Area Forecast Discussion
Issued by NWS Grand Forks, ND

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FXUS63 KFGF 152340
AFDFGF

Area Forecast Discussion
National Weather Service Grand Forks ND
640 PM CDT Tue May 15 2018

.UPDATE...
Issued at 631 PM CDT Tue May 15 2018

Updated discussion for 00Z aviation forecast (see below).

Primary concern for public/fire forecast continues to be
dangerous fire weather conditions although wind gusts are slightly
backing off...and gustiness should decline by 8 PM. At current
time no reason to change Red Flag Warning headlines (ending at 8
PM CDT) with winds beginning to decline.

&&

.SHORT TERM...(This evening through Wednesday)
Issued at 325 PM CDT Tue May 15 2018

An upper level wave is passing to the north of the area today,
with a surface low moving ESE across southern MB. Dry southwesterly
winds have increased ahead of this feature...resulting in fire
weather concerns across the area. Showers associated with the wave
will just clip Lake of the Woods this evening. Otherwise, a cold
front pushes south tomorrow, but will not make it all the way
through the area. It will likely get hung up from the Red
Lakes/Bemidji area through the central Red River Valley. Temps
tomorrow afternoon in the north will be mostly in the 70s to near
80 and temps in the south will be in the 80s. Instability looks
to be enough for a few isolated thunderstorms near the Bemidji
area tomorrow late afternoon. Shear and upper support is lacking,
so not much is expected in regards to any severe weather if storms
do fire.

.LONG TERM...(Wednesday night through Tuesday)
Issued at 325 PM CDT Tue May 15 2018

Precipitation along a stalled frontal boundary is expected to begin
late Wednesday evening across the region. Most guidance suggests a
small amount of instability that will allow for a few thunderstorms
overnight Wednesday, although forecast soundings suggest poor mid
level lapse rates that will limit the severity of any convection
that develops.

There is still some uncertainty regarding the evolution of the
mesoscale environment for Thursday. Rain chances will increase again
during the day as a stronger upper level shortwave pushes
southeastward out of Canada. A few thunderstorms will be possible
across the southern River Valley and as far north as the Devils Lake
region depending on morning/mid day cloud cover and moisture return.
While most guidance suggests 500-1000 J/kg of MUCAPE across the
region, recent NAM forecast soundings suggest a well mixed boundary
layer developing allowing for higher CAPE values across southern
North Dakota that are supportive of stronger thunderstorms, while
GFS soundings show a cooler, more capped environment due to
widespread stratiform rain. Details about the potential for
convective development on Thursday will become more clear in the
coming day.

Regardless, rain is expected to continue through Friday afternoon
for the region. As the upper level trough pushes east/southeastward
surface pressure rises will give a southward push of cooler air.
Precipitation will wind down from northwest to southeast as the
effective cold front pushes through the region. Both deterministic
and ensemble guidance suggests rainfall totals by Friday afternoon
could reach from 0.5" to 1.0" for many locations.

Breezy and cooler weather is expected for Saturday as surface high
pressure builds across the region and temperatures climb to the mid
to upper 60s. A return to warm weather is likely for Sunday and
Monday with afternoon highs in the 70s.

&&

.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 631 PM CDT Tue May 15 2018

Gusty west northwest winds will settle down with gusts declining
while steady winds remain in the 10 to 20 mph range. Expect most
sites to turn northerly and eventually northeasterly by Tue PM as
a cool front drops in from the north. Be alert for elevated have
layers as inversion sets up over night and traps smoke from local
fires, esp over NW Minnesota. Could significantly reduce nighttime
forward vsby.

&&

.FIRE WEATHER...
Issued at 325 PM CDT Tue May 15 2018

Red Flag conditions continue across the northern zones...with
near critical conditions in the central zones. Wind gusts as high
as 40 mph have been reported at some of the automated airport
observing sites. Conditions improve tonight as relative humidity
recovers and winds decrease. A cold front will bring a wind shift
to much of the area tomorrow...and winds will be much lighter
tomorrow as well. Minimum RH will be in the 20s south to 30s north
tomorrow. A couple of upper waves will bring a good chance for rainfall
to much of the area by the end of the week.

&&

.FGF WATCHES/WARNINGS/ADVISORIES...
ND...Red Flag Warning until 8 PM CDT this evening for NDZ006>008-
     014>016-026-027-054.

MN...Red Flag Warning until 8 PM CDT this evening for MNZ001-004>009-
     013>016.

&&

$$

UPDATE...Speicher
SHORT TERM...Knutsvig
LONG TERM...AM
AVIATION...Speicher
FIRE WEATHER...Knutsvig



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