Another storm is expected to dump another 6 inches or more of snow late tonight into early tomorrow morning. Here is the NWS output this morning:
.LOW PRESSURE OVER THE GREAT LAKES STATES TODAY WILL MOVE EAST...
AS A SECONDARY LOW PRESSURE SYSTEM DEVELOPS OVER SOUTHERN NEW
ENGLAND THURSDAY MORNING. THE SECONDARY LOW WILL MOVE SLOWLY
NORTHEAST ALONG THE MAINE COAST THURSDAY AFTERNOON. THE
COMBINATION OF SYSTEMS WILL BRING A SIGNIFICANT WINTER STORM TO
THE REGION...BEGINNING LATE THIS AFTERNOON IN NEW HAMPSHIRE AND
SPREADING EAST INTO MAINE THIS EVENING.
SNOW WILL MOVE INTO SOUTHWESTERN NEW HAMPSHIRE LATE THIS
AFTERNOON...SPREADING NORTHEAST INTO CENTRAL MAINE BY LATE THIS
EVENING. SNOW WILL INITIALLY BE LIGHT...BUT WILL PICK UP IN
INTENSITY AFTER MIDNIGHT. A BAND OF HEAVY SNOW IS EXPECTED TO MOVE
ACROSS THE REGION DURING THE EARLY MORNING HOURS AND INTO THE
MORNING COMMUTE ON THURSDAY.
ALONG THE COAST AND IN FAR SOUTHERN NEW HAMPSHIRE...SNOW WILL MIX WITH AND
EVENTUALLY CHANGE TO RAIN LATE TONIGHT AND THURSDAY MORNING. THIS
WILL HOLD DOWN SNOWFALL ACCUMULATIONS THERE.
THE LOW WILL STALL ACROSS MAINE ON THURSDAY AFTERNOON. THIS WILL
CAUSE LIGHT SNOW TO LINGER IN CENTRAL MAINE AND THE MOUNTAINS A
BIT LONGER...WITH SOME ADDITIONAL ACCUMULATION POSSIBLE THROUGH
THURSDAY NIGHT.
Because I am lazy, and don’t feel like competing, I am sending you to Norman’s page for a reliable forecast for Plymouth.
Good Morning, and I wish you all a happy Jared Rennie Day today!
Now I know what you’re thinking….What the heck is Jared Rennie Day? Well don’t worry, here are some answers to your questions:
- Yes, it is a national holiday in the following countries: United States, Zimbabwe, and Petoria
- Yes, you are required to send me a gift ($50 minimum). Don’t worry though, if you haven’t bought anything yet, you are welcome to send a check to me, as long as the post office receives it by 5pm today
- No, it is not a made up holiday. Jared Rennie Day was actually observed in the City of Woburn, Massachusetts on February 16th, 2002. Don’t believe me? here is the proof:
On February 16th, 2002, A ceremony was held to honor my Eagle Scout Award. The award is the highest honor in the Boy Scouts of America, and only very few scouts have received this award. To earn it a scout must receive 21 specific merit badges (don’t worry, I have the Weather Merit Badge) as well a coordinating ones own Eagle Scout Leadership Service Project. For my project, I refurbished a playground behind a Little League Park the City of Woburn was going to tear down. Only 1.7 million scouts have received this award since 1911, including Stephen Spielberg, Wynton Marsalls, and President Gerald Ford.
During the ceremony, the mayor came and presented the documentation above declaring that day as Jared Rennie Day. And yea…I laughed too, but this day was not my idea, it was a Mayor’s idea. And mayor’s have a lot of credibility, much more than me. Which is why I still celebrate this day every year.
So put on your Jared Rennie glasses, turn on the Weather Channel and crack yourself open a cold Dunkin Donuts Iced Coffee, and have yourself a Jared Rennie-iffic Day!.
OK so I have not done one of these in a long time, but we had an interesting weather event over the past few days. This system that passed through the US not only caused the tornado outbreak Tuesday, but also gave New England abnormally high temperatures.
When doing a case study, it’s good to start large scale, then move down. So let’s start at the upper levels
The above is the 850mb map from Tuesday night (SOURCE: Storm Prediction Center). We can see a very narrow trough over the center US. This trough is generating strong southerly flow downstream of the trough. This flow is bringing warm moist air over the Oklahoma area, indicating areas of strong WAA, which induces rising motion, which helps generate precipitation. Now look at this trough 24 hours later:
It has moved towards the northeast, but it is still bringing warm air towards the New England area, which helps explain why we had temps in the 50′s and even 60′s for areas of southern New England.
Now let’s move on to the tornadic situation. The SPC has gotten 6 tornado reports on Tuesday night (including one near Pawnee Oklahoma….sound familiar?) . Let’s take a look at a sounding launched that evening in Norman, Oklahoma:
The red line is the actual temperature recorded by the weather balloon, and the yellow line is the parcel temperature (the temperature if a air parcel rose from the surface to the top of the atmosphere). The general rule of thumb is if the parcel temperature is GREATER than the environmental temperature (yellow line to the right of the red line), the parcel will continue to rise on its own. So if we have some sort of lifting mechanism (like a strong cold front or WAA at low levels…which in this case, we do), then we can get strong vertical motion which can induce severe weather.
Also note some of the severe weather indices on the right hand side of the chart:
- CAPE: 1207 — Storms will build vertically very quickly
- LI: -5.4 — Large Instability
- TT: 58 — Scattered Severe Storms
- KI: 34 — Moderate Convection Potential
- SW: 494 — Tornadoes Possible
Needless to say this storm brought some devasting damage for the eastern parts of Oklahoma, and also caused the ice on the roof of my house to fall overnight last night!
One of the tools weather forcasters use for nowcasting tornadoes is the use of Radar. The Radar images you see on the news most of the time is the base reflectivity, which essentially shows where it is precipitating. But the WSR-88D can produce many different types of products. One of the other main products is radial velocity, which determines if the generic flow is moving towards or away from a radar.
The generic rule of thumb is the following:
Green: Inbound Velocity; flow towards the radar
Red: Outbound Velocity; flow away from the radar
Using this concept, one can look at the radial velocity and see the synoptic flow. But if looked at very closely, one can depict small scale phenomena. A velocity couplet is an area where there is strong inbound and outbound velocity near each other. If positioned correctly, we can see cyclonic convergence. This indicates that the flow is counter clockwise, and converging into one spot. This can be one of the indicators for a TVS, or a tornadic vortex signature. When this is seen, there is a moderate chance that a tornado has, or will form.
Why am I bringing this up? Well we have had a severe weather day in the great state of Oklahoma. I plan on doing a case study sometime tomorrow (stay tuned!) But for now take a look at the image below (SOURCE: GRLEVEL3) :
The area over Pawnee, Oklahoma is experiencing a cyclonic converging event. It is important to note that the radar is SW of this image. Using that concept we can see that the inbound velocity is to the left (towards the radar, so a NE wind), and the outbound velocity to the right (away from the radar, so a SW wind). This indicates an area of cyclonic flow. Also notice how due south of Pawnee, there appears to be an area of red and green close together. This is an area of convergence. And finally, because this is all in the same spot, it is cyclonically convergent.
Notice the red box? That is a tornado warning that was issued by the National Weather Service earlier this evening. I guess they agree that this was a cyclonic converging cell capable of producing tornadoes.
The lower troposphere wants to show it’s love for the northeast. Look at this morning’s 850mb temps above (SOURCE Plymouth State Vortex) The -20 degree fill is in the shape of a heart *cues studio audience’s aww* Too bad they are 9 days short. (AND 11 days short of Jared Rennie Day…the nerve)
But doesn’t it just warm you up? Speaking of that. The ridge of warm temperatures are forecasted to clip the NE over this weekend. The 850mb temps could reach ABOVE freezing! This means that if we mix well, Highs could reach the low to mid 40′s this Saturday and Sunday!
