Saturday, March 24, 2012

Weather It Is (Winter's Last Gasp)

It's certainly been nice and today (Shabbat) was the nicest day in quite a while -- although a bit of dust in the air made the day seem not quite as nice as it might have been.

On the other hand, things are never quite exactly how we want them, and it's usually the wanting that causes the discontent, if not problems.

Well with that said, I think I'll mention that the weather is suppose to muddle along for another day and then turn colder.  If everything fell into place, there might even be some snow (flakes) mixed in with the rain that should fall during the mid-week period. Right now, there is still a lot uncertainty in the forecast rain amounts, with greater amounts being associated with colder, more "winter-like" weather.  So, it will either be rainy, or maybe really rainy with winter cold.

Until then, enjoy another nice day, and if you see any UN folks around, bring them over to our local Rami-Levy so they can shop with our local Arab neighbors.

Barry Lynn

Monday, March 19, 2012

Weather It Is (Up and Down)

It's been brought to my attention that there will be an influx of dust along with our easterly winds.  This certainly makes for greater difficulty for people with Asthma, etc.

Well, the weather certainly is nice, although a bit nippy. In fact, this morning felt colder than yesterday's real cold -- as there was a stiff wind from the north.

Looking ahead, one sees pretty much nothing to write about all week, except for a bit of an up, and then a bit of a down in the temperatures, before another up (of no real consequence).  Looking a bit farther out, there may be some rain early next week, but at the moment the "impending" foul weather doesn't look too foul.

Speaking of looking ahead, I've decided that one really should look where one is going, lest one end up somewhere unexpected.  Putting this idea into practice, though, is bit too farsighted for me.

Barry Lynn

Thursday, March 15, 2012

Weather It Is (Going for a run?)

Good Afternoon:

Our Prime Minister recognizes that "There is no such thing as hermetic protection against rockets."  Of course, this depends on how many are being fired at once.  Over on this side of the country, there are no rockets being fired -- because the army rooted out the Palestinian war making ability when it entered Palestinian towns again back on 2002/03.  The opposite is the case on the Western side of the country, where the army left Gaza in 2006, but not before uprooting about 10,000 people from their homes.

The problem is that the missile shield -- although an amazing technical achievement -- still leaks like a leaky umbrella on a rainy and windy day.  Or, if you don't want to get wet, don't go out in the rain. Too bad the government treats the missile threat like the weather forecast -- you do your "best," and hope the worst doesn't happen. The iron dome -- like a good umbrella -- should be the last resort against missiles -- an insurance policy rather than the raincoat itself.

Speaking of rain, did you ever try to run a marathon with an Umbrella?  Good for the country, but not so good for the marathoners, the weather will not cooperate tomorrow.  In fact, the weather is going to start out rainy and just get rainier as the day progresses, with strong winds and temperatures only around 8 C.

Then, as the afternoon progresses, it's going to get a lot colder.  I can't say that one should take out the skis again, but certainly there should be sleet and rain together, and possibly light snow in the evening and night, followed by blustery and chilly weather on Shabbat.

After this storm passes, there will be very good missile launching weather for about a week, before the next winter storm threatens.

Barry Lynn

Wednesday, March 14, 2012

Weather It Is (Where did Spring go?)

It's Wednesday afternoon and it doesn't feel like Spring anymore.  What happened?  Spring's old nemesis, Winter, is making a comeback.  You might call it a bit of luck, since it's not necessarily cold and stormy elsewhere.

Of course, we were quite "lucky" during the last "round" of fighting.  No-one on our side was killed, and this was a distinct possibility since the Iron-Dome system shot down about 75% of all the missiles launched from Gaza.  Fortunately, we also have a defense minister, Ehud Barak, who's an optimist, and thinks that relative "calm" is really just fine, so long as it's not me who gets hit on the head by the next one.

Did I say cold, well: I meant it.  The cold is courtesy of a trough digging southward,  It really is going to get cold, but the atmosphere doesn't seem (just yet) to be as cold as it could be, meaning that this weather system is weighted towards the bottom, with most of the cold air concentrated closer to the surface.  It would actually be nice to see some snow from this system, late Friday afternoon and night, but it's too early to really say we should look out for it.

Following this system, the weather will be in a relative calm, but not the kind of relative calm that makes one run for cover at the sound of a siren.

Barry Lynn

Thursday, March 8, 2012

Weather It Is (It was a beautiful day)

Today (Purim) was a beautiful day, but it wasn't a hot day.  It was quite pleasant, for sure, but it wasn't hot.  Now, it might have felt hot because it was the warmest day in quite a while, but it wasn't.

That said, we should probably note that early next week will be hot, as southerly winds ahead of low pressure bring a taste of early summer.  However, after the passage of the low pressure area, which
may be accompanied by a period of rain, temperatures should trend downward. 

How far downward? At this time, it's not very clear just how cold it will get.  However, there are a few ensemble members that want to bring back winter to our area. However, they are not the majority, so we'll just make mention of this interesting fact, but not make a big deal about it.

Purim Samaech,

Barry Lynn

Sunday, March 4, 2012

Weather It Is (Life and fall of a snowflake)

The snow that fell Friday morning was a beautiful snow: the flakes were large and fluffy.
In Gush Etzion, the temperature fell to freezing or below, and the snow accumulated as white powder
on the streets, sidewalks, lawns and gardens.  Temperatures at 500 mb were forecast to be near or below -25 C, at 700 mb below -11 C (and as low as -13 C), and at 850 mb at -2 C or below. These conditions are apparently good conditions for growing snow crystals, rather than small hail stones (which we call "sleet," but sleet is really rain drops that freeze on the way down). 

In strong wintertime thunderstorms, we often get snow pellets and sleet, and these pellets are not fluffy like the snow we had (made of dendrites).  Rather these type of snow pellets grow in strong updrafts and descend in strong downdrafts, and are often a kernal of snow frozen into a rather stiff form of ice.   This is most uncomfortable, at least for one who happens to be a "snow-flake."

In contrast, our Friday snow formed in weakly ascending, moist air that had time to form large snowflakes from dendrites. 

Predicting snow amounts in such a situation is tricky.  I have to mention, though, that no self-respecting snowflake wants to end its life as a raindrop as it falls to ground, which is what happened to many such snowflakes during our last storm, where greater than 150 mm of rain fell. The problem is that the larger the flakes become, the harder it is for them to stay aloft. On the other hand, the larger the flakes the more likely they are to survive the plunge to earth below.  So, eventually, these large flakes do decide to take a chance, in the hopes that they will join their fellow comrade flakes on the ground.

You have to understand, though, that while the ice-type snow can fall very fast and coat the ground with ice particles even when the temperature is above freezing. the fluffy like snow falls slowly (due to its low density and large size) and  usually melts before it reaches the ground -- unless the surface temperatures are at or below freezing.  Sometimes, though, if enough snow melts, the energy required to melt the snow can lead to cooling the ground and near-surface air enough that snow can accumulate.  This is when predicting snow amounts becomes very tricky.

In Gush Etzion, it was cold enough that the snow accumulated without melting.  In Jerusalem, it didn't, and instead had to freeze the ground first and then due to air temperatures just above freezing the snow became slush in many places.  One could say with confidence that there would be more snow in Gush Etzion than in Jerusalem, but it was difficult to say how little in Jerusalem.

Looking ahead in our weather: for a moment it looked like cold air might return at Purim time, but now the majority of ensemble members show that warmer weather is on the way, at least until early next week. So, enjoy the nice Purim weather and dry out a bit too.

Barry Lynn

Friday, March 2, 2012

Weather It Is (Winter Storm Update #8)

Hi;

The previous post was written a few hours before, but didn't get posted -- sorry.

The temperatures have warmed up a bit.  Currently, only light precipitation is indicated, and because the ground has warmed up a bit, it should
help with the roads. 

Later this afternoon the air will be cooling off a bit, but only light precipitation is forecast.  We'll see how the next update comes in.

The temperatures will warm up a bit tomorrow and a period of rain is forecast for Shabbat.

A storm will approach on Purim day, but may remain far enough north of us to give us only a good dose of rain.

Shabbat Shalom,

Barry Lynn

Weather It Is (Winter Storm Update #7)

The latest GFS forecast continues to show cold weather, with a reinforcing shot of cold air
later today.

Periods of snow will continue this morning (mostly in the center), and for this reason travel is not recommended.

However, there should be a short break in the weather (at least based on last night's data), and then
even colder air will come in aloft later in the afternoon.  Snow should fall again and there should be
off an on precipitation until Shabbat morning.  Shabbat will remain cold.

The IMS is predicting 10 cm of snow in Jerusalem.  That would be great, but I am not sure if it will
be cold enough to make it accumulate so much.  We'll know more about this with the next update in
a few hours.

Barry Lynn

Thursday, March 1, 2012

Weather It Is (Where will it snow?)

We're looking at the sounding data for Jerusalem, and we see that early tomorrow morning the temperatures at 900 mb will drop just below freezing. However, the surface temperatures are still suppose to be above freezing.  This implies that any snow that any (moderate) snow that falls will create at most a slushy accumulation.  After a mid-day warm-up, the potential for snow returns in the evening.  However, we should mention that there is still some uncertainty in tomorrow morning's forecast. In fact, the GFS ensemble has a range of almost four degrees, with most clustered around -27.5 C at 500 mb.  A little "Mazol" might bring the white stuff to Jerusalem.

In contrast, in Gush Etzion, the forecast temperatures are suppose to be at and below breezing during a period of first moderate and then heavy snow.  This should lead to a quick accumulation of snow on the ground and roads.  There to there should be a bit of a warm-up towards mid-day, but colder air again comes in aloft towards late afternoon.  This coupled with additional cooling aloft will raise the chances of snow again.

A warming trend begins on Sunday.

Barry Lynn

Weather It Is (Winter Storm Update #6)

Heavy precipitation continues to fall, and where it is snowing, it's snowing, and where it's raining, it's raining. The temperatures haven't really changed much since yesterday evening.

However, from around mid-night onwards, the temperatures should start to creep and then fall downwards, and the mixture of snow and rain should change to all snow and accumulate at least several centimeters by morning in Central Israel.  The coldest air is forecast for Friday evening, so we would expect additional accumulation on Friday.  Jerusalem should also receive at least a light accumulation of snow towards morning.

You can see the snow-map under Maps: "Today's Snow Forecast."

Barry Lynn