Area Forecast Discussion
Issued by NWS Rapid City, SD

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000
FXUS63 KUNR 261522
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
922 AM MDT SUN JUL 26 2015

.UPDATE...
ISSUED AT 909 AM MDT SUN JUL 26 2015

WATER VAPOR SHOWS DISTINCT SHORT WAVE NEAR THE UT/CO/WY BORDER AND
EJECTING NEWD. 12Z NAM AND SEVERAL CAMS SHOWING A CONCENTRATED
AREA OF LIFT MOVING INTO SWRN/SCNTRL SD AROUND MID-AFTN
COINCIDENT WITH MAX HEATING...WITH A GOOD CHANCE FOR CONVECTION IN
THAT AREA SO HAVE RAISED POPS. PLENTY OF MUCAPE TO TAP INTO
(1700J/KG) PER KUNR 12Z RAOB...AND DEEP LAYER SHEAR EXPECTED TO
INCREASE AS SHORT WAVE NEARS SO A FEW STRONGER/SVR STORMS
POSSIBLE. OTHERWISE...HOT TEMPS EXPECTED WITH THERMAL RIDGE
BUILDING THROUGH ERN WY INTO WRN SD.

&&

.SHORT TERM...TODAY THROUGH MONDAY NIGHT
ISSUED AT 210 AM MDT SUN JUL 26 2015

LATEST WATER VAPOR IMAGES SHOWED UPPER LOWS OVER BC AND THE
HUDSON BAY...WITH UPPER-LEVEL HIGH PRESSURE CENTERED OVER THE TX
PAN. WEST-SOUTHWEST FLOW ALOFT ACROSS THE NRN US WAS USHERING
SUBTLE SHORT-WAVE TROUGHS ACROSS THIS REGION...WITH ONE PUSHING AN
MCS ACROSS MN/IA AND ANOTHER PRODUCING ISOLD/SCT TSRA OVER ID/MT.
ON THE LARGE SCALE THE UPPER HIGH WILL DOMINATE THE SCNTRL/SERN US
THROUGH 12Z TUE AS THE UPPER LOW OVER BC MOVES TO NERN MT. MODELS
ARE IN GOOD AGREEMENT WITH THIS SCENARIO...ALBEIT THE NAM IS A BIT
SLOWER. HAVE THUS WENT WITH A GFS/ECMWF SOLUTION.

FOR TODAY...THE WEAK S/W TROF APPROACHES AS AN 850-MB THERMAL RIDGE
SETS UP OVER THE AREA WITH A LEE SFC TROF OVER ERN WY...LEADING TO
RATHER WARM CONDITIONS. MOISTURE AND INSTABILITY WILL BE SUFFICIENT
OVER WRN SD FOR ISOLD TSRA TO DEVELOP THIS AFTN...WITH ONLY A
MARGINAL RISK FOR SVR STORMS SINCE CAPE AND SHEAR WILL BE LOWER
THAN YESTERDAY. TNGT...SOUTHWEST FLOW ALOFT WILL PREVAIL AS A
25-35KT LOW-LEVEL JET SETS UP ACROSS THE CWA AND A SFC LOW DEEPENS
OVER SERN MT. ONLY ISOLD TSRA ARE EXPECTED GIVEN LACK OF A WELL-
DEFINED UPPER WAVE.

ON MONDAY A S/W TROF WILL ROTATE THRU THE CWA AS THE UPPER LOW MOVES
OVER WRN MT. THE SFC LOW WILL MOVE TO WRN ND WITH A COLD FRONT AND
DRYLINE TRAILING SOUTHWEST AND SOUTH...RESPECTIVELY. ISOLD-TO-SCT
TSRA ARE EXPECTED ALONG AND AHEAD OF THE DRYLINE ACROSS FAR NERN WY
AND WRN SD. ON MONDAY NGT A STRONG COLD FRONT WILL PASS THROUGH THE
CWA WITH 25-45KT 850-MB WINDS IN ITS WAKE. THIS WILL BRING MUCH
DRIER AND COOLER AIR INTO THE REGION ON GUSTY NORTHWEST WINDS. A DRY
SLOT AND LARGE-SCALE Q-VECTOR CONVERGENCE WILL PRECLUDE TSRA FOR
MOST OF THE CWA.

.LONG TERM...TUESDAY THROUGH SATURDAY
ISSUED AT 210 AM MDT SUN JUL 26 2015

DEEP CLOSED UPPER LOW WILL CONTINUE MOVING ALONG THE CANADIAN/ND
BORDER TUESDAY...DRAGGING A SECONDARY COOL FRONT THROUGH THE
REGION. ALTHOUGH CAA AND PRESSURE RISES DO NOT LOOK AS SIGNIFICANT
AS WITH THE FIRST PUSH OF COLD AIR...JET STREAK OVER THE AREA AND
40KT 850MB WINDS DURING OPTIMAL MIXING HOURS SUPPORT STRONG WINDS
OVER THE NORTHERN HALF OF THE CWA. RAISED WINDS A BIT THERE AS
GUIDANCE SUGGESTED...AND LATER SHIFTS MAY HAVE TO CONSIDER WIND
HEADLINES. HIGHS TUESDAY WILL BE TRICKY DEPENDING ON TIMING OF
FRONT...BUT CURRENTLY HAVE TEMPS RANGING FROM THE LOWER 70S ACROSS
NORTHWESTERN SD...THE BLACK HILLS...AND NORTHEASTERN WYOMING TO
THE MID 80S ACROSS SOUTH CENTRAL SD.

REGION WILL REMAIN UNDER NORTHWEST FLOW FOR THE REST OF THE WEEK AS
UPPER RIDGE BUILDS OVER THE WESTERN CONUS...RESULTING IN MAINLY DRY
WEATHER AND A GRADUAL WARMING TREND.

&&

.AVIATION...FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING
ISSUED AT 457 AM MDT SUN JUL 26 2015

THUNDERSTORMS EXPECTED AGAIN ACROSS THE AREA THIS
AFTERNOON/EVENING...WITH MVFR CONDITIONS EXPECTED NEAR ANY STORMS.
OTHERWISE VFR CONDITIONS WILL PREVAIL THROUGH THE FORECAST PERIOD.


&&

.FIRE WEATHER...
ISSUED AT 210 AM MDT SUN JUL 26 2015

A DEEP UPPER LOW WILL MOVE ACROSS MT MONDAY AND TUESDAY. AHEAD OF
THE LOW...VERY WARM SOUTHERLY FLOW WILL BRING DRIER AIR INTO NERN
WY. THE GUSTY SOUTH WINDS...HIGH/WARM TEMPERATURES...AND LOW
HUMIDITIES WILL LEAD TO POTENTIAL RED FLAG CONDITIONS MONDAY
AFTN/EVNG. ISOLD TSRA ALSO MAY DEVELOP MONDAY AFTN...AND COULD
RESULT IN DRY LIGHTNING. ON MONDAY EVNG A COLD FRONT WILL SWEEP
ACROSS NERN WY AND BRING GUSTY NORTHWEST WINDS. WITH INCREASINGLY
DRY FUELS...THE NORTHEAST WYOMING PLAINS MAY SEE CRITICAL FIRE
WEATHER CONDITIONS MONDAY AFTN/EVNG.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...WY...FIRE WEATHER WATCH FROM MONDAY AFTERNOON THROUGH MONDAY EVENING
     FOR WYZ259-297-298.

&&

$$

UPDATE...JOHNSON
SHORT TERM...BUNKERS
LONG TERM...POJORLIE
AVIATION...POJORLIE
FIRE WEATHER...BUNKERS


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