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Matthew is poised to graze Florida’s Space Coast early tomorrow morning as a category 4 hurricane.  There is still much debate at this late hour as to whether it actually penetrates image-10-6-16-at-10-01-pminland or remains slightly offshore.  It’s the trickiest of forecasts with significant implications to subsequent storm strength farther north up the coast, including in NC.

I’ll leave the nowcasting to your local media outlets as Matthew tracks north.  What I’d like to put out there are a couple of points:

The models have waffled back and forth as to the track.  I’ve always been of the opinion that Matthew will track just offshore from Melbourne, FL all the way north to Cape Fear… mimicking the shape of the coastline.  Models have insisted on a sharp right turn out to sea near Charleston, but this evening’s 0Z guidance leans more towards my camp, suggesting a farther northward motion before the push to sea takes place.  Obviously, this would mean more rain, wind and surge for NC.

No matter the exact track, the interaction of Matthew with an inverted trough along the coast and the impinging cold front from the west, will combine to funnel a ton of moisture into eastern NC.  Indications this evening are that totals could trend higher.  At least 2-3″ in Raleigh on the low end.  More likely to be 4-6″ for us.

 

Matthew…so complicated

I suppose it’s time to weigh in on Matthew.

I’ve gotten a lot of emails asking for an update, saying that I’ve been silent.  Not really.  Twitter is a fairly effective tool for quick bursts of info.  And so, I encourage you to follow me there:  @trextrex14

There’s a lot of good information in the media on this storm, so I’ll write this post from the perspective that you’ve heard all of that…and more.  I hope to value add, to give you a couple of considerations in why the forecast could go perfectly as planned, or why it may be a total bust.

As of midday today, all the numerical guidance seemed to be converging to a tidy solution (albeit problematic in itself…for reasons I’ll talk about next).  That solution had the track of Matthew basically mirroring the concave SE coastline from FL thru GA and SC to NC then curving out to sea.  In this scenario, Matthew would track just offshore, pounding the coastline from FL to NC.  The problematic part of this is that since the shape of the coastline and the track would be nearly the same.  Any deviation of the track to the left would push the hurricane inland and significantly weaken Matthew for all locales north, i.e. less wind and surge, but still decent wind and lots of rain.  So that’s what’s hard if there was just that.

However, the Euro came in this afternoon with a literal curveball.  It depicted Matthew grazing the FL coast before doing a loop off GA back toward FL.  Then a couple of the Euro ensemble members had loops, and several had a hard right turn near GA.  Then the 18Z American ensembles came in continuing this new idea of out to sea and not up the coast.  Now, hot off the presses, the 0Z dynamical guidance echoes a similar theme…out to sea.

So, at this point I would like to be able to tell you there is confidence in a solution.  Tonight, there is more uncertainty than ever.  Hold tight, make plans for how to be prepared, but I would say there’s no need to act upon them until we see more data.  Remember we still have more than 3 days to work this out.

 

Squall Line on Our Backdoor

Don’t be fooled by the sun and blue skies.  If anything this just adds fuel to the fire.  The main line of storms will affect Raleigh close to 5pm.  Expect strong gusty winds (even outside of the storms), could be some hail, and we’ll monitor any spin ups for the possibility of a tornado or two.  Obviously, there is that possibility as evidenced by several already observed today.

Once this line moves through your area with will clear behind and the severe threat will be gone.  Although remember that winds may still gust above 40 mph and with rain swollen ground trees can uproot more easily.

Twitter: @trextrex14

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Severe Threat Imminent

Today’s potential for severe thunderstorms, tornadoes and strong winds has been well advertised in the local media.  Hopefully everyone will be extra attentive today to warnings when they are issued.

The greatest threat will be from Raleigh and points east, however that doesn’t mean there will be a magical line akin to NC winter weather setups where you can rest easy to the west.

This AM’s cold air is being scoured out as warm air rushes in behind a couple of warm fronts from the south. (The temp at RDU rose 9° in the last hour!).  This should rocket temps thru the 60s and into the low 70s by lunch.  Showers and thunderstorms will increase in coverage thru the morning.  The main threat of severe storms in Raleigh looks to be between 12 and 5pm.  And there could be two rounds before things head east thru dinner time.  Yes there is the potential for tornadoes, but in general a greater number of people stand to be affected by strong straight-line winds inside AND outside of the thunderstorms.  So don’t think that you got off easy if you “just get” a severe t-storm warning  and not the tornado warming.  The winds will be gusty this afternoon anyway with gust 40-50mph, and the t-storms will enhance these even more.

I expect to see a tornado watch issued shortly.  So, stay alert and heed the warnings!

Follow on Twitter for more frequent updates: @trextrex14

 

Heavy Rain for the AM Commute

Indeed the cold wedge has held firm as it took until 7pm for RDU to reach the freezing mark.  And even as the temperature slowly climbed thru the afternoon, the glazing was kept in check because of indirect solar radiation bleed thru and upwelling ground warmth.  It’s nearly impossible to achieve a significant ice storm without a continuous supply of fresh cold air to counteract the self-limiting process of freezing rain drops, which tends to warm the local environment through release of latent heat.  That’s what you saw today…despite temps in the upper 20s, there was only light glazing to 1/10th of an inch.  And in the end, it all went pretty much according to plan…but maybe a little lighter on the snow/sleet than i thought.

Looking to tomorrow AM, temps will rise over night.  And we’ll have our second messy commute in a row.  This time, we’ll just be fight heavy downpours and gusty winds.  There should be moderate to heavy off and on rain with the narrow heaviest band progged to sweep thru Raleigh close to 7:30am.  Here’s the HRRR’s (short term model) depiction of what the radar might look like at 7:15am tomorrow:

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The rest of the week should be mild.  Enjoy.

Looking ahead…Is winter over?!  Nope.

We have elements coming together for the next major East Coast winter storm next Wed or so.  Will we be cold enough?  The storm track looks favorable.  Stay tuned.

 

 

For Raleigh, Things Seem on Plan

The northern part of the Triangle got some bonus snow on the front end this evening with only 27 flakes in Raleigh…or was it 28?

So the idea that the steady (light to moderate) snow moves back in early morning before sunrise still holds. And at that point begins the game of nowcasting banding structure and figuring out who wins for the initial snow/sleet accumulation.  Right now indications are that the enhanced axis probably lies north of Raleigh.  But we’ll see…that’s why you play the game, right?

More tomorrow and for more frequent updates, follow me on Twitter @trextrex14

Winter Weather Nuisance

For the Triangle, we will dodge another winter weather bullet.  Unfortunately for the snow geese, it is unlikely that Raleigh looks anything like this tomorrow…

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While we will end up with a wintry mess for tomorrow morning’s commute, the impacts in the Triangle should be limited to some minor snow/sleet accumulations followed by minor ice accrual owing to warming aloft.  Surface temperatures should be able to rise just above freezing by mid-afternoon to bring the party to an end.

North and west, surface temps will hold under freezing for longer, allowing slightly more significant accumulations of both snow/sleet and freezing rain.  South and east there will be little to no accumulations of either.  The quicker the precip arrives, the more likely we are to achieve snow/sleet accumulations and a delayed onset would mean something like only a dusting.

Right now the best estimate for how this plays in Raleigh is for the steady light snow to begin between 3:30-4:30am (there could be flurries this evening, though).  The snow relatively quickly mixes with and changes to sleet toward daybreak.  Then, through the morning the sleet mixes with and changes to freezing rain until the temperature creeps up to freezing just after lunch.  Best guess for our accumulation is 1/2 to 1″ of snow/sleet with a 1/10th of an inch of ice accrual from the freezing rain.

So while tomorrow, especially in the morning, will be a winter potpourri, the accumulations should be relatively light and short-lived.  Temps will continue to rise overnight Monday into the 40s and rocket into the upper 50s with heavy rain on Tuesday.

What’s the forecast bust potential??

downside risk- the precip overnight and into tomorrow AM aligns itself along an axis farther north near the VA border, leaving Raleigh with only a couple hundredths of liquid equivalent from a couple of snow/sleet showers and a quick bout of freezing rain.  In this scenario…little to no sensible impact.

upside risk- 1) the steady precip arrives a bit ahead of schedule and is slightly stronger and more banded over the Triangle, 2) the cold air damming is more pronounce and more stubborn to erode than the models depict.  In these cases, 1) would give Raleigh the chance for up to 1.5″ of snow/sleet and 2) would extend the period of freezing rain so that the glaze could reach .15 of an inch.  Any way you look at it, even the upside risk is not a particularly significant storm.  Even if number like those were achieved, the warm air at all levels will eventually win out Monday evening and the Monday night and Tuesday’s heavy rain will was it all away.

I’ll be watching the latest trends and update this evening.  And remember, don’t freak out when you see a snow flurry this evening.  The real stuff won’t arrive until overnight.

 

Winter Storm Potential Discussion this Afternoon

Central NC will experience a round of wintry weather late tonight thru midday Monday before temps rise above freezing and we have heavy rain Mon night into Tues.  There seems there will be enough precip to cause problems before the changeover.  I’ll give a full discussion and update late this afternoon.

The Trend Ain’t Your Friend…

…not this evening.  Numerical guidance tonight seems to be poo-pooing any accumulation in Raleigh.  Really, I can’t see much of any reason to expect any more than a flurry here and there this far west.  Precisely the reason I haven’t mentined this possibility over the last week.  Anything of consequence is simply unlikely to happen.09Maybe we could get lucky, but even the ‘lucky’ upside potential is only an inch or so. Hope you did your homework!

Precip on Monday will be the bigger story.  Let’s see how that evolves. At this point, it’s hard to get excited about a lasting wintry event.  More likely is frozen on the front end that all to soon changes to rain.  So many details to figure out…all dependent on the low track.

Lots of time to clarify all the details.

 

Winter Is Coming…

…to which some of you are probably saying, “What are you talking about?!  Winter is here!  It’s cold!” Which it is, yes.  But an even colder weekend lies ahead with two chances for wintry precip flanking it on either side.  Your Valentine may have good reason to be “cold hearted” this time around!

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About tomorrow…  Upper level energy will spawn a relatively weak surface low off the SC coast tomorrow AM.  The resultant confluent moisture and lift now looks to be sufficient to generate an area of snow over eastern NC.  The available moisture gradient increases as you go east.  It’s difficult to exactly pin down what the QPF field will look like, but the short term models are beginning to indicate that the axis of greatest precip will orient itself generally west to east or wsw to ene…again with the heaviest totals on the eastern side of that band.  While the models have trended generally ‘wetter’, this still looks to be a generally light event, especially this far west in the Triangle.  I can say with confidence that most from the Triangle east will see some snow, but it’s difficult to pinpoint what will happen in your backyard until we see where the aforementioned axis sets up.  In this axis is probably 1″ in the west to 2″ in the east.  As you go farther east warm temperatures being to play a role in the precip falling as all snow.  Back west toward Raleigh, it should be mostly snow, altho you could rule out a little sleet.

Bottom line…flurries and snow showers begin tomorrow around daybreak and increase in intensity thru lunch.  With the cold of recent days, the snow that falls shouldn’t have much of a problem sticking to the ground and untreated roads.  Look for a dusting to a half inch for now with the potential for an inch if things setup right.

About the cold over the weekend… Brrr.  Saturday evening lows to should run in the low teens in town with maybe some single digits north.  High on Valentine’s Day probably not making it out of the 20s.

All this cold sets the stage for a southern track low to arrive on Monday.  At this point, I’m sorry to disappoint, but it’s doesn’t look to be the classic snow setup.  It looks to be a snow to sleet to freezing rain to rain mess.  Lots of time to work that out.  But be prepared for a what could be a high impact event.