000
FXUS63 KBIS 140622
AFDBIS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BISMARCK ND
122 AM CDT TUE MAY 14 2013

.UPDATE...
ISSUED AT 122 AM CDT TUE MAY 14 2013

A COLD FRONT WAS ALONG THE BORDER OF MONTANA AND NORTH
DAKOTA...AND A CLUSTER OF SHOWERS AND THUNDERSTORMS AHEAD AND
BEHIND THE FRONT WERE AFFECTING NORTHEASTERN MONTANA AND
NORTHWESTERN NORTH DAKOTA. IN FACT...OUT AHEAD OF THE COLD
FRONT...A PERSISTENT LINE OF STRONG TO SEVERE THUNDERSTORMS WAS
MOVING ACROSS DIVIDE AND WILLIAMS COUNTIES AT THIS TIME. THE UPPER
LEVEL SHORTWAVE ASSOCIATED WITH THE CONVECTION IS PROGGED TO
CONTINUE MOVING EAST ACROSS THE STATE. HAVE RAISED CHANCES OF
THUNDERSTORMS TO LIKELY CATEGORY ACROSS THE NORTH FOR THE
OVERNIGHT HOURS. OTHERWISE ANOTHER LINE OF SHOWERS WITH SOME
ISOLATED THUNDER WAS PROGRESSING EASTWARD...EXTENDING FROM
BOTTINEAU TO NEAR MCCLUSKY AND WING.

UPDATE ISSUED AT 917 CDT MON MAY 13 2013

GIVEN THE 18 UTC NAM/GFS AND INCOMING 00 UTC NAM...DECIDED TO
CHANGE THE HIGH WIND WATCH TO A WIND ADVISORY FOR ALL BUT
SOUTHWEST NORTH DAKOTA. THE LATEST RUNS SUGGEST THAT A WEAKENING
PRESSURE RISE BUBBLE AND 40-45 KTS AT THE TOP OF THE MIXED LAYER
BEHIND THE COLD FRONT WILL ONLY ALLOW FOR SUSTAINED WINDS TO 35
MPH WITH GUSTS TO 50 MPH FOR MUCH OF THE AREA. DID MAINTAIN THE
HIGH WIND WATCH FOR THE SOUTHWEST WHERE THERE MAY BE A BRIEF
WINDOW TO REACH HIGH WIND CRITERIA TUESDAY MORNING WHEN
ISALLOBARIC FORCING IS GREATEST.

OTHERWISE FOR TONIGHT...CONTINUING TO MONITOR THUNDERSTORMS EAST
OF GLASGOW...PROGGED TO REACH THE BORDER BY 330-400 UTC. HAVE HAD
A COUPLE REPORTS OF GUSTS TO 60 MPH NEAR FORT PECK WITH THESE
STORMS. WHILE THEY HAVE SHOWN A SLIGHT WEAKENING TREND...GIVEN THE
HIGH BASES...EVAPORATIVE POTENTIAL AND STEEP LAPSE RATES THROUGH
MUCH OF THE TROPOSPHERE...ISOLATED SEVERE WIND GUSTS CANNOT BE
RULED OUT...ALONG WITH HEAT BURSTS AS THESE STORMS PROPAGATE
GENERALLY ACROSS NORTHWEST AND NORTH CENTRAL NORTH DAKOTA TONIGHT.

UPDATE ISSUED AT 701 PM CDT MON MAY 13 2013

A CLUSTER OF THUNDERSTORMS CONTINUES TO SLOWLY INCREASE BETWEEN
GLASGOW AND LEWISTOWN MONTANA...AND ARE PROGGED TO APPROACH THE
BORDER WITH NORTHWEST NORTH DAKOTA AROUND 03-04 UTC. GIVEN THE
HIGH BASES...EVAPORATIVE POTENTIAL AND STEEP LAPSE RATES THROUGH
MUCH OF THE TROPOSPHERE...ISOLATED SEVERE WIND GUSTS CANNOT BE
RULED OUT...ALONG WITH HEAT BURSTS AS THESE STORMS PROPAGATE
GENERALLY ACROSS NORTHWEST AND NORTH CENTRAL NORTH DAKOTA TONIGHT.
GIVEN THE LATEST 18 UTC NAM AND GFS...IT APPEARS THAT MUCH OF THE
AREA WILL HAVE A TOUGH TIME APPROACHING HIGH WIND WARNING
SUSTAINED OR GUST CRITERIA ON TUESDAY AND MAY REPLACE MOST OR
ALL OF THE WATCH WITH A WIND ADVISORY AT THE 10 PM UPDATE SHOULD
TRENDS CONTINUE WITH THE 00 UTC RUNS.

&&

.SHORT TERM...(THIS EVENING THROUGH TUESDAY)
ISSUED AT 345 PM CDT MON MAY 13 2013

SEVERAL CONCERNS THIS AFTERNOON REGARDING WINDS AND FIRE WEATHER.
WELL MIXED ATMOSPHERE THIS AFTERNOON ACROSS WEST AND CENTRAL NORTH
DAKOTA. DEBATED ABOUT ISSUING HIGH WIND WARNING ACROSS THE
SOUTHWEST FOR LATE TONIGHT AND TUESDAY. MODELS NOT IN COMPLETE
AGREEMENT ON THE MAX WIND POTENTIAL. NAM BRINGS IN A 9 MB PRESSURE
RISE BUBBLE ACROSS THE SOUTHWEST AROUND 12Z ASSOCIATED WITH A COLD
FRONTAL PASSAGE. GEOSTROPHIC 1000 MB AND H850 WINDS INDICATE
MARGINAL HIGH WIND WARNING...BUT BOUNDARY LAYER WINDS SUGGEST HIGH
END WIND ADVISORY. GFS INDICATING SOMEWHAT LOWER WINDS AND HIGH END
WIND ADVISORY WOULD BE APPROPRIATE FOLLOWING THE GFS. FOR NOW WILL
CONTINUE WITH THE HIGH WIND WATCH DUE TO THE UNCERTAINTY.

TONIGHT...STRONG ARM ADVECTION WILL SUPPORT SHOWERS AND SCATTERED
THUNDERSTORMS MAINLY NORTH. THERE COULD BE SOME GUSTY WINDS WITH
THE THUNDERSTORMS NORTHWEST DUE TO STRONG MID LEVEL WINDS. AT THIS
TIME DID NOT MENTION SEVERE AS BELIEVE TO ISOLATED THREAT.

.LONG TERM...(TUESDAY NIGHT THROUGH MONDAY)
ISSUED AT 345 CDT MON MAY 13 2013

THE FOCUS IN THE LONG TERM WILL BE ON THE TOTAL PRECIPITATION
THURSDAY THROUGH THE WEEKEND...AND THE POTENTIAL FOR SEVERE WEATHER
THURSDAY THROUGH SATURDAY.

QUASI ZONAL FLOW ALOFT TUESDAY AND WEDNESDAY WILL TRANSITION TO
RIDGING ALOFT THURSDAY OVER THE CENTRAL CONUS. LIKEWISE A TROUGH
WILL DEVELOP OVER THE WESTERN CONUS THURSDAY AND WILL DEEPEN INTO
SATURDAY. THIS WILL PROVIDE SOUTHWEST FLOW ALOFT FOR WESTERN AND
CENTRAL NORTH DAKOTA THURSDAY INTO SATURDAY...AS THE UPPER LEVEL
TROUGH PROPAGATES ACROSS THE ROCKIES AND INTO THE PLAIN STATES BY
SUNDAY. MODELS ARE IN GOOD AGREEMENT ON THIS PATTERN AND ON THE
ARRIVAL OF THE TROUGH OVER THE CENTRAL AND NORTHERN PLAINS. MODELS
DURING THE 18 UTC THURSDAY TO 06 UTC SUNDAY TIME FRAME SHOW SEVERAL
OPPORTUNITIES FOR PRECIPITATION OVER CENTRAL AND WESTERN NORTH
DAKOTA. BEGINNING SUNDAY THE GFS AND EURO DIVERGE ON THE POSITION OF
THE TROUGH. THE EURO HAS THE TROUGH STALLING OUT OVER THE CENTRAL
AND NORTHERN PLAINS...WITH A CLOSED LOW FORMING DIRECTLY OVER
NORTHERN NORTH DAKOTA. THIS SOLUTION KEEPS CHANCES FOR MODERATE
RAINFALL OVER NORTHERN AND EASTERN NORTH DAKOTA INTO MONDAY NIGHT.
THE GFS ON THE OTHER HAND PUSHES THE TROUGH FURTHER EAST BEFORE
DEVELOPING A CLOSED LOW JUST NORTH OF MINNESOTA...WHICH HAS CENTRAL
AND WESTERN NORTH DAKOTA ESSENTIALLY RAIN FREE FROM SUNDAY 18 UTC
ON. THIS WILL BE CLOSELY MONITORED MOVING FORWARD...AS WPC HAS QPF
VALUES JUST OVER AN INCH OVER NORTH DAKOTA FROM THURSDAY
THROUGH SUNDAY. THIS WOULD BE SUFFICIENT RAINFALL TO INCREASE
GREENNESS ACROSS THE STATE AND MINIMIZE FIRE WEATHER CONCERNS.

AS FOR SEVERE WEATHER...THE FIRST CHANCE LOOKS TO BE THURSDAY
AFTERNOON WEST FROM A FRONTAL BOUNDARY MOVING IN FROM EASTERN
MONTANA. THERE WILL ALSO BE CHANCES ON FRIDAY AND SATURDAY SOUTH
CENTRAL AND SOUTHWEST FROM A SURFACE LOW AND WARM FRONT SET UP IN
SOUTH DAKOTA. OVER THIS TIME FRAME DEEP LAYER BULK SHEAR VALUES WILL
BE IN THE 40 TO 50 KT RANGE WITH MOST UNSTABLE CAPE VALUES IN THE
1000 TO 2000 J/KG RANGE. THIS IS CERTAINLY ENOUGH FOR THUNDERSTORMS
TO DEVELOP OVER WESTERN AND SOUTH CENTRAL NORTH DAKOTA...HOWEVER
SEVERE WEATHER WILL ALMOST CERTAINLY BE LIMITED IN SOME RESPECT BY
CLOUD COVER AND THE WIDESPREAD SHOWER ACTIVITY GOING ON DURING THIS
TIME FRAME.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 122 AM CDT TUE MAY 14 2013

HAVE KISN AND KMOT IN VCTS FOR MUCH OF THE OVERNIGHT HOURS AS
AREA OF SHOWERS AND THUNDERSTORMS MOVES EAST ACROSS THE STATE
TONIGHT. COLD FRONT WAS AT THE BORDER OF MONTANA AND NORTH DAKOTA
AND EXPECT WINDS TO BECOME WEST AND INCREASE AT KISN TONIGHT. BY
15Z MOST TAF SITES SHOULD SEE WEST WINDS INCREASING TO 20-30
KNOTS...AND BY 18Z NORTHWEST WINDS OF 25 TO 30 KNOTS FOR MUCH OF
THE AFTERNOON BEFORE DECREASING AFTER 00Z.

&&

.FIRE WEATHER...
ISSUED AT 345 PM CDT MON MAY 13 2013

RED FLAG WARNING CONTINUES THIS AFTERNOON AND EARLY EVENING FOR
LOW RELATIVE HUMIDITY...GUSTY WINDS AND DRY PASTURES.

UPGRADED FIRE WEATHER WATCH TO RED FLAG WARNING FOR TUESDAY FOR
STRONG WINDS...LOW RELATIVE HUMIDITY...AND DRY RANGELAND
CONDITIONS.

&&

.BIS WATCHES/WARNINGS/ADVISORIES...
RED FLAG WARNING FROM NOON CDT /11 AM MDT/ TODAY TO 9 PM CDT /8
PM MDT/ THIS EVENING FOR NDZ001>005-009>013-017>023-025-031>037-
040>048-050-051.

WIND ADVISORY FROM 9 AM CDT /8 AM MDT/ THIS MORNING TO 9 PM CDT
/8 PM MDT/ THIS EVENING FOR NDZ003-004-011-012-019>022-034-035-
042-045-046.

HIGH WIND WATCH FROM 5 AM MDT EARLY THIS MORNING THROUGH THIS
EVENING FOR NDZ031>033-040-041-043-044.

WIND ADVISORY FROM 6 AM THIS MORNING TO 9 PM CDT THIS EVENING
FOR NDZ001-002-009-010-017-018.

WIND ADVISORY FROM NOON TODAY TO 9 PM CDT THIS EVENING FOR
NDZ005-013-023-025-036-037-047-048-050-051.

&&

$$

UPDATE...JV
SHORT TERM...WAA
LONG TERM...MM/KS
AVIATION...JV
FIRE WEATHER...WAA