1. Forecast Verification time!
Perfect Forecast ?

2. The Dr. Titley residence (one block from campus)79 SE

3. Perfect Forecast
ERI 79 SE
PIT
SPC
HAR
PIT
PHL

4. DAY 2 Winners

5. Let’s talk about those surface winds ….
SURFACE PRS + WINDS

6. Let’s talk about that Philly TD (Dew Point) ….
SURFACE MAP

7. 45
Convection 58
Conduction 64
Sun heats
ground

8. Convection = Buoyancy
Examples ….
Swimming Pool (B-Ball)
This is cool!

9. Forecast Techniques Climatology Persistence = No change from prior day
Modified Persistence
First Guess = Persistence
Modify FG based on changes

10. TEMPERATURE Cause of temperature to change: Sunshine? Cloud Cover?
Wind direction?
Bodies of water

11. MONDAY H

12. TUESDAY H

13. 500 mb map- GFS model. Valid 8 p.m. TUESDAY
Z = EDT
12z=8 am
18z=2 pm
00z=8pm
06z=?

14. SLP map- NAM model. Valid 8 p.m. EDTH

15. SLP map- NAM model. Valid 8 p.m. EDTH
SPC

16. Penn State Weather Camps
Basic Weather Forecasting Guidelines
Sat I – Sat II – Sat III - NWS – SPC - NHC – Radar - Radar - Radar
E-WALL - sfc. map 1 - sfc. map 2 - ltg

17. THIS EVENING – 500MB
SPC

18. THIS EVENING – SURFACE MAP
SPC

19. DEW POINT TEMP TODAY ( 2PM – 8 PM EDT)
SPC

21. THIS EVENING – 700MB RH

22. ACCUM PRECIP – 18Z TO 00Z
(2 PM – 8 PM)

23. Joe Schmo 90 Y
3.50” PA

24. WHAT IS CLIMATOLOGY ? How the weather behaves over
a long period of time.
Weather – Behavior of the atmospheric over a much shorter
period of time

25. NORMAL? CLIMATOLOGY 81 TEMPS Avg./mean: Median: Range: 82 90 - 68
30 year period - common 81
NORMAL?
TEMPS
Avg./mean:
Conforming to a
regular pattern;
typical
Median:
Range: 82
Std. dev. 7
60’s =
70’s =
80’s =
90’s = 2 8 18
RAIN
Avg./Mean:
Range:
% time:
0.15”
0-1.79”
43%

26. ASSUMES NO CHANGE ! WHAT HAPPENED … WILL CONTINUE TO HAPPEN
WHAT IS PERSISTENCE ?
ASSUMES NO CHANGE !
WHAT HAPPENED …
WILL CONTINUE TO HAPPEN

27. Climatology Forecast
Persistence Forecast
Key West Chicago
CLI 6/ 6/ 6/ 6/ 6/ 6/ 6/
AVG ERR.
1.3 9
Key West Chicago 6/ 6/ 6/ 6/ 6/ 6/ 6/
AVG ERR.

28. PSU SNOWFALL

29. Penn State Weather Camps
Basic Weather Forecasting Guidelines
Sat I – Sat II – Sat III - NWS – SPC - NHC – Radar - Radar - Radar
E-WALL - sfc. map 1 - sfc. map 2 - ltg

30. Traditional 4-Panel Model Output
SLP map + THK
500 mb
700 mb
Accumulate Precip

31. Upper Level Map (i.e. 500mb)
Balance between 2 forces ….
Pressure Gradient + ??

32. SURFACE PRESSURE (SLP)? ? ?

33. Geostationary Satellite
22,000 miles above equator

34. De donde son ustedes?

35. JET STREAM This Afternoon
500 mb (~18,000 feet) L H

36. JET STREAM – LATER THIS WEEK

37. Basic Forecast Guidelines - TEMP
Cause of temperature to change:
Sunshine?
Wind direction?

38. Location – STATE COLLEGE TEMP – PRECIP – SKY COVER
WX CAMP - Forecasting
Location – STATE COLLEGE
TEMP – PRECIP – SKY COVER ?
90F
YES

39. Joe Smith 81
Yes 8

40. Basic Forecast Guidelines
What causes rain?
Need clouds!
Will any ole cloud do?
Moisture
Bodies of water – Moisture content of air

41. NORMAL
Conforming to a standard; usual, typical, or expected.

43. Basic Forecast Guidelines
What causes temperature to change?
How much sunshine?
How much precipitation?
Wind direction?

44. Basic Forecast Guidelines
Extrapolation= Look upstream to see what’s coming!
Sat IR - Sat II - Sat VIS - Radar - sfc. map 1 - sfc. map 2 – sfc map 3

45. Basic Forecast Guidelines
The “Models”
What are they?
Lower Res. (GFS)
Higher Res. (GFS)
Higher Res. (NAM)
Higher Res. (HRRR)
MOS - Statistical guidance

46. TROF AVIS PA
TROF AVIS

47. Cyclogenesis

53. Air Mass
Large volume of air with certain Temp and Moisture Characteristics
Continental Tropical, Maritime Tropical,
Continental Polar, Maritime Polar

54. Continental Polar
Maritime
Polar
Continental Tropical
Maritime Tropical

55. Summer - Day Winter- Day T = 105 TD = 38 T = 15 TD = -5 T = 67 TD = 58
Maritime Tropical
Maritime Polar
Continental Tropical
Continental Polar

56. RH Calculator Relative Humidity – How close the air is to saturation
- Varies between?
- If in a cloud ….. RH = ?
Dew Point – Absolute humidity (how much H20 v)
T = 85
D = 65
RH = 51%
How can we make a cloud?
RH Calculator

57. RH at 700 mb 18z WED
MOS - clouds
E-WALL - clouds

58. SFC Temperature Forecasting Techniques Climatology Persistence
Modified Persistence
Models
2 meter temp output
MOS (statistical)

59. Basic Forecast Guidelines
Climatology Forecast = averages for today
Persistence Forecast = yesterday’s values
Modified Persistence = Persistence + Any changes

60. Nighttime infrared satellite imagery suggests that the circulation associated with the low pressure area in the Gulf of Mexico is
gradually becoming better defined. However, the system is struggling to maintain organized convection near the center, and
the radius of maximum winds remains large. Based on this, the system is still maintained as a potential tropical cyclone.

61. The low is moving erratically northwestward around the southwestern portion of a deep-layer ridge located over the western Atlantic and Florida. The large-scale models suggest this ridge will strengthen some during the next 36 hours or so and cause the low to turn a little more westward. This would be followed by a northward turn around the western end of the ridge and eventual recurvature into the westerlies. Overall, there has been a left shift of the track guidance models since the previous advisory. The new forecast track is also shifted left, but it is to the right of the model consensus, especially at h. Given the nature of the circulation, though, and the fact that the wind and rain hazards extend well north and east of the center, users are encouraged to not focus on the details of the track forecast.

62. The initial intensity remains 35 kt based on partial scatterometer overpasses and continuity from the previous advisory. Significant strengthening is unlikely due to strong vertical shear caused by an upper-level trough over the northwestern Gulf of Mexico and entrainment of dry air into the system. However, the large-scale models suggest slight strengthening before landfall, and thus the intensity forecast is unchanged from the previous advisory. One change from the previous advisory is that it now appears more likely that the system would become a subtropical cyclone rather than a tropical cyclone due to the current structure of the low and interaction with the aforementioned trough. That being said, development into a tropical cyclone remains possible. The primary hazard from this disturbance is expected to be heavy rainfall over portions of the central and eastern Gulf Coast.

63. FORECAST POSITIONS AND MAX WINDS
INIT 20/0900Z 24.8N 90.1W 35 KT 40 MPH...POTENTIAL TROP CYCLONE
12H 20/1800Z 25.7N 91.0W 35 KT 40 MPH...SUBTROPICAL CYCLONE
24H 21/0600Z 26.6N 92.1W 40 KT 45 MPH
36H 21/1800Z 27.5N 93.0W 40 KT 45 MPH
48H 22/0600Z 28.9N 93.5W 40 KT 45 MPH
72H 23/0600Z 32.5N 93.5W 25 KT 30 MPH...INLAND
96H 24/0600Z 36.5N 88.0W 20 KT 25 MPH...POST- TROP/INLAND

64. Our friends …. Storms Prediction Center

65. NAM MODEL – 4 panel map
Valid at 8 a.m. (12z) YESTERDAY

66. L H H NAM MODEL – 500 mb. map Valid 8 a.m. (12z) YESTERDAY Ridge
Trough

67. NAM MODEL – SFC map
Valid 8 a.m. (12z) YESTERDAY

68. NAM MODEL – SFC map
Valid 8 P.M. (00z) YESTERDAY

69. LIFTED INDEX
Valid 2 P.M. (18z) YESTERDAY

70. 5 a.m. (09z)

71. NAM MODEL – 4 panel map
Valid at 2 p.m. (18z)

72. NAM MODEL – sfc map
Valid at 2 p.m. (18z)

73. NAM MODEL – 500 mb
Valid at 2 p.m. (18z) L
Trough
axis

74. LIFTED INDEX
Valid 2 P.M. (18z) TODAY

75. Penn State Weather Camps
Basic Weather Forecasting Guidelines
Sat I – Sat II – Sat III – Sat WV - NWS - NHC – Radar - Radar
sfc. map 1 - sfc. map 2 – sfc map 3

76. NAM MODEL – Precip. map
Totals (2 pm – 8 pm)
(18z – 00z)
GFS MODEL – Precip. map
Totals (2 pm – 8 pm)
(18z – 00z)

77. NAM MODEL – Precip. map
Totals (2 pm – 8 pm)
(18z – 00z)
GFS MODEL – Precip. map
Totals (2 pm – 8 pm)
(18z – 00z)

78. SURFACE PRESSURE ? ? ? ? ?

79. SURFACE PRESSURE

80. Warm Sector vs. Cool Sector

83. MOS – Model Output S …
Accu Friends
Wx Channel Friends
NWS Friends

84. Know what to expect! = Climo.NH RH NL RL
Know what to expect! = Climo.

87. Big Picture …. Then details 
Soundings ?
Model soundings
Other fun output
Meteograms

88. Big Picture …. Then details 
Temps + Clouds
Soundings – What are these?
Model soundings
Other fun output
Meteograms