Area Forecast Discussion
Issued by NWS Glasgow, MT
FXUS65 KGGW 271446
Area Forecast Discussion
National Weather Service GLASGOW MT
846 AM MDT FRI MAY 27 2016
.SHORT TERM...for northeast Montana...today through Sun...
Morning Update... Morning fog across Nemont is expected to
rapidly burn off leaving scattered mid level clouds. A frontal
boundary just outside the CWA to the northeast is expected to move
forward and generate an area of showers and thunderstorms across
the northeastern third of the CWA. While conditions are stable at
the moment they are expected to become more unstable with the
surface layer baking through the late morning and early afternoon.
A second wave of showers and thunderstorms are expected tonight
along a narrow could frontal boundary entering from the west.
These seem to be accounted for rather well at the moment. GAH
Previous Short Term Discussion...
While the upper low has moved into North Dakota overnight, the
cyclonic circulation associated with the low will continue over
the eastern half of the forecast area this morning. This will
combine with somewhat unstable air mass to allow a few showers to
develop over the area today.
To the west, an upper trough currently over the Pacific NW will
move into Western Montana this afternoon and bring a frontal
boundary into Central Montana. This front will move through
Eastern Montana late tonight and Saturday and become the focus for
showers and thunderstorms. At this point, it looks like the precip
will limited to about a 100 mile wide area along the front as the
lift will be primarily frontal with subsidence to the east and
west of this area. As a result, the eastern zones will be mainly
dry tonight and the chances of precip will quickly diminish
Saturday afternoon in the west and Saturday Night in the east
once the front moves to the east. The upper trough moves northeast
through the forecast area Saturday afternoon and evening and into
Saskatchewan late Saturday Night.
Look for zonal flow aloft on Sunday with surface high pressure
over the area and dry weather under mostly clear skies. Forrester
.LONG TERM...Sun night through Fri...
The extended period begins Sunday evening with a weak ridge in
place over the Northern High Plains and western flow aloft
producing mild conditions. Off to the west an upper trough will be
digging into British Columbia and the Pacific Northwest producing
cooler conditions and widespread precipitation there.
As the trough plows through the Northern Rockies upper flow over
Northeast Montana will begin to back to the southwest, introducing
moisture and instability. Expect rain showers sometime after
midnight, spreading east and increasing on Monday.
With the associated cold front moving across the area, convective
parameters become moderate to strong, enough to produce afternoon
and evening thunderstorms with the showers. Expect the upper and
lower low centers of this storm to stack up by tuesday morning
into a compact cyclone with strong gusty winds and areas of heavy
rain. The storm will be a slow mover, not exiting the region until
Wednesday evening a strong upper level ridge will have developed
over the West Coast producing northwest flow aloft over Montana.
This ridge will slowly progress eastward for the remainder of the
period, bringing warmer and drier conditions.
High confidence for the general upper flow pattern, and becoming
stormy by Monday, then diminishing the unsettled conditions
around late Wednesday, followed by increasing temperatures and dry
conditions late in the period. Generally continued the trend to
FLIGHT CATEGORY: VFR.
SYNOPSIS: The closed low pressure system that brought rain
showers to the area Thursday will stall over southern Manitoba and
Western North Dakota this morning, which will continue bringing
isolated rain showers to Northeast Montana through today and into
this evening. Convective parameters will be on the weak side, but
isolated general thunderstorms will remain possible in the
afternoon and early evening. A narrow, weak ridge over the local
area will make the showers much more intermittent by evening. Near
the end of the TAF cycle a cold front from teh west will bring a
second round of showers and thunderstorms with impacts starting
at KGGW right towards the end of the cycle and spreading to the
remaining terminals just beyond.
WIND: From the east at less than 10kts.