Weather It Is (Winter Storm Update)

The evening forecast is very similar to the previous forecast. 

The main event will be a period of snow in the Jerusalem area followed by even more extreme cold on Thursday and Friday morning than we just experienced.

Otherwise, periods of rain in the morning into the night over other areas.  Some areas could see 30 to 40 mm during the morning hours, especially in northern areas.

At this time, it's not clear whether there will be a few centimeters or several or even 10.   It will probably depend strongly on elevation.  In any case, the roads will freeze over in the late afternoon and/or evening, so people will be headed home by then.

Have a good night.

Weather It Is (Winter Storm Warning/Extreme Cold)

 Good Morning:

As discussed in our "Israel Winter Weather" group, forecast conditions have trended towards both snow and extreme cold.  In areas that normally see snow during winter storms (including Jerusalem), this combination will create impassable driving conditions late Wednesday into Thursday, if not later where frozen precipitation remains on the roads. Snow accumulations are potentially between 10 and 20 cm in the Jerusalem area, depending on elevation.  Lighter snow amounts are expected in the north.

In our previous storm, the forecast trended away (towards lower probability) as we approached the storm event, leaving us with just extreme cold.  But, we've been watching this potential event for several days, and the trend towards a deeper 500 mb trough, and more prolonged and heavy precipitation has continued to this day (Tuesday).

Some important details: this storm should bring even colder weather than our last.  More importantly, later in the afternoon and evening, high relative humidity in the "Dendritic" zone (-12 to -18 Celsius), will lead to rapid formation of large snowflakes. These snowflakes will form as moisture from the sea overruns the cold air at the surface and within the mountain ridges.  The snow will accumulate quickly, closing roads, so travel will probably be impossible from late afternoon Wednesday into Thursday. The heaviest snow should fall in the late afternoon and evening hours. The deep freeze should last into Friday morning.

Be Safe,

Barry Lynn

Weather It Is (Extreme Cold, Snow?)

 Good morning:

Temperatures on Thursday are forecast to be 2 to 3 degrees Celsius lower than their lows Monday morning.  This means lows around -2 to -4 C in higher locations, or in normally cooler locations in the mountains of Jerusalem and northern mountains.  Coastal areas should be comparatively colder as well, with near freezing temperatures in inland areas.

Currently, the global forecast models GFS and EURO disagree on the type of weather to expect Wednesday.  Both forecast heavy rain as the storm approaches Tuesday night into Wednesday morning. Yet, they differ on the extent of the precipitation and how fast the cold enters our area on Wednesday.  Based on the Euro, there is a likelihood of snow in the central mountains Wednesday afternoon into Wednesday evening, followed by the freeze of Thursday, which should last into Friday.  The GFS predicts less precipitation than the EURO, leaving us just extremely cold.  Tomorrow's forecast  from both models should hopefully indicate better agreement. Incidentally, the EURO was more accurate for our previous storm in terms of the location of the 500 mb trough. It was predicting a more easterly position for the 500 mb trough than the GFS, while now it predicts a more westerly position.

Next week, there is a signal in the global ensembles for a more prolonged storm, possibly snow.

Barry Lynn 

Weather It Is (Extreme Cold and Snow)

 Good afternoon:

The synoptic forcing of rainfall has ended, but not before many places received 100 mm or more.

Now, we're in store for a cold wave, which will probably last into next week, if not the end of next week.

There is some leftover 700 mb moisture, which might lead to light showers and light snow as the cold air rushes in this afternoon. Temperatures should remain near freezing in the highest elevations of the north and central mountains until Tuesday afternoon.  Ice could form on the roads where standing water persists.

Late Wednesday, we're expecting another blast of frigidly cold air that should last until late Friday. There will be a deeper moisture layer with this cold air intrusion, so a period of snow is likely with this event on mountain peaks of the north and the central mountains of Jerusalem.

Next week, another storm is expected.  Current indications are that this storm may bring a more substantial amount of snow, in addition to the unusually cold temperatures.

Barry Lynn

Weather It Is (Extreme Cold)

 Good evening:

As a trough of low pressure dips southward from the polar jet stream, heavy rain should occur on Sunday.

The trough is forecast to move to our east Sunday evening, but as it does it will usher in the coldest air of the season (by far).  

Synoptic forcing for precipitation should be cut off as the trough moves to our east Sunday afternoon.  Normally, this would be the end of the precipitation.  However, the extremely cold air passing over the sea could combine with  lingering moisture in the middle of the atmosphere (at 700 mb) to produce snow squalls later Thursday afternoon and evening (with possible accumulation).  

Temperatures will be close to or below freezing in many locations on Monday and Tuesday mornings.  Similarly cold air should return on Thursday and Friday, and early next week there are stronger indications for our first snowstorm of the year (but the signal for this is just that, and we'll have to see if all the "pieces" fit together (the upper level trough needs to nose down not to our east -- as in the current situation -- but just to our west as the cold air sweeps in at the surface)). 

Cold temperatures are forecast until or through the last week in January.

Shavua Tov,

Barry Lynn

Cold Weather Update

Good Afternoon:

Extreme cold expected.

Most global forecasts indicate that the coldest air will remain to our north this Friday into Saturday, and then extremely cold air on Monday will lack upper level support for more than possible snow showers.  Still, there should be plenty of moisture for heavy rains throughout the period, and snow on the Hermon.

However, there is still a 10% chance of snow in the Jerusalem mountains Friday night into Shabbat morning, and (as noted) extremely cold weather expected on Monday, with widespread frost. Unusually, cold weather is forecast to last until the end of the month.

Otherwise, expect 25 to 50 mm of rain generally, and even some rain over southern areas where flooding can occur.  Locally 75 to 100 mm of precipitation is predicted over central coastal cities from Thursday night into early Monday.

Barry Lynn

Weather It Is (Weekend Storm)

 Good Afternoon:

In the end, the most likely scenario is that the coldest air will remain to our north and east.  In other words, a "bubble" of very cold air no longer is forecast to drift southward towards our area on Friday and Shabbat.  The chance of this happening is less than 10%.  Instead, it will rain generally across the area, except on the Hermon where there will be snow.

The next couple of weeks look to be chilly, with periodic chances of rain, if not snow.

Barry Lynn