Here is the latest MOS output for KBDR from the GFS Model. (That stands for Global Forecast System.) It's based on the 12Z model run on Wednesday, March 4th, and looks 84 hours into the future. The block of time we are interestd in is from 21Z Friday the 6th to 00Z Saturday the 7th.
KBDR GFS MOS GUIDANCE 3/04/2009 1200 UTC
DT /MAR4 /MAR5 /MAR6 /MAR7
HR 18 21 00 03 06 09 12 15 18 21 00 03 06 09 12 15 18 21 00 06
N/X 14 40 31 45
TMP 28 29 26 24 20 18 17 29 37 39 36 34 33 33 34 37 42 43 42 40
DPT 8 9 11 11 10 9 9 13 17 21 25 26 29 30 31 33 36 38 38 35
CLD CL CL CL CL CL CL CL CL CL FW BK OV OV OV OV OV BK SC BK OV
WDR 29 29 28 30 29 31 31 26 22 20 19 20 21 20 22 25 26 25 26 27
WSP 10 09 06 04 04 04 02 04 06 06 06 08 07 07 10 12 13 09 07 04
P06 0 0 0 0 1 6 24 18 3 0
P12 0 1 27 22
Q06 0 0 0 0 0 0 0 0 0 0
Q12 0 0 0 0
T06 0/ 0 0/ 2 0/ 0 0/ 0 0/ 0 0/ 0 0/ 0 0/ 0 1/ 3 0
T12 0/ 2 0/ 0 0/ 0 2/ 0 1/ 6
POZ 2 2 0 1 0 0 2 1 2 1 4 6 18 18 13 5 4 2 0 0
POS 87 95 95 95 94 91 96 97 93 88 71 29 19 11 1 0 0 0 1 4
TYP S S S S S S S S S S S R R R R R R R R R
SNW 0 0
CIG 8 8 8 8 8 8 8 8 8 8 8 8 7 7 8 6 7 8 8 8
VIS 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 2
OBV N N N N N N N N N N N N N N N N N N N FG
As you can see, this model is forecasting a temperature of 43 deg F at 21Z on the 6th (that's 4 o'clock in the afternoon EST) with a 5 degree spread between temperature and dew point. The probability of precipitation is very low (3% or so) and the ceiling and visibility are both expected to be good. (An "8" for ceiling means that any solid cloud deck will be at least 12,000 feet up and a visibility of "7" means you can see more than 6 miles.) Note that the model is calling for fog to develop around 06Z (about 1:00AM), reducing visibility to less than a mile.
If you use the link at right (in my link list) to look at the MOS site, you can check on the forecast for this block of time at other stations on the expected route. I've had a look at Lancaster, PA (KLNS) and Washington, DC (KDCA) and found similar conditions -- temps in the low 50's at Lancaster, high 50's at DCA...low POP's, high ceilings and good viz in both places. The model forecasts winds at DCA from 210 deg at 7 knots at 00Z. This is all good!
While we're at that site, though, we should look at the forecast from a different model, the NAM (North American Mesoscale model). This model crunches the data differently and is not nearly so encouraging! For Bridgeport it predicts a temperature of 41 degrees F, a POP of about 30% and an overcast between 1,000 and 1,900 feet above the ground (albeit with good visibility underneath). Lancaster has 48 degrees and a 25% POP with the overcast between 3,100 and 6,500 while at DCA the model forecasts 54 degrees, minimal POP and the ceiling up to between 6,600 and 12,000 feet with wind from 220 degrees at 7 knots.
So if the GFS model is right then visual flight conditions will prevail...but if the NAM model has it closer then it's IMC for at least the beginning of the trip. This makes it very important to understand how far above the ground the freezing level will be. We'll look at that in the next post.
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