It appears as of now that this storm will produce some wintery weather for the triangle on Saturday night, however accumulation amounts look to be on the lighter side.
HPC prefers a blend of the 00z ECMWF and the 12z GFS. The GFS wraps moisture around a weak low pressure which will be located off the southeast coast Saturday night. WRF model data shows a weak 850 low skirting the S. Carolina/N. Carolina border helping to produce precip along the deformation zone axis. GFS shows about 1/4 inch of qpf for the triangle while the WRF actually spits out close to a half an inch. Expect the precip associated with these features to occur after sun set. The timing should help in regards to boundary level conditions, but I do think some mixing will occur through the event before ending as snow. Reasoning is due to potential warming aloft with southwesterly flow ahead of the 850 low. I only looked at the GFS bufkit sounding since this is what HPC prefers.
Not to get too detailed with the timing, but at this time it appears the best chance for moderate snow associated with the deform zone for the triangle will be between 8:00 PM and 2:00 AM with a potential isothermal layer setting up due to diabatic cooling processes. That's a 6 hour window of potential snowfall with the heaviest precip falling in the middle of that time frame. Expect rain to mix in when the snow is falling relatively light and perhaps remaining all snow during heavier precip. I do think mixing will occur through the event.
Because of this I have to predict only around an inch of snow possible for the triangle on Saturday night.
Will update tonight if there are any significant changes.
Friday, December 17, 2010
Thursday, December 16, 2010
12/18 - 12/19 storm
Last night's GFS and NAM had the storm far to the east over the Atlantic and as an open wave, with little to no impact for the triangle.
Today's model runs are a different story with both the GFS and NAM showing the position of the low to be much closer to the coast, with a potential significant snow for the triangle. No reason to post any details until the models show some consistency. I'll do a 1st forecast tomorrow morning or afternoon for the Saturday afternoon/night storm.
Today's model runs are a different story with both the GFS and NAM showing the position of the low to be much closer to the coast, with a potential significant snow for the triangle. No reason to post any details until the models show some consistency. I'll do a 1st forecast tomorrow morning or afternoon for the Saturday afternoon/night storm.
Wednesday, December 15, 2010
Update on 12/16 storm
GFS - Light snow starts at 7:00 AM tomorrow morning, transitions to sleet at 10:00 - 11:00 and then freezing rain at 11:30ish before turning to rain at about 2:00 PM.. .3 qpf rain equivalent before change over to rain.
NAM - Light snow starts at 7:00 AM tomorrow morning, transitions to sleet/zr around 10:30 AM to all rain at noon. rain equivalent precip about .15 - .2 inches. frozen precip less than .1
HPC - Prefers a compromise with the GFS and the ECMWF which is basically a slightly more NWD solution of the GFS.
Forecast:
Tomorrow morning: Light snow starting at around 7:00 changing to a mix of sleet and freezing rain by 10:00... changing to all freezing rain by 11:oo before changing to all rain by noon. Snow accumulation less than an inch possible along with some light ice accumulation of less then a tenth of an inch.
Winter Weather Advisory will probably be issued by the Raleigh NWS office.
12/18 - 12/19 storm... Nice isothermal layer setup in the GFS bufkit soundings.
NAM - Light snow starts at 7:00 AM tomorrow morning, transitions to sleet/zr around 10:30 AM to all rain at noon. rain equivalent precip about .15 - .2 inches. frozen precip less than .1
HPC - Prefers a compromise with the GFS and the ECMWF which is basically a slightly more NWD solution of the GFS.
Forecast:
Tomorrow morning: Light snow starting at around 7:00 changing to a mix of sleet and freezing rain by 10:00... changing to all freezing rain by 11:oo before changing to all rain by noon. Snow accumulation less than an inch possible along with some light ice accumulation of less then a tenth of an inch.
Winter Weather Advisory will probably be issued by the Raleigh NWS office.
12/18 - 12/19 storm... Nice isothermal layer setup in the GFS bufkit soundings.
Tuesday, December 14, 2010
12/14 update for upcoming systems
12/16 storm:
As of now most of the moisture will be north of the triangle. NAM shows quite a bit of precip extending well out ahead of the surface low. Precip could start out as snow for an our or two before transitioning over to sleet and finally to rain. This looks like it will mainly be a light rain event based on soundings and lack of cold air aloft at approximately H85. Any frozen precip should stick and stay on the ground through rush hour so the morning commute could be troublesome if the precip arrives before the warm air aloft. With this in mind it is important to iterate that the warm air will be located aloft. Therefore expect surface temps to remain an issue until around lunch time.
The biggest issue with this storm is precip amount. Neither the GFS or NAM are showing much at all for the triangle. Most of the precip is to the north. Only .10 to .2 of an inch for the whole event is being shown by both models. Temps may be ok Thursday morning, but the lack of precip makes that irrelevant.
This could be a more significant event if the precip shield and associated dynamics shift significantly south. But as of now a chance of snow between 2-5 am Wed night transition to sleet and then to rain at around noon. This may not be a big snow event but sleet and freezing rain could be an issue during the Thursday morning commute. While this doesn't appear to be a major event at this time, you never know what can happen.
I do think there could be some accumulation and a winter weather advisory will maybe be issued by the NWS... sleet will be the predominant frozen precip type.
12/18 to 12/19 storm:
Potential for a major winter storm.. GFS and Euro coming into closer agreement on a potential major winter storm for the east coast. Cold air concerns exist with this storm due to a relatively weak surface high providing cold air ahead of the arrival of the surface low, which is predicted to track somewhere near or off the North Carolina coast. The Euro is beginning to show a more amplified with the gfs already showing a well amplified system which will undertake bombogenesis as it moves up the coast. This could be a historic blizzard for parts of New England if the GFS continues to amplify the sytem.
This type of set up has led to major snowfalls for the triangle. It's similar to the January 2-3 2002 winter storm which dropped a foot of snow in the triangle, but with one major difference. The strength of the parent high over the midwest is weaker. But the high over the midwest for the future system is a piece of a strong canadian high pressure and expect the low pressure to advect cold air from the north as it starts to move up the coast.
The bottom line is that the triangle could be in a position to get dumped on by the deformation band associated with this system. Several hours of heavy snow fall is possible. This will definitely be a storm to keep an eye on.
As of now most of the moisture will be north of the triangle. NAM shows quite a bit of precip extending well out ahead of the surface low. Precip could start out as snow for an our or two before transitioning over to sleet and finally to rain. This looks like it will mainly be a light rain event based on soundings and lack of cold air aloft at approximately H85. Any frozen precip should stick and stay on the ground through rush hour so the morning commute could be troublesome if the precip arrives before the warm air aloft. With this in mind it is important to iterate that the warm air will be located aloft. Therefore expect surface temps to remain an issue until around lunch time.
The biggest issue with this storm is precip amount. Neither the GFS or NAM are showing much at all for the triangle. Most of the precip is to the north. Only .10 to .2 of an inch for the whole event is being shown by both models. Temps may be ok Thursday morning, but the lack of precip makes that irrelevant.
This could be a more significant event if the precip shield and associated dynamics shift significantly south. But as of now a chance of snow between 2-5 am Wed night transition to sleet and then to rain at around noon. This may not be a big snow event but sleet and freezing rain could be an issue during the Thursday morning commute. While this doesn't appear to be a major event at this time, you never know what can happen.
I do think there could be some accumulation and a winter weather advisory will maybe be issued by the NWS... sleet will be the predominant frozen precip type.
12/18 to 12/19 storm:
Potential for a major winter storm.. GFS and Euro coming into closer agreement on a potential major winter storm for the east coast. Cold air concerns exist with this storm due to a relatively weak surface high providing cold air ahead of the arrival of the surface low, which is predicted to track somewhere near or off the North Carolina coast. The Euro is beginning to show a more amplified with the gfs already showing a well amplified system which will undertake bombogenesis as it moves up the coast. This could be a historic blizzard for parts of New England if the GFS continues to amplify the sytem.
This type of set up has led to major snowfalls for the triangle. It's similar to the January 2-3 2002 winter storm which dropped a foot of snow in the triangle, but with one major difference. The strength of the parent high over the midwest is weaker. But the high over the midwest for the future system is a piece of a strong canadian high pressure and expect the low pressure to advect cold air from the north as it starts to move up the coast.
The bottom line is that the triangle could be in a position to get dumped on by the deformation band associated with this system. Several hours of heavy snow fall is possible. This will definitely be a storm to keep an eye on.
Saturday, December 4, 2010
Update
Expect light snow to begin falling between 4 and 5. The heaviest snow (at most moderate) will fall this evening between 6 and 10 PM before it ends in a light mix by 1 AM
Up to an inch is possible.
Up to an inch is possible.
12/4 - 12/5 snow even
An upper level disturbance with an associated surface low will through the triangle region this evening and tonight. Light precip is expected to fall between 6:00 PM through the early morning hours. GFS and NAM are in disagreement on total qpf. HPC actually prefers the ECMWF model at this time. I don't see any reason to disagree as these types of upper level systems typically move through the region quickly. So will go with middle ground qpf amounts.
I expect the surface low to quickly and lightly strengthen as it spins over the App mountains. This occurred with a similar system last year and is supported by theories in centrifugal force in relation to atmospheric spinning parcels. Because of this effect expect slight warm air advection ahead of the surface low which should cause the majority of the light precip to fall as rain or a rain snow mix over the triangle. When the low pressure is to the east of the triangle the precip should transition to snow however, moisture levels will quickly fall as substinance moves over the region.
ECMWF trended sw with the system which would put it closer to the southernmost NAM solution... this could mean a bit more snow than mix.. as warm air advection would not be nearly as strong with a more southern solution.
The ground is warmish but the precip will be falling at night which should enhance potential ground accumulation. A band of moderate snow could fall around and especially north of the triangle as part of the associated weak deformation band. Expect the potential for up to an inch of accumulation especially in the grass areas over this more moderate band of precip.
A dusting to an inch of snow is possible tonight in the triangle.
I expect the surface low to quickly and lightly strengthen as it spins over the App mountains. This occurred with a similar system last year and is supported by theories in centrifugal force in relation to atmospheric spinning parcels. Because of this effect expect slight warm air advection ahead of the surface low which should cause the majority of the light precip to fall as rain or a rain snow mix over the triangle. When the low pressure is to the east of the triangle the precip should transition to snow however, moisture levels will quickly fall as substinance moves over the region.
ECMWF trended sw with the system which would put it closer to the southernmost NAM solution... this could mean a bit more snow than mix.. as warm air advection would not be nearly as strong with a more southern solution.
The ground is warmish but the precip will be falling at night which should enhance potential ground accumulation. A band of moderate snow could fall around and especially north of the triangle as part of the associated weak deformation band. Expect the potential for up to an inch of accumulation especially in the grass areas over this more moderate band of precip.
A dusting to an inch of snow is possible tonight in the triangle.
Tuesday, September 7, 2010
Beach weather
This is not a forecast... This post is just simply model statistical data extrapolated into an easier to read format:
Climatology: High 85 Low 66 Chance Rain: 31
Sunday: High 86 Low 72 Chance Rain: 74% Partly cloudy Precip: 0.25"
Monday: High 86 Low 70 Chance Rain: 28% Mostly clear skies Precip: 0.00"
Tuesday: High 88 Low 66 Chance Rain: 10% Mostly clear skies Precip: 0.00"
Wednesday: High 84 Low 66 Chance Rain: 18% Mostly clear skies Precip: 0.00"
Thursday: High 83 Low 66 Chance Rain: 28% Mostly clear skies Precip: 0.00"
Wind: 10-15 mph each day on the beach
Climatology: High 85 Low 66 Chance Rain: 31
Sunday: High 86 Low 72 Chance Rain: 74% Partly cloudy Precip: 0.25"
Monday: High 86 Low 70 Chance Rain: 28% Mostly clear skies Precip: 0.00"
Tuesday: High 88 Low 66 Chance Rain: 10% Mostly clear skies Precip: 0.00"
Wednesday: High 84 Low 66 Chance Rain: 18% Mostly clear skies Precip: 0.00"
Thursday: High 83 Low 66 Chance Rain: 28% Mostly clear skies Precip: 0.00"
Wind: 10-15 mph each day on the beach
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