Area Forecast Discussion
Issued by NWS Rapid City, SD

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42

000
FXUS63 KUNR 201653
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
1053 AM MDT Sun May 20 2018

.DISCUSSION...(Today Through Saturday)
Issued at 224 AM MDT Sun May 20 2018

08z surface analysis had weak high over the northern Plains.
Upper low spinning over northern central NE per water vapour loop.
It was spinning mid/high clouds over most of the CWA with some
leftover stratus across northeast WY and south central SD.

Today and tonight, upper low continues to weaken as it moves into
eastern SD. Upper trough over the western CONUS deepens with upper
low over developing over central CA. Surface high shifts east with
return flow/few breezy spots expected. Temperatures will be near
guidance.

Monday through Wednesday, CA upper low moves through the Rockies
into southern SK. Upper ridge develops ahead of it over the central
US with southwest flow aloft over the CWA. Temperatures will be
about 10F above normal for Tue/Wed as thermal ridge peaks. Moisture
will slowly increase during the period with sustained southeasterly
boundary layer flow. Weak shortwave moves through Monday with
stronger system for later Tuesday into Wednesday. Fairly low
coverage TSRA expected late Monday with better coverage expected
Tuesday night into Wednesday. Moderate MLCAPE and marginal 0-6km
bulk shear will combine to perhaps bring a strong TSRA to the CWA
Tuesday afternoon/evening.

Thursday through Saturday, upper low shifts east as an upper
trough across southern Canada as upper ridge develops over the
western CONUS. CWA will transition to drier northwest flow with
subsequent reduction in PoPs. Temperatures will be 5-10F above
normal.

&&

.AVIATION...(For the 18Z TAFS Through 18Z Monday)
Issued At 1051 AM MDT Sun May 20 2018

Conditions will be VFR through the period. Breezy SE winds can be
expected over NE WY today and tonight, and over northwestern SD
this afternoon.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...None.
WY...None.
&&

$$

DISCUSSION...Helgeson
AVIATION...Pojorlie



USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.