* Benchmark Hub at 2-1/2 week high
    * Prices rise above $4/mmBtu across most of the nation
    * Warmer weather on tap for much of the country

    By Eileen Houlihan
    NEW YORK, May 20 (Reuters) - U.S. spot natural gas prices
rose for the first time in three sessions on Monday, boosted by
the return of weekday industrial demand and warmer weather
blanketing most of the nation early this week.
    Nuclear power plant outages also remained above normal,
helping to lift near-term demand for replacement generation,
while stronger gas futures helped keep momentum to the upside.
    Forecaster MDA Weather Services called for a "hot start to
the week in the Midwest" and in its one- to five-day forecast
map showed above-normal temperatures for the East Coast, parts
of the Midwest and most of the South stretching across Texas.
    Gas for Tuesday delivery at the nation's benchmark Henry Hub
<NG-W-HH> in Louisiana jumped 21 cents, or more than 5 percent,
to $4.10 per million British thermal units, which is a 2-1/2
week high.
    Hub cash gas slid 12 cents on Friday for gas delivered
through Monday.
    On May 8 Hub cash gas slid to $3.86, its lowest average
price since mid-March, after climbing to a 21-month high of
$4.38 on April 19.
    Monday's Hub average remained below the May monthly index of
$4.16, but was still well above the year-ago price of $2.60.
Cash prices bottomed out last year in late April at a 10-year
low of $1.82.
    Late deals firmed slightly to 4 cents under the front-month
June natural gas futures contract on the New York Mercantile
Exchange, from deals done late Friday at a 7-cent
discount.
    The nearby futures contract traded late up about 6 cents at
$4.11, extending gains for a second straight session.
    In major consuming regions, gas on the Transco pipeline at
the New York citygate <NG-NYCZ6> jumped 41 cents to average
$4.37, while Chicago gas <NG-CHGC> was 26 cents higher on the
day at $4.20.
    Nuclear plant outages totaled 16,600 megawatts, or 17
percent of U.S. capacity, down from 18,100 MW out on Friday and
18,500 MW out a year ago, but up from a five-year average outage
rate of 16,200 MW. 
    Baker Hughes drilling rig data on Friday showed the
gas-directed rig count rose by four from the prior week's
18-year low of 350. 
    (Rig graphic: http://link.reuters.com/nuz86t)
    Early injection estimates for Thursday's gas storage report
from the U.S. Energy Information Administration range from 87
billion cubic feet to 99 bcf versus a 75-bcf build during the
same week last year and a five-year average rise for that week
of 90 bcf.
    
    Average prices at spot gas market points and previous day
prices follow (US$/mmBtu):  
                                    5/20/13             5/17/13 
       
  Henry Hub                           4.10                3.89  
              
  New York citygate                   4.37                3.96  
              
  Chicago citygate                    4.20                3.94  
              
  Panhandle (mid-Continent)           3.88                3.65  
              
  Northern at Demarcation  (Minn.)    4.10                3.83  
              
  Southern California border          4.16                3.83  
              
  Katy Hub (east Texas)               4.08                3.92  
              
  Waha (west Texas)                   4.05                3.86  
              
  Dominion-South (Appalachia region)  4.15                3.89  
              
  Columbia TCO (Appalachia region)    4.17                3.94  
              
    
    For more U.S. spot natural gas prices, click on <0#NG-US>
    
    RELATED LINKS 
    - U.S. Spot Gas versus Oil Comparisons.......... 
    - BTU U.S. Spot Natural Gas Prices..............<0#NG-BTU> 
    - North American Power Plant Outage Table ..... 
    - North American Power Transmission Table ..... 
    - U.S. EEI Electricity Output Report ...........     

 (Editing by Bob Burgdorfer)