SUCCESS 48 hour Meteorological Forecast

12z 16 April 1996

Forecast based on

Synopsis


Prog Discussion


The NGM, ETA, and AVN handle the speed of the Pacific northwest shortwave and placement of the northern Plains surface low differ- ently. We have gone with the slower ETA solution which keeps the surface trough west of the forecast area and schedules the frontal passages to occur after 00z Thu 18. All models show the upper level pattern to become zonal by 00z Thu 18. The MRF shows the zonal pattern to persist, and it does not change until 00z Mon 22.

48 hour Forecast:

12z 16 - 00Z 17 Apr: An upper level ridge is centered over the eastern Rockies. The ridge will flatten as a strong Pacific northwest shortwave moves through it. The winds will gradually increase throughout the day as the surface gradient increases in the northern and central Plains in response to a surface low progressing out of the Pacific northwest into Alberta/Sas- ketchewan. The day should be clear with increasing cirrus clouds. The temp- erature will rise into the upper 70's.

00Z 17 Apr - 12Z 17 Apr: A Pacific shortwave moves on shore. The 500 mb ridge axis is now centered over MN, IO, and MO. At the surface, a front is analyzed over TX/OK pandhandle and western Kansas. The warm southerly flow will keep the temperatures in the 50's.

12z 17 Apr - 12Z 18 Apr: The upper level flow will become zonal and a 120 kt jet is analyzed on the west coast at 35N. A cold frontal passage is progged for late Wed. night/early Thur. morning (LST). Ahead of the front, there is a slight chance of scattered thunderstorms if moisture advects from the south. The winds will remain strong (20-25 kts, gusts to 30 kts) and southernly. The temperatures will be in the upper 70's and lower 80's. High level clouds will persist.

Extended Range Discussion:


12z 18 Apr - 12Z 19 Apr: After the cold frontal passage, the daytime tempera- tures will drop by 10-15oF, and the winds will become northernly. The upper level flow pattern will be zonal at 500 and 300 mb, with the polar jet centered over southern CA and AZ.

Walker and Mace

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Last Updated: 15 Apr 1996