Severe Thunderstorm Warning 17, NWS Great Falls, MT

SOUTHWEST AND NORTH CENTRAL MONTANA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
245 AM MDT THU JUN 28 2001

.SHORT TERM...VERY BUSY NIGHT CONTINUES OVER THE AREA BUT CONVECTION
CONTINUES TO SLOWLY WEAKEN. BIGGEST THREAT FROM THE STORMS NOW APPEARS
TO BE FLOODING RAINS. FLASH FLOOD WARNING CONTINUES UNTIL 415 THIS
MORNING FOR SEVERAL EASTERN ZONES. MODELS IN RELATIVELY GOOD AGREEMENT
WITH REGARDS TO THE LARGE SCALE FEATURES. AVN SEEMS TO HAVE A BETTER
HANDLE ON THE POSITION OF THE SHORTWAVES AND WILL BE THE PREFERRED MODEL
OF CHOICE.

HIGHLY AMPLIFIED PATTERN IS FLATTENED A BIT AS UPPER LEVEL LOW AND TROF
SITTING OFF THE WEST COAST IS PUSHED TO THE NORTHWEST BY STRENGTHENING
H5 RIDGE. THIS PATTERN CHANGE WILL EFFECTIVELY PUSH MOST OF THE
SHORTWAVE ENERGY INTO SOUTHERN CANADA AS THE PERIOD PROGRESSES.
CONVECTION STILL OCCURRING ALONG A SURFACE CONVERGENCE ZONE ACROSS
CENTRAL MONTANA AIDED BY SHORTWAVE ENERGY AND VERY HIGH...ALMOST
TROPICAL...MOISTURE. LATEST STREAM LINE ANALYSIS SHOWS BOUNDARY
EXTENDING FROM SOUTHERN MEAGHER TO NORTHERN BLAINE COUNTIES. MODELS MOVE
THE BOUNDARY OUT OF THE COUNTY WARNING AREA BY MORNING AND DRY OUT THE
AIRMASS CONSIDERABLY. WILL CARRY OVER SCATTERED POPS FOR THE EASTERN
ZONES THIS MORNING.

BEST CHANCE OF CONVECTION ON THURSDAY WILL BE OVER SOUTHEAST MONTANA
WHERE BEST DYNAMICS AND MOST UNSTABLE AIR LIE. UPPER FLOW OVER AREA
BECOMES MORE CYCLONIC WITH REALLY NO STRONG SHORTWAVES TO SPEAK OF.
STILL...WITH CONTINUING SOUTHWEST FLOW AIRMASS DESTABILIZES OVER THE
SOUTHWEST THIS AFTERNOON WITH LIFTED INDICES OF -2 AND CAPES OF 1000.
WILL MENTION SOME SHOWERS AND STORMS. WEAK SHORTWAVE PASSES THROUGH
NORTHWEST MONTANA EARLY FRIDAY SO A FEW SHOWERS POSSIBLE AT THAT TIME.
AVN GUIDANCE NUMBERS LOOK GOOD AND WILL BE FOLLOWED PRETTY CLOSELY.

.EXTENDED...CURRENT EXTENDED FORECAST LOOKS PRETTY GOOD. UPPER TROUGH
WILL REMAIN PARKED OFF THE COAST EARLY IN THE PERIOD BEFORE BEING PUSHED
TO THE NORTHWEST AS STRONG H5 RIDGE REMAINS OVER THE 4 CORNERS AND
ACTUALLY RETROGRADES A BIT DURING THE PERIOD. JUST A FEW WEAK
DISTURBANCES TO WORRY ABOUT EARLY IN THE PERIOD BEFORE THE RIDGE AXIS
SHIFTS OVER WESTERN MONTANA WHICH SHOULD PROVIDE MAINLY DRY CONDITIONS
WITH A WARMING TREND. WILL REMOVE MENTION OF SHOWER AND THUNDERSTORMS
OVER THE MOUNTAINS. OTHERWISE NO SIGNIFICANT CHANGES.

GOUDSWARD

CCF NUMBERS
GTF BB 078/059 076 05311
CTB BB 076/048 074 05310
HLN BB 078/050 078 05221
BZN BB 080/048 078 05221
WEY BB 074/044 074 05221
DLN BB 078/048 076 05221
HVR BB 083/052 084 05532
LWT BB 076/048 075 05532

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE GREAT FALLS MT
1030 PM MDT WED JUN 27 2001

MTZ011-013-016-021-047-050-051-059-060-280530-
BLAINE-CENTRAL AND SOUTHEAST PHILLIPS-CHOUTEAU-FERGUS-HILL-JUDITH
BASIN-NORTHERN PHILLIPS-PETROLEUM-SOUTHWEST PHILLIPS-
1030 PM MDT WED JUN 27 2001

THE NATIONAL WEATHER SERVICE HAS CLEARED THE FOLLOWING COUNTIES FROM
SEVERE THUNDERSTORM WATCH NUMBER 474...

IN NORTH CENTRAL MONTANA:

BLAINE               CHOUTEAU            HILL

SEVERE THUNDERSTORM WATCH NUMBER 474 REMAINS IN EFFECT UNTIL 1 AM
MDT FOR...FERGUS...JUDITH BASIN...PETROLEUM AND PHILLIPS COUNTIES.

MTZ011-013-047-050-051-280800-

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE GREAT FALLS MT
102 AM MDT THU JUN 28 2001

...SEVERE THUNDERSTORM WATCH HAS EXPIRED...

THE SEVERE THUNDERSTORM WATCH THAT HAD BEEN IN EFFECT FOR
BLAINE...HILL...CHOUTEAU...JUDITH BASIN AND FERGUS COUNTIES HAS BEEN
ALLOWED TO EXPIRE.

NATIONAL WEATHER SERVICE DOPPLER RADAR CONTINUES TO SHOW NUMEROUS
THUNDERSTORMS STILL CONTINUING OVER THE REGION. THESE STORMS ARE
SLOWLY WEAKENING AND THE THREAT OF SEVERE WEATHER HAS ENDED.
HOWEVER...THESE STORMS ARE STILL CAPABLE OF PRODUCING GUSTY WINDS
NEAR 45 MPH... SMALL HAIL AND HEAVY RAINFALL FOR THE NEXT SEVERAL
HOURS.

A FLASH FLOOD WARNING CONTINUES UNTIL 415 AM FOR WEST CENTRAL FERGUS
COUNTY...NORTH CENTRAL JUDITH BASIN COUNTY AND EXTREME SOUTHEASTERN
CHOUTEAU COUNTY.

GOUDSWARD