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Area forecast discussion 
National Weather Service Grand Forks ND
939 PM CDT Thursday Sep 18 2014

Update...
issued at 933 PM CDT Thursday Sep 18 2014

No update needed at this time. Some weak echoes in central ND
heading this way. So far not impressed as not sure anything is
reaching the ground but will keep low probability of precipitation going as mesoscale
models continue to show some expansion in coverage later this
evening.

Update issued at 619 PM CDT Thursday Sep 18 2014

Main challenge this evening will be rain chances in strong warm
advection zone ahead of approaching trough. Currently some weak
echoes across the northern valley. Some isolated lightning strikes earlier
but convection has out run what instability there was. Have isolated
sprinkle mention into early evening for this area. Will monitor
trends elsewhere through the evening. No other changes.

&&

Short term...(this evening through Friday night)
issued at 339 PM CDT Thursday Sep 18 2014

Challenge for this forecast include probability of precipitation placement with active
period setting up for the next 48 hours. Models handling general
synoptic features well with the normal spread in convective qpfs
generated over the next couple days.

This afternoon into the overnight period will continue to see low
level jet bringing moisture and warmer blyr temperatures to the area.
With warm air advection and moisture streaming into the region mixing will
offset Sundown and allow surface winds to stay up. Later tonight...
around 9z...hrrr/rap/hop-WRF ensemble bring in some convection
across the Central Valley...will keep the chance of rain showers and
thunder.

By Friday 1.5 inch precipitable waters with a surface trough and westerly winds
nose into the western County warning forecast area. The moisture/instability combined
with the slow moving trough and zonal flow will allow for the
potential for any weak perturbation in the flow to initiate shower
and thunderstorms. Best chance will be along the track of the surface
low where models agreement is depicting it across the northern
valley into northwest Minnesota.

Long term...(saturday through thursday)
issued at 339 PM CDT Thursday Sep 18 2014

The next short wave is escorted on the nose of 300mb jet
Saturday. Cold core aloft with -20c advecting in at 500mb will
bring afternoon showers and thunder potential...given the current
timing best chances will be in northwest Minnesota. Wind potential in its wake
is a concern across east ND and Red River as 30 to 35 kts of northwest wind may
mix to near 800mb.

Extended period begins with long wave ridge over Pacific northwest
with trough over Great Lakes. Northwest dry flow indicated for the
northern plains as the upper pattern transitions to the east through
the middle of the week. This would place ridge over forecast area
Tuesday/Wednesday accompanied by above normal temperatures by 5 to 10 degrees. Some
disagreement between GFS and European model (ecmwf) enters the picture by later
Wednesday with troughiness in the GFS and more of a closed low for
the European model (ecmwf). Either of these solutions introduces low probability of precipitation to the
forecast during this time.

&&

Aviation...(for the 00z tafs through 00z Friday evening)
issued at 619 PM CDT Thursday Sep 18 2014

Kept ceilings/visibility VFR overnight. Most model guidance indicating some
MVFR possible IFR ceilings across the south and east in the the am and
followed guidance with ceilings in late periods.



&&

Fgf watches/warnings/advisories...
ND...none.
Minnesota...none.
&&

$$

Update...voelker
short term...jk
long term...wjb/jk
aviation...voelker

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