CLEX-9 October 14th, 2001 Operations

Synopsis

• The CLEX-9 forecast team has decided to stand by all operations for Sunday, October 14th.
  
  
• Weather Forecast (made at 1530 MDT 10/13/01):

  
            Mission Forecast: 
  
            As today, the western NE area will be in NW flow aloft tomorrow with embedded 
            weak short waves and associated mid-tropospheric moisture. The ETA and AVN bring 
            a moisture tongue through the LBF area tomorrow. As is typical with this scenario, 
            the NWP models are not entirely consistent on timing and details. ETA brings the 
            moisture in around 18z while AVN brings a weak disturbance through early AM (12z). 
            We will make a Nowcast at 0330 MDT to determine our exact mission time. Earliest 
            mission would be 0530 to 0600 MDT takeoff. 
  
            Weather Outlook: 
  
            On Monday, the NW'ly mid-tropospheric flow regime continues. Details are even more 
            murky on timing and location of mid-level clouds but conditions are generally 
            favorable for CLEX operations in western NE. Tuesday-Wednesday look less favorable 
            for NE/WY/CO region as a ridge builds at 500mb. 
  
            Larry/Adam          
  
  
    
  Morning Update (made at 0400 MDT 10/14/01): 
  
            The CLEX-9 field campaign is on GO status Sunday morning (10/14/01).  Larry expects 
            to take off in the Wyoming King Air by 0600 MDT.  The target this morning is another 
            widespread deck of mid-level clouds that has formed over the SE Wyoming/SW Nebraska 
            region (see IR satellite image below).  Unlike yesterday morning, there are patchy 
            mid-level clouds over North Platte.  A final update just before take off will determine 
            if the King Air will proceed to North Platte.  Operations will take place to the west 
            of North Platte if the situation is deemed necessary...
  
            Weather summary:  
  
            The situation looks very similar to yesterday's case study.  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.  The nose of a strong upper-level jet streak is nudging its way into the 
            SE Wyoming region.  
  
            John Davis is again preparing all surface instrumentation for a possible North Platte 
            CLEX-9 mission. 
  
            Adam (from CLEX-9 central) 
  
  

Post Mission #1 Update (made at 1100 MDT 10/14/01):

          Larry has landed in North Platte, NE after a successful morning CLEX-9 mission.  The 
          mission started out with a under cloud transit of the continuous mid-level cloud field 
          from just east of Laramie, WY to North Platte, NE.  The onboard cloud radar was able to 
          vertically profile the cloud deck during this entire transit.  

          Once in North Platte, Larry then proceeded with Eularian cloud sampling over the CLEX-9 
          ground site.  Several east-west oriented flight legs were run over North Platte at 
          different altitudes (7, 10, 13, 17  and 20 Kft).  They then completed this part of the 
          mission with an Eularian spiral downward.  During this time the cloud field above North 
          Platte was observed to be dissipating and no liquid water (though there was ice present) 
          noted.  

          Larry then proceeded to head NW to a thicker deck of mid-level cloud.  They sampled this 
          cloud deck with Lagrangian spirals and ascending profiles.  The cloud radar was used to 
          document the vertical profile of the cloud deck throughout the time they were present 
          within the cloud. 

          John Davis reported that he launched a rawindsonde to support this CLEX-9 mission around 
          0800 MDT.  He also reported that all ground instruments were working well during this 
          timeframe.  In addition, John reported that ground radio communication with the King Air 
          worked well.  Airspace restrictions today were again minimal.  

          Larry has decided to go up for another mission to sample the cloud deck under the 1140 MDT 
          TERRA overpass and then head back to Laramie.  

          Adam (from CLEX-9 central)

Post Mission #2 Update (made at 1400 MDT 10/14/01):

          
          Larry reported 1112 MDT takeoff, scanning the clouds overhead vertically.  They then made
          a straight run ascent to NW from LBF to 17-18 Kft (where cloud tops were observed).  Noted
          lots of water at cloud tops - began sampling with probes and side look cloud radar.  Very 
          bumpy at 17.2 Kft.  At 1138 MDT they turned around and headed SE back toward LBF in a 
          straight descent, still scanning with the side view cloud radar.  At 1154 MDT (at 8.5 Kft - 
          which put them under cloud base) they turned around and headed NW with the cloud radar in 
          vertical mode. By 1200 MDT they were level at 8.5 Kft under cloud base (pointing cloud radar 
          vertically) heading back NW.  At 1233 MDT they terminated the run under cloud and head back 
          to Laramie. Larry reported a cloud-sampling time of 1.5 hrs.  

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

CLEX-9 Morning Mission #1 Target Region (10/14/01)

(0615 MDT IR Satellite Image)









CLEX-9 Morning Mission #2 Target Region (10/14/01)

(1002 MDT IR Satellite Image)









10/14/01 Terra Orbit Track







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:

          Some of the highlights from this day of flying include observations of what appear to be 
          generating cells at cloud top with all liquid water at very top turning to mixed phase 
          within a few hundred meters or less.  The ice then sediments out of generating cells in 
          fall streaks to SE associated with NW'ly shear.  Ice from multiple generating cells/fall 
          streaks merge into one 1.5 km layer of mostly ice.  There is a hint of aggregation around 
          -12 C to -9 C in the middle of the ice layer in the 2D-C and also in enhanced reflectivities 
          there (-10 dBZ).  These generating cells (and corresponding fall streaks) can be seen in 
          the cloud radar cross section below.  Cells of this nature were also observed on yesterday's 
          CLEX-9 mission.