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1/28 - 1/30 Storm Thread II


burgertime

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Thanks Allan.  The 14z RAP 850 temps looked very good throughout.  I don't know if there is another level to pay attention to.  I looked at 700 and 925 too, and they looked good as well.

 

RAP on Bufkit shows the entire vertical layer safely below zero for RDU throughout the event.  Also shows snow overcoming the dry layer between 4 and 5 PM with moderate snow till about 3 AM.

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HRRR puts charlotte in the dry slot. in addition slams the mtns with snow and the coastal plain. 

 

That's funny because Brad P. showed differently had CLT with 3 inches of snow. 

 

Yeah, that was pretty cool watching his video, that was impressive for CLT, 3-4" on the HRRR it looked like.

It's a new run, guys. Also the HRRR doesn't go out that far to get total accumulations. Bigger dry slot, but if true relief is only a few hours behind so no worries, yet.

 

jZq8KgC.png

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Think RAP is starting to tick back SE, think it will, looks overdone...

The RAP can be useful to catch short term trends, but I usually dont put a ton of stock in its raw QPF forecasts, I have been burned both ways using it. The mesoscale/global model consensus has been pretty consistent, so that is what I stuck with, using the RAP for some short term trends/adjustment.s

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Does the RAP normally have a warm bias? It is considerably warmer at 2m than either the GFS or NAM along the Gulf Coast.

 

I'm pretty sure it has a pretty bad warm bias, beanskip.

 

BTW, I just saw your call map, Allan!  I like it! :)

 

The temperature is now down to 19 here.  This is going to be insane when it starts snowing.

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Interesting, GFS just ticked NW.  RAH is lowering amounts everywhere due to dry air and warm noses, interesting to see who is correct, RAH is usually spot on.

updated RDU AFD

NEAR TERM /THROUGH WEDNESDAY NIGHT/... AS OF 1035 AM TUESDAY... DUE TO THE FACT THAT LIGHT RADAR RETURNS OVER THE NORTHWEST PIEDMONT ARE INDEED HITTING THE GROUND AS SNOW AND QUICKLY LEAVING A DUSTING ON ALL SURFACES...WE HAVE EXTENDED THE WINTER WEATHER ADVISORY FORWARD IN TIME...SO IT IS NOW IN EFFECT. THE PRECIP IS GENERALLY LIGHT...METARS AND VISUAL REPORTS SUGGEST VSBYS ABOVE 6SM... AND IS OCCURRING IN THE RIGHT ENTRANCE REGION OF THE STRONG UPPER JET. THIS IS A LITTLE SOONER THAN FORECAST AND THE PRECIP DOES NOT SEEM TO BE HAVING MUCH PROBLEM OVERCOMING THE VERY DRY BOUNDARY LAYER. THE FORCING IS NOT EXPECTED TO STRENGTHEN UNTIL LATER THIS AFTERNOON WHEN THE STRONGER ISENTROPIC LIFT AND HEIGHT FALLS ALOFT ARRIVE...SO WE CURRENTLY DO NOT EXPECT THAT THE EARLY ARRIVAL OF PRECIP WILL INCREASE SNOW AMOUNTS INTO WARNING CRITERIA. FURTHER EAST...THE WINTER STORM WARNINGS WILL CONTINUE AS ADVERTISED. THE 12Z NAM CAM IN WITH A STRONGER WARM NOSE IN THE SOUTHEAST...SHOWING A 3-4C WARM NOSE JUST ABOVE 850MB THAT LAST FOR MOST OF THE EVENING HOURS. THIS AGREES PRETTY WELL WITH UPSTREAM OBSERVATIONS...850MB TEMPS OF 2C AT KFFC AND 7C AT KCHS. THE WARM NOSE IS COOLER AT KRWI AND EXTENDS WESTWARD TOWARD THE TRIANGLE. THIS WOULD LIKELY CUT DOWN SNOWFALL AMOUNTS IN THE SANDHILLS AND POSITIONS FO THE COASTAL PLAIN BUT ALSO COMPLICATE TRAVEL CONDITIONS. WE WILL DO A MIDDAY UPDATE ONCE THE 12Z GFS IS IN. SO FOR NOW...THE FORECAST WILL REMAIN MOSTLY UNCHANGED OUTSIDE OF THE PREVIOUSLY DISCUSSED CHANGES IN THE WEST.

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I'm pretty sure it has a pretty bad warm bias, beanskip.

 

BTW, I just saw your call map, Allan!  I like it! :)

 

The temperature is now down to 19 here.  This is going to be insane when it starts snowing.

 

 

We were loading up to head to durham this morning when I decided to pre treat some properties from Winston to Dobson  Ran in to moderate snow in King and Pilot mt.  Roads were right in 15 minutes still coming down  Robert emailed me last night and said I would have snow by 10am and it could be as little as an inch but don't be surprised if you get 4 inches.  I don't know about the 4 inches but Robert called this several days ago as he went against the models

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Not sure how accurate but after the sleet, snow starts at KFAY at 17:1 ratios per the cobb output on the 12z NAM...that's impressive nonetheless.

 

140129/0500Z  17  01011KT  20.9F  SNOW   17:1| 0.7|| 0.00|| 0.00|| 0.040   17:1|  0.7|| 0.75|| 0.00|| 0.41  100|  0|  0

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When the heavier rates move in we should see a quick temperature drop.  Up to 38 degrees which is a few degrees higher than what was forecasted yesterday.  We'll have to see how that affects final accumulations and precip types.  Looks like a healthy solid band headed towards central GA for the afternoon.  The NWS says all rain this afternoon, but Allan's map has me in a solid 2"-4" of snow.  I'm hoping Allan's right!

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updated RDU AFD

NEAR TERM /THROUGH WEDNESDAY NIGHT/... AS OF 1035 AM TUESDAY... DUE TO THE FACT THAT LIGHT RADAR RETURNS OVER THE NORTHWEST PIEDMONT ARE INDEED HITTING THE GROUND AS SNOW AND QUICKLY LEAVING A DUSTING ON ALL SURFACES...WE HAVE EXTENDED THE WINTER WEATHER ADVISORY FORWARD IN TIME...SO IT IS NOW IN EFFECT. THE PRECIP IS GENERALLY LIGHT...METARS AND VISUAL REPORTS SUGGEST VSBYS ABOVE 6SM... AND IS OCCURRING IN THE RIGHT ENTRANCE REGION OF THE STRONG UPPER JET. THIS IS A LITTLE SOONER THAN FORECAST AND THE PRECIP DOES NOT SEEM TO BE HAVING MUCH PROBLEM OVERCOMING THE VERY DRY BOUNDARY LAYER. THE FORCING IS NOT EXPECTED TO STRENGTHEN UNTIL LATER THIS AFTERNOON WHEN THE STRONGER ISENTROPIC LIFT AND HEIGHT FALLS ALOFT ARRIVE...SO WE CURRENTLY DO NOT EXPECT THAT THE EARLY ARRIVAL OF PRECIP WILL INCREASE SNOW AMOUNTS INTO WARNING CRITERIA. FURTHER EAST...THE WINTER STORM WARNINGS WILL CONTINUE AS ADVERTISED. THE 12Z NAM CAM IN WITH A STRONGER WARM NOSE IN THE SOUTHEAST...SHOWING A 3-4C WARM NOSE JUST ABOVE 850MB THAT LAST FOR MOST OF THE EVENING HOURS. THIS AGREES PRETTY WELL WITH UPSTREAM OBSERVATIONS...850MB TEMPS OF 2C AT KFFC AND 7C AT KCHS. THE WARM NOSE IS COOLER AT KRWI AND EXTENDS WESTWARD TOWARD THE TRIANGLE. THIS WOULD LIKELY CUT DOWN SNOWFALL AMOUNTS IN THE SANDHILLS AND POSITIONS FO THE COASTAL PLAIN BUT ALSO COMPLICATE TRAVEL CONDITIONS. WE WILL DO A MIDDAY UPDATE ONCE THE 12Z GFS IS IN. SO FOR NOW...THE FORECAST WILL REMAIN MOSTLY UNCHANGED OUTSIDE OF THE PREVIOUSLY DISCUSSED CHANGES IN THE WEST.

 

 

Good to hear the dry air shouldn't be that much of a problem.

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Here may be part of the reason for the increasing totals across the area...

A small low is trying to develop in western NC. I know it is weak, but when you combine it with the upper level features, it has the potential to be a wild card in this situation. It also has the potential to surprise a lot of people.

 

1560529_592709340815511_1221956088_n.jpg

 

That's the inverted trough I was referring to last night... its doing exactly what we expected producing a secondary axis of lift aiding in snowfall across WNC and even TN.

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My latest and probably last forecast.

I can not see how areas North and West of Greensboro in the Piedmont see even an inch with dry cold air still filtering in. I would be surprised if any location in Forsyth, Stokes, Surry, or Rockingam County sees an inch out of this. Hope I am wrong though for the people back home.

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Curious as to what this inverted trough over the upstate will do for this area as far as snow goes? Phil?

 

Well, what most of the mesoscale models are showing is that the trough axis should crash southward as more arctic air filters in, which should result in the band over TN and NC to sag ESE with time. However, as the inverted trough starts to sag south, it loses its lifting mechanism as the confluence between the CAD air vs. the arctic air on the other side of the mountains weakens moving out of the Appalachians. Thus, I think the current snow hole will fill in, but probably with less impressive rates than what we are currently seeing over TN (They are getting moderate snow currently in Knoxville, TN). Everyone might luck out though with widespread 1-3" similar to what GSP's snowfall map looks like. 

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Well, what most of the mesoscale models are showing is that the trough axis should crash southward as more arctic air filters in, which should result in the band over TN and NC to sag ESE with time. However, as the inverted trough starts to sag south, it loses its lifting mechanism as the confluence between the CAD air vs. the arctic air on the other side of the mountains weakens moving out of the Appalachians. Thus, I think the current snow hole will fill in, but probably with less impressive rates than what we are currently seeing over TN (They are getting moderate snow currently in Knoxville, TN). Everyone might luck out though with widespread 1-3" similar to what GSP's snowfall map looks like. 

Thanks Dr Phil, i'll gladly take it!

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