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

Deep low pressure is exiting the area this morning. The low
developed as a series of fastmoving shortwaves passed around the base of
a trough that moved slowly eastward over the Plains yesterday. A cool
northerly flow of air prevails over the plains while high pressure builds
from the west. The high amplitude ridge over the Rocky Mountains is
moving slowly eastward as several significant impulses aproach the west
coast of North America.

Prog Discussion

High pressure will build over the area today causing
the northerly winds to diminish and allow temperatures to moderate. As
the pacific impulses move onshore this afternoon, the Rocky Mountain ridge
will erode and move eastward. With the weakening ridge over the plains
and deepening low pressure in the West, high clouds are expected over the
region tomorrow. A trough in the lee of the Rockies will deepen tomorrow
afternoon resulting in a moderate southerly wind.

48 hour Forecast:

12z 15 Apr - 00Z 16 Apr: Mostly clear today with moderating temperatures
and diminishing northerly winds. Expect winds to decrease from 15 knots
this morning to 8-10 knots by evening and a high temperature in the
mid 50's.

00Z 16 Apr - 12Z 16 Apr: Continued clear with some fog possible by early
morning. Winds will be light and variable becoming light southerly by
sunrise. Temperatures will fall into the upper 30's.

12z 16 Apr - 12Z 17 Apr: The day should begin cloudless with a light
southerly surface wind that will increase in intensity during the day.
Thin cirrus are likely by noon. These clouds are expected to thicken during
the afternoon. Winds will increase from southerly at 10 knots during the
morning to southwesterly 15-20 knots gusting to 25 knots during the afternoon.
Temperatures will rise into the the 70's.

Extended Range Discussion:

12z 17 Apr - 12Z 18 Apr: Strong low pressure will develop in the northern
Rockies and approach the plains. Winds aloft will be southwesterly
and strong and should supply ample moisture for clouds in the middle and
upper troposphere. Surface pressure gradients will increase and winds will
be southerly 20 knots gusting to 30-35 knots by afternoon. Thunderstorms
are a distinct possibility during this period.

Mace and Walker