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Area forecast discussion 
National Weather Service Billings Montana
839 PM MDT Tuesday Jul 29 2014

weak energy moving through the high pressure ridge currently over
the area and has helped in setting off isolated convection this
evening over our western zones. Weak forcing also being provided
by right entrance region of the jet and light easterly surface
winds brining upslope flow. Loss of daytime heating and monsoonal
moisture is being suppress southward by the upper ridge and
precipitation chances over the plains have ended. Have removed
probability of precipitation over the plains for tonight. Some isolated convection will
continue over the Southwest Mountains through late evening.
Remainder of the forecast on track and no other changes needed.


Short term...valid for Wednesday and Thursday...

Strong upper level ridge remains in control of the region. Isolated
thunderstorms have developed over the crazy and beartooth/Absaroka Mountains
over the past a low shear monsoonal regime...but
otherwise shortwave dropping into the Dakotas on the east side of
the ridge is allowing for advection and mixing of drier air from
the northwest. Note dewpoints which have fallen to the middle 40s at Miles City
and Baker at 2 PM. A lone weak cell has developed over SW Powder
River County but this should not do much. For the early evening
will sustain isolated probability of precipitation over our west and south...otherwise it
will be a quiet night with clearing skies and seasonal low temperatures.

High pressure aloft will continue to dominate our weather for the
next two days...with any convective chances dominated by monsoonal
flow. Wednesday will see lower coverage than today as precipitable waters fall
to values closer to a half inch...but still cannot rule out an
isolated thunderstorm over the mountains precipitable waters will begin to increase late
Thursday so expect isolated to scattered coverage over our western
mountains and foothills. Will need to keep watch of moisture from Post-
Tropical Storm Hernan off the Baja California it is expected to
lift into the northern Great Basin Thursday and possibly give a
boost to convective potential for our SW mountains by Thursday night.
Will keep low probability of precipitation over the beartooth absarokas through Thursday
night. It GOES without saying that any thunderstorms over the next two
days will be unorganized and weak.

Temperatures will remain close to normal through the short term
period...with highs in the upper 80s to near 90f tomorrow and
into the lower 90s Thursday.


Long term...valid for Friday...Sat...sun...Mon...Tue...

Ridging aloft currently in place over the western United States is
expected to flatten between Friday and Tuesday concurrent with the large-
scale /albeit gradual/ Delaware-amplification of flow over the lower 48.
We expect a slow uptick in the chance of showers and storms across
southern Montana and north central Wyoming with this transition owing to the
passage of weak ridge-riding shortwave troughs and enhanced pushes
of monsoonal moisture. The timing of those features is not a high-
confidence item...but the 12 UTC GFS and European model (ecmwf) actually agree that
a better shortwave may arrive by Monday and we chose to show
a bit higher chance of convection in that time frame. Temperatures
will be near normal during the period...but highs may cool some on
Monday and Tuesday if monsoonal moisture increases significantly. Schultz



An isolated shower or thunderstorm and associated MVFR condition
will be possible over the mountains through 06z...although
mountain obscurations can be expected at times throughout the
night. Elsewhere across the forecast area...mostly clear skies and
VFR conditions will prevail. Hooley


Preliminary point temp/pops...

Wednesday Thursday Friday Sat sun Monday Tuesday
bil 060/089 062/091 062/091 062/089 062/088 061/088 063/085
00/u 01/u 12/T 22/T 22/T 23/T 32/T
lvm 052/087 053/090 055/091 055/087 054/086 055/084 056/084
11/b 12/T 22/T 22/T 22/T 23/T 33/T
hdn 056/091 057/092 058/093 060/091 060/090 059/090 063/086
00/u 00/u 01/u 22/T 22/T 23/T 33/T
mls 059/090 061/092 063/093 063/093 063/090 062/089 065/085
00/u 00/u 01/u 12/T 22/T 12/T 22/T
4bq 056/088 058/090 059/092 061/092 061/090 061/089 063/085
10/u 00/u 01/u 12/T 22/T 23/T 33/T
bhk 053/086 055/088 057/089 058/090 058/088 057/086 061/083
00/u 00/u 01/u 12/T 22/T 12/T 23/T
shr 053/087 053/089 054/089 056/087 055/087 056/086 059/083
10/u 01/u 12/T 22/T 23/T 33/T 33/T


Byz watches/warnings/advisories...



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