CAPE

A couple AFDs from Mount Holly leading up to the Dec 2009 KU. Pretty interesting reads. Seems the Euro sniffed this one out first, as it often did. AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MOUNT HOLLY NJ 1109 AM EST WED DEC 16 2009 .SYNOPSIS... STRONG HIGH PRESSURE WILL BUILD IN FROM THE NORTH AND WEST AND THEN WEAKEN THROUGH THE WORK WEEK. A SYSTEM THAT WILL DEVELOP NEAR THE GULF OF MEXICO AND MOVE OUT OVER THE ATLANTIC MAY HAVE SOME EFFECT ON US LATE IN THE WEEKEND. && .NEAR TERM /THROUGH TONIGHT/... FLURRY ACTIVITY HAS BEEN LIMITED TO THE NORTHWESTERN AREAS OF THE CWA. A VORT MAX IS EXPECTED TO ROTATE THROUGH THE AREA THIS AFTERNOON AND AS A RESULT FLURRIES MAY SPREAD SLIGHTLY FARTHER SOUTH THAN PREVIOUS THINKING. WE HAVE EXTENDED THE CHANCE FOR FLURRIES INTO THE LEHIGH VALLEY, ALTHOUGH MOST AREAS PROBABLY WILL NOT SEE TOO MANY FLAKES FALL AS THEY MAY EVAPORATE BEFORE REACHING THE GROUND. LAKE EFFECT CLOUDS WILL CONTINUE TO STREAM INTO THE AREA TODAY, AS THE FETCH OFF THE LAKES REMAINS. WINDS ARE GUSTY AND WILL REMAIN SO THROUGH THE DAY TODAY BEFORE STARTING TO DECREASE THIS EVENING. GUIDANCE TEMPERATURES WERE IN PRETTY GOOD AGREEMENT WITH CONTINUITY AND WERE ACCEPTED. && .SHORT TERM /THURSDAY THROUGH FRIDAY/... ANOTHER VORT MAX MOVES ACROSS THE AREA TONIGHT WITH SOME REINFORCING COLD AIR. THE ATMOSPHERE LOOKS TO BE DRIER, SO WE ARE CONFINING SNOW FLURRIES TO THE NORTHWEST AND GOING MOSTLY CLEAR ELSEWHERE FOR NOW. WINDS MAY PICK UP SOME AS THE SECONDARY PUSH OCCURS. GUIDANCE TEMPS AGAIN ARE IN GOOD AGREEMENT WITH CONTINUITY AND ARE ACCEPTED. THURSDAY THROUGH FRIDAY LOOKS DRY, ALTHOUGH WARM AIR ADVECTION ALOFT AND AN UPPER JET MAY BRING SOME MID AND HIGH CLOUDINESS INTO THE AREA THURSDAY NIGHT INTO FRIDAY. WINDS SHOULD BE DIMINISHING THROUGH THE PERIOD, AND WERE IT NOT FOR THE POSSIBILITY OF CLOUDS WE WOULD HAVE UNDERCUT GUIDANCE MINS ON THURSDAY NIGHT WITH EXCELLENT RADIATING CONDITIONS. AS IT IS, WE CONTINUED TO WALK A GUIDANCE-CONTINUITY LINE, WHICH HAS WORKED REASONABLY WELL. && .LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/... THE MODELS CONTINUE TO DIFFER AS TO HOW THEY HANDLE THE ROTATING UPPER LOW TO OUR NORTH ALONG WITH THE ASSOCIATED SHARPENING TROUGH. AT THE SURFACE, ALL MODELS DEVELOP A LOW ALONG THE SE COAST AND HEAD IT NE. MOST OF THE MODELS KEEP IT FAR ENOUGH S AND E OF OUR AREA SO THAT IT JUST BRUSHES OUR SE SECTIONS. THE OUTLIER AT THIS TIME IS THE ECMWF WHICH SHARPENS THE TROUGH AND DEVELOPS AN INTENSE EAST COAST STORM. IT IS ALSO MUCH FASTER THAN THE REST OF THE MODELS AND WOULD HAVE THE BIGGEST IMPACT LATE SATURDAY AND SATURDAY NIGHT RATHER THAN LATE SATURDAY NIGHT AND SUNDAY. FOR NOW WE WILL GO WITH THE MAJORITY AND BRING INCREASING CLOUDINESS IN LATE SATURDAY INTO SATURDAY NIGHT AND CALL FOR A CHANCE OF SNOW INLAND AND RAIN OR SNOW ALONG THE COAST LATE SATURDAY NIGHT AND SUNDAY. ONCE THE LOW MOVES OFF TO THE NE, HIGH PRESSURE WILL BRING ANOTHER BATCH OF COLD AIR INTO OUR AREA FOR THE BEGINNING OF NEXT WEEK. AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MOUNT HOLLY NJ 658 PM EST FRI DEC 18 2009 .SYNOPSIS... HIGH PRESSURE WILL CONTINUE TO MOVE OFF TO THE NORTHEAST THIS EVENING ALLOWING A MASSIVE LOW PRESSURE SYSTEM TO FILL IN BEHIND THIS WEEKEND. THIS LOW PRESSURE WILL BE ARRIVING BY EARLY MORNING SATURDAY AND HEADING TO THE NORTHEAST THROUGHOUT THE DAY. THE LOW SHOULD PULL FAR ENOUGH TO THE NORTHEAST ON SUNDAY THAT WE WILL SEE A BRIEF RETURN OF HIGH PRESSURE ON SUNDAY. THE HIGH PRESSURE WILL GIVE WAY TO ANOTHER LOW PRESSURE SYSTEM MOVING IN FROM THE NORTHWEST ON MONDAY AND TUESDAY. && .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/... A 20Z SURFACE ANALYSIS SHOWS AN INTENSE AREA OF LOW PRESSURE OVER THE SOUTHEASTERN UNITED STATES WHILE HIGH PRESSURE CONTINUES TO SIT OVER THE NORTHEAST. WINDS WILL REMAIN FAIRLY CALM THIS EVENING BUT WITH TEMPERATURES WELL BELOW FREEZING WINDS CHILLS WILL BE IN THE SINGLE DIGITS TO THE TEENS. WHILE FOLLOWING THE STORM SYSTEM DOWN IN THE SOUTHEAST UNITED STATES WE BROUGHT THE ONSET OF PRECIPITATION IN WILL START LATE TONIGHT IN THE FAR SOUTHERN ZONES AND PROGRESSIVELY SPREAD TO THE NORTH DURING THE DAY. && .SHORT TERM /6 AM SATURDAY MORNING THROUGH SUNDAY NIGHT/... AS IF THINGS COULD NOT GET ANY MORE COMPLICATED WITH THIS MASSIVE LOW PRESSURE SYSTEM IT APPEARS AS THOUGH THE EARLY MORNING NAM LEAVES US HIGH AND DRY...HOWEVER 6 HOURS LATER, WE ARE ONCE AGAIN WET. BOTH THE NAM AND ECMWF HAVE BEEN PRETTY GOOD RECENTLY WITH THEIR INITIALIZATIONS FIELDS AND OVERALL PERFORMANCE, SO IT IS REALLY HARD TO DISCREDIT THEIR RECENT SOLUTIONS. WITH THAT BEING SAID, BELIEVE A BLEND OF THE TWO MODELS WOULD PROVIDE THE BEST SOLUTION FOR SNOWFALL AMOUNTS ACROSS THE REGION. UPPER LEVEL DYNAMICS ADD TO THE DEEPENING OF THE LOW PRESSURE SYSTEM WHILE IT MOVES TO THE NORTHEAST. OUR CWA IS PLACED IN A GREAT REGION BETWEEN A COUPLED 250H JET STREAK TO SEE AN ENHANCEMENT OF UVM PROVIDING AN AREA OF MASS DIVERGENCE LEADING TO THE OFFSHORE LOW DEEPENING. THE INTERACTION WITH THE MID-LEVEL LOW IS A LITTLE MORE PRECARIOUS RIGHT NOW. BOTH MODELS ARE SHOWING SOME SLIGHT PHASING OF THE TWO REGIONS LATE SATURDAY WITH THE NAM BEING SLIGHTLY FASTER THAN THE EURO. THIS PHASING WOULD PROVIDE AN OVERALL SLOWING OF THE SYSTEM AND POSSIBLE OCCLUSION LEADING TO A GREATER CHANCE OF WRAP AROUND MOISTURE TO BE SLUNG OVER THE REGION ON SUNDAY. BOTH MODELS ALSO HINT AT A SLIGHT TROWAL EVENT WITH A DEFORMATION ZONE TO THE NORTHWEST OF THE PHILADELPHIA METRO AREA ALLOWING ENHANCED PRECIPITATION TO OCCUR. LOOKS LIKE THE HEAVIEST SNOW WILL BEGIN LATE SATURDAY EVENING THROUGH EARLY SUNDAY MORNING SOUTH OF I-95 CORRIDOR WHERE THE BEST OMEGA WILL BE MAINTAINED. THIS SYSTEMS TRACK HAS BEEN HANDLED FAIRLY WELL WITH PREVIOUS FORECASTS AND AMOUNT OF QPF. THIS SYSTEM WILL BE THE FIRST WIDE-SPREAD PLOW-ABLE SNOWFALL EVENT IN THIS EARLY SEASON. RECORDS SHOW THAT PHILADELPHIA HAS ONLY THREE SEPARATE OCCASIONS IN DECEMBER WITH DOUBLE DIGIT SNOWFALLS, 12/26/1909, 12/12/1960, AND 12/24/1966, COULD THIS BE THE FOURTH ONE? ACCUMULATIONS LOOK STAGGERING WITH AT LEAST AN 8 INCH SNOWFALL IN THE METRO AREA WITH LOCALLY HIGHER AMOUNTS SOUTH AND EAST OF THE CITY WHERE MESOSCALE BANDING APPEARS TO HAVE THE BEST CHANCE TO FORM.

A few webcams to watch for the epic Sierra Nevada blizzard- https://www.mammothmountain.com/on-the-mountain/mammoth-webcam/woolly-cam https://www.mammothmountain.com/on-the-mountain/mammoth-webcam/the-village https://www.enjoytahoe.com/tahoe-city-webcam

Sunday through next week looks to be within a couple degrees of 60. Latter part of the week looks a tad wet though.

low of 24. Haven't really been paying attention so a little surprised.

Given our geographical location, we have always sucked at snow. There are a few anomalous patterns that can shift the thermal boundary far enough south/east for more than a minute to give us a reasonable shot, and lately they are harder to come by.

The potential for around the 10th has looked like a Miller B type deal with the primary tracking well NW. Latest ens runs are further south with both the primary and secondary coastal development, but still plenty of spread. This period is probably it for snow chances in the lowlands. Beyond that it looks like a ridge over Hudson again with a trough digging out west. Then we are beyond mid month.

Dude, come on. This is a simulation, and it will be wrong. Way better chance we are 70 on April 1 than NC getting a snowstorm.

I think too much emphasis is probably placed on the PDO, similar to the MJO, when things 'go wrong'. The ENSO/PDO relationship is complicated and not that well understood, although there are apparent correlations with Nino/Nina events. All these indices interact in ways we simply don't have all the answers to, and ultimately impact the general longwave patterns. It is interesting and fascinating, but ofc our sole interest is all about cold and snow in the MA. It is kind of neurotic honestly lol. This is a straightforward and interesting read on what influences the PDO phase. I have posted this before. Still, it doesn't necessarily provide the ultimate answers we want. https://www.climate.gov/news-features/blogs/enso/going-out-ice-cream-first-date-pacific-decadal-oscillation

Pretty much. We seem to have a better shot of getting cross polar flow in Nina to produce a cold period if the Aleutian ridge morphs into a -EPO/+PNA pattern. With a gradient initially as the cold presses southeastward and flattens/dislodges the eastern ridge, just need a wave to move along the boundary. That's how the early Jan 2022 storm worked. Stayed cold for a few weeks with 2 more snow events, esp for the eastern part of the region.

SER will be back next year though. Hopefully it won't be a permanent fixture for the entire winter.

PNA has been variable, which is pretty typical in a Nino. Here is the h5 composite for the winter. This look isn't a winner baby. Not for cold and snow in the MA, at least not in current times.

No. Predominately an h5 ridge across east-central Canada with a mostly -PNA/+EPO, which means not very cold in our nearby source region. It has been mostly just seasonably chilly, but not a good pattern to lock cold in when storms approach. The exception was that 10 day period in January.

Sometimes I get Chuck speak, other times not so much lol.

I think Chuck might be referring to influences such as east Asian mountain torque on the earth's rotation. The hints in his post are mentions of friction and more high pressure. A +EAMT opposes the earth's rotation, and to conserve angular momentum there is an increase in westerly winds in the atmosphere(stronger jet stream).

There's not much to track in the LR realistically, other than maybe a chilly, miserable start to Spring. Might as well just let the convo flow. Some decent back and forth discussion going on. Well, with one possible exception. Just don't stalk me bro.

It did for inland areas, but it was a complete snowless torch outside of that event.

I honestly have no answer. With the random, fluky nature of wave timing, it could happen even if the PDO remains as is, and regardless of Enso state. Probably a weak to moderate east based Nina with some NA blocking episodes, or a Modoki Nino with blocking. A neutral Enso is the least likely to produce such an outcome.

Once in a blue moon, and mostly because of a KU and a few nickel and dimers. But I am afraid that Ninos have largely become impotent. Still have to test the Modoki with blocking, if that is even possible anymore. If we get that, and it fails, well, you know.

Great flick.

I will roll with a Nina- although they certainly can be a complete ratter like last winter, recent Ninos haven't been much better, and tend to struggle to bring even modest cold anymore. Ninas are more likely to feature h5 configurations that can bring legit cold periods to the east at times that at least give us a shot- and cold is the biggest issue now. Get a bit of timely NA help to slow the flow and there is a chance for a bigger storm that can also impact inland areas, like March 2018. All these periods in recent Ninas featured actual cold air and one or more snow events for parts of the MA east of the highlands-

The CFS at super long leads never has much blue esp on TT. It is a generally shitty model even at shorter leads. Follow the height lines and you get the general idea of what it's attempting to depict.

Not year round but its emerging here the last couple days. Also have some little clumps of onion grass that's been up for a couple weeks. All happening sooner than years past.

Maybe..

GEFS keeps giving the digital snow, esp for eastern areas. How long will it last?

Yeah I don't buy it. Just something to have fun with until it falls in line with the more skilled guidance.