Foot's Forecast | Weather Intelligence

"I'M WALKING ON SUNSHINE..."

by Aly & Aj from the Album "Into The Rush"

10:40 PM evening update

This is what walking on sunshine is like in the Foot household, when I can watch my little girl participate in her first big snowstorm. Ironically this is arriving on the 23rd anniversary of my first big snowstorm as a child, the Feb 11 Blizzard of 1983. (The date says 2/12 because the camera is set incorrectly, but trust me this was around 7 PM Saturday).

So here we are about to turn the corner and go into the long night of what may be terrifically heavy snow for some (DC to NYC ) or a long night of anticipation for others (Boston on north). Heck I even heard that Tampa NWS is calling for flurries tomorrow. At the current rate of snowfall in the Baltimore region, it appears my 4" is going to verify and probably go over. This might sound wishy-washy, but my original forecast as posted in earlier statements and on the email distribution list was 4" in Dundalk by midnight Saturday. That looks to be right on. But the storm is no where near over. I can now see on radar the long expected "pivoting" of the comma head and the Low now deepening off Albemarle Sound in coastal NC. It seems likely that bands of heavy snow will continue to redevelop over the I-95 corridor into the night as moisture rotating in from the Atlantic gets "wrapped around" by the return flow on the NW side of the storm. I also see that our old friend NAO has slowly trended from slightly negative to neutral in the past few days and I have said many times before that is an essential piece of the puzzle needed to get a Nor'easter to turn up the coast ever so gently in order for the Mid-Atlantic to get blasted.

The next graphic shows what accumulations I expect to occur over the next 8 hours... from 10:00 PM to 6:00 AM. This assumes that all of my numbers posted earlier verify and you would add on top of those to get your storm totals. For our friends in the North...specifically Southern New England, I will do a separate forecast for you Sunday morning. The numbers you see here are supposed to represent the locations of our frequent viewing friends and what I think will fall at your house between NOW and 6:00 AM. So please post your observations first thing tomorrow so we can compare notes.

I am not going to pretend that I was right all along and change my story to make it sound like I really nailed this one. I do think it is fair to say that I accurately predicted 3 days in advance the amount of snow that would be on the ground by midnight in my backyard. On Thursday 2/9 I said 4" by midnight. But in all fairness, I underestimated the ability of the storm to maintain a large snow shield when it was still in developmental stages. I also did not expect the storm to hug the coast as much as it did, and seeing the NAO now makes me realize that was probably going to be the case from the beginning. It will be interesting to see what the storm does once it moves out of the above normal waters of the Gulf Stream and into the below normal waters south of Long Island and off the Jersey Coast.

So the Final Word on this Storm, I think it will be ranked a 3 on the newly established NESIS (Northeast Snowfall Impact Scale) created by our buddy Paul Kocin of TWC and Louis Uccellini of NWS in 2004. I compare this most closely with the Jan 22, 1987 storm which has a special place in my heart for a few reasons I'll explain later.

IS IT TIME TO EMBRACE THE HORROR

OR REJECT THE HYPE?
How Big Kahuna #1 of 2006 may end up a Boston Blizzard and a Baltimore Bust

RED ALERT CHANGES TO THE WEBSITE FOR THIS STORM EVENT
COMMENTS HAVE BEEN ENABLED TO ACCEPT FROM ANYONE WITHOUT REGISTERING
PLEASE POST OBSERVATIONS WHEN YOU HAVE ONSET OR MEASUREABLE PRECIP
PICTURES OF THE EVENT WILL BE POSTED AS TIME AND CHILDREN PERMIT
If you wish to be added to the email distribution list, send a message to rfoot@bcps.org
If you already submitted your name, I added about 30 names just since 8AM. Thanks.

FOR THE BASIS OF SCIENTIFIC DISCUSSIONS, LET ME REMIND OF TWO THINGS:

1. While I believe parts of this storm will not deliver the predicted 8-14" for some areas, I did call the onset of this storm back on January 25 when I said, "Major East Coast Snowstorm in the February 10-20 time frame" that is for anyone who thought I was slipping in my old age.

2. I have been skeptical of the forecasts for this storm from the beginning, and since Thursday, 2/9 I have been flatly stating to colleagues in the Baltimore region that this would not deliver more than 4-5" all together. I am going to hold firm to that forecast UNTIL I see with my own eyes a solid 4" on the ground in my backyard. Then I will adjust amounts.

WHAT FOLLOWS IS A TRANSCRIPT OF MY EARLIER FORECASTS POSTED IN THE EMAIL LIST ON THU 2/9 AND FRI 2/10 for those who have just joined the distribution list today, so you know the basis of the forecast.

(Emailed Thursday 2/9/06 to the Distribution List)

SNOW: Yes.
WHEN: Saturday noon to Sunday morning
HOW MUCH: 4 inches on the ground by midnight Saturday in Dundalk, MD
COLD & WINDY: Yeah sort of... highs around 35 with winds of 15-20 mph
BLIZZARD: No.
EARLY DISMISSAL FRIDAY: No. Didn't you read the part about the storm starting SATURDAY.
DELAYED OR CLOSED MONDAY: No. Crews will have enough time to clear lots by Monday AM.
ANY CHANCE THIS COULD BUST AND GO OUT TO SEA OR BECOME ALL RAIN: Yes
CONFIDENCE INTERVAL OF THIS FORECAST: High
WHY? Because National Weather Service computers project roughly .5-1.0 inch of "liquid equivalent" to fall out of the sky over the Baltimore Metro region. See this link: http://www.hpc.ncep.noaa.gov/qpf/d13_fill.gif (The purple is about .50 inches)

In a normal storm situation, 1 inch of rain is 10 inches of snow at 30 degrees. Since the Saturday temp will be closer to 35, you have to knock a few inches off the possible 10", and a few more inches due to higher sun angle and a later start time, however the ground will be plenty cold for any precip to stick on contact. Factor in that this storm is likely to be a quick mover, and strong winds behind it will blow the snow around, hence 4 inches is my final answer. (Sat PM comment, actually the ground ended up being warmer than I thought)

My forecast accountability procedure dictates that I am graded on how close to the predicted number on either side of the equation (whether over or under). Thus, if prediction is 4" and we get 5" that is 80% and a B. Or if we get 3" of the 4" = 75% and a C.

(The following was emailed to the Distribution List on Friday morning 2/10)

If you read Thursday's comments on this storm, then you know everything there is to know about what will happen in the Baltimore Metro Region.

"BUT... BUT... THE NEWS SAID 6 - 12" !!!"
They're wrong. Ain't nobody in all of Baltimore County gonna get 12 inches.

All y'all will have 4 INCHES on the ground by midnight Saturday from
Towson on south to DC, and MAYBE 6 inches MAX from Towson on north
to the PA line. (Okay, Hereford gets 6.2) Here's why:

1. High Pressure in Canada is NOT in an ideal location for a big Baltimore storm.
That alone makes me discount this storm somewhat.

2. It's Cloudy right now (8AM Friday). That's baaadd, because the clouds act as
thermal insulator, and hold any heat at the surface in. Sun shines through clouds,
creating a wintertime greenhouse effect. Any heat generated today will be trapped
overnight, making more difficult for the early stages of the storm to produce heavy snow.

3. Though the sky is cloudy, the air is dry and this forces the storm to work harder
because it has to "moisten the column" of air in order for snow falling up there to
get down here before evaporating. Granted this phenomenon of "evaporative cooling"
will chill the atmosphere, but not so much that 4 inches turns into TWELVE! sheesh.

4. The orientation of the polar and subtropical jets are such that as the storm develops,
it will get squeezed by the jets as they amplify and come together, ejecting the storm
out by the Virginia capes. This will be a thump, dump, done storm.

5. To get the "12 inches of biblical porportions", any location would have to see at
least 1 inch per hour for over 10 hours. This storm will not have the staying power required
to sustain such consistently high snowfall rates over a long period of time.

Happy Friday!

Forecaster Foot