1. Predict Today S 18Z Temperature Using the ATH for the Following Cities: BOS, NYC, DCA

Lab 1 Fall 2009 Name

We will be using the analogous thickness technique (ATH) to make several temperature and dewpoint forecasts, max temps, and some cloud observations. Our primary guidance will be the 4-panel maps of the WRF and ETA. For this lab, “TODAY” is September 10.

1. Predict today’s 18Z temperature using the ATH for the following cities: BOS, NYC, DCA a. Begin by viewing the 30-hr forecast valid 18z, 9/10 ( http://www.meteo.psu.edu/~jps33/m415/f30.gif ). Note the thickness and sea level pressure value at each of the sites by filling in the table below. Also, mentally take note of each city’s location relative to general weather features such as fronts, and high/ low pressure systems. b. Now view the 06-hr forecast valid 18z, 9/09 to locate the analogous region (http://www.meteo.psu.edu/~jps33/m415/f06.gif ). Circle the analogous region on the 1000-500mb thickness panel of this 12-hr forecast. The size of your circle should be about one half of the size of Pennsylvania. c. Now circle the same region on the observed 18 Z surface chart (http://www.meteo.psu.edu/~jps33/m415/18Zobs0909NE.gif). and label each region accordingly (i.e. B = BOS, N = NYC, etc). Once you’ve done this, go ahead and make your excellent forecast by taking an “average” value inside the analogous region.

http://www.meteo.psu.edu/~jps33/m415/18Zobs0909USA National 18Z obs THK SLP YOUR 18 Z FORECAST BOS NYC DCA

2. Predict today’s 18z dewpoint temperature using the ATH for the following cities: BOS, NYC, DCA. a. Begin by viewing the 30-hr forecast valid 18z on 9/10 (http://www.meteo.psu.edu/~jps33/m415/f30.gif). Note the thickness and sea level pressure value at each of the sites by filling in the table below. Also, mentally take note of each city’s location relative to general weather features such as fronts, and high/ low pressure systems. b. Now view the 6-hr forecast valid 18z on 09/09 to locate the analogous region (http://www.meteo.psu.edu/~jps33/m415/f06.gif ). Circle the analogous region on the 1000-500mb thickness panel of the 12-hr forecast.

c. Now turn to the today’s 18z surface analysis to determine the dewpoints in the analogous region (http://www.meteo.psu.edu/~jps33/m415/18Zobs0909NE.gif). Circle this same region on this chart and label accordingly. Then make your fantastic forecast by taking an “average” value inside the analogous region.

http://www.meteo.psu.edu/~jps33/m415/18Zobs0909USA National 18Z obs

THK SLP YOUR FORECAST (Td)

BOS NYC DCA

3. Predict today’s MAX temperature using the ATH for the following cities: BOS, NYC, DCA a. Begin by viewing the 30-hr forecast valid 18z, 9/10 ( http://www.meteo.psu.edu/~jps33/m415/f30.gif ). Note the thickness and sea level pressure value at each of the sites by filling in the table below. Also, mentally take note of each city’s location relative to general weather features such as fronts, and high/ low pressure systems. b. Now view the 06-hr forecast valid 18z, 9/09 to locate the analogous region (http://www.meteo.psu.edu/~jps33/m415/f06.gif ). Circle the analogous region on the 1000-500mb thickness panel of this 12-hr forecast.

c. Now circle the same region on the observed max temp chart (http://www.meteo.psu.edu/~jps33/m415/maxtemp.gif ). and label each region accordingly Once you’ve done this, go ahead and make your excellent forecast by taking an “average” value inside the analogous region.

THK SLP YOUR MAX TEMP FORECAST BOS NYC DCA

4. This question involves using analogous methods to forecast cloud location. a. Begin by viewing the satellite picture valid at 18z Monday September the 6th, (Labor Day 2004), and note where it is mostly cloudy. http://www.meteo.psu.edu/~miner/m415/sat.gif

b. Trace the location of clouds from this satellite picture onto the 700mb relative humidity panel of the 6-hr ETA forecast (also valid at 18z, http://www.meteo.psu.edu/~jps33/m415/20040906.png ). c. What conclusions can you make about the relationship between the 700mb relative humidity and where it is mostly cloudy? Explain below

d. Take note of the clouds in south-central Pennsylvania in the satellite picture. What is the ETA’s approximate 700mb RH at this time over central PA? . Would you have predicted these clouds to be in central PA given the ETA’s 700mb relative humidity forecast? Explain:

e. Although 700mb is a good level to correlate relative humidity with cloud cover, sometimes it is useful to observe the RH at other layers to catch low clouds or high clouds. Given this, take a look at the ETA RH pattern 850 mb, just to the right of the 700 mb panel. At what altitude are these clouds in south-central Pennsylvania?, What type of clouds are they?

http://www.meteo.psu.edu/~jps33/m415/20040907.png ).