Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Glasgow Montana
846 PM MDT Monday Apr 20 2015
Short term...for northeast Montana...tonight through Wednesday...
north-northwest jet and possibly a weak surface low over Saskatchewan creating clouds
and virga over the eastern zones but this should dissipated
overnight as energy drops south and drier air moves in. Forecast for
the most part has this covered well...but adjusted mainly the sky
grids to account for this. Tfj
synoptic flow pattern and picture is virtually unchanged from
yesterday with NE Montana under northwest flow aloft sandwiched between
an upper low center just north of Minnesota and large upper ridge
over the West Coast.
Todays cloud streak is maximized from our north central County Warning Area to the southeast
corner. Cumulus cloud base began around 6kft earlier and has now
risen to around 8 or 9 kft this afternoon.
Models retain excellent agreement through Wednesday afternoon in
keeping all precipitation away from NE Montana through the
forecast period. Winds are expected to calm tonight...then shift
around from the NE Tuesday...then from due east on Wednesday.
Cloud formation and concentration will tend to limit potential
high temperatures by a few degrees...and given the cloud model
consensus I could find...I tried to incorporate that effect into
the temperature forecast. Generally...expecting lows around 30
and highs around 60 with slightly further extremes in the NE and
Tonight...expecting scattered clouds to linger over our NE and
SW corners with early and strong clearing in-between.
Tuesday...after some lingering morning cloudiness...most of the
County Warning Area will see sunny skies during the afternoon. Wednesday...some
upper-level clouds will arrive from the west amid an otherwise
mostly sunny day. Bmickelson
Long term...Wednesday night through Monday...
model trending toward a somewhat more progressive pattern for the
end of the week into the weekend...although still differences
among the model solutions. Various shortwave expected to push
under the Rocky Mountain ridge during the period and could bring
showers to the region...but timing differences result in low
confidence forecast for any specific period. Will maintain
broadbrush probability of precipitation with near normal temperatures. Ebert
Previous long term discussion...significant model differences
continue which results in a low confidence forecast. GFS maintains
the idea of the blocking ridge over Montana through the weekend
while the European model (ecmwf) wants to be more progressive and move the ridge to
the east on Friday. Both models have a shortwave trough cutting
through the ridge across southern Alberta and Saskatchewan
Thursday and Friday with a few showers possible. Will add a slight
chance of showers to that part of the forecast.
For the weekend...GFS maintains a relatively weak shortwave moving
across the ridge in Montana but keeping most of the precipitation to the
south and west. European model (ecmwf) wants to bring an upper low across the area.
Will become more broadbrush with slight chance of showers at
GFS moves the ridge to the east on Monday and brings a moist SW
flow aloft into the area. European model (ecmwf) builds an upper ridge into
Montana. Will have a slight chance of showers and see if the
models can sort out their differences over the next few nights. Forrester
VFR ceilings and visibilities will continue overnight with light and variable