Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

fxus65 kgjt 261749 

Area forecast discussion
National Weather Service Grand Junction Colorado
1149 am MDT Wed Jun 26 2019

Short term...(today through thursday)
issued at 430 am MDT Wed Jun 26 2019

A broad trough is expected to pivot southward into the Pacific
northwest this afternoon. Ahead of this system, a seasonably
strong jet aloft will come ashore and spread inland through the
Great Basin by this evening. Over eastern Utah and southwest
Colorado, flow aloft will gradually shift from west to
southwesterly and increase throughout the day. Mainly clear skies,
rising heights aloft and warm air advection will all combine to
allow for steady warming both today and tomorrow over The Four
Corners region. By this afternoon, mixing heights should be
sufficiently high to tap into stronger flow aloft. This will allow
momentum Transfer to the surface and thus some stronger wind gusts
in the 30-40 mph range, especially over eastern Utah and far
northwest Colorado. Combined with low relative humidity values and critical fuels
in some locations, a red flag warning has been issued for several
zones on the western slope. See the latest rfwgjt for additional

Overnight, winds will relax as the surface decouples shortly after
sunset. Expect a benign night on Wednesday with only a few passing
clouds in the North. Heights continue to rise on Thursday as warm
air surges northward from the Desert Southwest. The core of the
jet ahead of the pacnw low pressure will remain to our west,
however deep mixing will once again tap stronger flow aloft
resulting in another gusty afternoon. High temperatures are
expected to run near or slightly above normal for late June. An
isolated thunderstorm can not be ruled out in the far southern San
Juan Mountains near the New Mexico border as some moisture sneaks
northward, however pop chances remain at or below 15% in this
forecast package. Overall, not much changes to the short-term
overnight other than slight adjustments to temperatures using a
blend of MOS guidance.

Long term...(thursday night through tuesday)
issued at 430 am MDT Wed Jun 26 2019

Friday is shaping up to be the hottest day of the year so far
across all of eastern Utah and western Colorado. A sprawling 594dm
ridge at 500mb over the Southern Plains will drift westward,
while at the same time 500mb heights will fall throughout the
Great Basin as a trough/front drag eastward. This will result in a
squeeze-play over The Four Corners. Southwesterly flow will
continue the warm-air advection regime in place. Mainly sunny
skies and continued low relative humidity values will support maximum surface heating
potential. High temperatures are expected to approach the triple
digits in Canyon Country of eastern Utah, with mid-90s possible
throughout the Grand Valley. Forecast highs were kept at
reasonable model-blend averages for now, but it is Worth
mentioning that highs could run slightly above current values of
some of the more aggressive ensemble solutions come to fruition.

The dry and windy pattern finally comes to an end on Saturday,
and in a rather interesting way. Our first tropical system in the
eastern Pacific, currently a depression off the coast of southern
Mexico, will drift northward and weaken by early this weekend.
Forecast guidance has shown some consistency in bringing the
remnant clouds and a bit of mid-level moisture northward as
future-tropical-storm-Alvin weakens. In addition to Alvin, moisture
will continue to drift northward underneath the Southern- Plains
high pressure system. This high pressure will force faster flow
away from the western slope, resulting in lower wind speeds on
both Saturday and Sunday as well as better chances of showers and
thunderstorms in the higher terrain. By Monday and Tuesday, high
pressure will flatten out with a weak trough passing to the north.
Showers and thunderstorms will continue to be favored in the
higher terrain, however predictability and model consistency
decrease markedly by early next week.


Aviation...(for the 18z tafs through 18z Thursday afternoon)
issued at 1149 am MDT Wed Jun 26 2019

VFR conditions are expected to dominate the area on Wednesday.
However, breezy southwesterly winds will develop at all terminals
early Wednesday afternoon, diminishing in the early evening. Dry
and mostly clear weather is expected overnight, with breezy
southwesterly winds developing again on Thursday afternoon.


Fire weather...
issued at 430 am MDT Wed Jun 26 2019

Critical fire weather conditions are expected over the next three days.
Southwesterly flow will strengthen over Utah and Colorado by this afternoon
bringing dry air through The Four Corners. A combination of wind gusts over
30 mph and low relative humidity will result in critical fire weather conditions in areas
where fuels have dried. By the weekend, some moisture will stream northward
which will increase relative humidity values and precipitation chances, reducing the
threat of red flag conditions. &&

Gjt watches/warnings/advisories... flag warning from noon today to 9 PM MDT this evening for

Fire Weather Watch from this evening through Friday evening for
coz207-290-292. flag warning from noon today to 9 PM MDT this evening for


Gjt watches/warnings/advisories... flag warning until 9 PM MDT this evening for coz207-290-292.

Fire Weather Watch from 9 PM MDT this evening through Friday
evening for coz207-290-292. flag warning until 9 PM MDT this evening for utz490.



National Weather Service Glossary of Abbreviations