Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

fxus63 kfgf 210951 
afdfgf

Area forecast discussion
National Weather Service Grand Forks ND
351 am CST Thu Nov 21 2019

Short term...(today through friday)
issued at 350 am CST Thu Nov 21 2019

Early this morning: elongated southwest to northeast axis of light
snow is lingering near weakening region of positive 700mb
frontogenesis in our southeast cwa, with a few pockets of flurries
further north. WV imagery shows deep subsidence beginning to spread
eastward into central ND. So far satellite/regional radar/obs trends
are reflecting consensus of cams, and expect most measurable precip
to end by 12z in our County Warning Area. A few pockets of very light freezing
drizzle still can't be ruled out, however are deeper cont is
continuing to advect north to south the window for this is closing.
The intensity of snow has greatly diminished, coverage or impacts of
freezing drizzle are uncertain, and at most an additional dusting
(less than 0.5") would be possible before tapering to flurries.
Considering this, I went ahead and allowed the Winter Weather
Advisory to expire at 3am as scheduled, as any additional impacts
through 6am will be minimal and highly localized.

Today-friday: shortwave ridging aloft, and 1025mb surface high
pressure will continue to build into our County Warning Area today with clearing
skies west to east. A few flurries may linger this morning after
main light snow bands end (mainly in our east. Overall expecting
trend toward dry conditions through these periods. Surface gradient
ahead of this high pressure will still support some gusts 20-30 mph
this morning (mainly in the southern Red River valley). Winds should
decrease through the day with weakening of surface gradient.

Cold air advection continues through the day and with 925mb temps as low as -14c
possible there may not be much difference between morning and
afternoon temperatures. In our southeast, morning temperatures in
the 30s decrease to 20s by this afternoon. Temperatures upstream
over southern Saskatchewan are already in the single digit temps this
morning and that is where our air mass is coming from. Gefs and nbm
favoring low to mid teens with colder pockets in the single digits,
however with new snow pack in our north and ideal radiation
conditions we may see single digit lows over a larger part of our
area than indicated (new snow fields always result in a delay in
bias adjustments). Hard to say how much colder, but single digits
seems reasonable for our north, and teens may still be favored in
our south tonight.

Warm air advection is expected Friday as west-southwest flow develops ahead of a
shortwave trough, and there is a strong consensus/signal in ensembles
of highs warming back at least to the 30s (granted deeper snow pack
could temper this a bit in our north). Increase in gradient Friday
should support increasing SW and potential for gusts around 25 mph
by the afternoon (based on potential momentum Transfer/Max bl
winds).

Long term...(friday night through wednesday)
issued at 350 am CST Thu Nov 21 2019

00z Sat - 12z sun

Short wave trough now off the West Coast will move across the
northern plains Fri night and Sat morning. Respectable short wave
with better than 100 meter height rise/fall couplet will move
across the area. Will bump up winds for Fri night into Sat. Another
short wave will move across southern man Sat afternoon and should
keep precip in southern Canada.

Sun - Wed

Upper level air pattern to remain relatively progressive through the
period. Long wave trough deepens and broadens a bit over the lower
Ohio River valley. Long wave ridge over western Canada weakens and
shifts south and west. Upper level jet over southwest Canada shifts
south into the southwest US by the end of the period.

Series of short waves will move across the northern plains/southern
Canada. Another short wave will move across southern Canada and the
western US sun. Models tend to follow the same trend with
differences in timing. The ensemble mean tended to be a slower
solution. Little difference between the the gefs and European model (ecmwf)
ensemble means this period.

&&

Aviation...(for the 06z tafs through 06z Thursday night)
issued at 1134 PM CST Wed Nov 20 2019

North winds expected for the period with some afternoon gusts
around 20kts. Will see stratus deck currently IFR with snow or
freezing drizzle and or fog ending overnight and VFR conditions
develop tomorrow morning for all taf sites.



&&

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

$$

National Weather Service Glossary of Abbreviations