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

A tightly wound up surface low in the Gulf of Alaska is associated with a
strong shortwave and upper level jet on the Pacific Northwest coast. Plently
of mid and upper level moisture exists with this feature. Cirrus is spilling
over the ridge which is ahead of the Pacific trough into ID, MT, and WY. With
these conditions, wave clouds are expected to form along the Front Range and
over Medicine Bow.

Over Kansas, high pressure has built in. The winds are light, and the skies
are blue.

Prog Discussion

As the Pacific Northwest shortwave moves on shore and into the Rockies, the ridge
will progress eastward and start to deamplify. By 00Z Thu 25, the 500 mb
flow will almost be zonal. At the surface, the high will slide down into Texas
and the Gulf. As the shortwave moves eastward, a surface low forms in the northern
Plains with a trough forming in the lee of the Rockies.

48 hour Forecast:

12z 23 Apr - 00Z 24 Apr: Sunny skies with thin upper level clouds increasing toward
the evening. Highs in the 70s. Winds southerly 10 kts.

00Z 24 Apr - 12Z 24 Apr: Increasing cirrus. Lows in the lower 50s. Winds out of
the south 10-15 kts.

12z 24 Apr - 12Z 25 Apr: Partly cloudy. Cirrus will vary in cover and thickness.
Warm and windy: upper 70's, southwestly winds 20+ kts.

Extended Range Discussion:

12z 25 Apr - 12Z 26 Apr: Trough will form over the midwest. After cold frontal
passage on morning of 25th, temperatures will taper by 10 or more degrees. The
winds will be out of the northwest at 15-20 kts. Some mid level clouds.

Walker and Mace