Area Forecast Discussion
Issued by NWS Grand Forks, ND

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FXUS63 KFGF 241744

Area Forecast Discussion
National Weather Service Grand Forks ND
1244 PM CDT Thu May 24 2018

Issued at 1102 AM CDT Thu May 24 2018

Adjustments made to account for current trends in PoPs/Wx (based
on radar/satellite) and temps based on area obs.

Warm front actively lifting north over our CWA and a surface
trough axis trailing this front have acted as focus for
shower/thunderstorm initiation this morning. This has been aided
by forcing ahead of incoming PV anomaly (associated with dry slot
to our west). LPL heights on mesoanalysis support convection
becoming surface based, and with very moist (Tds in mid 60s) and
warm (temps already around 80F) SB CAPE values are already in the
2000-25000 J/KG range ahead of surface trough. Surface layer is
still somewhat capped (CINh about 100), and ML CAPE is less
impressive (250-1000 J/KG), but this could change rapidly with
additional heating. LLJ is transitioning northward, but there is
enough of a low to mid level speed max to support effective shear
in the 30-35kt range for an early window late this morning/early
this afternoon. There is at least a potential for a few strong or
severe updrafts through the early afternoon in our east, before
large scale subsidence/dry slot transitions over our CWA. Then
there should be a lull (and "reloading" period) before the window
for additional activity arrives later this afternoon/evening in
line with previous forecast expectations.

UPDATE Issued at 647 AM CDT Thu May 24 2018

Still have a few lingering showers and weak thunderstorms, but
overall activity continues to wane. Previous forecast still in
line, so no other changes needed.


.SHORT TERM...(Today and tonight)
Issued at 401 AM CDT Thu May 24 2018

There are a few different areas of convection across the FA this
morning. The main one is up around the Lake of the Woods region,
where slow moving thunderstorms are likely dropping some small
hail at times and producing some localized heavier rain. There
were storms in our southeast FA during the late evening, but these
have since shifted into the Brainerd to Little Falls area. Another
area of storms was located west of Jamestown, with another small
cell east of Cando. So generally expect some weak convection to
linger into the morning hours, but pretty isolated in overall

Looking ahead into today, SPC has the entire FA in a slight risk
for severe thunderstorms. However, think most of the morning
through early afternoon will be like it is now, pretty isolated
in coverage if anything at all. By mid to late afternoon, the high
resolution models develop a line of thunderstorms over the
eastern FA, from the Lake of the Woods down toward Elbow Lake,
then quickly shift them off to the east of the FA. About the same
time or even a little later, they develop more storms over central
ND. These would track eastward into the Red River Valley during
the early evening. Think these have the best shot of bringing a
few severe storms, with large hail and strong winds. Bulk shear
values look to come up some, but still not that great, which will
limit the overall threat. Think the severe weather threat should
taper off by mid to late evening again.

.LONG TERM...(Friday through Wednesday)
Issued at 401 AM CDT Thu May 24 2018

Friday to Saturday Night...Upper level trough over southern MAN
and southern SASK will continue to move east. SASK trough will
move across the Lake of the Woods area Fri night and produce
scattered showers and storms for the northeast zones Fri night.
Ridge building occurs for Sat and Sat night with next upper trough
will move into the Intermountain West. Some warm advection precip
will be possible for Sat night in the western zones.

Sunday to Wednesday...Split flow was across North America with
northern stream over Canada and southern stream over the states.
In northern stream, long wave ridge over central/western Canada
flattens and shifts east. In southern stream, long wave trough
over the west coast weakens while long wave ridge over the
Northern Plains shift a little east.

The ECMWF was a little faster with the northern stream while the GFS
was faster with the southern stream.

Little change to high temperatures for Sun and Wed. Mon highs were
decreased zero to two degrees and Tue highs were decreased one to
three degrees compared to yesterdays forecast.


.AVIATION...(For the 18Z TAFS through 18Z Friday afternoon)
Issued at 1244 PM CDT Thu May 24 2018

VFR conditions should prevail across eastern ND and northwest MN,
with reductions possible where thunderstorm activity occurs. Early
in the TAF period a line of showers/thunderstorms (some strong)
will continue to transition eastward (impacting KBJI). Another
round of thunderstorms should develop by 23-00Z over eastern ND,
transitioning eastward through the evening (strong/severe
possible). Gusty winds should diminish this evening, though
through the afternoon there may be some gusts 25-30kt possible
(mainly in the Red River Valley).




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