CLEX-9 October 13th, 2001 Operations

Synopsis

• The CLEX-9 forecast team has decided to stand by all operations for Saturday, October 13th.
  
  
• Weather Forecast (made at 1530 MDT 10/13/01):

  
            Weather Discussion:
  
            An vacating upper-level short-wave trough will leave us under NW flow aloft.  
            Timing will be critical for cloud formation/dissipation tomorrow morning, 
            with  cloud cover forecasted to be on the decrease by sunrise over the Nebraska 
            region.  Previous CLEX field campaigns have observed mid-level cloud formation 
            in similar NW flow regimes...
  
            Weather Outlook:
  
            Conditions for mid-level cloud formation look favorable for Sunday and On.  For 
            Sunday, another shortwave looks to nudge into the NE region with a significant 
            plume of 500 mb moisture.  The timing of the models now suggests a possible 
            afternoon mission (will have to wait and see about this).  Longer term looks 
            favorable with continued NW flow regime aloft and embedded shortwave disturbances 
            present.  
  
            Adam/Larry/Curtis
  
  
    
  Morning Update (made at 0400 MDT 10/13/01): 
  
            The CLEX-9 field campaign is on GO status this morning (10/13/01).  Larry expects 
            take off in the Wyoming King Air by 0600 MDT.  The target this morning is a 
            widespread deck of mid-level clouds that has formed over the SE Wyoming/SW Nebraska 
            region.  Operations will take place over North Platte if the target clouds advect 
            to this region.  If the clouds do not advect that far east, operations will take 
            place to the west of North Platte...
  
            Weather summary:  Significant mid-level cloud cover has formed within the NW flow 
            over the WY region advecting ESE through the NE panhandle.  The IR satellite cloud 
            tops are near -20 C, with no surface precipitation being recorded.  Cloud bases are 
            being reported at 11 Kft (at 0500 MDT) near Cheyenne.
  
            Adam (from CLEX-9 central) 
  
  

Post Mission Update (made at 1100 MDT 10/13/01):

          The 12 Oct 2001 CLEX-9 mission over the Scott's Bluff/Sydney, NE region has been completed.  

          Larry was able to sample a long-lived mid-level cloud field for three hours (with a total 
          mission length of four hours).  They recorded three complete Lagrangian spirals in a cloud 
          field that ranged from 11 Kft (base) to 21 Kft (top).  The cloud field was mostly single 
          layer with a few occurrences of two layers noted.  Cloud top temps were as cold as -27 C.  
          Significant cloud top liquid water was also noted throughout the mission.  The Wyoming 
          Cloud Radar observed widely varying cloud structure present with higher reflecting ice 
          regions often located about a thousand feet below cloud top.  They then ascended to this 
          level for corresponding in-situ measurements of this in-cloud region.

          Larry reported that they were fortunate again to have unrestricted airspace throughout 
          the entire mission.  All instruments were in working order.

          This is an excellent Lagrangian case study of a cloud field that did not dissipate through 
          sunrise.  It is noted (on satellite imagery) that several large adjoining regions of clouds 
          did visibly dissipate through the sunrise timeframe.

          Adam (from CLEX-9 central)

Sunrise Information for North Platte, NE

Sunrise   
                     Central Daylight Time          

        Begin civil twilight       7:24 a.m.                 
        Sunrise                    7:52 a.m.                 
        Sun transit                1:29 p.m.                 
        Sunset                     7:07 p.m.                 
        End civil twilight         7:35 p.m.                 

Weather Details

1200Z 500 mb Map



1215Z GOES IR Image and CLEX-9 13 Oct 2001 Target Region


 




1200Z North Platte, NE Sounding


 







 

Aircraft Operations

• UW King Air Operations: Total time aloft was 4 hours (with 3 of those hours dedicated to sampling cloud)

North Platte, NE Ground Operations

• Ground Instrument Status: Everything working well
  

Data Collection Highlights:

• Summary: Updated as soon as possible