METR 360

METR 360 Fall, 2017

Exam 2

Directions: Answer all parts of all questions in the blue books or write a text file which you may e-mail to Jerome.Blechman@oneonta.edu. For calculations, show all work. You may use any source, including your notes, any textbook or the Internet. You may NOT talk during the exam, except to me. Raise your hand if you have a question.

The following information may (or may not) be useful:

1. For the last forecast for Salt Lake City in WxChallenge you should have viewed the following MOS and direct model outputs:

GFS MOS (MAV)

KSLC GFS MOS GUIDANCE 11/02/2017 1200 UTC

DT /NOV 2/NOV 3 /NOV 4 /NOV 5

HR 18 21 00 03 06 09 12 15 18 21 00 03 06 09 12 15 18 21 00 06 12

N/X 58 70 51 65 44

TMP 65 69 68 61 61 61 62 62 65 65 62 55 53 54 54 57 61 59 55 49 46

DPT 39 36 36 38 38 39 40 41 42 39 38 39 37 36 36 37 36 34 35 37 38

CLD OV OV OV OV OV OV OV OV OV BK BK OV OV BK BK OV OV OV OV OV OV

WDR 18 19 16 16 16 16 16 16 18 22 29 15 16 16 16 16 19 22 31 34 14

WSP 14 14 11 12 16 21 23 19 21 15 11 10 15 15 15 16 21 21 15 05 07

P06 0 7 18 30 20 14 11 14 24 41 42

P12 19 31 16 30 53

Q06 0 0 0 0 0 0 0 0 0 1 1

Q12 0 0 0 0 1

T06 2/ 0 1/ 0 2/ 0 2/ 0 2/ 0 1/ 0 1/ 0 1/ 0 4/ 0 2/ 0

T12 2/ 0 2/ 1 2/ 1 1/ 0 4/ 0

POZ 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

POS 6 0 0 2 4 15 15 11 16 8 10 8 13 23 34 15 16 8 6 33 38

TYP R R R R R R R R R R R R R R R R R R R R R

SNW 0 0 0

CIG 8 8 8 7 8 7 7 7 7 7 7 7 8 8 8 8 8 8 7 7 7

VIS 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7

OBV N N N N N N N N N N N N N N N N N N N N N

NAM MOS (MET)

KSLC NAM MOS GUIDANCE 11/02/2017 1200 UTC

DT /NOV 2/NOV 3 /NOV 4 /NOV 5

HR 18 21 00 03 06 09 12 15 18 21 00 03 06 09 12 15 18 21 00 06 12

N/X 52 59 46 56 40

TMP 62 66 65 64 64 64 63 52 55 56 54 51 50 50 49 49 52 53 50 45 43

DPT 37 35 35 34 35 36 37 40 41 39 38 38 37 37 38 35 36 35 35 36 36

CLD BK BK OV OV OV OV OV OV OV OV OV OV OV OV OV OV OV OV OV OV OV

WDR 20 23 21 16 16 16 16 17 17 19 19 16 17 16 17 17 17 19 18 19 18

WSP 08 10 09 13 19 21 23 22 21 18 13 09 12 17 18 17 18 15 15 14 11

P06 1 1 7 32 20 6 2 3 16 39 57

P12 7 47 6 32 57

Q06 0 0 0 0 0 0 0 0 0 1 3

Q12 0 1 0 0 2

T06 1/ 2 2/ 0 1/ 0 2/ 1 2/ 0 1/ 1 0/ 0 1/ 2 3/ 2 12/ 2

T12 2/ 2 2/ 1 2/ 1 1/ 2 17/ 2

POZ 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

POS 6 4 1 0 7 1 5 5 9 8 14 19 12 11 14 16 12 14 12 22 34

TYP R R R R R R R R R R R R R R R R R R R R R

SNW 0 0 0

CIG 8 8 8 7 8 7 6 6 6 6 7 7 7 7 7 7 6 7 6 6 6

VIS 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7

OBV N N N N N N N N N N N N N N N N N N N N N

NAM Direct Model Output

Station: KSLC Lat: 40.78 Lon:-111.97 Elev:1286 Closest grid pt: 18.3 km.

Initialization Time: 17-11-02 1200 UTC

PARAMETER/TIME 000 006 012 018 024 030 036 042 048

------------------- ------ ------ ------ ------ ------ ------ ------ ------ ------

DAY / HOUR 02/12 02/18 03/00 03/06 03/12 03/18 04/00 04/06 04/12

------------------- ------ ------ ------ ------ ------ ------ ------ ------ ------

TEMPS

2 M (F) 52 52 46 42 42 42 39 37

850 MB (C) 12 15 11 8 8 9 7 6

700 MB (C) 1 2 3 -1 -3 -3 -4 -4

500 MB (C) -15 -15 -16 -16 -16 -16 -18 -18

1000-500 THCK 559 562 559 555 554 554 552 550

MOISTURE

2 M DEW POINT (F) 34 34 40 40 39 36 32 34

850 MB DP(C)/RH 3/54 3/44 7/78 7/95 7/90 5/77 3/76 4/90

700 MB DP(C)/RH -7/58 -3/67 -3/66 -1/94 -3/96 -4/97 -4/96 -7/76

500 MB DP(C)/RH -18/75 -18/77 -18/87 -34/19 -35/18 -28/34 -22/72 -26/52

PRCPABLE WTR (IN) 0.38 0.49 0.55 0.47 0.42 0.41 0.43 0.38

CONV PRECIP (IN) 0.00 0.00 0.00 0.00 0.01 0.01 0.00 0.00

TOTAL PRECIP (IN) 0.00 0.00 0.00 0.01 0.04 0.03 0.01 0.01

WIND DD/FFF (Kts)

10 M 23/010 19/007 18/015 19/014 21/013 21/009 19/010 19/011

850 MB 24/009 19/008 19/015 19/013 21/012 21/009 20/009 19/011

700 MB 26/025 22/022 22/023 22/026 22/024 21/024 22/026 23/029

500 MB 27/050 26/047 24/039 24/039 25/041 25/043 25/048 24/057

250 MB 27/075 26/076 24/080 25/084 25/088 25/103 25/108 24/094

PRESS/HEIGHTS

MSL PRESSURE 1010.2 1006.5 1010.4 1011.8 1012.2 1010.6 1013.3 1012.6

850 MB HGT 147 145 146 146 147 145 146 145

700 MB HGT 306 305 305 303 304 303 303 301

500 MB HGT 568 568 568 564 564 562 563 560

250 MB HGT 1056 1057 1055 1050 1048 1047 1046 1042

VERTICAL VEL (uB/S)

850 MB 29 -6 -21 -3 18 17 -2 -13

700 MB 55 4 17 48 52 16 18 21

500 MB -34 13 -2 -18 -9 3 -8 -3

GFS Direct Model Output

Station: KSLC Lat: 40.78 Lon:-111.97 Elev:1286 Closest grid pt: 18.3 km.

Initialization Time: 17-11-02 1200 UTC

PARAMETER/TIME 000 006 012 018 024 030 036 042 048

------------------- ------ ------ ------ ------ ------ ------ ------ ------ ------

DAY / HOUR 02/12 02/18 03/00 03/06 03/12 03/18 04/00 04/06 04/12

------------------- ------ ------ ------ ------ ------ ------ ------ ------ ------

TEMPS

SFC (2 M) (F) 43 53 53 46 45 49 48 42 39

850 MB (C) 10 14 15 11 10 11 12 9 7

700 MB (C) 2 1 2 2 0 -2 0 -1 -2

500 MB (C) -15 -15 -15 -15 -16 -17 -16 -17 -19

1000-500 THCK 558 559 561 559 556 555 556 555 552

MOISTURE

30 M AVG RH 67 56 47 67 82 68 60 54 64

850 MB DP/RH 6/73 4/53 4/46 5/66 7/80 5/64 4/59 1/57 1/66

700 MB DP/RH -6/56 -5/64 -2/74 -3/71 -2/89 -3/93 -3/81 -5/70 -7/68

500 MB DP/RH -24/46 -17/86 -17/86 -20/70 -29/33 -22/62 -27/38 -19/85 -23/70

CONV PRECIP (IN)

TOTAL PRECIP (IN) 0.00 0.00 0.00 0.03 0.03 0.03 0.00 0.00

WIND DD/FFF (Kts)

30 M AVG 20/013 22/011 20/009 19/017 19/018 21/016 22/006 19/015 19/013

850 MB 18/009 22/009 20/006 18/012 19/013 21/014 22/004 18/010 18/008

700 MB 25/020 24/021 22/022 22/025 22/027 22/023 22/022 22/027 23/026

500 MB 28/055 26/047 26/046 24/038 24/038 24/036 25/040 25/046 24/051

250 MB 28/082 27/076 26/076 25/077 25/081 25/079 25/097 24/104 25/095

VERTICAL VEL (uB/S)

850 MB 18 0 -17 -9 23 14 -14 -21

700 MB 44 27 38 35 35 55 35 46

500 MB -18 6 -10 -9 -12 -25 3 7

OTHER

MSL PRES (MB) 1008 1010 1009 1011 1011 1011 1009 1011 1009

500 MB HGT (DM) 565 568 569 569 565 565 564 564 561

500 MB ABS VORT 6.8 4.6 9.2 4.9 12.9 12.6 13.5 8.4 11.8

The verification for November 3 was Max: (64°F) Min: (48°F) Wind (24 knots) Precip: 0.01" In comparison, the verification for November 2 was (72°F) Min: (49°F) Wind (23 knots) Precip: 0.00"

a. ( 5%) The GFS and NAM MOS forecasts were very different and both wrong. Other than N/X, what guidance shown on this exam was consistent with cool surface temperatures at KSLC that would max out at 64°F on November 3? Note: I’m not asking for your own personal forecast. Look at this guidance (MOS and Direct Model Output) only.

b. ( 9%) It rained at KSLC! It was only 0.01” but only one person on the NYO team (Delaney) went for nonzero precipitation. What three (3) predictions other than TOTAL PRECIP (IN), shown on the Direct Model Output only were consistent with measurable (>0.00”) precipitation at KSLC in the period from 06Z Nov 3 to 06Z Nov 4? Be specific about what parameters you are picking and what day/time these occurred. You do not have to explain why you picked them or how they worked. And you may pick any combination of parameters from GFS and NAM Direct Model Output (e.g. 2 from GFS and 1 from NAM or 0 from GFS and 3 from NAM, etc.)

c. ( 16%) Describe the weather (temperature, humidity, precipitation) that was forecasted to be experienced at KSLC from 06Z November 3 to 06Z November 4. Write two separate descriptions, one for the forecast by the NAM model and one for the forecast by the GFS model. Relate each of those two descriptions to surface weather elements which would fit. For example, was there a frontal passage at the surface? If so, describe what kind of front, when it would pass, and what the effects would be.

2. For this question, refer to the series of 500 mb maps from October 2016, shown in a PowerPoint file.

a. ( 6%) The trough axis travels from KUIL (Quillayute!) to KBOS (Boston) in exactly three days or 72 hours. Using a GoogleMaps product, those two NWS stations are 2567 miles apart. What is the speed of that trough for those three days? Do not use the Rossby wave equation. Express your answer in m s^-1. Show your work for the calculation.

b. ( 3%) Using your answer to part a, was that wave progressive, retrograde, or blocked? Short answer

c. ( 8%) Again, using the speed you calculated for part a, if the latitude of the wave was 49°N, what was the mean west-east wind speed across the U.S.? For this you use the Rossby wave equation. Express your answer in knots. Show your work for the calculation.

d. ( 5%) While the wave was in the midwestern U.S. at 00Z on Oct 13, 2016, the winds were around 60 knots from 270° in central Illinois. That was probably different from your answer to part c. Briefly explain why, assuming that both your calculations and the observed 60 knot wind were correct.

3. This is a question about the situation on October 24, 2017. You have a small CONUS map, a large North American map, and the 850 mb, 700 mb, 500 mb, and 300 mb maps.

a. ( 3%) On the 850 mb map, KALB is reporting a south wind at 65 knots with a temperature of 12°C. Does this situation mean cold air advection, warm air advection, or neither?

b. ( 6%) Is the flow at 300 mb zonal, meridional, or neither? Why did you choose that answer?

c. ( 5%) The 500 mb map shows heights and vorticity. There is a Low (marked L) over northern Lake Michigan. What is the maximum value of vorticity associated with that Low? You may need to magnify the map to see it. Use the correct units and scaling.

d. ( 6%) Describe the vertical tilt of the storm that is shown at the Great Lakes at the surface. This need not be quantitative, but you must refer to locations on the upper air maps and specify the direction of the tilt from map to map up to 300 mb.

e. ( 6%) Considering the tilt you described in part d, how does that tilt affect the weather at the Earth’s surface? Be as specific as you can. Hint: look closely at the CONUS to see the weather being reported.

4. This question refers to a closeup 500 mb map with stations plotted but not analyzed for isopleths. Stations A, B, C, and D are shown with observations which have been embellished for this question only. A and B are 400 km apart. C and D are also 400 km apart. The fictional station KNYX is located directly in the middle, where lines connecting A to B and C to D would intersect. KNYX is at 42.5°N.

a. ( 8%) Using the information given, calculate the relative vorticity (ζ) and absolute vorticity (η) using the correct units. Show your work. Watch your signs!

b. ( 3%) What type of vertical motion would be associated with your answer to part a? Short answer

5. For this question you have a 12Z CONUS surface map, the North America Zoom-in map, the 12Z 850 mb map, and a lake surface temperature map.

a. ( 5%) Name the areas which are likely to be receiving lake effect precipitation from the Great Lakes (e.g., northern Wisconsin, southern Michigan, Pennsylvania and New York, etc.).

b. ( 6%) List the factors that were present that were favorable for lake effect precipitation in the areas you chose for part a.