Tuesday, June 30, 2009

Frontal Weather

Last Friday's trip from Connecticut to Maryland turned out to be an adventure in dealing with frontal weather. It was obvious on Thursday evening that the cold front approaching from the west would require adaptive planning but the details were well in the future so I filed an IFR flight plan for the route from KBDR to KVKX that the Air Traffic Control computer always gives me:

SAX V249 SBJ V30 ETX V39 LNS V93 BAL Direct

By mid-afternoon on Friday it was clear that that was not going to work! Severe weather associated with the front was generating Convective SIGMETs in eastern Pennsylvania and the associated lines of thunderstorms were heading east at about 25 knots...so most of the filed route would not be flyable.

After discussing the situation with Flight Service I amended my flight plan for a more easterly routing:

DPK V16 ENO V379 OTT Direct

This would take me across the sound to Long Island, over Kennedy Airport, down the New Jersey coast to Dover, DE then into Maryland and home. The idea was to get down into the DC area before the frontal weather crossed New Jersey to close off the route.

By the time I got to Sikorsky Memorial Airport, there was nothing much happening. The latest observation was:

KBDR 262052Z 34003KT 10SM FEW110 26/19 A2967 RMK AO2 SLP049 60001 T02610189

Just a slight breeze from the north, with ample ceiling and visibility. However, severe weather was approaching. The situation on the NEXRAD display looked like this:

NEXRAD image of KBDR area at 2033Z 26 June 2009

(You can click on any of the images in this post to view a larger version.)

I needed to be on my way in something of a hurry...and that clearly needed to involve departing to the south. So after pre-flighting N631S with all deliberate speed I called KBDR Clearance Delivery and was unsurprisingly given "Radar vectors to SAX, V249, SBJ,...etc."

My response was, "I cannot accept that clearance due to the active Convective SIGMET over V30 and V39. Request Direct Deer Park, V16 to ENO, direct OTT direct." That produced a "631S, stand by," from the tower and I proceeded to "stand by" for about ten minutes. As the weather approaching from the northwest got to look ever more menacing.

About five minutes before the point when I would have to give up on the trip, the tower called to offer a revised clearance:

Radar vectors to DPK V16 DIXIE V1 ATR BILIT DCA Direct.

Now I knew they did not want me to going to DCA (the VOR on the field at National Airport in DC). But this was not the time to argue a fine point so I read back the clearance, got cleared for takeoff and departed. Wheels off the runway about 5:17 PM. By that point the situation looked like this:

NEXRAD image of KBDR area at 2115Z 26 June 2009

That small white dot just off the Connecticut coast is labeled N631S. (The position is taken from the FlightAware track log.) At that point I was on an 090 vector (i.e., eastbound) assigned by New York Approach for sequencing onto V16. In short order they turned me to the south across the sound, then to the west toward DPK, the Deer Park VOR.

At about this time the weather at KBDR was deteriorating rapidly:

KBDR 262138Z 34013G17KT 10SM FEW026 BKN033 BKN090 24/19 A2968 RMK AO2=

Winds at 13 knots, gusting 17 from the northwest with layered clouds. Just a few minutes later the storm arrived:

KBDR 262147Z 33014G21KT 10SM -TSRA SCT029 BKN048 OVC090 23/16 A2970

Inside N631S approaching JFK on V16, the Garmin GPSMap 396 NEXRAD image showed this situation:

GPSMap396 image 2150Z on 26 June 2009

This display is "track up" so north is on the right. All of that colorful stuff is the frontal weather arriving at the Connecticut coastline. By this point it was clear that I'd easily make the southbound turn at JFK before the weather became excessively entertaining. This occurred at about 2155Z:

Headed away from JFK to the south at 6,000 feet the air was smooth and visibility good.

I listened as the weather closed in on the New York airports and JFK, LGA, TEB and EWR became unavailable for arrivals. Lots of holding instructions were being issued to commercial traffic and a number of crews were expressing concern about fuel state.

I was pleased to be clear of the New York area and looking forward to a period of "clear sailing". But I still had to be concerned about the weather at my destination. My plan was to watch the weather in the DC area. If it closed off early I'd divert to an airport along my route (Atlantic City or Millville or perhaps even Baltimore). If it appeared that KVKX weather was holding up I'd proceed inbound and if necessary divert to the south (possibly to Richmond).

When I was handed off to Dover Approach I took advantage of the opportunity to clear up that nonsense about having DCA in my clearance. In fact, they were surprised because their strip showed me routed after ATR to OTT thence direct to KVKX. OTT is the Nottingham VOR and that made a great deal of sense. Problem solved.

I was keeping a weather eye (pun intended) on a storm cell just to the north of DC and moving ver-r-r-r-y slowly toward where I wanted to go. That was going to be the challenge!

Arrival at KVKX was going to be at about 2340Z and at 2315Z the situation looked like this:

The white dot over the Maryland eastern shore is N631S and the dot just south of the severe weather is KVKX. At this point Washington National (KDCA) was reporting:

KDCA 262312Z 21008KT 10SM FEW030 BKN065 BKN250 29/21 A2970 RMK AO2

Gentle southwest breeze, good visibility, plenty of ceiling. Press on!

I crossed Chesapeake Bay and cleared OTT. Potomac Approach brought me down to 3,000 feet and I could see the weather in the distance. I did not slow the airplane down. By 2329Z I was close in and could see the airport:

A short time later the controller at Potomac Approach, who was staying with me and doing a great job, said that DCA had just reported a major wind shift. But I was just then turning base for Runway 24 at KVKX. I landed in a flat calm at 2337Z:

It should be noted that these NEXRAD images show composite reflectivity and that the surface weather was not as evil as the depiction just above would have you think. I had time to fuel the airplane and taxi to the hangar before the storm arrived in earnest. I watched it rain from inside the hangar for about fifteen minutes and then winched N631S inside and put it to bed.

To summarize this very long post, here is the track graphic from FlightAware:

KVKX did not get the worst of that storm cell but Andrews AFB, just a few miles away, did record some pretty serious weather. At five minutes after the hour:

SPECI KADW 270005Z 09014G61KT 060V120 M1/4SM R01R/0500V2200FTR01L/1200V4000FT +TSRA VV016 20/17 A2976 RMK AO2A PK WND 04061/0001 WSHFT 2350 PRESRR SLP079=

Yes, that was a 61 knot gust at 0001Z during heavy rain.


LarryPetro said...

Frank, Ah, ATC's mysterious routing. I've flown from KVKX to near, or over KBDR (KHPN, KFRG, KOWD, and KBED). Departing KHPN, I had an experience similar to yours - big storms and a front over SBJ and ETX, quite reasonable to the South along V16. I filed the route that you were eventually given, along V16. Clearance gave me the route to the West, through the thunderstorms. They were unwilling to change. Fortunately I could depart VFR, which I did and continued VFR. My 396 allowed me to verify the slow progress of the front and weather at airports ahead of me. -Larry

Frank Van Haste said...


One reason that I was able to get the reasonable route and you weren't may be that Bridgeport Tower is quite good about advocating for their pilots with TRACON...and I don't get the feeling that KHPN Tower is all that interested in we small fry.

Regards, and thanks for commenting,