Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Grand Forks ND
304 PM CDT sun may 3 2015
Short term...(this evening through Monday night)
issued at 300 PM CDT sun may 3 2015
Main forecast challenges will be temperatures and increasing precipitation
chances towards midweek. Models overall in fair agreement with
some precipitation placement differences midweek which is no big surprise.
Will continue with persistence in later periods as a result.
Tonight high pressure will build into the forecast area for diminishing
winds. Could still see some middle/upper level clouds over the southeast forecast area
for a time this evening however by late evening generally sky clear
expected across the region. With cooler column across the forecast area
should see more consistent minimums across the forecast area around 40 or so.
High pressure remains over the forecast area Monday for sunshine...light
winds and seasonal temperatures.
Modest return flow sets up Monday night however fairly dry/cool
column in place so minimum temperatures again will be close to
Long term...(tuesday through sunday)
issued at 300 PM CDT sun may 3 2015
Upper low will begin to lift NE from 4 corners area Tuesday. As it
does surface low pressure organizes over the central/southern High
Plains with east-west boundary setting up across the plains on northern
fringe of northward advancing moisture flux. At this point any
convection associated with boundary will remain south of the forecast area.
Tuesday night and Wednesday boundary and deeper layered relative humidity will
continue to lift northward as upper trough lifts NE. Expect band
of precipitation to lift northward overnight Tuesday night into Wednesday.
With model differences too tough at this time to Pin Point probability of precipitation so
increased probability of precipitation from S-north Tuesday night and kept general likely probability of precipitation
through Wednesday. T potential not overly impressive until possibly
later Wednesday. Temperatures will hinge on cloud cover however
column fairly mild so general above average temperatures expected.
Long term...(wednesday night through sunday)
active and wet pattern expected throughout the period with deep 500 mb
trough digging into the southwest Continental U.S. Through Saturday and then
slowly lifting through the intermountain west into the following
week. This keep an unstable southwesterly upper flow pattern over
the forecast area through the extended period... and allows for a deepening
southerly low level moisture flow to develop across the southern and
Central Plains... feeding storm systems into the northern plains.
GFS and European model (ecmwf) continue to alternate phasing of shortwave impulses
lifting through the pattern though consensus has deep convection
threat from Wednesday morning through Thursday afternoon... with a
more stable precipitation /wraparound/ band from late Thursday into Friday.
Current models depict a break in precipitation from middle Friday into Sat...
with a second low pressure center tracking through the area for
Sunday and Monday. So expect periods of rain and sun with
temperatures steadily cooling into the weekend.
Aviation...(for the 18z tafs through 18z Monday afternoon)
issued at 1245 PM CDT sun may 3 2015
Moderate northwest boundary layer winds across the forecast area this afternoon
will diminish with nightfall. Middle to upper level clouds along and east
of a Rox-rdr-jms line will steadily shift eastward with VFR conds
persisting throughout the period. Surface high pressure should be
centered over the Red River early Monday morning with light and variable
winds and fair skies.