Area forecast discussion
National Weather Service Grand Forks ND
1052 am CDT Sat may 18 2013
Update...
issued at 1049 am CDT Sat may 18 2013
Late morning update was to go dry through late afternoon in southeast ND into
west-central Minnesota. Temperatures somewhat of an issue and lowered a bit especially northern
zones where low 60s in Langdon-Cando may be all that can be done.
Kept high probability of precipitation far northern forecast area in NE ND/northwest Minnesota with showers
moving through. Still thinking lower 80s or so far southeast ND...but
depends on amount of sun. Latest hrrr/rap all indicate main warm
front and convection developing in northern South Dakota into central Minnesota 22z-00z
period and then maybe lifting north into southeast ND.
&&
Short term...(today through sunday)
issued at 326 am CDT Sat may 18 2013
Forecast challenge through the short term will continue to be precipitation
chances as well as severe storm and heavy rain potential. Models
in fair agreement with main features however subtle differences
exist with surface low/boundary positions today.
Arc of weakening convection lifting NE through forecast area at 30kts will
continue to propagate NE through the morning and into early
afternoon. Will attempt to adjust/time probability of precipitation accordingly.
Temperatures will be tricky and dependent on degree of cloud cover
and how far north warm front gets. With warm column any breaks
will really boost temperatures.
Later today and into tonight. Surface inverted trough to sharpen
across forecast area providing good source of low level convergence. Tough to
determine any specific short wave however region comes under
entrance region of modest jet streak which will aid in upper
support. Models differ on location of surface low which will ride
northward along trough as well as position of warm frontal
boundary. Models indicating good surface moisture flux with 60
dewpoints spreading northward through most of forecast area. Precipitable water
values increase to around 1.5 by evening. Greatest instability and
cape across south half of forecast area and looks to be the favored location
for severe potential. Some capping may initially delay convective
initiation during the afternoon. Heavy rain potential there but with
differences in surface low position to enhance low level
convergence not as clear cut.
Inverted trough to drift east Sunday which will put heavier rain
threat into Minnesota. Temperatures to be quite a bit cooler on back side
of inverted trough.
Long term...(sunday night through friday)
issued at 326 am CDT Sat may 18 2013
Cut off low takes over and drifts across east South Dakota into S Minnesota to start work
week for continued moderate rain potential and cooler temperatures.
Tuesday-Friday...the upper low will slowly shift eastward from the
central/northern plains into the Great Lakes during this period. The
00z GFS/12z European model (ecmwf) begin to shift shower activity south and east on
Wednesday...with the Gem slower in ending the precipitation. Will continue
to mention probability of precipitation across the southeast through Wednesday night. Surface
high pressure is expected to build across the area towards the end
of the week as middle/upper level ridging develops across the plains.
Below normal temperatures will moderate back to near normal by late next
week.
&&
Aviation...(for the 12z tafs through 12z Sunday morning)
issued at 650 am CDT Sat may 18 2013
With showers in the vicinity ceilings vary greatly. Ceilings generally bouncing
between MVFR/VFR with mostly VFR ceilings. There is however some
localized IFR ceilings in br but not limited to within rain band.
Expect condition to persist through the morning as rain showers lift
northward. Could see more VFR conditions this afternoon with thunderstorms and rain
possible late afternoon.
&&
Fgf watches/warnings/advisories...
ND...none.
Minnesota...none.
&&
$$
Update...Riddle
short term...voelker
long term...makowski/voelker
aviation...voelker
