next big weather changer looks to be developing in the NW over the weekend. By Monday/Tuesday a well definied trough will be digging across the Rockies, and our impact from this trough should be around Thursday and little into Friday. We are still pretty far out to talk seriously on the timing of this trough, and even the depth of the trough into our region seems very early to nail down anything solid. A few models have shown me only a light shower event, but I must still be aware of the possibility for more of a moderate rainfall event. The one thing we must remember as we enter into the "cool months" is the amount of energy we need for uplift (rain) events. We experience more stable atmospheres in the winter months so we need more vertical uplift and vorticity to to spur on credible rain forecast. All this can be compared to the summer, when our incredible unstable atmosphere only needs a little vorticity and UVVs to create a rain event.
Enjoy your weekend! Be sure to enjoy the beautiful clear nights!
Tuesday, October 28, 2008
The weather scene is perfect for what we call radiational cooling, but let me first explain what hinders radiational cooling. During the day the ground heats up from absorbing the shortwave radiation from the sun, but the ground doesn't gain any energy once the sun sets. At night the ground emits longwave radiation (energy), but clouds aid in keeping the heat (energy) in the lower levels of the atmosphere. This event will allow the night-time temperature to level-off as oppossed to decreasing dramatically. Now our forecast tonight doesn't involve clouds so nothing will hold back the energy removed from the ground. The clear skies will allow the energy to lost from the low levels of the atmosphere.
Also, high winds will cause the lower level temperature to remain in the lower level. Think of this as a big mixing bowl. The ground's temperature won't be able to leave the lower levels as effieciently as calm winds. Calm winds act as a quick escape for the ground's energy. Our forecast tonight include calm winds.
So tonight will be cold. Break out the winter quilts and turn on the heater because tonight we will experience textbook longwave radiational cooling.
****Also, tomorrow premiers the 1st episode of "The Tanner Cade Hour minus 55 minutes or so" on www.wdam.com. This is my show for a once-a-week episodes (web only).
Saturday, October 25, 2008
On to the forecast:
My thoughts going into our forecast hinge on one factor: another cold front. Yes, we have another cold front already brewing in the Northern Plains. This front will bring us more of a true "Canadian" air mass into the lower MS River Valley, but we will be warming tomorrow ahead of the front.
Right now we have a 1020mb high over the ARLaMiss (just to our west), but this high will quietly move a little south by mid-day tomorrow and bring in a slight push of moisture from the west. The increase in moisture and 850 temps to 12°C will allow us to see temps in the upper 70s across South Mississippi. Although things will continue to change as we move through the day tomorrow. Our biggest change will be ramming down the whole Eastern Corridor of the nation. We, however, will be located in the NVA (negative vorticity advection) zone of the cold front. This really means we will find ourselves on the "left side" of the trough where the convergence and lift are not available for rainfall activity (or even cumulus clouds). Also dewpoint temps will really crash into the upper 20s on Monday Night. Another interesting note should be made about the 1035mb High settling in over the Southern Plains by Tuesday.
So what do I see from this? The front will move through late Sunday night and into early Monday morning, which allows monday afternoons temps to struggle getting into the mid-60s. Most of Miss. will see lower 60s and upper 50s. Basically, our air will be nearly "bone" dry Monday night allowing excellent longwave radiational cooling. Right now I have a forecast low of 36 but you wouldn't have to pull my arm to hard to drop in the lower 30s. Now I must also realize that several folks in our state will potentially see their first frost of the year during this episode.
After Monday things will still be mild. Tuesday looks to be very similar to Monday's forecast, but things will slowly become more "mild" by the middle of the week. Wednesday highs will be the upper 60s before the late-week highs jumping into the lower 70s for Thursday/Friday.
Monday, October 20, 2008
I know it might be hard to tell from this picture, but the GFS shows the rain starting Thursday morning.
One more note, this pattern in October is defines one reason why I love weather. I simply love the change of weather from warm and cloudy to cool and clear. My feelings on this probably begin because I enjoy not being able to habitually love and experience one weather scene. Right now I love the fall, but in the spring I will tell you I love the spring.
Sunday, October 12, 2008
My forecast has this inverted trough moving out of the way by early Tuesday morning, which will allow more sunshine on Tuesday and Wednesday. The next big weather factor comes into our forecast on Thurdsay/Friday as we will begin to see the influence of a cold front. This front shouldn't cause to much rain, but temps will decrease a little bit.
By Saturday and into the next week I expect a major Ridge/Trough pattern to lace itself across the nation. With a ridge developed over the Western U.S. we will see the impact of a Trough sitting/stalling in the Eastern Conus of the U.States. For us we will experience cooler temps and only a small chance of rain through next week.
Wednesday, October 8, 2008
And for the remainder of the week our fair weather friend, a high pressure system, moves into the Southeast US. This is good news for those wanting to enjoy a weekend outside. Although our temperatures will definitely be more seasonable by Friday with highs in the lower 80s and up to about 84/85.
My eye is caught on our next major front. The GFS, which often moves fronts too far south too quickly, has backed off a bit on the intensity for us, but we will see some influence of this front by Sunday or Monday. More moisture will be able to filter back into Mississippi by Sunday. After we see an increase in moisture I'll be waiting around for the front to move through. Right now the European Model shows 850 temps starting to lower by Wednesday morning, but the Canadian Model's spaghetti plot isn't very confident in the exact placement of the trough by Mid-week. Tuesday through Thursday seems to be my range of days for my forecast of frontal movement, but many things are still "up in the air."
Right now my best guess looks more at the European with a Wednesday influence of the front, and rainfall will probably fall along the same day. No matter what actually happens, I'm banking on a front moving through the Pine Belt by Thursday afternoon.
Tuesday, October 7, 2008
Pine Belt Regional: 0.20"
Bobby L. Chain (Hatt.): **0.01"(not quality controlled)
Jackson Int. Airport: 0.23"
McComb Pike County: 0.03"
Meridian Key Field: 0.59"
Pascagoula (Lott Int. Arp): 0.02"
Gulport-Biloxi Arpt: 0.46"
Hammond, LA: 0.12"