Area Forecast Discussion
Issued by NWS Grand Forks, ND

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FXUS63 KFGF 241816
AFDFGF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND FORKS ND
116 PM CDT THU APR 24 2014

.UPDATE...
ISSUED AT 111 PM CDT THU APR 24 2014

12Z NCEP MODELS AND LATEST RAP/HRRR STILL FOCUS A NARROW RIBBON OF
700 J/KG AND SHOWWALTERS -3C ALONG WITH NON-SUPERCELL TSTM
PARAMETERS OF GREATER THAN 2 IN AN AXIS FROM ROLLA THROUGH DEVILS
LAKE TO BTWN VALLEY CITY-FARGO TO JUST WEST OF WAHPETON. HOWEVER
CURRENT SPC MESO PAGE HAS NR 1000 MOST UNSTABLE CAPE IN SOUTHEAST
SASK AND STORMS ARE IN THAT AREA WITH SOME CAPE INTO FAR NW ND AND
A FEW ECHOES INTO THAT AREA. LATEST HRRR INDICATE STORMS IN THE
TURTLE MOUNTAIN REGION DEVELOPING SOUTHEAST ALONG AXIS MENTIONED
ABOVE IN THAT 21Z-01Z PERIOD. OTHER THAN THAT AREA OF SOLID RAIN
IN MINNESOTA WILL CONTINUE TO MOVE NORTH AND SLOWLY TAPER OFF IN
FAR WRN MN DURING THE AFTN. TIGHT TEMP GRADIENT WITH UPR 30S-LOW
40S EAST AND 50S WEST. REPORT OF WET SNOW MIXED WITH RAIN IN OTTER
TAIL COUNTY MN JUST BEFORE NOON IN POCKET OF HEAVIER PCPN. DONT
THINK THIS WILL LAST LONG UNLIKE LAST EVE.


&&

.SHORT TERM...(TODAY THROUGH FRIDAY)
ISSUED AT 330 AM CDT THU APR 24 2014

MANY CHALLENGES THROUGH THE SHORT AND INTO THE LONG TERM AS ACTIVE
AND AT TIMES COMPLEX PATTERN CONTINUES. CONSIDERING ACTIVE PATTERN
MODELS IN PRETTY GOOD AGREEMENT.

INTERESTING DAY AHEAD WITH TEMPERATURES...RAIN...THUNDERSTORM AND
ACCUMULATING SNOW POTENTIAL ALL CONTRIBUTING TO CHALLENGING
FORECAST. SUBSIDENCE IN THE WAKE OF SHORTWAVE LIFTING INTO CANADA
HAS DIMINISHED SHOWERS IN THE NEAR TERM. HOWEVER ELEVATED BOUNDARY
OVER THE CENTRAL DAKOTAS WILL PROPAGATE EAST ACROSS FA ALONG WITH
BAND OF FRONTOGENETIC FORCING AND WARM ADVECTION. GLOBAL AND
MESOSCALE MODELS ALL SUPPORT SHOWERS BECOMING MORE ORGANIZED FROM
VALLEY EAST THIS MORNING. PCPN AREA WILL THEN SHIFT EAST MAINLY ACROSS
WESTERN MN. IN THE WAKE OF THIS ELEVATED TROUGH DRYING WILL MOVE
INTO AREAS MAINLY WEST OF THE VALLEY AND COULD SEE SOME SOLAR
THERE WHICH WOULD HELP BOOST TEMPERATURES CLOSE TO AVERAGE WHERE
AREAS IN THE RAIN WILL LIKELY HOLD IN THE 40S. IN THE MEAN TIME
UPPER LOW AND ASSOCIATED COLD POOL WILL PROPAGATE SE REACHING FA
AT PRIME HEATING. WITH COLD POOL WILL SEE SOME PRETTY STEEP LAPSE
RATES ALONG WITH SUFFICIENT INSTABILITY AND AROUND 400J/KG OF
MIXED LAYER CAPE. ASSOCIATED SURFACE LOW WILL ALSO BE OVER FA AT
SAME TIME PROVIDING LOW LEVEL CONVERGENCE. SO EVEN WITH DRYING
ALLOWING PRECIPITABLE H2O VALUES TO DROP TO AROUND A HALF INCH
THERE WILL BE POTENTIAL FOR THUNDERSTORM DEVELOPMENT. WITH UPPER
AND SURFACE LOW OVER FA CANNOT RULE OUT POTENTIAL FOR A FEW SPIN-
UPS UNDER STRONGER STORMS.

TONIGHT COULD CONTINUE TO SEE SOME SPOTTY CONVECTION MAINLY EITHER
SIDE OF THE VALLEY UNTIL LOSS OF HEATING. BEST LIFT TONIGHT WILL
BE ACROSS THE FAR NE AHEAD OF SHARP SHEAR AXIS. WITH COLUMN COLD
ENOUGH WILL NEED TO MONITOR THE LAKE OF THE WOODS REGION FOR SOME
ACCUMULATING SNOW.

FRIDAY SHOULD BE RELATIVELY QUIET WITH ANY PCPN CONFINED TO THE NE
FA CLOSER TO DEPARTING SURFACE BOUNDARY. MODELS IN DISAGREEMENT ON
HOW FAR SOUTH COLDER AIR WILL SPREAD WITH GFS THE COLDEST. AT ANY
RATE LOOKS TO BE A RESPECTABLE NE-SW ORIENTED THERMAL GRADIENT
ACROSS THE FA WHICH WILL MAKE THE TEMPERATURE FORECAST TRICKY.

.LONG TERM...(FRIDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 330 AM CDT THU APR 24 2014

ON SATURDAY BAND OF WARM ADVECTION LIFTS NORTH THROUGH THE WESTERN
FA AS NEXT AREA OF LOW PRESSURE ORGANIZES OVER THE CENTRAL HIGH
PLAINS. WITH GOOD MODEL AGREEMENT INCREASE POPS ACROSS THE WEST.

SURFACE LOW DEEPENS SATURDAY NIGHT OVER CENTRAL HIGH PLAINS AS
NEXT UPPER LOW CROSSES THE CENTRAL ROCKIES. WILL MAINTAIN CURRENT
POPS AS BROAD AREA OF ISENTROPIC LIFT AND LOWERING CONDENSATION
PRESSURE DEFICITS SETS UP.

SUNDAY-WEDNESDAY...HIGH LATITUDE BLOCKING WILL SET UP OVER EASTERN
CANADA...WITH AN INTENSE UPPER WAVE EXPECTED TO LIFT INTO THE
CENTRAL HIGH PLAINS ON SUNDAY BEFORE SLOWLY MEANDERING INTO THE
UPPER MISSISSIPPI VALLEY/GREAT LAKES FOR MID-WEEK. A MAIN SOURCE OF
UNCERTAINTY IS THE DETAILS OF THE EVOLUTION OF THE UPPER LOW AND
DOWNSTREAM RIDGE. MODELS SUGGEST DEEP RELATIVELY MOIST
SOUTH/SOUTHEAST FLOW UPSTREAM FROM THE RIDGE AXIS INTO THE NORTHERN
PLAINS WILL HELP TO PROMOTE WIDESPREAD PRECIPITATION IN THIS REGION
INTO EARLY NEXT WEEK...WITH DRIER AIR ASSOCIATED WITH SFC HIGH
PRESSURE OVER EASTERN CANADA POTENTIALLY INHIBITING PRECIP FARTHER
EAST FOR AT LEAST SOME TIME PERIOD...ESPECIALLY IF THE AMPLIFIED
UPPER RIDGE ENDS UP DISPLACED SLIGHTLY WEST. THERMAL FIELDS VARY
SOMEWHAT AMONG MODELS...BUT KEPT THE IDEA OF PRIMARILY RAIN DURING
THE DAYTIME HOURS WITH PERHAPS SOME MIXED SNOW AT NIGHT. TEMPS ARE
GENERALLY EXPECTED TO REMAIN ON THE COOL SIDE THROUGH THE PERIOD.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 111 PM  CDT THU APR 24 2014

EXPECT LINGERING IFR CIGS AT GFK...BJI AND TVF TO SLOWLY RISE TO
MVFR CIGS THIS EARLY AFTN. EXPECT PREDOMINANT CONDS THROUGH
TOMORROW MORNING TO BE MVFR CIGS WITH SOME FLUCTUATIONS UP OR
DOWN. LOW CONFIDENCE THE CLEARING WE ARE SEEING AT FAR WILL REACH
GFK AND CERTAINLY NOT OUR MN TAF SITES. DVL...WHICH IS
CLEAR...SHOULD CU UP AND SEE A THREAT FOR TSTMS ACTIVITY THIS
AFTN. WITH FAR STILL OVC...DO NOT EXPECT CLEARING WILL ALLOW IT TO
HEAT SUFFICIENTLY FOR TSTMS TO GENERATE ALTHOUGH STORMS COULD
ADVECT IN FROM WEST. WILL NOT MENTION TS AT FAR AT THIS TIME.


&&

.FGF WATCHES/WARNINGS/ADVISORIES...
ND...NONE.
MN...NONE.
&&

$$

UPDATE...RIDDLE
SHORT TERM...VOELKER
LONG TERM...MAKOWSKI/VOELKER
AVIATION...SPEICHER






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