A large tropical cyclone formed from a tropical wave that crossed Central America and developed south of Mexico. The system became a tropical depression at 1200 UTC on 12 July 2004 and strengthened into Tropical Storm Blas by about 1800 UTC that same day. Blas moved generally northwestward on 12–13 July, reached peak intensity on 13 July, then turned west‑northwest and moved over progressively cooler waters. It weakened to a tropical depression by 1800 UTC 14 July, became a remnant low by 0600 UTC 15 July, and finally dissipated well west of central Baja California on 19 July.
Blas did not make landfall. Its center remained well offshore of the Baja California peninsula throughout its life, although the storm’s broad circulation produced effects along the southern tip of the peninsula.
The storm’s maximum sustained winds peaked at 55 kt (about 63 mph) around 1200 UTC 13 July, with an estimated minimum central pressure of 991 mb. At that time Blas was a moderate tropical storm (not a hurricane).
Storm surge was not reported as producing notable coastal inundation. Rainfall and surge totals were limited because the center stayed at sea; however, gusty winds and outer bands affected extreme southern Baja California. An automated station just north of Cabo San Lucas (elevation 225 m) recorded a maximum sustained wind of 41 kt (about 47 mph) at 1630 UTC 13 July and a peak gust of 57 kt (about 66 mph) at 1750 UTC on 13 July. A ship (call sign ELYS4) near 22.2°N, 113.6°W reported winds 33 kt and a pressure of 1006.0 mb on 14 July.
There were no reports of damage or casualties directly associated with Blas. The most affected area by winds and gusts was extreme southern Baja California, including the vicinity of Cabo San Lucas, but no injuries or property losses were reported in the NHC record.
Noteworthy aspects include Blas’s unusually large size for a tropical storm, with tropical-storm-force winds extending roughly 200 nautical miles northeast and northwest of the center on 13 July. Early forecast tracks had a slow bias that led to some overprediction of intensity because the storm moved over cooler waters sooner than expected.
Paid members can generate summaries tailored to the counties of their choice. The Blas TCR covers impacts across many counties and states — a Pinellas County resident doesn't need the Asheville detail, and a Buncombe County resident doesn't need the Tampa surge data.
Upgrade for county-specific summariesSummary above produced from the National Hurricane Center's official post-storm Tropical Cyclone Report. Read the full report for casualty lists, damage estimates by area, forecast critique, and detailed meteorological discussion:
📄 Read NHC's full report on Blas → (opens at nhc.noaa.gov)| Time (UTC) | Status | Lat | Lon | Winds (kt) | Pressure (mb) | Record |
|---|---|---|---|---|---|---|
| 2004-07-12 12:00 | TD | 14.60 | -105.50 | 30 | 1006 | |
| 2004-07-12 18:00 | TS | 15.50 | -106.80 | 35 | 1002 | |
| 2004-07-13 00:00 | TS | 16.40 | -108.00 | 45 | 997 | |
| 2004-07-13 06:00 | TS | 17.30 | -109.30 | 50 | 994 | |
| 2004-07-13 12:00 | TS | 18.40 | -110.80 | 55 | 991 | |
| 2004-07-13 18:00 | TS | 19.60 | -112.20 | 50 | 994 | |
| 2004-07-14 00:00 | TS | 20.70 | -113.70 | 45 | 997 | |
| 2004-07-14 06:00 | TS | 21.50 | -115.10 | 40 | 999 | |
| 2004-07-14 12:00 | TS | 22.10 | -116.60 | 35 | 1002 | |
| 2004-07-14 18:00 | TD | 22.50 | -117.90 | 30 | 1004 | |
| 2004-07-15 00:00 | TD | 22.90 | -119.20 | 30 | 1005 | |
| 2004-07-15 06:00 | LO | 23.20 | -120.40 | 30 | 1006 | |
| 2004-07-15 12:00 | LO | 23.40 | -121.40 | 25 | 1007 | |
| 2004-07-15 18:00 | LO | 23.60 | -122.30 | 25 | 1008 | |
| 2004-07-16 00:00 | LO | 23.80 | -123.30 | 25 | 1008 | |
| 2004-07-16 06:00 | LO | 24.00 | -124.50 | 25 | 1008 | |
| 2004-07-16 12:00 | LO | 24.10 | -125.50 | 20 | 1008 | |
| 2004-07-16 18:00 | LO | 24.20 | -126.30 | 20 | 1008 | |
| 2004-07-17 00:00 | LO | 24.40 | -127.00 | 20 | 1009 | |
| 2004-07-17 06:00 | LO | 24.80 | -127.50 | 20 | 1009 | |
| 2004-07-17 12:00 | LO | 25.20 | -127.80 | 20 | 1009 | |
| 2004-07-17 18:00 | LO | 25.60 | -128.10 | 15 | 1010 | |
| 2004-07-18 00:00 | LO | 26.00 | -128.30 | 15 | 1010 | |
| 2004-07-18 06:00 | LO | 26.40 | -128.40 | 15 | 1011 | |
| 2004-07-18 12:00 | LO | 26.70 | -128.20 | 15 | 1012 | |
| 2004-07-18 18:00 | LO | 26.90 | -127.90 | 15 | 1013 | |
| 2004-07-19 00:00 | LO | 26.90 | -127.60 | 15 | 1014 | |
| 2004-07-19 06:00 | LO | 26.90 | -127.30 | 15 | 1015 |
Source: NOAA National Hurricane Center HURDAT2 best-track database (nhc.noaa.gov/data). Data is in the public domain. Best-track positions and intensities are post-storm reanalysis estimates and may differ from real-time advisories.