FXUS65 KGGW 010232

AFDGGW



AREA FORECAST DISCUSSION

NATIONAL WEATHER SERVICE GLASGOW MT

832 PM MDT SAT JUL 31 2010



.SHORT TERM...FOR NORTHEAST MONTANA...TONIGHT THROUGH MONDAY...



UPDATE...SEVERE THUNDERSTORM WATCH FOR ALL OF NORTHEAST MONTANA

UNTIL 2AM. 



PLENTY OF OUTFLOW BOUNDARIES AROUND THE CWA THIS EVENING. THE

BOUNDRY OR LEE TROUGH REMAINS ALONG A LINE FROM THE NORTHWEST

CORNER OF PHILLIPS COUNTY INTO GARFIELD COUNTY. LOW LEVEL MOISTURE

IS INCREASING TO THE EAST OF THIS LINE. THE RUC MODEL HAS A THE

NOSE OF A JET STREAK MOVING INTO CENTRAL MONTANA WILL CONTINUE TO

MOVE INTO NORTHEAST MONTANA. RUC ALSO NOTES A WIND MAXIMUM OVER

THE MT/SASKATCHEWAN BORDER WITH THE RIGHT ENTRANCE REGION OVER OUR

NORTHEASTERN ZONES...WHICH SEEMS TO BE WORKING OUT WITH THE

CURRENT RADAR TRENDS. OUR SOUTHWEST AREAS COULD SEE A PERK UP

ACTIVITY IN THE NEXT COUPLE OF HOURS IF THIS OTHER JET STREAK

STARTS TO ENHANCE ACTIVITY OVER OUR SOUTHWESTERN ZONES.  PROTON



THE UPPER RIDGE AXIS HAS SHIFTED TO OUR EAST RESULTING IN UPPER

FLOW BACKING TO THE SW. MOISTURE CONTINUES TO BE EJECTED INTO THIS

UPPER FLOW FROM TROUGH ALONG THE PACNW COAST. THUNDERSTORMS HAVE

ALREADY STARTED TO FIRE OFF OVER THE INTER-MOUNTAIN WEST AND THE

ROCKY MOUNTAINS OF IDAHO. THESE STORMS WILL WORK THEIR WAY IN OUR

DIRECTION LATER TODAY OR EVENING. WITH A SURFACE TROUGH SLIDING

OVER THE LOCAL AREA...SEVERAL DISTURBANCES IN THE UPPER FLOW AND

TEMPERATURES EXPECTED TO RISE ABOVE THE TRIGGER TEMPERATURE OF

32*C...THUNDERSTORMS ARE EXPECTED. CONVECTIVE PARAMETERS SUGGEST

MODERATE INSTABILITY...WHICH HAS PROMPTED SPC TO PLACE THE ENTIRE

REGION WITHIN THE SLIGHT RISK ZONE ON THE CONVECTIVE OUTLOOK FOR

TODAY AND THIS EVENING. SO MAINTAINED SEVERE WORDING IN WX GRIDS

FOR THIS EVENING. 18Z GGW SOUNDING WAS CONDUCTED...INDICATED

ALMOST AND INCH OF PRECIPITABLE WATER...LIFTED INDEX OF -3.7*C AND

MODERATE POSITIVE ENERGY.



BEFORE FORECAST PACKAGE WENT OUT...SPC ISSUED A SEVERE

THUNDERSTORM WATCH FOR WESTERN MONTANA TO INCLUDE OUR WESTERN

ZONES. HAIL TO ONE AND A HALF INCH AND THUNDERSTORM WIND GUSTS TO

75 MPH ARE POSSIBLE. ALSO ANTICIPATE AN ADDITIONAL CONVECTIVE

WATCH POSSIBLE FOR THE REMAINDER OF OUR ZONES LATER THIS

AFTERNOON.



SUNDAY...SURFACE TROUGH SLIDES INTO NORTH DAKOTA WHILE THE SHORT-

WAVE UPPER LOW SHIFTS EAST INTO THE NORTHERN ROCKIES AND SOUTHERN

ALBERTA...SENDING A COLD FRONT INTO THE REGION. THIS BOUNDARY WILL

FOCUS SHOWERS AND THUNDERSTORMS TOWARDS THE NORTHERN ZONES. AGAIN

MODERATE INSTABILITY COULD TRIGGER MORE SEVERE STORMS IN OUR

NORTHEAST AND EASTERN ZONES BY AFTERNOON AND EVENING. THE COLD

FRONT WILL DEPRESS THERMAL RIDGING MORE TO THE SOUTH SO

TEMPERATURES SHOULD RUN AROUND NORMAL. 



MONDAY...SLIGHT UPPER RIDGING SHOULD QUIET CONDITIONS AND

NORTHWESTERLY FLOW ALOFT SHOULD KEEP TEMPERATURE NEAR NORMAL.

HOWEVER SOUTHWESTERLY FLOW ALOFT OVER WESTERN MONTANA COULD

GENERATE ADDITIONAL STORMS THERE...SOME OF WHICH COULD DRIFT INTO

OUR AREA. SO WILL MAINTAIN SLIGHT CHANCE FOR THE AFTERNOON. SCT



.LONG TERM...MONDAY NIGHT THROUGH SATURDAY...

PERSISTENT TROUGH OVER THE NW CONUS AFFECTS THE TUESDAY THROUGH

SATURDAY PERIODS. THIS GIVES A GENERALLY SOUTHWEST MIDLEVEL FLOW

AND CHANCES FOR PPT AND THUNDER EVERYDAY OF THE EXTENDED. LATEST

GFS AND EC MODELS HAVE SIGNIFICANT SHORTWAVE ACTIVITY EJECTING

FROM THE TROUGH AND IMPACTING THE CWA EVERY COUPLE DAYS WITH

POSSIBLE PERIODS OF RELATIVELY INACTIVE WEATHER IN BETWEEN THESE FEATURES

...THOUGH DETAILS HAVE TYPICAL TIMING AND INTENSITY DISAGREEMENTS.

THIS ACTIVITY WILL KEEP TEMPERATURES DOWN A BIT WITH HIGHS AROUND

90. SURFACE WINDS CURRENTLY APPEAR TO BE PERSISTENTLY MODERATE IN

STRENGTH.  MARTIN



PREVIOUS LONG TERM DISCUSSION...

LITTLE CHANGE IN THE UPPER AIR PATTERN OVER THE NEXT WEEK...WITH

QUITE STRONG HUDSON BAY LOW COUNTERED BY SUBTROPICAL HIGH OVER THE

SOUTHERN STATES. FURTHER WEST A WEAK LOW/TROF LINGERS OVER THE

PACIFIC NORTHWEST...RESULTING IN NEARLY ZONAL FLOW ACROSS THE

NORTHERN PLAINS THROUGH NEXT WEEKEND. SUBTLETIES IN THE FLOW WILL

HAVE THE MOST INFLUENCE ON THE SENSIBLE WEATHER...BUT MODELS

SHIFTING TIMING AND POSITION OF SMALL SCALE FEATURES SO FAIRLY

BROAD BRUSH APPROACH SEEMS BEST AT THIS TIME.



OVERALL KEPT POPS NEAR CLIMATOLOGICAL NORMS FOR LATE SUMMER AS

MONSOONAL MOISTURE NUDGING NORTHWARD AND WEAK ENERGY FLOWING OVER

THE MOUNTAINS. DID GO A LITTLE DRIER ON WEDNESDAY AS SOME

INDICATION OF SLIGHT RIDGE DEVELOPING OVER WESTERN MONTANA. HEAT

BUILDING UNDER THIS RIDGE EXPECTED TO MOVE EASTWARD INTO THE END

OF THE WEEK...BUT LATEST RUN OF THE ECMWF PULLING A FAIRLY STRONG

AND COOL SHORTWAVE ACROSS THE CANADIAN PRAIRIES LATE IN THE WEEK.

THIS INCREASES THE SPREAD OF POTENTIAL TEMPERATURES FOR THE END OF

THE FORECAST...SO KEPT READINGS FOR MAXIMUMS JUST A FEW DEGREES

ABOVE NORMAL. EBERT





&&



.AVIATION...

MOST OF THE AREA SHOULD REMAIN WITH VFR CONDITIONS. HOWEVER WITH

STRONG THUNDERSTORMS DEVELOPING OVER THE AREA WILL BRING CONDITIONS

DOWN TO IFR AND LIFR CONDITIONS BRIEFLY WITH THE MOST INTENSE

STORMS. STORMS SHOULD CONTINUE ACROSS THE REGION WELL INTO THE

OVERNIGHT HOURS.    PROTON





&&



.GLASGOW WATCHES/WARNINGS/ADVISORIES...NONE.



&&



$$



WEATHER.GOV/GLASGOW