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Area forecast discussion 
National Weather Service Grand Junction Colorado
424 am MDT Tuesday Sep 23 2014

Short term...(today through wednesday)
issued at 423 am MDT Tuesday Sep 23 2014

Today...following the last two days of rain...surface humidity is
running high and areas of fog are expected through midmorning at
many locations of northeast Utah and western Colorado.

The main trough in the upper levels passed east of the area last
night and its weak surface and midlevel front will slowly drag
across northern Colorado and NE Utah today. A thick bank of middle and low
level clouds over NE Utah and most of northwest and central Colorado will
gradually dissipate and move east today.

Dry conditions will persist as high pressure builds over the
region. By Wednesday afternoon this large high pressure ridge will
extend from the Desert Southwest north-northeast across the
central rockies and into the northern plains and southern
Saskatchewan. The warming trend already underway will continue.
However in the drier air mass... little change is expected in
overnight lows as compared to this morning/S. Then daytime highs
on Wednesday will increase another few degrees over
today/S...reaching 5-10 degrees above normal.

Long term...(wednesday night through monday)
issued at 423 am MDT Tuesday Sep 23 2014

The high center will work its way north/northeast-Ward...making
it into South Dakota by Thursday afternoon. As this happens...low
pressure will begin to undercut the high from the east-northeast
tilting the upper ridge. A modest amount of moisture will begin to
creep up from the southeast...with a few thunderstorms possible
along the peaks of the San Juans and south-central Divide
mountains Thursday afternoon. The warming trend will continue as the
thermal high moves to a position over the central rocking by 00z
Friday.

Wednesday night through Monday...high pressure and dry conditions
will continue through Thursday morning...though by about 21z Thursday in the
GFS the ridge will have eroded enough to allow some moisture to
seep into SW Colorado and southeast Utah from Arizona and nm.

On Friday the closed low off the West Coast will begin moving
inland and the ridge will have slid east. This allows a
strengthening SW flow aloft to draw moisture north and into the
area. This pattern continues through Saturday. The models are
reaching a better consensus...which is similar to early European model (ecmwf)
solution...where the low deepens and stalls over northern California. This
will allow substantial moisture to advect north across the SW
u... the front will make slower progress across the Great
Basin. Currently it appears the front will not reach eastern Utah
and western Colorado until Sunday afternoon and evening. Have increased
cloud cover and chance of rain across the area for all day Sunday
through early Monday morning.

&&

Aviation...(for the 12z tafs through 12z Wednesday morning)
issued at 423 am MDT Tuesday Sep 23 2014

North of the bookcliffs low clouds and areas of fog will cause
obscured mountains and passes...with local MVFR visibilities in fog.
Areas of fog are also expected until about 15z in the valleys of
central and SW Colorado. Otherwise VFR conditions are expected today
through tonight.

&&

Gjt watches/warnings/advisories...
Colorado...none.
Utah...none.
&&

$$

Short term...cc/eh
long term...eh/cc
aviation...cirrocumulus

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