The National Weather Service is pointing out the intense cold snap coming our way this weekend.
Here’s forecast map of temperatures a mile up (850mb pressure height) in the atmosphere for Saturday night. If we were to bring these temperatures down to the surface, warming as its pressure increases, our surface temperature wouldn’t be above 5 degrees Fahrenheit.
850mb heights and temperatures (degrees C) 10pm Sat Feb 13 (03GMT Sun Feb 14) Notice -30 deg C in the northeast US (1 mile up). Good luck finding a colder place.
But this air won’t be sticking around long enough to give us more than a few days of record-setting cold weather. Here’s the forecast discussion from the NYC NWS….
WITH THE EXTREMELY COLD AIR MASS FORECAST SATURDAY INTO
SUNDAY...RECORD MINIMUMS AND RECORD LOW MAXIMUMS MAY BE REACHED.
HERE ARE THE RECORDS AND FORECASTS...
STATION......RECORD/FCST MINIMUM...RECORD LOW MAXIMUM/FCST HIGH
FOR 2/14 FOR 2/14
NYC...........2 (1916) / 1.............17 (1979) / 19
LGA...........1 (1979) / 2.............15 (1979) / 19
JFK...........4 (1979) / 2.............17 (1979) / 19
ISP...........7 (2015) / 1.............26 (1987) / 18
EWR...........0 (1979) / 0.............15 (1979) / 19
BDR...........3 (2015*) / 0.............18 (1979) / 17
*IN 1979 AS WELL
Next post will show how many low and high records the USA had recently.
The Moon near Jupiter early Thursday morning caught the attention of anyone who looked up in the pre-dawn sky.
With five bright planets in the morning sky, there’s more striking scenes to come! Click on the diagrams to see them full size (you may need to hit the ‘back’ arrow to get back to this page).
Monday morning, Feb 1st, the last quarter moon stands by reddish Mars:
Moon and Mars in Libra in the southern sky.
Wednesday morning, Feb 3rd, the crescent moon stops by Saturn.
Saturn and the Moon in the southeast sky.
Friday and Saturday morning, Feb 5th and 6th, a thinner moon poses above dazzling Venus and more subtle, but visible without optical aid, Mercury, low, very low in the southeast sky just before the sky gets bright.
Fri Feb 5 Moon above Venus and Mercury
Sat Feb 6 Moon with Venus and Mercury
Even if we take the computer forecast models at their word, we go from a few inches of snow to a foot and a half in the distance from Newburgh to the Bronx, from the north boarder of Connecticut to Long Island Sound. A little wobble in a wobbly spinning storm means a large change in the results. More cold air will help the precipitation stay all snow, but also bring drier air and choke off the snow. Winds off the water will add more moisture, but the ocean is warmer than normal, so even more moisture, but warmer air gets mixed in. (Warmer ocean from December’s heat waves.) More likely for DC and perhaps Phily to be deep in the snow (see Capital Weather Gang )
From the National Weather Service NYC…. 6pm forecast discussion….
MODELS DIFFER ON THE PACE AT WHICH THE CUT OFF LOW AND THEN
OCCLUSION TRACK TO THE EAST NORTHEAST OVER THE WEEKEND. THIS RESULTS
IN DIFFERENCES IN THE TIMING/STRENGTH/PLACEMENT OF THE ASSOCIATED
SURFACE LOW. WHAT THE MODELS ARE IN FAIRLY GOOD AGREEMENT ON IS . .
A HIGH WILL REMAIN SUFFICIENTLY STRONG AS IT RETREATS TO THE
NORTHEAST TO KEEP A SUPPLY OF LOW LEVEL COLD AIR FEEDING DOWN INTO
THE REGION THROUGH THE STORM. AS A RESULT...EXCEPT FOR POSSIBLY
MIXING WITH RAIN/SNOW MIX OVER EASTERN AND SOUTHWESTERN SUFFOLK
COUNTY SATURDAY AFTERNOON/EVENING...PRECIPITATION SHOULD BE ALL SNOW
DURING THE EVENT.
THERE IS SOME UNCERTAINTY IN HOW RAPIDLY SNOW PUSHES NE INTO THE
CWA...WITH SOME POSSIBILITY THAT MOST...IF NOT ALL...OF THE CWA DOES
NOT RECEIVE ANY SNOWFALL UNTIL SATURDAY MORNING.
Perhaps not a flake on Friday?
Then…. how much?
CONFIDENCE HAS INCREASED THAT THE STORM WILL BRING MEASURABLE
PRECIPITATION INTO ALL BUT NORTHERN INTERIOR PORTIONS OF THE TRI-
STATE.... . . . PRECIPITATION SHOULD TAPPER
OFF OVER MOST AREAS SUNDAY MORNING.... . . .
CONFIDENCE IS ALSO INCREASING IN THE IDEA THAT MOST...IF NOT ALL OF
THE SOUTHERN 1/2 OF THE CWA WILL RECEIVE AT LEAST 6 INCHES OF
SNOW...EXCEPT FOR POSSIBLY EASTERN SUFFOLK COUNTY...WHERE RAIN
MIXING IN COULD LIMIT AMOUNTS. FARTHER NORTH...IT IS BECOMING MORE
CERTAIN THAT AN ADVISORY LEVEL (3-6 INCH RANGE) SNOWFALL SHOULD
OCCUR...EXCEPT FOR ACROSS FAR N PORTIONS OF THE LOWER HUDSON
VALLEY/SW CT...WHERE 3 INCHES OF SNOW IS STILL IN QUESTION...BUT
DEFINITELY POSSIBLE. EVEN IN THE NORTHERN 1/2 OF THE CWA...WARNING
LEVEL SNOWS ARE STILL WITHIN THE REASONABLE REALM OF POSSIBILITIES
FOR THIS SYSTEM. GIVEN THE UNCERTAINTY...AND THAT MOST...IF NOT ALL
THE SNOW WILL NOT START FALLING UNTIL SATURDAY...HAVE DECIDED NOT
TO ISSUE ANY WINTER WEATHER HEADLINES WITH THIS ISSUANCE.
The storm brings strong, sustained winds, especially late Friday night into late Saturday, with tides well above normal, helped by the full moon, until the storm gets by us and winds come from the north.
In any case, get ready to be in a safe place by Friday night and ready to stay for a while.
Overnight, the kink in the jet stream that will spark our a possible winter storm this weekend for the east came ashore on the Pacific coast of the United States. The packet of energy is seen in the bending of the jet stream just off the coast of Washington state (see the 7pm Tuesday evening map, below).
Tuesday evening jet stream at 500 mb pressure height (5 to 6 km high)
To get a blizzard for the mid-atlantic states, this kink needs t0 settle in on the east coast, gathering up other packets of jet stream energy and making the air spin so strongly the jet stream spins into a circle as seen in this frame from the forecast 500mb jet stream for Saturday evening.
500mb map for Saturday evening
The strength and location of the center of the spin (an upper air low pressure system) will determine how much snow will fall and where the rain/snow line will be. Think of a wobbling top – this upper air storm is wobbly and the small wobbles are hard for the computer models to predict.
So, if you are looking at the predictions of snow amounts for the weekend and the time when the snow will start – realize how precarious this forecast is for a storm who’s energy is still on the other side of the country.
For those of us north of NYC, we are on the northern edge of the precipitation from the possible storm. Earlier today, the total precip was 1 1/2 inches. The later run of the computer forecast model has us with 3/4 of an inch, which would vary the amount of snow (if it’s all snow) by a range of 7 to 15 inches.
So there’s a lot of uncertainty being on the edge of a possible storm, several days in advance.
Areas closest to the likely center of the storm – DC, Philadelphia – are getting more certainty in their forecasts.
But there’s still quite a ways to go. The models will be get better at forecasting this storm as the pieces come over the upper air network over land.
NWS forecast precip through Sunday (Human-made product)
Total rainfall forecast through Sunday from the US Global Forecast model.
Wednesday morning (and any morning the rest of this week, if it’s clear out) is great for seeing the brightest planets. Out to the southeast, you’ll see brilliantly bright Venus. Next to it will be the planet Saturn. To its upper right will be the Moon on Wednesday. Then, continuing to the upper right is Mars, then the bright star Spica, and way over the upper right, to the southwest, very bright Jupiter.
If you are up before 6:30am, it should be dark enough to see all this and the earthshine on the shadowed part of the Moon. Later, the Moon, Jupiter and Venus should still be visible even as the sky gets brighter. Saturn will move up and past Venus, closest Saturday morning. Compare very much brighter Venus with exquisite, but much fainter Saturn in a telescope, if you can. Faint Comet Catalina is up above bright star Arcturus, high above this scene. You’ll need a telescope to see Catalina. (It’s not the comet shown on this map.)