Area forecast discussion
National Weather Service Grand Forks ND
325 PM CDT Sat may 25 2013
Short term...(this evening through Sunday night)
issued at 320 PM CDT Sat may 25 2013
Forecast challenge concerns mainly rain chances and temperatures.
Models continue to trend to over doing quantitative precipitation forecast so far. Convection
persists across western into the central Dakotas just barely
crossing Missouri River. As short wave ridge over forecast area shifts
gradually east middle level flow becomes more SW with time. As a
result convection may be able to gradually propagate farther east.
Generally trended a slow eastward progression of probability of precipitation although
with main convergence to our west not sure how convection will
hold together so kept probability of precipitation low. Low level moisture flux
gradually increasing which will hold temperatures up.
Rain chances Sunday-Sunday night also in question as low level forcing
remains well to our west so again how far east can convection
propagate. Maintained current probability of precipitation but at this time not enough
confidence to increase. NE third of forecast area to remain rain free longest with
drier air in place. Similar to today cloud cover will have a big
impact on temperatures. Thermal profiles do not change much so
probably not a big change in temperatures. Models do maintain low
level moist layer although convective temperatures much higher.
Long term...(monday through saturday)
issued at 320 PM CDT Sat may 25 2013
As surface low pressure drifts gradually east will see better
chances for precipitation for the early start of the week. Column warms
along with increase in instability to T to be more prominent.
Depending on solar temperatures look closer to average.
Guidance in agreement with pronounced southwest flow aloft from the
Southern Plains to the upper Midwest. They also agree on a closed
low somewhere over the region by days 6/7. This is indicated by both
the operational models and GFS ensembles. The European model (ecmwf) is more vigorous
with the low with a Dakotas placement...while the GFS is more
progressive driving the circulation into Ontario by Saturday.
At the surface this should translate to an active period with
several convective episodes Tuesday night through Thursday...with
more of a light rain or showers regime for the end of the
week...perhaps slackening or ending by Saturday. Temperatures will
be near seasonal norms during the afternoons...above normal for the
cloudy overnights.
&&
Aviation...(for the 18z tafs through 18z Sunday afternoon)
issued at 1239 PM CDT Sat may 25 2013
IFR ceilings have lifted out of kdvl...eastward progress has been limited
to kgfk and brief period of MVFR there. Looking at low VFR ceilings
through this taf period as main moisture stays well west of region
for the time being. Gusty wind character should abate by sunset...as
direction stays southeast everywhere. Not much if any precipitation
expected through Sunday morning...reflected in dry tafs.
&&
Fgf watches/warnings/advisories...
ND...Flash Flood Watch through Sunday afternoon for ndz008.
Minnesota...none.
&&
$$
Short term...voelker
long term...Rogers/voelker
aviation...wjb
