Forecast Verification time! Perfect Forecast ?

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

Perfect Forecast ERI 79 SE PIT SPC HAR PIT PHL

DAY 2 Winners

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

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

45 Convection 58 Conduction 64 Sun heats ground

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

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

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

MONDAY H

TUESDAY H

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

SLP map- NAM model. Valid 8 p.m. EDT H

SLP map- NAM model. Valid 8 p.m. EDT H SPC

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

THIS EVENING – 500MB SPC

THIS EVENING – SURFACE MAP SPC

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

THIS EVENING – 700MB RH

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

Joe Schmo 90 Y 3.50” PA

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

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 90 - 68 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%

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

Climatology Forecast Persistence Forecast Key West Chicago CLI 88 80 6/17 88 93 6/18 86 95 6/19 89 81 6/20 90 77 6/21 87 67 6/22 89 64 6/23 90 81 AVG ERR. 1.3 9 Key West Chicago 6/17 88 93 6/18 -2 +2 6/19 +3 -14 6/20 +1 -4 6/21 -3 -10 6/22 +2 -3 6/23 +1 +17 AVG ERR. 2 9

PSU SNOWFALL

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

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

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

SURFACE PRESSURE (SLP) ? ? ?

Geostationary Satellite 22,000 miles above equator

De donde son ustedes?

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

JET STREAM – LATER THIS WEEK

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

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

Joe Smith 81 Yes 8

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

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

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

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

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

TROF AVIS PA TROF AVIS

Cyclogenesis

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

Continental Polar Maritime Polar Continental Tropical Maritime Tropical

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

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

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

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

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

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.

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 36-48 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.

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.

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

Our friends …. Storms Prediction Center

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

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

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

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

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

5 a.m. (09z)

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

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

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

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

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

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

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

SURFACE PRESSURE ? ? ? ? ?

SURFACE PRESSURE

Warm Sector vs. Cool Sector

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

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

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

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