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 43 44 45 46 47 48 49 50

000
FXUS63 KUNR 291533
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
933 AM MDT MON SEP 29 2014

.UPDATE...
ISSUED AT 924 AM MDT MON SEP 29 2014

N-S BAND OF HEAVIEST RAINFALL HAS SHIFTED SLIGHTLY EASTWARD THIS
MORNING AND MAY SHIFT A BIT FARTHER EASTWARD THIS AFTERNOON AS
DEPICTED IN SOME OF THE 12Z MODELS. HAVE UPDATED FORECAST TO BETTER
DEPICT THIS SCENERIO. HAVE ALSO LOWERED THE FORECAST HIGH
TEMPERATURES DUE TO THE EXTENSIVE CLOUD COVER AND EASTERLY LOW
LEVEL WINDS.

&&

.SHORT TERM...TODAY THROUGH TUESDAY NIGHT
ISSUED AT 231 AM MDT MON SEP 29 2014

08Z SURFACE ANALYSIS HAD LOW PRESSURE OVER EASTERN CO AND HIGH
PRESSURE OVER THE NORTHERN PLAINS. LOW LEVEL NORTHEASTERLY
BOUNDARY LAYER FLOW AS A RESULT. WATER VAPOUR SHOWED UPPER LOW
SPINNING OVER NORTHEAST NV/NORTHWEST UT WITH A COUPLE OF
SHORTWAVES WRAPPING AROUND IT...ONE OVER SOUTHWEST SD AND ANOTHER
OVER SOUTH CENTRAL WY. INITIAL WAVE CAUSING CLUSTER OF ELEVATED
CONVECTION OVER CWA AT THE MOMENT WITH NEXT CLUSTER OVER SOUTHEAST
WY...ALL HEADING TO THE NORTH/NORTH-NORTHWEST. MODELS IN GOOD
AGREEMENT WITH EVOLUTION OF THIS SYSTEM.

TODAY THROUGH TUESDAY AFTERNOON...UPPER LOW WILL SPIN NORTHEAST
WRAPPING UP QUITE TIGHTLY OVER THE CWA 12Z TUESDAY AND THEN RACING
NORTHEAST INTO EASTERN ND TUESDAY AFTERNOON. FORCING AHEAD OF IT
WILL BE QUITE PRONOUNCED WITH SUSTAINED UPPER LEVEL DIVERGENCE ON
NOSE OF 110KT JET STREAK. LOW LEVEL FLOW BECOMES INCREASINGLY STRONG
AS SURFACE LOW OVER EASTERN CO DEEPENS AND HEADS NORTH
TONIGHT...STACKING UNDER LOW OVER CWA TUESDAY. SUSTAINED 850-700MB
THETA-E ADVECTION AS WELL AS STRONG ISENTROPIC LIFT WILL GENERATE
WAVES OF SHRA/TSRA OVER THE AREA THROUGH TUESDAY AFTERNOON. HEAVIEST
RAIN SHOULD FALL TONIGHT/EARLY TUESDAY WHEN DEEP LAYER UPSIDENCE
MAXIMIZED. 0.5-1.5 INCHES RAIN LIKELY TO FALL OVER MUCH OF THE
CWA...EXCEPT PERHAPS OVER THE FAR EAST WHEN DRY SLOW MAY DEVELOP
LATER TONIGHT/TUESDAY. LOCAL 1.5-2.5 INCH AMOUNTS LIKELY OVER FAR
NORTHEAST WY/FAR WESTERN SD...ESPECIALLY NEAR THE BLACK HILLS WHERE
UPSLOPE ENHANCEMENT OCCURS. GIVEN ANTECEDENT DRY WEATHER...TIME OF
YEAR...AND EXPECTED SOAKING NATURE OF RAINS...WILL FORGO ANY HYDRO
HEADLINES. EXPECT GUSTY WINDS AHEAD OF AND BEHIND LOW...POSSIBLY
REACHING ADVISORY CRITERIA TUESDAY. TEMPERATURES WILL BE FALL-LIKE
WITH THE SUSTAINED PRECIPITATION...BUT NEAR NORMAL OVER SOUTH
CENTRAL SD. FINALLY...CAPE/SHEAR MAY BE SUFFICIENT FOR A COUPLE OF
STRONG/ISOLATED SEVERE STORMS SNEAKING INTO THE FAR SOUTH LATE
THIS AFTERNOON/EARLY THIS EVENING.

TUESDAY NIGHT...SYSTEM QUICKLY MOVES AWAY BUT IT WILL LEAVE CYCLONIC
FLOW/MOISTURE IN IT/S WAKE. LEFTOVER -SHRA EXPECTED.

&&

.LONG TERM...WEDNESDAY THROUGH SUNDAY
ISSUED AT 231 AM MDT MON SEP 29 2014

CYCLONIC FLOW WILL CONTINUE OVER THE REGION WEDNESDAY WITH SOME
SHOWERS POSSIBLE AS A SECONDARY UPPER WAVE ROUNDS THE BASE OF THE
BROAD TROUGH. A COOLER AIRMASS WILL ADVECT AS THE BACKSIDE OF THE
TROUGH PUSHES INTO THE UPPER MIDWEST. UPPER RIDGING WILL BUILD
ACROSS THE WESTERN CONUS FOR THE SECOND HALF OF THE WEEK...WITH
NORTHWEST FLOW REMAINING OVER THE NORTHERN PLAINS. THIS WILL KEEP
DRIER WEATHER ACROSS THE AREA ALONG WITH TEMPERATURES WILL BELOW
SEASONAL AVERAGES.

&&

.AVIATION...FOR THE 12Z TAFS THROUGH 12Z TUESDAY MORNING
ISSUED AT 432 AM MDT MON SEP 29 2014

MVFR/IFR CONDITIONS WILL CONTINUE TODAY AND TONIGHT AS A STRONG
STORM SYSTEM SLOWLY CROSSES THE REGION. THIS SYSTEM WILL CONTINUE
TO BRING WIDESPREAD SHOWERS/ISOLATED STORMS TO THE AREA. MVFR VSBY
IS EXPECTED WITH THE HEAVIER PRECIP.


&&

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

$$

UPDATE...10
SHORT TERM...HELGESON
LONG TERM...13
AVIATION...13





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