July 26.                       min.      max.       avg

Bitt 2nw valley        58.1       77.6       67.8

Garrett College        61.0       78.4      69.7

Can-Heights            59.5        74.2      66.8

CRN-Canaan           57.6        74.1      65.8

Cabin Mt                 57.7        71.6      64.6

Cabin Mt north      58.6        72.7     65.6

Spruce Knob          56.5        70.5     63.5

Snowshoe               58.8        70.2     64.5

Can-Valley Floor    48.2        77.0     62.6

7Springs                  61.5        75.0     68.2

Dreary looking start, some fog, low clouds and that then burnt off for a mix of clouds and sun of varying amounts from late morning, through evening with the sunny side of things increasing as the day went by.

Temp profile this afternoon

Satellite this afternoon

Radar, mostly last evening in where it did rain, with 24 hour estimates running back to 7pm 7/25

Flow

surface features and 500mb height anomalies

500mb flow

SST(Sea Surface Temperature) anomalies and 7 day change

Off The Models

Meteogram off the 12z ECMWF for Garrett County

12Z ECMWF

3 hourly precip

Total Precipitation

18z GFS

6 hourly precipitation

Total Precipitation

18Z 3km Nam

2m Temperatures

2m Dew Points

Simulated Radar

Total Precipitation

10:30pm reality, model comparison

The new 0z 3km Nam run is in. So thats the go to choice. The formula I’v been watching, to get a good feel for what the cold frost pockets can achieve is

1- 10m wind off the 3km Nam calm. In this case, we can check that off. At least for the valley spots. While 3km is high res, its still not tight enough to pinpoint details, but gives great hints.

2- Cloud cover, are we seeing clear skies. The 3km nam does very well at this. In this case, checked this off. 

3- 2m Dewpoints. Pretty big component. Again, 3km nam is detailed, but not tight enough for minute details. The observations and comparisons has led to the conclusion on many many occasions, that, with a dry air mass incoming, or in place, calm winds, clear skies, subtract 4-8° from the 3km nam modeled dewpoint and that is generally where the 2m temp comes in at in the cold pockets. Placement of the modeled 2m Dewpoints is not important. If conditions above(1&2) check off the list. Ex. If the models lowest dewpoint is in Elkins at 45 and Canaan reads 55 on the model,  Canaans frost pocket actual dewpoint, air temp, if conditions(calm, clear)of 1 and 2 are equal to Elkins, (on the model) reality should run 38-42° 2m air temp.  In the case below off tonights 0z 3km nam, 56.2° dewpoint is the min at the example time. All in all for this example, lowest dewpoints are in the ballpark area of the conversation, despite it doesn’t have to be. 

4- While in cases of east flows, CAD events, even daytime maxes with a breeze I love the 3km nam, (best there is bar none, beats HRRR easily) it is not good at hitting cold pockets. Again, not in tight enough for small details even at 3km, but I would think as in the current case, and many other times observed, it should do better. With 0 wind, 56° dewpoint, clear skies, why is it not modeling pockets of cooler temps? 3km should be enough to do that. This aspect of the model is one of its problems on 2m temps. Its not always great at convective storms and will falsely on the model cool locations that do not occur. That’s another downfall.  It is though great for frontal timing however. Currently, thumbs down for tonights example on temps. Way to warm. 

Reality views. While the valley frost pocket has no anemometer, its evident conditions are calm, while at 4000′ a 10mph exist. The model, looks decent. At 4000 its 63°, not bad on the model, 51° in the colder valley area, no clue on the model, except using the 1,2,3 formula from observations of the model to reality.

Reality at a little past 10:30pm

(To note, Hrrr last night showed clear skies through daybreak, 3km nam showed increasing cloud cover and temps creeping up, 3km Nam did well.)