Live/Radar/Every radar/TJUA
Single radar / Puerto Rico
San Juan radar TJUA
The weather service radar at San Juan, Puerto Rico, alone: each picture it makes from its own scans, at four tilts from its lowest up, every few minutes. Reflectivity, velocity, storm relative velocity, correlation coefficient and differential reflectivity, the storms it tracks and where they are headed, and how high its beam passes. How to read them.
- Latest scan
- Scanning
- Precipitation mode, pattern 215
- Tilts
- 0.5°, 1.3°, 2.4°, 3.1°
- Stands at
- 18.116°N 66.078°W, 2,844 ft above sea level
- Reaches
- 286 mi with reflectivity, 186 mi with velocity, 143 mi with storm relative velocity
Storms it tracks
The radar follows each storm cell from scan to scan, measures the way it is moving, and puts it ahead 15 to 60 minutes. Each is drawn on the map above, its track to the hour ahead marked each quarter hour.
| Storm | Where | Moving | In 30 minutes | In 60 minutes | Last forecast off by |
|---|---|---|---|---|---|
| V9 | 89 mi south of the radar89 mi from the radar, bearing 169° | Toward the west at 31 mph | - | - | 2.6 mi |
| B3 | 125 mi south of the radar125 mi from the radar, bearing 179° | Toward the west northwest at 26 mph | 121 mi south of the radar | 116 mi south of the radar | 0.1 mi |
| S1 | 48 mi southeast of the radar48 mi from the radar, bearing 132° | Toward the west at 28 mph | 37 mi southeast of the radar | 30 mi south southeast of the radar | 0.5 mi |
| W1 | 98 mi south southwest of the radar98 mi from the radar, bearing 196° | First seen this scan | - | - | 0 mi |
| X1 | 116 mi southeast of the radar116 mi from the radar, bearing 144° | Toward the west northwest at 31 mph | 104 mi south southeast of the radar | 91 mi south southeast of the radar | 0.9 mi |
| W0 | 112 mi south southeast of the radar112 mi from the radar, bearing 155° | Toward the west northwest at 36 mph | 101 mi south southeast of the radar | 94 mi south of the radar | 1.2 mi |
| Z7 | 54 mi southwest of the radar54 mi from the radar, bearing 222° | Toward the west northwest at 29 mph | 60 mi southwest of the radar | - | 1.8 mi |
| P1 | 44 mi east of the radar44 mi from the radar, bearing 98° | Toward the west northwest at 26 mph | 31 mi east of the radar | 17 mi east of the radar | 0.1 mi |
| K9 | 102 mi south of the radar102 mi from the radar, bearing 189° | Toward the west northwest at 24 mph | - | - | 2.6 mi |
| C7 | 68 mi west southwest of the radar68 mi from the radar, bearing 248° | Toward the west at 31 mph | 82 mi west southwest of the radar | 97 mi west southwest of the radar | 1.2 mi |
| B1 | 69 mi east northeast of the radar69 mi from the radar, bearing 71° | First seen this scan | - | - | 0 mi |
| P2 | 107 mi east northeast of the radar107 mi from the radar, bearing 68° | First seen this scan | - | - | 0 mi |
| O1 | 98 mi east northeast of the radar98 mi from the radar, bearing 67° | Toward the west northwest at 20 mph | 90 mi east northeast of the radar | 83 mi east northeast of the radar | 1.2 mi |
| B0 | 62 mi south southeast of the radar62 mi from the radar, bearing 165° | Toward the west northwest at 23 mph | - | - | 2.8 mi |
| R0 | 78 mi southeast of the radar78 mi from the radar, bearing 140° | Toward the west northwest at 28 mph | 67 mi southeast of the radar | 58 mi south southeast of the radar | 0.5 mi |
| Z0 | 8 mi southeast of the radar8 mi from the radar, bearing 136° | Toward the west at 16 mph | 6 mi south southwest of the radar | - | 1.6 mi |
| K8 | 115 mi south southeast of the radar115 mi from the radar, bearing 160° | Toward the west at 28 mph | 109 mi south southeast of the radar | - | 1.4 mi |
| C1 | 43 mi north of the radar43 mi from the radar, bearing 359° | Toward the west at 22 mph | 46 mi north northwest of the radar | 52 mi north northwest of the radar | 0.8 mi |
| G2 | 91 mi south of the radar91 mi from the radar, bearing 181° | Toward the west at 21 mph | 91 mi south of the radar | - | 1.4 mi |
| T1 | 64 mi southwest of the radar64 mi from the radar, bearing 220° | Toward the west northwest at 44 mph | 71 mi west southwest of the radar | - | 2.2 mi |
| N1 | 71 mi southeast of the radar71 mi from the radar, bearing 132° | Toward the west northwest at 25 mph | 60 mi southeast of the radar | 49 mi southeast of the radar | 0.8 mi |
| J2 | 81 mi east northeast of the radar81 mi from the radar, bearing 61° | Toward the west northwest at 25 mph | 72 mi northeast of the radar | - | 1.5 mi |
| Z2 | 86 mi southeast of the radar86 mi from the radar, bearing 137° | Toward the west northwest at 38 mph | 69 mi southeast of the radar | - | 1.5 mi |
| I2 | 54 mi southeast of the radar54 mi from the radar, bearing 144° | Toward the west at 24 mph | 46 mi south southeast of the radar | 40 mi south of the radar | 0.7 mi |
| S6 | 78 mi east southeast of the radar78 mi from the radar, bearing 122° | Toward the west at 36 mph | 63 mi southeast of the radar | 51 mi southeast of the radar | 0.8 mi |
| A1 | 49 mi south of the radar50 mi from the radar, bearing 171° | Toward the west at 26 mph | 49 mi south of the radar | 53 mi south southwest of the radar | 0.7 mi |
| W2 | 93 mi south southeast of the radar93 mi from the radar, bearing 166° | First seen this scan | - | - | 0 mi |
| D3 | 32 mi east northeast of the radar32 mi from the radar, bearing 77° | First seen this scan | - | - | 0 mi |
| Q2 | 72 mi south southwest of the radar73 mi from the radar, bearing 192° | Toward the south southwest at 10 mph | - | - | 2.5 mi |
| J1 | 44 mi south southeast of the radar44 mi from the radar, bearing 165° | Toward the west northwest at 24 mph | 39 mi south of the radar | 39 mi south southwest of the radar | 0.5 mi |
How high it sees
The beam leaves the radar tilted up and the earth curves away under it, so the farther from the radar, the higher it passes. Rain or snow falling under the lowest beam is not seen: far from the radar, shallow snow and drizzle can fall unseen. The heights are the standard ones, the air bending the beam as the weather service’s own rule takes it.
| Tilt | 25 mi | 50 mi | 100 mi | 150 mi | 200 mi |
|---|---|---|---|---|---|
| 0.5° | 1,500 ft | 3,600 ft | 9,600 ft | 18,200 ft | 29,200 ft |
| 1.3° | 3,300 ft | 7,200 ft | 17,000 ft | 29,300 ft | 44,000 ft |
| 2.4° | 5,800 ft | 12,300 ft | 27,200 ft | 44,500 ft | 64,400 ft |
| 3.1° | 7,500 ft | 15,600 ft | 33,600 ft | 54,200 ft | 77,400 ft |
| Width | 2,200 ft | 4,400 ft | 8,800 ft | 13,100 ft | 17,500 ft |
How to read the pictures
- Reflectivity
- How strongly rain, snow and hail send the pulse back, in dBZ: the stronger, the heavier.
- Velocity
- The wind along the beam, in mph: green toward the radar, red away. Where the two meet tightly, the wind turns.
- Storm relative velocity
- The same wind with the storms’ own motion taken away, so a storm’s turning stands out: a tight pair of green and red is a rotating storm.
- Correlation coefficient
- How alike the returns of one pulse are, 0 to 1: rain and snow near 1, hail and melting snow lower, and debris a tornado lifts well below 0.8.
- Differential reflectivity
- How much wider than tall what falls is, in dB: large flat raindrops read high, hail and dry snow near 0.
Each picture is one tilt of one scan, as the radar sent it: its lowest tilt first, then three above it, the angles its scan pattern sets. A picture at a higher tilt sees higher into a storm, and farther over the ground at each distance. Press a point on the map to read the value there.
As data: /radar/now.json?show=sref&site=TJUA, the times of its frames, and /radar/s/TJUA/storms.json, the storms it tracks.