Rules of thumb to inerpret these.   Seattle Pilots Briefing Page Facebook  Digg   StumbleUpon   Twitter   Buzz Up!  
TTAA00KSEW210315        
**SEWGRADIENTTABLE10/21/1403Z**210315Z    
          
 UIL-OTH-PDX-OLM-UIL-HQM-AST-BLI-UKI-AST-BLI-BLI-
DD/HHBLISEABLIBLINUWSEAUILYZTUILSEAYQQYWL
21/03-1.3+2.8+2.3+0.8-1.1-0.8+1.9+4.5+9.5-0.9+2.2+4.2
21/01-0.7+2.3+2.2+1.1-0.8-0.6+1.4+3.9+8.0-0.9+1.6+4.0
20/23-0.8+1.2+2.0+0.8-0.8-1.1+1.3+3.9+7.2-1.3+1.7+4.6
20/21-0.8+1.0+2.1+0.7-1.0-1.3+1.4+4.2+7.2-1.3+1.8+4.8
20/19-1.3+1.3+2.1+0.6-1.2-1.1+1.4+5.2+7.9-1.3+2.7+5.0
20/17-0.5+1.1+2.2+1.4-1.2-1.0+1.5+4.3+8.3-1.1+2.2+4.3
20/15-0.5+1.1+3.1+1.7-0.5-0.8+2.0+4.1+7.7-0.9+1.9+4.0
20/13-0.9+1.8+2.6+0.8-0.2-0.7+1.6+4.5+6.9-0.8+2.7+4.5
20/11-0.4+1.1+1.9+0.7-0.7-0.8+1.6+4.3+7.0-0.8+2.5+3.9
20/09-0.7+1.3+1.6+1.0-0.5-1.4+1.3+4.8+7.6-1.7+2.6+3.1
20/07M+1.8+2.3+1.0MMM+5.1M-0.8+2.3+3.6
20/05MMMMMMMMMMMM
20/03+0.9+0.8+2.3+2.5+0.3-0.6+1.1+5.1+6.2-1.1+1.2+2.9
          
 PDX-UIL-CLM-SEA-SEA-OLM-SEA-YKM-SHN-SHN-SEA-SMP-
DD/HHDLSCLMNUWEATYKMYKMGEGGEGSEANUWSMPEAT
21/03+0.1-0.7-0.4+1.2-0.2-0.9+1.2+1.4-1.5+0.2MM
21/010.0-0.4-0.4+1.2+0.2-0.3+2.1+1.9-1.4+0.1MM
20/23-0.2-0.3-0.5+1.1+0.5-0.5+2.1+1.6-2.2-0.4MM
20/21+0.1-0.5-0.5+2.0+0.3-0.9+1.7+1.4-2.2-0.5MM
20/19+1.2-0.4-0.8+1.7+1.1+0.3+1.2+0.1-1.6-0.1MM
20/17+0.1-0.5-0.7+1.5+0.5-0.2+0.6+0.1-1.5-0.1MM
20/15+1.0-0.2-0.3+0.9+0.3-0.4-0.2-0.5-1.5+0.9MM
20/13+1.1-0.20.0+0.7-0.1-0.8-0.10.0-1.4+0.8MM
20/11+0.4-0.2-0.5+0.6+0.4-0.9+0.1-0.3-1.6+0.1MM
20/09+0.1-0.2-0.3+0.6+0.3-1.0+0.2-0.1-2.0+0.5MM
20/07+0.6M-1.2-0.4-0.4-1.2-1.0-0.6-1.8-0.4MM
20/05MMMMMMMMMMMM
20/03-0.4+0.1+0.2-1.1-0.8-1.4-2.4-1.6-1.3+1.2MM
          

.03 inches --> 1 millibar    or 1 inch --> 33.86 millibars

Rules of thumb for estimating wind speed and direction based on local pressure gradients:
(UIL-BLI) * 10 	= 	West wind in Strait of Juan De Fuca if gradient is positive
(UIL-BLI) * 5 	= 	East wind in Strait of Juan De Fuca if gradient is negative
(OTH-SEA)	= 	South wind at SEA if gradient is positive. North wind if gradient is negative.
(PDX-BLI) * 5 	= 	South wind at SEA if gradient positive. North wind if gradient negative.
(OLM-BLI) * 10	= 	South wind at SEA if gradient positive. North wind if gradient negative.
(SEA-EAT) 	= 	Westerly component at SEA if gradient positive. Easterly if gradient negative.
(SEA-GEG) 	= 	Westerly component at SEA if gradient positive. Easterly if gradient negative.
(SEA-SMP) 	= 	Westerly component at SEA if gradient positive. Easterly if gradient negative.
transpose the table
Pressure gradients from regional airports. Large numbers indicate strong winds from high to low pressure.
So when UIL-NUW Quillayute — Whidbey NAS is a large positive number, expect strong West winds in the Strait of Juan de Fuca.

Previous Page     |   Original Source Table at NWS
BC WILLIAMS LAKE AR YWL    52 11N  122 04W 
BC PORT HARDY AIRPO YZT    50 40N  127 22W   22
BC COMOX (CAN MIL)  YQQ    49 43N  124 54W   24 

WA BELLINGHAM       BLI    48 48N  122 32W   50 
WA QUILLAYUTE       UIL    47 56N  124 33W   54 
WA WHIDBEY IS. NAS  NUW    48 21N  122 39W   14  
WA SEATTLE/METRO    SEA    47 27N  122 19W  136 
WA HOQUIAM          HQM    46 58N  123 56W    7 
WA OLYMPIA          OLM    46 58N  122 54W   58 
WA SPOKANE/METRO    GEG    47 37N  117 32W  735 
WA STAMPEDE PASS    SMP    47 17N  121 20W 1208 
WA YAKIMA           YKM    46 34N  120 32W  324 
WA SHELTON          SHN    47 14N  123 08W   82 
WA WENATCHEE        EAT    47 24N  120 12W  377 
WA PORT ANGELES     CLM    48 07N  123 30W   85 

OR ASTORIA          AST    46 09N  123 53W    3 
OR PORTLAND         PDX    45 35N  122 36W    7
OR THE DALLES       DLS    45 37N  121 10W   71  
OR NORTH BEND       OTH    43 25N  124 15W    4

CA UKIAH            UKI    39 07N  123 12W  187 

Full list of Stations