Friday, March 16, 2012

Now for Some Real IFR!

The cold temperatures prevailing aloft for the last few months have ensured that most flights conducted under Instrument Flight Rules (IFR) have actually proceeded in Visual Meteorological Conditions (VMC)...i.e., there's been ice in them clouds! So today I'm looking forward to actually getting N631S wet! I'm planning a departure a bit after 20Z from Connecticut and expecting a route over eastern Pennsylvania then down over Baltimore and into the DC area.
The key to this is a really big bubble of warm air over the middle of the country, working its way east. The plot at left shows the freezing isotherm for around 9,000 feet MSL projected to be well to the north of my flight path. (You can click on the image to make it bigger.) So whether there are clouds in my way, or not, doesn't matter much. I can be fairly certain that icing won't be an issue today.

Of course, you do have to take off and land. For those purposes, the forecasts for my departure and arrival airports are fairly benign. Here are the current Terminal Area Forecasts (TAF's):

KBDR 161325Z 1613/1712 12009KT P6SM OVC015 
     TEMPO 1613/1615 4SM -DZ BR BKN006 OVC010 
     FM161600 VRB05KT P6SM BKN010 OVC030 
     FM162300 VRB04KT P6SM SCT025 BKN040 
     FM170400 VRB03KT 4SM BR SCT020 OVC040 
     FM170700 VRB03KT 2SM BR BKN020
KDCA 161122Z 1612/1712 04007KT 4SM BR OVC006 
     FM161400 VRB04KT P6SM BKN008 OVC100 
     FM161500 VRB04KT P6SM BKN060 OVC100 
     FM161700 20005KT P6SM VCSH BKN050CB OVC090 
     FM162100 VRB03KT P6SM -SHRA BKN040CB OVC100
     FM162300 VRB03KT P6SM FEW040 OVC100 
     FM170300 33004KT P6SM BKN100
The pertinent forecast lines are highlighted in red. For departure from KBDR it looks like I should expect light winds, good visibility, and a broken ceiling at around 1,000 feet, overcast above. Arriving in the DC area I can look for light rain showers beneath a broken 4,000 foot ceiling of cumulonimbus (CB). The presence of CB's in the TAF implies a chance of convective activity, but not enough for thundershowers to be part of the forecast. And, as it will be getting on toward the valid time for the next line in the forecast (from 23Z) as I get there, conditions may be improving.

It looks like it should be a good flight.

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