NASA - National Aeronautics and Space Administration

Forecast Based on

• on satellite
• current surface observations
• 00 UTC ETA
• 00 UTC NGM
• 09 UTC MAPS/RUC
• MRF
• 12z ECWMF

Synopsis

The upper level flow is fairly zonal across the US with a hint of the building ridge
off British Columbia and the Pacific northwest coast. A shortwave over KS/OK has led
to some mid level cloudiness. High pressure dominates most of the midwest and all of
the South. A low has formed in New Mexico, and this feature is the one to watch later
today and tomorrow. Satellite imagery shows a jet streak across the US. The water
vapor loop has a dry slot dropping down from the northwest into WY and CO. The Gulf
is free of convection with fog and low level clouds.

There are mid and upper level clouds over KS/OK at this time.

Prog Discussion

All the models are in close agreement in handling the development of the upper level
trough over the Great Basin and the surface low in the TX panhandle in the next 36 hrs.
As the low develops Sat. evening into Sun. morning, the surface dew points will increase
across OK and s/se KS. With strong upper level dynamics, the chance of thunderstorms and
showers in OK is very probable late Sat. night/early Sun. morning. Kansas will have
gusty northeasterly winds, low clouds, and precipitation on Sun. Wide spread
thunderstorms are more likely in the southern and southeastern parts of Kansas.

48 hour Forecast:

12z 27 Apr - 00Z 28 Apr: Partly cloudy. Highs in the mid to upper 60s. Winds northerly
at 10 kts.

00Z 28 Apr - 12Z 28 Apr: Continued cloudiness. Chance of rain. Lows in the mid 40s.
Thunderstorms possible in the southeast. Winds will increase from the northeast.

12z 28 Apr - 12Z 29 Apr: Colder with rain likely in the east and a chance for rain in
the west. Wide spread thunderstorms possible to s and se. Highs ~50. Winds should
20+ kts all day from the northeast.

Extended Range Discussion:

12z 29 Apr - 12Z 30 Apr: Continued cool. Highs in the 50s. Cloudy and chance for rain
in southeast.

The MRF continues to forecast the omega block pattern out to May 6th. The ECMWF showed
a different longwave pattern. Yesterdays ECMWF agreed with the MRF, yet last nights ECMWF
run has the trough progressing to the east and the flow becoming zonal in the next 6 days,
i.e. the persistent pattern since the middle of April.

Walker and Mace