San Diego Weather
Watches/Warnings
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Current Watches, Warnings, and Alerts
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Current 500 mb Chart
Current Surface Analysis
National Forecast Maps
Day 1
Pressure/Height Anomalies
MSLP
WPC Short-Term Prog Charts - Surface
6 Hr
12 Hr
3 Hr
6 Hr
WPC Short Term Forecast
WPC Extended Range Forecast
WPC Prog Charts - 500mb
Day 3
24 Hr
Current Warnings/Watches & Discussions
Watches
SPC
WPC
San Diego Area Forecast Discussion
Relative 700-300mb Relative Humidity
Latest Local METARS
Western U.S. Models
Current HRRR MSLP & 10m Wind
Current GFS MSLP & 10m Wind
Current ECMWF MSLP & 10m Wind
Temperatures
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UV Index
Rain
Day 1
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Day 2
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Day 3
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Day 4
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Day 5
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5 Day Cumulative
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Day 2 |
Day 3 |
Day 4 |
Outlook
Monitor
Monthly Outlook
Seasonal Outlook
Atmospheric Sounding
Skew-T Diagram Cheat Sheet
1. Axes and Basic Layout
- X-Axis (Bottom): Temperature in °C (skewed right with height)
- Y-Axis (Left): Pressure in hPa (logarithmic scale)
- Isobars: Horizontal constant pressure lines (e.g., 1000, 850, 700, 500, 300 hPa)
- Isotherms: Diagonal lines (skewed right); constant temperature
- Dry Adiabats: Curved, upward-right; dry parcel ascent path
- Moist Adiabats: Curved, upward-left; saturated parcel ascent path
- Mixing Ratio Lines: Dashed, upward-right; constant dew point depression
2. Key Plotted Lines
- Environmental Temperature: Red or black solid line (actual air temperature)
- Dew Point Temperature: Green or blue solid line (moisture profile)
- Parcel Ascent Line: Usually yellow or dashed; follows adiabats for lifted parcel
3. Wind Barbs (Right Margin)
- Full barb: 10 knots
- Half barb: 5 knots
- Pennant (flag): 50 knots
- Direction: Where wind is coming from
4. Important Atmospheric Features
| Feature | Interpretation |
|---|---|
| LCL (Lifting Condensation Level) | Cloud base; where T and Td converge |
| LFC (Level of Free Convection) | Parcel rises freely; indicates instability |
| EL (Equilibrium Level) | Parcel cools below environment; near cloud top |
| CAPE | Positive energy; >1000 J/kg = storms; >2500 = strong storms |
| CIN | Negative energy; CIN > 50 J/kg may suppress convection |
| Inversion | Temp increases with height; suppresses convection |
| Dry Layer | Large T-Td difference; limits clouds/enhances downdrafts |
| Moist Layer | Small T-Td difference; promotes fog/clouds near surface |
5. Rule-of-Thumb Values
Instability – CAPE
| CAPE | Interpretation |
|---|---|
| 0–500 J/kg | Stable / weak convection |
| 500–1000 | Marginal instability |
| 1000–2500 | Moderate instability |
| 2500–3500 | Strong instability |
| >3500 | Extreme (severe storm potential) |
Wind Shear (0–6 km Bulk Shear)
- <20 kt: Weak shear – pulse storms
- 20–35 kt: Moderate shear – organized storms possible
- >35 kt: Strong shear – supercells/severe potential
Lapse Rate (700–500 hPa)
- >6.5°C/km: Steep lapse rate = more instability
- <6.0°C/km: Stable or neutral layer
6. Specialized Indicators
| Indicator | What to Watch For |
|---|---|
| Veering Winds | Clockwise with height; warm-air advection |
| Backing Winds | Counterclockwise; cold-air advection |
| Critical Thickness (~540 dam) | Useful for winter snow prediction |
| Dry Slot | Mid-level dry air; evaporation/microburst risk |
7. Example Scenarios
Thunderstorm Likely
- CAPE > 1000 J/kg
- LCL < 1500 m
- LFC present
- Wind shear > 20 kt
- CIN < 25 J/kg
Fog Formation
- Surface T ≈ Td
- Saturated boundary layer
- Light/calm winds
- Surface inversion
Supercell Environment
- CAPE > 2000
- Shear > 40 kt
- High lapse rates
- Veering winds with height
Marine Forecasts
Coastal Forecast
Offshore Forecast - California Waters
NHC Outlook
2 Day Outlook
7 Day Outlook
Active Tropical Cyclones (PTC and higher)
Experimental/Academic Tropical Resources
- Tropical Tidbits Aircraft Reconnaissance
- NOAA STAR Aircraft Reconnaissance
- Tomer Burg's TroPYCal
- CyclonicWX
- Brian Tang's Tropical Trends
- NCEP Hurricane Model Archive
- Historical Hurricane Tracks
- Google DeepMind Hurricane AI Public Preview
- Morphed Integrated Microwave Imagery at CIMSS (MIMIC-TC)
- Colorado State Current Season ACE
- NHC Current/Historical Hurricane Seasons and TC Reports
Outlook
Discussion
0-168 hr
0-48 hr
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0-120 hr
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0-120hr Verification This Season
NOTE: These statistics ignore completely the current intensity or motion of the storm
and are based solely on a climatology based on the current position. They are prone to large forecast error.
Users should use only official forecasts for decisions, such as those provided by NHC, JTWC, and CHC.
California
500mb Vorticity
Shear Support
Generalized Shear
Vertical Instability
Mid Atmospheric Winds
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