Area Forecast Discussion
Issued by NWS Billings, MT

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FXUS65 KBYZ 241519
AFDBYZ

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE BILLINGS MT
919 AM MDT SUN AUG 24 2014

.UPDATE...
POWERFUL UPPER LOW NOW POSITIONED OVER EASTERN MONTANA. SATELLITE
AND RADAR TRENDS SHOW CONSIDERABLE LIFT AND MOISTURE WRAPPING BACK
AROUND LOWS CENTER INTO NORTHERN AND CENTRAL ZONES WHILE JUST SOME
ISOLATED TO SCATTERED SHOWERS REMAIN IN THE COMMA DRY SLOT OVER
OUR FAR EASTERN ZONES. MODELS AGREE WRAP AROUND WILL CONTINUE INTO
THE AFTERNOON INTO OUR FORECAST AREA BEFORE SYSTEM FINALLY PULLS
AWAY TO THE NE. MASSAGED POPS FOR CURRENT RADAR AND MESOSCALE
MODEL TRENDS. LOWERED TEMPS A BIT AS CLOUD COVER AND COOLING RAIN
MAY BE RATHER PERSISTENT TODAY WITH COLD UPPER LOW OVER US.

WILL CONTINUE FLOOD WARNING IN NW ZONES AND FLOOD ADVISORIES IN
EAST. HAD ADDITIONAL REPORTS OF MINOR SMALL STREAM FLOODING
NORTHEAST OF EKALAKA THIS MORNING. WILL GATHER DATA AND DETERMINE
IF THESE NEED TO BE EXTENDED AT MIDDAY. BT

&&

.SHORT TERM...VALID FOR TDY AND MON...

IMPRESSIVE STORM SYSTEM CONTINUED TO BRING WIDESPREAD RAINFALL TO
SC/SE MT OVERNIGHT. THE HEAVIEST RAINFALL WAS ACROSS OUR NORTHERN
ZONES WHERE RADAR ESTIMATED AN ADDITIONAL RAINFALL AMOUNT OF 1 TO
3. THE UPPER TROUGH AND ASSOCIATED CLOSED UPPER LOW WERE LOCATED
OVER SOUTH CENTRAL MONTANA THIS MORNING. THE LOW WAS WRAPPING DRY
AIR INTO SOUTHEAST MONTANA BASED ON WATER VAPOR SATELLITE WHILE
STRONG DIVERGENCE AND DIFFLUENCE ALOFT WAS COMBINING WITH
ISENTROPIC LIFT AND DEEP MOISTURE FEED TO BRING MODERATE RAINFALL
TO OUR NORTHERN ZONES. HAVE RAISED POPS TO CATEGORICAL ALONG AND
NORTH OF A LINE FROM MILES CITY TO BILLINGS AND WEST TO
LIVINGSTON. THE HEAVIEST RAINFALL WILL REMAIN FROM HARLOWTON EAST
THROUGH ROUNDUP. PRECIPITATION WILL BEGIN DECREASING THIS
AFTERNOON AS THE UPPER LOW/TROUGH SHIFT EAST AND NORTHWARD INTO
THE DAKOTAS AND CANADA. A BREEZY DAY WILL BE IN STORE FOR MOST OF
THE AREA GIVEN THE PRESSURE RISES MOVING IN TO AREA BEHIND THE
TROUGH. WINDS WILL BE NORTHWEST 15 TO 25 MPH AT MOST LOCATIONS.
WINDS WILL DECREASE LATE TONIGHT AND THIS WILL LEND TO THE CHANCE
OF FOG DEVELOPING AFTER MIDNIGHT...ESPECIALLY WITH THE LOW LEVELS
SATURATED WITH THE AMOUNT OF RAINFALL WE HAVE RECEIVED. GUIDANCE
INDICATING TEMPERATURE/DEW POINT SPREADS OF 1 DEGREE AND HAVE
ADDED PATCHY FOG FROM BILLINGS TO FORSYTH. EXPECTING WINDS TO STAY
UP OVER OUR FOUR EASTERN ZONES WHICH WILL KEEP FOG FROM
DEVELOPING.

MONDAY...ANOTHER TROUGH OF LOW PRESSURE WILL MOVE IN FROM THE
WEST. THIS SYSTEM WILL BRING A CHANCE OF SHOWERS AND THUNDERSTORMS
TO OUR WESTERN ZONES...SPREADING INTO THE PLAINS THROUGH THE DAY.
MOISTURE IS LACKING WITH THIS SYSTEM AND QPF VALUES WILL BE LIGHT.

HIGH TEMPERATURES TODAY AND MONDAY WILL CONTINUE TO RUN WELL BELOW
NORMAL. TEMPERATURES WILL BE 15 TO 25 DEGREES BELOW NORMAL FOR
THIS TIME OF THE YEAR. LOW TEMPERATURES TONIGHT WILL BE IN THE
MID TO UPPER 40S FOR MOST LOCATIONS.

HYRDO....HAVE HAD NO ADDITIONAL REPORTS ON FLOODING OVERNIGHT BUT
WILL KEEP CURRENT HIGHLIGHTS GOING GIVEN THE AMOUNT OF RAINFALL WE
HAVE RECEIVED DURING THE PAST TWO DAYS. THERE IS STILL A POTENTIAL
OF PONDING OF WATER ON ROADWAYS AND SMALL STREAM FLOODING IN OUR
NORTH AND FAR EASTERN ZONES. HYDROGRAPHS SHOWING RIVER LEVELS ON
THE MUSSELSHELL RIVER HAVE LEVELED OUT AT HARLOWTON AND SHAWMUT
WHICH ARE WELL BELOW FLOOD STAGE. RICHMOND

.LONG TERM...VALID FOR TUE...WED...THU...FRI...SAT...

MODELS CONTINUE TO BE IN DECENT AGREEMENT THROUGH THE MAJORITY OF
THE EXTENDED PERIOD BUT DO DIVERGE BY NEXT WEEKEND AS ANOTHER
TROUGH MOVES ACROSS THE PACIFIC NORTHWEST AND NORTHERN ROCKIES.
ANOTHER UPPER LOW...ALTHOUGH NOT AS STRONG AS THE CURRENT ONE OVER
OUR AREA...MOVES ACROSS THE GREAT BASIN AND CENTRAL ROCKIES AREA
ON TUESDAY. THIS WILL BRING CONTINUED CHANCES FOR SHOWERS AND
ISOLATED THUNDERSTORMS...WITH THE BETTER CHANCES CLOSER TO THE
MONTANA/WYOMING AND DAKOTA BORDERS. THIS LOW SHIFTS EAST LATE
WEDNESDAY AND IS FOLLOWED BY WEAK RIDGING ACROSS OUR FORECAST AREA
THURSDAY INTO FRIDAY RESULTING IN MAINLY DRY CONDITIONS. MODELS
THEN DIVERGE BY NEXT WEEKEND AS THEY BRING ANOTHER UPPER LOW AND
TROUGH ACROSS THE NORTHERN ROCKIES. HOWEVER...DIFFERENCES IN
STRENGTH AND TIMING WITH THE MODELS CONTINUE. TEMPERATURES WILL
REMAIN WELL BELOW NORMAL TUESDAY BEFORE A SLOW WARMUP BEGINS
WEDNESDAY WITH TEMPERATURES REACHING NORMAL TO SLIGHTLY ABOVE
NORMAL BY THE END OF THE WEEK INTO NEXT WEEKEND. HOOLEY
&&

.AVIATION...

SCATTERED TO NUMEROUS SHOWERS WILL CONTINUE OVER THE AREA THROUGH
THE AFTERNOON. THE HIGHEST CONCENTRATION OF SHOWERS WILL BE FROM
HARLOWTON TO PRYOR TO FORSYTH N THROUGH 18Z. THE BEST COVERAGE OF
SHOWERS WILL SHIFT E...TO N AND E OF KBIL THIS AFTERNOON. EXPECT
MVFR TO IFR CONDITIONS IN THE SHOWERS. THE SHOWERS WILL LIFT NE
OUT OF THE AREA TONIGHT. PATCHY FOG WILL DEVELOP OVER THE AREA
OVERNIGHT WITH POSSIBLE MVFR CONDITIONS. AREAS OF MOUNTAIN
OBSCURATION THROUGH THE AFTERNOON WILL DECREASE TONIGHT. ARTHUR
&&

.PRELIMINARY POINT TEMP/POPS...

    TDY MON     TUE     WED     THU     FRI     SAT
-------------------------------------------------------
BIL 059 046/066 051/071 050/080 057/085 061/087 061/085
    +/W 11/E    22/T    11/U    01/U    11/U    22/T
LVM 062 042/066 045/071 045/081 051/084 051/086 053/085
    4/W 13/T    32/T    11/U    10/U    02/T    22/T
HDN 060 045/069 050/073 048/081 055/086 059/090 059/087
    8/W 21/B    22/T    11/U    01/U    11/U    12/T
MLS 058 047/067 051/070 050/080 057/085 062/092 062/091
    8/W 41/E    22/T    11/U    11/U    11/U    12/T
4BQ 060 046/068 052/069 048/079 056/085 060/091 062/091
    4/W 21/B    43/T    21/B    11/U    11/U    11/U
BHK 056 044/064 046/067 045/076 053/081 059/088 058/087
    6/W 31/E    34/T    11/U    11/U    11/U    11/U
SHR 063 043/068 048/070 045/079 051/085 055/091 056/088
    3/W 11/B    34/T    21/U    00/U    01/U    11/U

&&

.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...NONE.
WY...NONE.

&&

$$
WEATHER.GOV/BILLINGS


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