Tuesday: Partly cloudy with a 60% chance of afternoon/evening storms. High around 80.
Wednesday: Mostly Cloudy in the morning with a chance of rain and then an 80% chance of afternoon showers and storms. High around 83
Thursday: Partly cloudy in the morning and mostly cloudy in the afternoon with a 30% chance of afternoon/evening storms. High around 83
Friday: Partly cloudy with a 20% chance of afternoon/evening storms. High around 81
I expect the storms to be more prevalent just off the coast where there is more lift and more instability throughout the day. But afternoon storminess is expected through the forecast period moreso on Tuesday and Wednesday.
Friday, September 16, 2011
Monday, January 10, 2011
Winter storm update
NWS went ahead and issued the winter storm warning for the triangle, which is not surprising given the possibility of significant ice accumulations. The forecast basically remains unchanged with the latest RUC data coming in.
Already some flurries flying in the Cary area. More moderate snow is expected to begin falling in the triangle between noon and 2 PM and expected to possibly begin mixing sometime shortly after or around sunset. Around an inch of accumulation is possible with a max of 3 inches if the changeover occurs later than expected or precip falls heavier then expect. But in general I really only expect around an inch in the triangle. The problem is going to be overnight after the precip mix with sleet and eventually changes over to freezing rain through Tuesday morning. The potential for significant icing accumulation exist. I think up to a third of an inch of ice accumulation is not out of the question in some sweet spots. Using the Piltz - Sperry index shows that due to a lack of high winds utility lines should not be in danger however, road conditions could be quite bad Tuesday morning especially on bridges and overpasses.
So expect the potential for accumulating snow to begin after noon and last through the daylight hours and mixing w/ sleet and changing to sleet shortly after or around sunset. A quick changeover to freezing rain is likey by midnight with freezing drizzle lasting through lunch time on Tuesday.
.1 - .33 inches of ice accumulation are likely on top of potentially around an inch of snow/sleet w/ a max in some spots of 3 inches.
At this point the confidence is higher in the ice accumulation then the snow accumulation potential.
Already some flurries flying in the Cary area. More moderate snow is expected to begin falling in the triangle between noon and 2 PM and expected to possibly begin mixing sometime shortly after or around sunset. Around an inch of accumulation is possible with a max of 3 inches if the changeover occurs later than expected or precip falls heavier then expect. But in general I really only expect around an inch in the triangle. The problem is going to be overnight after the precip mix with sleet and eventually changes over to freezing rain through Tuesday morning. The potential for significant icing accumulation exist. I think up to a third of an inch of ice accumulation is not out of the question in some sweet spots. Using the Piltz - Sperry index shows that due to a lack of high winds utility lines should not be in danger however, road conditions could be quite bad Tuesday morning especially on bridges and overpasses.
So expect the potential for accumulating snow to begin after noon and last through the daylight hours and mixing w/ sleet and changing to sleet shortly after or around sunset. A quick changeover to freezing rain is likey by midnight with freezing drizzle lasting through lunch time on Tuesday.
.1 - .33 inches of ice accumulation are likely on top of potentially around an inch of snow/sleet w/ a max in some spots of 3 inches.
At this point the confidence is higher in the ice accumulation then the snow accumulation potential.
Sunday, January 9, 2011
Update on Monday through Tuesday morning storm
Potential for snow to begin falling Monday afternoon across the region. At this time snow accumulation appears light. NAM has the snowfall inching further north with each new model run, but keeps a dry layer near/in the boundary layer. If this boundary layer moistens unlike what the NAM is showing then a signifcant snow event would occur over the triangle. The latest NAM actually only allows about an hour of accumulating snow to fall after sunset before quickly transitioning the precip over to sleet or "heavy" freezing drizzle.
Imo, the worst case scenario is what the NAM is showing where the triangle picks up a good half an inch liquid equivalent of "heavy" freezing drizzle. This worst case scenario is looking more likely for the triangle. Hopefully the lift will shift a bit northward enough to moisten the entire column and put the triangle in an all snow event.
Expect more precip in Cary and less in NE Raleigh with Cary picking up maybe half an inch in liquid and NE Raleigh picking up maybe 1/3 of an inch.
Monday: A chance of snow after noon. Snow accumulation of around an inch possible
Monday night: Snow changing sleet quickly changing to freezing drizzle. It could be a "heavy" drizzle, if that makes sense, which would coat everything in a fairly thick layer of ice.
Imo, the worst case scenario is what the NAM is showing where the triangle picks up a good half an inch liquid equivalent of "heavy" freezing drizzle. This worst case scenario is looking more likely for the triangle. Hopefully the lift will shift a bit northward enough to moisten the entire column and put the triangle in an all snow event.
Expect more precip in Cary and less in NE Raleigh with Cary picking up maybe half an inch in liquid and NE Raleigh picking up maybe 1/3 of an inch.
Monday: A chance of snow after noon. Snow accumulation of around an inch possible
Monday night: Snow changing sleet quickly changing to freezing drizzle. It could be a "heavy" drizzle, if that makes sense, which would coat everything in a fairly thick layer of ice.
Saturday, January 8, 2011
Quick update
Just following some trends on Monday and Monday night's winter storm. This looks like it could be a mostly sleet and freezing rain event with approximately .25 to .5 inches of liquid equivalent ice falling around the triangle.
Temps should stay below freezing through the event however, it will be close enough to freezing to potentially cause a quick change over to rain at times. It does look like the morning commute on Tuesday could be quite treacherous.
I'll update tomorrow when I have more time.
Most of the precip that would fall on Monday would be snow with the change over to ice occurring Monday night.
Temps should stay below freezing through the event however, it will be close enough to freezing to potentially cause a quick change over to rain at times. It does look like the morning commute on Tuesday could be quite treacherous.
I'll update tomorrow when I have more time.
Most of the precip that would fall on Monday would be snow with the change over to ice occurring Monday night.
Friday, January 7, 2011
Update on tonight's system
I was able to look at the vertical thermal profiles for tonight's event looking at several model runs, and came to conclusion that mixing is going to be too much of an issue for this to be much of anything significant.
Therefore I'm only predicting less than an inch for the Raleigh area due to a Snow/rain mix tonight. Snow is more likely when the precip is heavier.
Info on early next weeks system:
On Sunday/Monday a southern stream system will move along the northern gulf coast and eventually become sheared as it nears the east coast of Florida. This system will drop significant snow and ice in central and northern MS, AL and GA. While this system is wreaking havoc in those areas northern stream energy will begin to enter the region from the west Monday night.
This energy will merge with the sheared out and weakened southern stream system and lead to surface developement off the southeast coast. This surface feature will be much weaker than the last system however, it will be much slow to exit the area. Because of this expect a sustained period of light precip, all of which will be frozen. A feature out west will also lead to warm air advection in the upper levels which will lead to an above freezing layer. This will be after a period of snow has already fallen over the triangle. However at that time surface temps will be struggling to get out of the upper 20's.
All of that leads to this initial forecast:
Monday afternoon: A slight chance of snow
Monday night: A chance of snow possibly mixed with sleet.. changing to sleet after midnight before quickly changing over to freezing rain
Tuesday: Light freezing rain through the afternoon.
Total snow/sleet accumulations of 1-3 inches possible with around 1/8 - 1/4 inch of ice accrual possible.
That forecast would like be enough to warrant a winter storm warning for the triangle.
Therefore I'm only predicting less than an inch for the Raleigh area due to a Snow/rain mix tonight. Snow is more likely when the precip is heavier.
Info on early next weeks system:
On Sunday/Monday a southern stream system will move along the northern gulf coast and eventually become sheared as it nears the east coast of Florida. This system will drop significant snow and ice in central and northern MS, AL and GA. While this system is wreaking havoc in those areas northern stream energy will begin to enter the region from the west Monday night.
This energy will merge with the sheared out and weakened southern stream system and lead to surface developement off the southeast coast. This surface feature will be much weaker than the last system however, it will be much slow to exit the area. Because of this expect a sustained period of light precip, all of which will be frozen. A feature out west will also lead to warm air advection in the upper levels which will lead to an above freezing layer. This will be after a period of snow has already fallen over the triangle. However at that time surface temps will be struggling to get out of the upper 20's.
All of that leads to this initial forecast:
Monday afternoon: A slight chance of snow
Monday night: A chance of snow possibly mixed with sleet.. changing to sleet after midnight before quickly changing over to freezing rain
Tuesday: Light freezing rain through the afternoon.
Total snow/sleet accumulations of 1-3 inches possible with around 1/8 - 1/4 inch of ice accrual possible.
That forecast would like be enough to warrant a winter storm warning for the triangle.
quick update on tonight's snow.
A fast moving very strong upper level disturbance will move through the region after sunset tonight. Upper level dynamics and thermodynamics suggest enough lift to cause moderate and even heavy at times precip in a relatively small south to north band of about 50 miles somewhere near the US 64 corridor. 2-4 inches of snow will be possible w/n this relatively thin band of heavy precip. This is an extremely rare event for this type of system therefore past climate data is virtually non existent. The big question is exactly where does this band of heavier precip set up and will there be any rain mixed in. Ground temps are also an issue right now, which normally you'd expect about an inch of snow wasted to cool the ground. Also, if the precip arrives before sunset, boundary layer conditions would likely mean more rain at the start. Will update more after lunch time on this one.
Thursday, January 6, 2011
Updates on 2 winter systems
Chance of snow/rain mix Friday night as an unusually strong clipper systems moves through the region. This type of system rarely causes issues for the triangle due to a lack of moisture however, the location and intensity of this clipper system will likely lead to precipitation for the triangle. A surprise 1-2 inches is possible with this system.
Snow and ice are likely for Monday and especially Monday night. Will wait to pin down predominant precip type, but models are in good agreement that a major winter storm will impact the deep south. Will wait a wee bit longer before I make posts in regards to precip type and amounts for the triangle. As of now it appears the biggest impact will be in Northern and parts of central Alabama, Mississippi, Georgia and South Carolina. But a significant even is possible in North Carolina as well.
Snow and ice are likely for Monday and especially Monday night. Will wait to pin down predominant precip type, but models are in good agreement that a major winter storm will impact the deep south. Will wait a wee bit longer before I make posts in regards to precip type and amounts for the triangle. As of now it appears the biggest impact will be in Northern and parts of central Alabama, Mississippi, Georgia and South Carolina. But a significant even is possible in North Carolina as well.
Wednesday, January 5, 2011
1/05 Update on 2 potential winter weather systems
Up to an inch of snow is possible in the triangle region as a weak surface features] moves into the western Atlantic through the deep south. Scattered snow showers, associated with this system's deformation zone, are likely and up to an inch of snow is possible. qpf of about .1 on both the NAM and GFS with decent ratios could cause some problems for rush hour commute. Expect the heaviest snow to fall between 5 AM and 9 AM in the triangle. The precip will start as light rain before mixing with and likely changing to all snow. Surface temps will likely stay above freezing through the even which should help to dampen accumulation. Therefore while an inch of snow is possible, it is quite unlikely that more than a dusting will occur. Also, warming just above the surface is likely due to a weak low pressure forming on the Lee side of the Apps in response to the upper level feature. This could keep precip mixed throughout the event.
A winter weather advisory still may be issued tonight by the NWS.
The next system will arrive in the 6-7 day period. This system has the potential to produce signficant snowfall for the triangle. But with it being this far out it is only worth keeping an eye on at this time. Very cold air will follow behind this storm system.
A winter weather advisory still may be issued tonight by the NWS.
The next system will arrive in the 6-7 day period. This system has the potential to produce signficant snowfall for the triangle. But with it being this far out it is only worth keeping an eye on at this time. Very cold air will follow behind this storm system.
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