Forecast Based on

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

Synopsis

Persistence sums up the weather. Zonal flow still dominates over the US, with the jet and any strong shortwaves well north of KS. A surface low remains over the panhandle of TX/OK and sw KS, with the east/west stationary front across KS moving slightly to the south over the last 24 hrs.

The satellite pictures were not being updated this morning. The water vapor loop shows a north/south gradient over OK/NM/AZ at 03z and 06z. The cutoff low at 150W has started to move eastward.

Over night, severe convection occurred across KS, bringing strong winds, 1.41'' of rain, and lightening to Salina. One of the convective cells east of Russell produced hail. By 12z all of the convection was east of Salina. A strong cap over OK and a lesser one over KS will prevent convection from occurring today.

Prog Discussion

The NGM and ETA agree well, except at 48 hrs where the NGM tries to move the surface low and stationary front. With the flow being zonal, this trend is questionable. The NGM does show the cutoff low in the Pacific being picked up into the westerly flow by 48 hrs. The satellite loop confirms the movement of the low.

With the stationary front across KS or postioned slightly to the south of the state, thunderstorms are likely to occur again this evening.

48 hour Forecast:

12z 04 May - 00Z 05 May: Mostly cloudy. Highs ~70. Winds 10-15 kts out of the northeast. Chance of thunderstorms.

00Z 05 May - 12Z 05 May: Chance of thunderstorms, possibly severe. Lows in the mid 50s.

12z 05 May - 12Z 06 May: Chance for some early morning showers. Partly cloudy, with possible clearing. Highs in the 70s.

12z 06 May - 12Z 07 May: Chance of thunderstorms. Highs in the 70s. Lows in the 50s.

Both the MRF and ECMWF pick up the cutoff low in the Pacific and form a trough on the Pacific Northwest, with the trough extending down over northern CA. The ECMWF builds a ridge over the middle of the US by Tues. The model has the ridge axis extending well into Sasskatchewan/Manitoba by Wed./Thur. The MRF does not amplify the ridge as much.

With this pattern and with the possibility of moisture advecting in from the inclusion of the Pacific low, Mon. or Tues. could be good cirrus days at the CART site.

Walker and Mace